css-fonts/Fonts.html

Mon, 08 Jul 2013 14:54:37 +0900

author
John Daggett <jdaggett@mozilla.com>
date
Mon, 08 Jul 2013 14:54:37 +0900
changeset 8654
aad9d3a5502b
parent 8653
cf5a35e610f8
child 8655
ab973f06eb50
permissions
-rw-r--r--

[css3-fonts] more map class wording tweaks

     1 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN"
     2 "http://www.w3.org/TR/html4/strict.dtd">
     4 <html lang=en>
     5  <head><meta content="text/html;charset=utf-8" http-equiv=Content-Type>
     7   <title>CSS Fonts Module Level 3</title>
     8   <!--
     9       FIXME when publishing: copy the current default.css and link to
    10       "default.css" rather than "../default.css"
    11    -->
    12   <link href="../default.css" rel=stylesheet type="text/css">
    13   <link href="../csslogo.ico" rel="shortcut icon" type="image/x-icon">
    14   <!-- I'm just experimenting here, don't get your bee in a bonnet -->
    15   <script src="http://use.typekit.com/xon2bky.js"
    16   type="text/javascript"></script>
    17   <script type="text/javascript">try{Typekit.load();}catch(e){}</script>
    19   <style type="text/css">
    21   body, th, td, h1, h2, h3, h4, h5, h6 {
    22     font-family: "myriad-pro", sans-serif !important;
    23   }
    25   body {
    26     padding: 2em 70px 2em 70px;
    27   }
    29   p + p, p.mtb {
    30     margin-top: 0.8em;
    31     text-indent: 0px;
    32   }
    34   #bolderlighter {
    35     width: 40%;
    36   }
    38   #bolderlighter th {
    39     text-align: center;
    40   }
    42   #fontformats td, #eventhandlers td, #fontformats th, #eventhandlers th {
    43     padding-right: 2em;
    44     text-align: left;
    45   }
    47   dd {
    48     margin-bottom: 1em;
    49   }
    51   #authors dd {
    52     margin-bottom: 0;
    53   }
    55   #fontstylematchingalg {
    56     list-style-type: lower-alpha;
    57   }
    59   #fontmatchingalg ul, #fontmatchingalg ol {
    60     margin-top: 0.8em;
    61   }
    63   #fontmatchingalg li + li {
    64     margin-top: 0.8em;
    65   }
    67   div.example {
    68     padding: 1em;
    69     margin-top: 1em;
    70   }
    72   div.example + div.example {
    73     margin-top: 2em;
    74   }
    76   div.figure {
    77     page-break-inside: avoid;
    78   }
    80   pre.prod { white-space: pre-wrap; margin: 1em 0 1em 2em }
    82   div.featex {
    83     width: 700px;
    84   }
    86   div.featex img {
    87     margin: auto;
    88     display: block;
    89   }
    91   span.tag {
    92     font-family: monospace;
    93     font-size: 120%;
    94   }
    96   ol ol {
    97     list-style-type: lower-alpha;
    98   }
   100   .idl-code {
   101     font-weight: bold;
   102     color: #c50;
   103   }
   104   </style>
   105   <link href="http://www.w3.org/StyleSheets/TR/W3C-ED.css" rel=stylesheet
   106   type="text/css">
   107   <script defer=defer
   108   src="http://test.csswg.org/harness/annotate.js#CSS3-FONTS_DEV"
   109   type="text/javascript"></script>
   111  <body>
   112   <div class=head> <!--begin-logo-->
   113    <p><a href="http://www.w3.org/"><img alt=W3C height=48
   114     src="http://www.w3.org/Icons/w3c_home" width=72></a> <!--end-logo-->
   116    <h1>CSS Fonts Module Level 3</h1>
   118    <h2 class="no-num no-toc" id=editors-draft-8-july-2013>Editor's Draft 8
   119     July 2013</h2>
   121    <dl id=authors>
   122     <dt>This version:
   124     <dd><a
   125      href="http://dev.w3.org/csswg/css-fonts/">http://dev.w3.org/csswg/css-fonts/</a>
   126      <!-- <dd><a href="http://www.w3.org/TR/2013/ED-css-fonts-3-20130708/">http://www.w3.org/TR/2013/ED-css-fonts-3-20130708/</a> -->
   129     <dt>Latest version:
   131     <dd><a
   132      href="http://www.w3.org/TR/css3-fonts/">http://www.w3.org/TR/css-fonts-3/</a>
   134     <dt>Latest editor's draft:
   136     <dd><a
   137      href="http://dev.w3.org/csswg/css-fonts/">http://dev.w3.org/csswg/css-fonts/</a>
   138      (<a
   139      href="https://dvcs.w3.org/hg/csswg/log/tip/css-fonts/Fonts.html">change
   140      log</a>)
   142     <dt>Previous version:
   144     <dd><a
   145      href="http://www.w3.org/TR/2013/WD-css3-fonts-20130212/">http://www.w3.org/TR/2013/WD-css3-fonts-20130212/</a>
   147     <dt>Issues List:
   149     <dd><a href="http://www.w3.org/Style/CSS/Tracker/products/18">CSS3 Fonts
   150      issues in Tracker</a>
   152     <dd><a
   153      href="https://www.w3.org/Bugs/Public/buglist.cgi?query_format=advanced&amp;product=CSS&amp;component=Fonts&amp;bug_status=NEW&amp;bug_status=ASSIGNED&amp;bug_status=REOPENED">CSS3
   154      Fonts issues in Bugzilla</a>
   156     <dt>Discussion:
   158     <dd><a
   159      href="mailto:www-style@w3.org?subject=%5Bcss-fonts%5D%20feedback">www-style@w3.org</a>
   160      with subject line “<kbd>[css-fonts] <var>… message topic
   161      …</var></kbd>” (<a
   162      href="http://lists.w3.org/Archives/Public/www-style/"
   163      rel=discussion>archives</a>)
   165     <dt>Editor:
   167     <dd><a href="mailto:jdaggett@mozilla.com">John Daggett (Mozilla)</a>
   168    </dl>
   169    <!--begin-copyright-->
   170    <p class=copyright><a
   171     href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright"
   172     rel=license>Copyright</a> © 2013 <a href="http://www.w3.org/"><abbr
   173     title="World Wide Web Consortium">W3C</abbr></a><sup>®</sup> (<a
   174     href="http://www.csail.mit.edu/"><abbr title="Massachusetts Institute of
   175     Technology">MIT</abbr></a>, <a href="http://www.ercim.eu/"><abbr
   176     title="European Research Consortium for Informatics and
   177     Mathematics">ERCIM</abbr></a>, <a href="http://www.keio.ac.jp/">Keio</a>,
   178     <a href="http://ev.buaa.edu.cn/">Beihang</a>), All Rights Reserved. W3C
   179     <a
   180     href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>,
   181     <a
   182     href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a>
   183     and <a
   184     href="http://www.w3.org/Consortium/Legal/copyright-documents">document
   185     use</a> rules apply.</p>
   186    <!--end-copyright-->
   187    <hr title="Separator for header">
   188   </div>
   190   <h2 class="no-num no-toc" id=abstract>Abstract</h2>
   192   <p>This CSS3 module describes how font properties are specified and how
   193    font resources are loaded dynamically. The contents of this specification
   194    are a consolidation of content previously divided into <a
   195    href="http://www.w3.org/TR/2002/WD-css3-fonts-20020802/">CSS3 Fonts</a>
   196    and <a href="http://www.w3.org/TR/2002/WD-css3-webfonts-20020802/">CSS3
   197    Web Fonts</a> modules. The description of font load events was moved into
   198    the <a href="http://dev.w3.org/csswg/css-font-load-events/">CSS3 Font Load
   199    Events</a> module.
   201   <h2 class="no-num no-toc" id=status>Status of this document</h2>
   202   <!--begin-status-->
   204   <p>This is a public copy of the editors' draft. It is provided for
   205    discussion only and may change at any moment. Its publication here does
   206    not imply endorsement of its contents by W3C. Don't cite this document
   207    other than as work in progress.
   209   <p>The (<a
   210    href="http://lists.w3.org/Archives/Public/www-style/">archived</a>) public
   211    mailing list <a
   212    href="mailto:www-style@w3.org?Subject=%5Bcss3-fonts%5D%20PUT%20SUBJECT%20HERE">
   213    www-style@w3.org</a> (see <a
   214    href="http://www.w3.org/Mail/Request">instructions</a>) is preferred for
   215    discussion of this specification. When sending e-mail, please put the text
   216    “css3-fonts” in the subject, preferably like this:
   217    “[<!---->css3-fonts<!---->] <em>…summary of comment…</em>”
   219   <p>This document was produced by the <a
   220    href="http://www.w3.org/Style/CSS/members">CSS Working Group</a> (part of
   221    the <a href="http://www.w3.org/Style/">Style Activity</a>).
   223   <p>This document was produced by a group operating under the <a
   224    href="http://www.w3.org/Consortium/Patent-Policy-20040205/">5 February
   225    2004 W3C Patent Policy</a>. W3C maintains a <a
   226    href="http://www.w3.org/2004/01/pp-impl/32061/status"
   227    rel=disclosure>public list of any patent disclosures</a> made in
   228    connection with the deliverables of the group; that page also includes
   229    instructions for disclosing a patent. An individual who has actual
   230    knowledge of a patent which the individual believes contains <a
   231    href="http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">Essential
   232    Claim(s)</a> must disclose the information in accordance with <a
   233    href="http://www.w3.org/Consortium/Patent-Policy-20040205/#sec-Disclosure">section
   234    6 of the W3C Patent Policy</a>.</p>
   235   <!--end-status-->
   237   <h3 class="no-num no-toc" id=atrisk>Features at risk</h3>
   239   <p>The following features are at risk and may be removed when exiting CR:
   241   <ul>
   242    <li>fallback handling for text decoration in superscript/subscript variant
   243     glyphs (‘<a href="#propdef-font-variant-position"><code
   244     class=property>font-variant-position</code></a>’)
   246    <li>‘<a href="#propdef-font-language-override"><code
   247     class=property>font-language-override</code></a>’ property
   248   </ul>
   250   <p>This draft is a <strong>Last Call Working Draft</strong>. Please send
   251    comments to the <a
   252    href="http://lists.w3.org/Archives/Public/www-style/">www-style mailing
   253    list</a> as described above. The <strong>deadline for comments</strong> is
   254    six weeks after the date of publication in the header, 22 August 2013.
   256   <h2 class="no-num no-toc" id=contents>Table of contents</h2>
   257   <!--begin-toc-->
   259   <ul class=toc>
   260    <li><a href="#introduction"><span class=secno>1 </span>Introduction</a>
   262    <li><a href="#typography-background"><span class=secno>2 </span>Typography
   263     Background</a>
   265    <li><a href="#basic-font-props"><span class=secno>3 </span>Basic Font
   266     Properties</a>
   267     <ul class=toc>
   268      <li><a href="#font-family-prop"><span class=secno>3.1 </span>Font
   269       family: the font-family property</a>
   270       <ul class=toc>
   271        <li><a href="#generic-font-families"><span class=secno>3.1.1
   272         </span>Generic font families</a>
   273       </ul>
   275      <li><a href="#font-weight-prop"><span class=secno>3.2 </span>Font
   276       weight: the font-weight property</a>
   278      <li><a href="#font-stretch-prop"><span class=secno>3.3 </span>Font
   279       width: the font-stretch property</a>
   281      <li><a href="#font-style-prop"><span class=secno>3.4 </span>Font style:
   282       the font-style property</a>
   284      <li><a href="#font-size-prop"><span class=secno>3.5 </span>Font size:
   285       the font-size property</a>
   287      <li><a href="#font-size-adjust-prop"><span class=secno>3.6
   288       </span>Relative sizing: the font-size-adjust property</a>
   290      <li><a href="#font-prop"><span class=secno>3.7 </span>Shorthand font
   291       property: the font property</a>
   293      <li><a href="#font-synthesis-prop"><span class=secno>3.8
   294       </span>Controlling synthetic faces: the font-synthesis property</a>
   295     </ul>
   297    <li><a href="#font-resources"><span class=secno>4 </span>Font
   298     Resources</a>
   299     <ul class=toc>
   300      <li><a href="#font-face-rule"><span class=secno>4.1 </span>The
   301       <code>@font-face</code> rule</a>
   303      <li><a href="#font-family-desc"><span class=secno>4.2 </span>Font
   304       family: the font-family descriptor</a>
   306      <li><a href="#src-desc"><span class=secno>4.3 </span>Font reference: the
   307       src descriptor</a>
   309      <li><a href="#font-prop-desc"><span class=secno>4.4 </span>Font property
   310       descriptors: the font-style, font-weight, font-stretch descriptors</a>
   312      <li><a href="#unicode-range-desc"><span class=secno>4.5 </span>Character
   313       range: the unicode-range descriptor</a>
   315      <li><a href="#composite-fonts"><span class=secno>4.6 </span>Using
   316       character ranges to define composite fonts</a>
   318      <li><a href="#font-rend-desc"><span class=secno>4.7 </span>Font
   319       features: the font-variant and font-feature-settings descriptors</a>
   321      <li><a href="#font-face-loading"><span class=secno>4.8 </span>Font
   322       loading guidelines</a>
   324      <li><a href="#same-origin-restriction"><span class=secno>4.9
   325       </span>Same-origin restriction for fonts</a>
   326       <ul class=toc>
   327        <li><a href="#default-same-origin-restriction"><span class=secno>4.9.1
   328         </span>Default same-origin restriction</a>
   330        <li><a href="#allowing-cross-origin-font-loading"><span
   331         class=secno>4.9.2 </span>Allowing cross-origin font loading</a>
   332       </ul>
   333     </ul>
   335    <li><a href="#font-matching-algorithm"><span class=secno>5 </span>Font
   336     Matching Algorithm</a>
   337     <ul class=toc>
   338      <li><a href="#font-family-casing"><span class=secno>5.1 </span>Case
   339       sensitivity of font family names</a>
   341      <li><a href="#font-style-matching"><span class=secno>5.2 </span>Matching
   342       font styles</a>
   344      <li><a href="#cluster-matching"><span class=secno>5.3 </span>Cluster
   345       matching</a>
   347      <li><a href="#char-handling-issues"><span class=secno>5.4
   348       </span>Character handling issues</a>
   350      <li><a href="#font-matching-changes"><span class=secno>5.5 </span>Font
   351       matching changes since CSS 2.1</a>
   353      <li><a href="#font-matching-examples"><span class=secno>5.6 </span>Font
   354       matching examples</a>
   355     </ul>
   357    <li><a href="#font-rend-props"><span class=secno>6 </span>Font Feature
   358     Properties</a>
   359     <ul class=toc>
   360      <li><a href="#glyph-selection-positioning"><span class=secno>6.1
   361       </span>Glyph selection and positioning</a>
   363      <li><a href="#language-specific-support"><span class=secno>6.2
   364       </span>Language-specific display</a>
   366      <li><a href="#font-kerning-prop"><span class=secno>6.3 </span>Kerning:
   367       the font-kerning property</a>
   369      <li><a href="#font-variant-ligatures-prop"><span class=secno>6.4
   370       </span>Ligatures: the font-variant-ligatures property</a>
   372      <li><a href="#font-variant-position-prop"><span class=secno>6.5
   373       </span>Subscript and superscript forms: the font-variant-position
   374       property</a>
   376      <li><a href="#font-variant-caps-prop"><span class=secno>6.6
   377       </span>Capitalization: the font-variant-caps property</a>
   379      <li><a href="#font-variant-numeric-prop"><span class=secno>6.7
   380       </span>Numerical formatting: the font-variant-numeric property</a>
   382      <li><a href="#font-variant-alternates-prop"><span class=secno>6.8
   383       </span>Alternates and swashes: the font-variant-alternates property</a>
   386      <li><a href="#font-feature-values"><span class=secno>6.9 </span>Defining
   387       font specific alternates: the <code>@font-feature-values</code>
   388       rule</a>
   389       <ul class=toc>
   390        <li><a href="#basic-syntax"><span class=secno>6.9.1 </span>Basic
   391         syntax</a>
   393        <li><a href="#multi-valued-feature-value-definitions"><span
   394         class=secno>6.9.2 </span>Multi-valued feature value definitions</a>
   395       </ul>
   397      <li><a href="#font-variant-east-asian-prop"><span class=secno>6.10
   398       </span>East Asian text rendering: the font-variant-east-asian
   399       property</a>
   401      <li><a href="#font-variant-prop"><span class=secno>6.11 </span>Overall
   402       shorthand for font rendering: the font-variant property</a>
   404      <li><a href="#font-feature-settings-prop"><span class=secno>6.12
   405       </span>Low-level font feature settings control: the
   406       font-feature-settings property</a>
   408      <li><a href="#font-language-override-prop"><span class=secno>6.13
   409       </span>Font language override: the font-language-override property</a>
   410     </ul>
   412    <li><a href="#font-feature-resolution"><span class=secno>7 </span>Font
   413     Feature Resolution </a>
   414     <ul class=toc>
   415      <li><a href="#default-features"><span class=secno>7.1 </span>Default
   416       features</a>
   418      <li><a href="#feature-precedence"><span class=secno>7.2 </span>Feature
   419       precedence</a>
   421      <li><a href="#feature-precedence-examples"><span class=secno>7.3
   422       </span>Feature precedence examples</a>
   423     </ul>
   425    <li><a href="#object-model"><span class=secno>8 </span>Object Model</a>
   426     <ul class=toc>
   427      <li><a href="#om-fontface"><span class=secno>8.1 </span>The
   428       <code>CSSFontFaceRule</code> interface</a>
   430      <li><a href="#om-fontfeaturevalues"><span class=secno>8.2 </span>The
   431       <code>CSSFontFeatureValuesRule</code> interface</a>
   432     </ul>
   434    <li class=no-num><a href="#platform-props-to-css">Appendix A: Mapping
   435     platform font properties to CSS properties</a>
   437    <li class=no-num><a href="#ch-ch-ch-changes">Changes</a>
   438     <ul class=toc>
   439      <li class=no-num><a href="#recent-changes"> Changes from the February
   440       2013 CSS3 Fonts Working Draft</a>
   441     </ul>
   443    <li class=no-num><a href="#acknowledgments">Acknowledgments</a>
   445    <li class=no-num><a href="#conformance"> Conformance</a>
   446     <ul class=toc>
   447      <li class=no-num><a href="#conventions"> Document Conventions</a>
   449      <li class=no-num><a href="#conformance-classes"> Conformance Classes</a>
   452      <li class=no-num><a href="#partial"> Partial Implementations</a>
   454      <li class=no-num><a href="#experimental"> Experimental
   455       Implementations</a>
   457      <li class=no-num><a href="#testing"> Non-Experimental
   458       Implementations</a>
   459     </ul>
   461    <li class=no-num><a href="#references">References</a>
   462     <ul class=toc>
   463      <li class=no-num><a href="#normative-references">Normative
   464       References</a>
   466      <li class=no-num><a href="#other-references">Other References</a>
   467     </ul>
   469    <li class=no-num><a href="#index">Index</a>
   471    <li class=no-num><a href="#property-index">Property index</a>
   472   </ul>
   473   <!--end-toc-->
   475   <h2 id=introduction><span class=secno>1 </span>Introduction</h2>
   477   <p>A font provides a resource containing the visual representation of
   478    characters. At the simplest level it contains information that maps
   479    character codes to shapes (called glyphs) that represent these characters.
   480    Fonts sharing a common design style are commonly grouped into font
   481    families classified by a set of standard font properties. Within a family,
   482    the shape displayed for a given character can vary by stroke weight, slant
   483    or relative width, among others. An individual font face is described by a
   484    unique combination of these properties. For a given range of text, CSS
   485    font properties are used to select a font family and a specific font face
   486    within that family to be used when rendering that text. As a simple
   487    example, to use the bold form of Helvetica one could use:
   489   <pre>body {
   490     font-family: Helvetica;
   491     font-weight: bold;
   492 }</pre>
   494   <p>Font resources may be installed locally on the system on which a user
   495    agent is running or downloadable. For local font resources descriptive
   496    information can be obtained directly from the font resource. For
   497    downloadable font resources (sometimes referred to as web fonts), the
   498    descriptive information is included with the reference to the font
   499    resource.
   501   <p>Families of fonts typically don't contain a single face for each
   502    possible variation of font properties. The CSS font selection mechanism
   503    describes how to match a given set of CSS font properties to a single font
   504    face.
   506   <h2 id=typography-background><span class=secno>2 </span>Typography
   507    Background</h2>
   509   <p><em>This section is non-normative.</em>
   511   <p> Typographic traditions vary across the globe, so there is no unique way
   512    to classify all fonts across languages and cultures. For even common Latin
   513    letters, wide variations are possible:
   515   <div class=figure><img alt="variations in glyphs for a single character"
   516    src=aaaaaa.png>
   517    <p class=caption>One character, many glyph variations
   518   </div>
   520   <p>Differences in the anatomy of letterforms is one way to distinguish
   521    fonts. For Latin fonts, flourishes at the ends of a character's main
   522    strokes, or serifs, can distinguish a font from those without. Similar
   523    comparisons exist in non-Latin fonts between fonts with tapered strokes
   524    and those using primarily uniform strokes:
   526   <div class=figure><img alt="serif vs. non-serifs" src=serifvssansserif.png>
   527    <p class=caption>Letterforms with and without serifs
   528   </div>
   530   <div class=figure><img alt="serif vs. non-serifs for japanese"
   531    src=minchovsgothic.png>
   532    <p class=caption>Similar groupings for Japanese typefaces
   533   </div>
   535   <p>Fonts contain letterforms and the data needed to map characters to these
   536    letterforms. Often this may be a simple one-to-one mapping, but more
   537    complex mappings are also possible. The use of combining diacritic marks
   538    creates many variations for an underlying letterform:
   540   <div class=figure><img alt="diacritic marks" src=aaaaaa-diacritics.png>
   541    <p class=caption>Variations with diacritic marks
   542   </div>
   544   <p>A sequence of characters can be represented by a single glyph known as a
   545    ligature:
   547   <div class=figure><img alt="example of a fi ligature"
   548    src=final-ligature.png>
   549    <p class=caption>Ligature example
   550   </div>
   552   <p>Visual transformations based on textual context are often stylistic
   553    option in European languages. They are required to correctly render
   554    languages like Arabic, the lam and alef characters below <em>must</em> be
   555    combined when they exist in sequence:
   557   <div class=figure><img alt="lam alef ligature" src=lamaleflig.png>
   558    <p class=caption>Required Arabic ligature
   559   </div>
   561   <p>The relative complexity of these shaping transformations requires
   562    additional data within the font.
   564   <p>Sets of font faces with various stylistic variations are often grouped
   565    together into font families. In the simplest case a regular face is
   566    supplemented with bold and italic faces, but much more extensive groupings
   567    are possible. Variations in the thickness of letterform strokes, the <dfn
   568    id=weight>weight</dfn>, and the overall proportions of the letterform, the
   569    <dfn id=width>width</dfn>, are most common. In the example below, each
   570    letter uses a different font face within the Univers font family. The
   571    width used increases from top to bottom and the weight increases from left
   572    to right:
   574   <div class=figure><img alt="various width and weight variations within a
   575    single family" src=weightwidthvariations.png>
   576    <p class=caption>Weight and width variations within a single font family
   577   </div>
   579   <p>Creating fonts that support multiple scripts is a difficult task;
   580    designers need to understand the cultural traditions surrounding the use
   581    of type in different scripts and come up with letterforms that somehow
   582    share a common theme. Many languages often share a common script and each
   583    of these languages may have noticeable stylistic differences. For example,
   584    the Arabic script is shared by Persian and Urdu and Cyrillic is used with
   585    many languages, not just Russian.
   587   <p>The <a href="#character-map"><em>character map</em></a> of a font
   588    defines the mapping of characters to glyphs for that font. If a document
   589    contains characters not supported by the <a href="#character-map"><em
   590    title="character map">character maps</em></a> of the fonts contained in a
   591    font family list, a user agent may use a <a
   592    href="#system-font-fallback"><em>system font fallback</em></a> procedure
   593    to locate an appropriate font that does. If no appropriate font can be
   594    found, some form of "missing glyph" character will be rendered by the user
   595    agent. System fallback can occur when the specified list of font families
   596    does not include a font that supports a given character.
   598   <p>Although the <a href="#character-map"><em>character map</em></a> of a
   599    font maps a given character to a glyph for that character, modern font
   600    technologies such as OpenType and AAT (Apple Advanced Typography) provide
   601    ways of mapping a character to different glyphs based upon feature
   602    settings. Fonts in these formats allow these features to be embedded in
   603    the font itself and controlled by applications. Common typographic
   604    features which can be specified this way include ligatures, swashes,
   605    contextual alternates, proportional and tabular figures, and automatic
   606    fractions, to list just a few. For a visual overview of OpenType features,
   607    see the <a href="#OPENTYPE-FONT-GUIDE"
   608    rel=biblioentry>[OPENTYPE-FONT-GUIDE]<!--{{OPENTYPE-FONT-GUIDE}}--></a>.
   610   <h2 id=basic-font-props><span class=secno>3 </span>Basic Font Properties</h2>
   612   <p>The particular font face used to render a character is determined by the
   613    font family and other font properties that apply to a given element. This
   614    structure allows settings to be varied independent of each other.</p>
   615   <!-- prop: font-family -->
   617   <h3 id=font-family-prop><span class=secno>3.1 </span>Font family: the <a
   618    href="#propdef-font-family">font-family</a> property</h3>
   620   <table class=propdef id=namefont-familyvalue-ltfamily-namegt-ltg>
   621    <tbody>
   622     <tr>
   623      <td>Name:
   625      <td><dfn id=propdef-font-family
   626       title="font-family!!property">font-family</dfn>
   628     <tr>
   629      <td>Value:
   631      <td>[ <a href="#family-name-value"><var>&lt;family-name&gt;</var></a> |
   632       <a href="#generic-family-value"><var>&lt;generic-family&gt;</var></a> ]
   633       #
   635     <tr>
   636      <td>Initial:
   638      <td>depends on user agent
   640     <tr>
   641      <td>Applies to:
   643      <td>all elements
   645     <tr>
   646      <td>Inherited:
   648      <td>yes
   650     <tr>
   651      <td>Percentages:
   653      <td>N/A
   655     <tr>
   656      <td>Media:
   658      <td>visual
   660     <tr>
   661      <td>Computed value:
   663      <td>as specified
   665     <tr>
   666      <td>Animatable:
   668      <td>no
   669   </table>
   671   <p>This property specifies a prioritized list of font family names or
   672    generic family names. A font family defines a set of faces that vary in
   673    weight, width or slope. CSS uses the combination of a family name with
   674    other style attributes to select an individual face. Using this selection
   675    mechanism, rather than selecting a face via the style name as is often
   676    done in design applications, allows some degree of regularity in textual
   677    display when fallback occurs.
   679   <p class=note>Designers should note that the CSS definition of font
   680    attributes used for selection are explicitly not intended to define a font
   681    taxonomy. A type designer's idea of a family may often extend to a set of
   682    faces that vary along axes other than just the standard axes of weight,
   683    width and slope. A family may extend to include both a set of serif faces
   684    and a set of sans-serif faces or vary along axes that are unique to that
   685    family. The CSS font selection mechanism merely provides a way to
   686    determine the “closest” substitute when substitution is necessary.
   688   <p>Unlike other CSS properties, component values are a comma-separated list
   689    indicating alternatives. A user agent iterates through the list of family
   690    names until it matches an available font that contains a glyph for the
   691    character to be rendered. This allows for differences in available fonts
   692    across platforms and for differences in the range of characters supported
   693    by individual fonts.
   695   <p>A font family name only specifies a name given to a set of font faces,
   696    it does not specify an individual face. For example, given the
   697    availability of the fonts below, Futura would match but Futura Medium
   698    would not:
   700   <div class=figure><img alt="family and face names"
   701    src=familyvsfacename.png>
   702    <p class=caption>Family and individual face names
   703   </div>
   705   <p>Consider the example below:
   707   <div class=example>
   708    <pre>body {
   709     font-family: Helvetica, Verdana, sans-serif;
   710 }</pre>
   712    <p>If Helvetica is available it will be used when rendering. If neither
   713     Helvetica nor Verdana is present, then the user-agent-defined sans serif
   714     font will be used.</p>
   715   </div>
   717   <p>There are two types of font family names:
   719   <dl>
   720    <dt><dfn id=family-name-value><var>&lt;family-name&gt;</var></dfn>
   722    <dd>The name of a font family of choice such as Helvetica or Verdana in
   723     the previous example.
   725    <dt><dfn id=generic-family-value><var>&lt;generic-family&gt;</var></dfn>
   727    <dd> The following generic family keywords are defined: ‘<a
   728     href="#serif"><code class=property>serif</code></a>’, ‘<a
   729     href="#sans-serif"><code class=property>sans-serif</code></a>’, ‘<a
   730     href="#cursive"><code class=property>cursive</code></a>’, ‘<a
   731     href="#fantasy"><code class=property>fantasy</code></a>’, and ‘<a
   732     href="#monospace"><code class=property>monospace</code></a>’. These
   733     keywords can be used as a general fallback mechanism when an author's
   734     desired font choices are not available. As keywords, they must not be
   735     quoted. Authors are encouraged to append a generic font family as a last
   736     alternative for improved robustness.
   737   </dl>
   739   <p>Font family names other than generic families must either be given
   740    quoted as <a
   741    href="//www.w3.org/TR/CSS21/syndata.html#strings">strings,</a> or unquoted
   742    as a sequence of one or more <a
   743    href="//www.w3.org/TR/CSS21/syndata.html#value-def-identifier">identifiers.</a>
   744    This means most punctuation characters and digits at the start of each
   745    token must be escaped in unquoted font family names.
   747   <p>To illustrate this, the following declarations are invalid:
   749   <pre>
   750 font-family: Red/Black, sans-serif;
   751 font-family: "Lucida" Grande, sans-serif;
   752 font-family: Ahem!, sans-serif;
   753 font-family: test@foo, sans-serif;
   754 font-family: #POUND, sans-serif;
   755 font-family: Hawaii 5-0, sans-serif;
   756 </pre>
   758   <p>If a sequence of identifiers is given as a font family name, the
   759    computed value is the name converted to a string by joining all the
   760    identifiers in the sequence by single spaces.
   762   <p>To avoid mistakes in escaping, it is recommended to quote font family
   763    names that contain white space, digits, or punctuation characters other
   764    than hyphens:
   766   <pre>
   767 body { font-family: "New Century Schoolbook", serif }
   769 &lt;BODY STYLE="font-family: '21st Century', fantasy">
   770 </pre>
   772   <p>Font family <em>names</em> that happen to be the same as a keyword value
   773    (‘<code class=property>inherit</code>’, ‘<a href="#serif"><code
   774    class=property>serif</code></a>’, ‘<a href="#sans-serif"><code
   775    class=property>sans-serif</code></a>’, ‘<a href="#monospace"><code
   776    class=property>monospace</code></a>’, ‘<a href="#fantasy"><code
   777    class=property>fantasy</code></a>’, and ‘<a href="#cursive"><code
   778    class=property>cursive</code></a>’) must be quoted to prevent confusion
   779    with the keywords with the same names. The keywords ‘<code
   780    class=property>initial</code>’ and ‘<code
   781    class=property>default</code>’ are reserved for future use and must also
   782    be quoted when used as font names. UAs must not consider these keywords as
   783    matching the <a
   784    href="#family-name-value"><var>&lt;family-name&gt;</var></a> type.
   786   <p>The precise way a set of fonts are grouped into font families varies
   787    depending upon the platform font management API's. The Windows GDI API
   788    only allows four faces to be grouped into a family while the DirectWrite
   789    API and API's on OSX and other platforms support font families with a
   790    variety of weights, widths and slopes (see <a
   791    href="#platform-props-to-css">Appendix A</a> for more details).
   793   <p>Some font formats allow fonts to carry multiple localizations of the
   794    family name. User agents must recognize and correctly match all of these
   795    names independent of the underlying platform localization, system API used
   796    or document encoding:
   798   <div class=figure><img alt="examples of localized family names"
   799    src=localizedfamilynames.png>
   800    <p class=caption>Localized family names
   801   </div>
   803   <h4 id=generic-font-families><span class=secno>3.1.1 </span>Generic font
   804    families</h4>
   806   <p>All five generic font families are defined to exist in all CSS
   807    implementations (they need not necessarily map to five distinct actual
   808    fonts). User agents should provide reasonable default choices for the
   809    generic font families, which express the characteristics of each family as
   810    well as possible within the limits allowed by the underlying technology.
   811    User agents are encouraged to allow users to select alternative choices
   812    for the generic fonts.
   814   <h5 class="no-num no-toc"> <span class=index-def id=serif0 title="serif,
   815    definition of"><a name=serif-def><dfn id=serif>serif</dfn></a></span></h5>
   817   <p>Serif fonts represent the formal text style for a script. This often
   818    means but is not limited to glyphs that have finishing strokes, flared or
   819    tapering ends, or have actual serifed endings (including slab serifs).
   820    Serif fonts are typically proportionately-spaced. They often display a
   821    greater variation between thick and thin strokes than fonts from the ‘<a
   822    href="#sans-serif"><code class=property>sans-serif</code></a>’ generic
   823    font family. CSS uses the term ‘<a href="#serif"><code
   824    class=property>serif</code></a>’ to apply to a font for any script,
   825    although other names may be more familiar for particular scripts, such as
   826    Mincho (Japanese), Sung, Song or Kai (Chinese), Batang (Korean). For
   827    Arabic, the Naskh style would correspond to ‘<a href="#serif"><code
   828    class=property>serif</code></a>’ more due to its typographic role rather
   829    than its actual design style. Any font that is so described may be used to
   830    represent the generic ‘<a href="#serif"><code
   831    class=property>serif</code></a>’ family.
   833   <div class=figure><img alt="sample serif fonts" src=serifexamples.png>
   834    <p class=caption>Sample serif fonts
   835   </div>
   837   <h5 class="no-num no-toc"> <span class=index-def id=sans-serif0
   838    title="sans-serif, definition of"> <a name=sans-serif-def><dfn
   839    id=sans-serif>sans-serif</dfn></a></span></h5>
   841   <p>Glyphs in sans-serif fonts, as the term is used in CSS, are generally
   842    low contrast (vertical and horizontal stems have the close to the same
   843    thickness) and have stroke endings that are plain -- without any flaring,
   844    cross stroke, or other ornamentation. Sans-serif fonts are typically
   845    proportionately-spaced. They often have little variation between thick and
   846    thin strokes, compared to fonts from the ‘<a href="#serif"><code
   847    class=property>serif</code></a>’ family. CSS uses the term ‘<a
   848    href="#sans-serif"><code class=property>sans-serif</code></a>’ to apply
   849    to a font for any script, although other names may be more familiar for
   850    particular scripts, such as Gothic (Japanese), Hei (Chinese), or Gulim
   851    (Korean). Any font that is so described may be used to represent the
   852    generic ‘<a href="#sans-serif"><code
   853    class=property>sans-serif</code></a>’ family.
   855   <div class=figure><img alt="sample sans-serif fonts"
   856    src=sansserifexamples.png>
   857    <p class=caption>Sample sans-serif fonts
   858   </div>
   860   <h5 class="no-num no-toc"> <span class=index-def id=cursive0
   861    title="cursive, definition of"> <a name=cursive-def><dfn
   862    id=cursive>cursive</dfn></a></span></h5>
   864   <p>Glyphs in cursive fonts generally use a more informal script style, and
   865    the result looks more like handwritten pen or brush writing than printed
   866    letterwork. CSS uses the term ‘<a href="#cursive"><code
   867    class=property>cursive</code></a>’ to apply to a font for any script,
   868    although other names such as Chancery, Brush, Swing and Script are also
   869    used in font names.
   871   <div class=figure><img alt="sample cursive fonts" src=cursiveexamples.png>
   872    <p class=caption>Sample cursive fonts
   873   </div>
   875   <h5 class="no-num no-toc"> <span class=index-def id=fantasy0
   876    title="fantasy, definition of"> <a name=fantasy-def><dfn
   877    id=fantasy>fantasy</dfn></a></span></h5>
   879   <p>Fantasy fonts are primarily decorative or expressive fonts that contain
   880    playful representations of characters. These do not include Pi or Picture
   881    fonts which do not represent actual characters.
   883   <div class=figure><img alt="sample fantasy fonts" src=fantasyexamples.png>
   884    <p class=caption>Sample fantasy fonts
   885   </div>
   887   <h5 class="no-num no-toc"> <span class=index-def id=monospace0
   888    title="monospace, definition of"> <a name=monospace-def><dfn
   889    id=monospace>monospace</dfn></a></span></h5>
   891   <p>The sole criterion of a monospace font is that all glyphs have the same
   892    fixed width. This is often used to render samples of computer code.
   894   <div class=figure><img alt="sample monospace fonts"
   895    src=monospaceexamples.png>
   896    <p class=caption>Sample monospace fonts
   897   </div>
   898   <!-- prop: font-weight -->
   900   <h3 id=font-weight-prop><span class=secno>3.2 </span>Font weight: the <a
   901    href="#propdef-font-weight">font-weight</a> property</h3>
   903   <table class=propdef id=namefont-weightvaluenormal-bold-bolder-l>
   904    <tbody>
   905     <tr>
   906      <td>Name:
   908      <td><dfn id=propdef-font-weight
   909       title="font-weight!!property">font-weight</dfn>
   911     <tr>
   912      <td>Value:
   914      <td><a href="#font-weight-normal-value"
   915       title="normal!!font-weight">normal</a> | <a href="#bold">bold</a> | <a
   916       href="#bolder">bolder</a> | <a href="#lighter">lighter</a> | <a
   917       href="#font-weight-numeric-values" title="100...900 weight
   918       values">100</a> | <a href="#font-weight-numeric-values"
   919       title="100...900 weight values">200</a> | <a
   920       href="#font-weight-numeric-values" title="100...900 weight
   921       values">300</a> | <a href="#font-weight-numeric-values"
   922       title="100...900 weight values">400</a> | <a
   923       href="#font-weight-numeric-values" title="100...900 weight
   924       values">500</a> | <a href="#font-weight-numeric-values"
   925       title="100...900 weight values">600</a> | <a
   926       href="#font-weight-numeric-values" title="100...900 weight
   927       values">700</a> | <a href="#font-weight-numeric-values"
   928       title="100...900 weight values">800</a> | <a
   929       href="#font-weight-numeric-values" title="100...900 weight
   930       values">900</a>
   932     <tr>
   933      <td>Initial:
   935      <td>normal
   937     <tr>
   938      <td>Applies to:
   940      <td>all elements
   942     <tr>
   943      <td>Inherited:
   945      <td>yes
   947     <tr>
   948      <td>Percentages:
   950      <td>N/A
   952     <tr>
   953      <td>Media:
   955      <td>visual
   957     <tr>
   958      <td>Computed value:
   960      <td>numeric weight value (see description)
   962     <tr>
   963      <td>Animatable:
   965      <td>as <a
   966       href="http://dev.w3.org/csswg/css3-transitions/#animtype-font-weight">font
   967       weight</a>
   968   </table>
   970   <p>The <a href="#propdef-font-weight"
   971    title="font-weight!!property">‘<code
   972    class=property>font-weight</code>’</a> property specifies the weight of
   973    glyphs in the font, their degree of blackness or stroke thickness.
   975   <p>Values have the following meanings:
   977   <dl>
   978    <dt><dfn id=font-weight-numeric-values title="100...900 weight values">100
   979     to 900</dfn>
   981    <dd>These values form an ordered sequence, where each number indicates a
   982     weight that is at least as dark as its predecessor. These roughly
   983     correspond to the commonly used weight names below:
   984   </dl>
   986   <ul>
   987    <li>100 - Thin
   989    <li>200 - Extra Light (Ultra Light)
   991    <li>300 - Light
   993    <li>400 - Normal
   995    <li>500 - Medium
   997    <li>600 - Semi Bold (Demi Bold)
   999    <li>700 - Bold
  1001    <li>800 - Extra Bold (Ultra Bold)
  1003    <li>900 - Black (Heavy)
  1004   </ul>
  1006   <dl>
  1007    <dt><dfn id=font-weight-normal-value
  1008     title="normal!!font-weight">normal</dfn>
  1010    <dd>Same as ‘<code class=css>400</code>’.
  1012    <dt><dfn id=bold>bold</dfn>
  1014    <dd>Same as ‘<code class=css>700</code>’.
  1016    <dt><dfn id=bolder>bolder</dfn>
  1018    <dd>Specifies a bolder weight than the inherited value.
  1020    <dt><dfn id=lighter>lighter</dfn>
  1022    <dd>Specifies a lighter weight than the inherited value.
  1023   </dl>
  1025   <p>Font formats that use a scale other than a nine-step scale should map
  1026    their scale onto the CSS scale so that 400 roughly corresponds with a face
  1027    that would be labeled as Regular, Book, Roman and 700 roughly matches a
  1028    face that would be labeled as Bold. Or weights may be inferred from the
  1029    style names, ones that correspond roughly with the scale above. The scale
  1030    is relative, so a face with a larger weight value must never appear
  1031    lighter. If style names are used to infer weights, care should be taken to
  1032    handle variations in style names across locales.
  1034   <p>Quite often there are only a few weights available for a particular font
  1035    family. When a weight is specified for which no face exists, a face with a
  1036    nearby weight is used. In general, bold weights map to faces with heavier
  1037    weights and light weights map to faces with lighter weights (see the <a
  1038    href="#font-matching-algorithm">font matching section below</a> for a
  1039    precise definition). The examples here illustrate which face is used for
  1040    different weights, grey indicates a face for that weight does not exist so
  1041    a face with a nearby weight is used:
  1043   <div class=figure><img alt="weight mappings for a family with 400, 700 and
  1044    900 weights" src=optimaweights.png>
  1045    <p class=caption>Weight mappings for a font family with 400, 700 and 900
  1046     weight faces
  1047   </div>
  1049   <div class=figure><img alt="weight mappings for a family with 300, 600
  1050    weights" src=hiraginoweights.png>
  1051    <p class=caption>Weight mappings for a font family with 300 and 600 weight
  1052     faces
  1053   </div>
  1055   <p>Although the practice is not well-loved by typographers, bold faces are
  1056    often synthesized by user agents for faces that lack actual bold faces.
  1057    For the purposes of style matching, these faces must be treated as if they
  1058    exist within the family. Authors can explicitly avoid this behavior by
  1059    using the ‘<a href="#propdef-font-synthesis"><code
  1060    class=property>font-synthesis</code></a>’ property.
  1062   <p>Specified values of ‘<a href="#bolder"><code
  1063    class=property>bolder</code></a>’ and ‘<a href="#lighter"><code
  1064    class=property>lighter</code></a>’ indicate weights relative to the
  1065    weight of the parent element. The computed weight is calculated based on
  1066    the inherited <a href="#propdef-font-weight"
  1067    title="font-weight!!property">‘<code
  1068    class=property>font-weight</code>’</a> value using the chart below.
  1070   <table class=data id=bolderlighter summary="Bolder/lighter mappings">
  1071    <thead>
  1072     <tr>
  1073      <th>Inherited value
  1075      <th>bolder
  1077      <th>lighter
  1079    <tbody>
  1080     <tr>
  1081      <th>100
  1083      <td>400
  1085      <td>100
  1087     <tr>
  1088      <th>200
  1090      <td>400
  1092      <td>100
  1094     <tr>
  1095      <th>300
  1097      <td>400
  1099      <td>100
  1101     <tr>
  1102      <th>400
  1104      <td>700
  1106      <td>100
  1108     <tr>
  1109      <th>500
  1111      <td>700
  1113      <td>100
  1115     <tr>
  1116      <th>600
  1118      <td>900
  1120      <td>400
  1122     <tr>
  1123      <th>700
  1125      <td>900
  1127      <td>400
  1129     <tr>
  1130      <th>800
  1132      <td>900
  1134      <td>700
  1136     <tr>
  1137      <th>900
  1139      <td>900
  1141      <td>700
  1142   </table>
  1144   <p>The table above is equivalent to selecting the next relative bolder or
  1145    lighter face, given a font family containing normal and bold faces along
  1146    with a thin and a heavy face. Authors who desire finer control over the
  1147    exact weight values used for a given element may use numerical values
  1148    instead of relative weights.</p>
  1149   <!-- prop: font-stretch -->
  1151   <h3 id=font-stretch-prop><span class=secno>3.3 </span>Font width: the <a
  1152    href="#propdef-font-stretch">font-stretch</a> property</h3>
  1154   <table class=propdef id=namefont-stretchvalue-normal-ultra-conde>
  1155    <tbody>
  1156     <tr>
  1157      <td>Name:
  1159      <td><dfn id=propdef-font-stretch
  1160       title="font-stretch!!property">font-stretch</dfn>
  1162     <tr>
  1163      <td>Value:
  1165      <td> <a href="#font-stretch-normal-value"
  1166       title="normal!!font-stretch">normal</a> | <a
  1167       href="#ultra-condensed">ultra-condensed</a> | <a
  1168       href="#extra-condensed">extra-condensed</a> | <a
  1169       href="#condensed">condensed</a> | <a
  1170       href="#semi-condensed-">semi-condensed</a> | <a
  1171       href="#semi-expanded">semi-expanded</a> | <a
  1172       href="#expanded">expanded</a> | <a
  1173       href="#extra-expanded">extra-expanded</a> | <a
  1174       href="#ultra-expanded">ultra-expanded</a>
  1176     <tr>
  1177      <td>Initial:
  1179      <td>normal
  1181     <tr>
  1182      <td>Applies to:
  1184      <td>all elements
  1186     <tr>
  1187      <td>Inherited:
  1189      <td>yes
  1191     <tr>
  1192      <td>Percentages:
  1194      <td>N/A
  1196     <tr>
  1197      <td>Media:
  1199      <td>visual
  1201     <tr>
  1202      <td>Computed value:
  1204      <td>as specified
  1206     <tr>
  1207      <td>Animatable:
  1209      <td>as <a href="#font-stretch-animation">font stretch</a>
  1210   </table>
  1212   <p>The <a href="#propdef-font-stretch"
  1213    title="font-stretch!!property">‘<code
  1214    class=property>font-stretch</code>’</a> property selects a normal,
  1215    condensed, or expanded face from a font family. Absolute keyword values
  1216    have the following ordering, from narrowest to widest:
  1218   <ul>
  1219    <li><dfn id=ultra-condensed>ultra-condensed</dfn>
  1221    <li><dfn id=extra-condensed>extra-condensed</dfn>
  1223    <li><dfn id=condensed>condensed</dfn>
  1225    <li><dfn id=semi-condensed->semi-condensed </dfn>
  1227    <li><dfn id=font-stretch-normal-value
  1228     title="normal!!font-stretch">normal</dfn>
  1230    <li><dfn id=semi-expanded>semi-expanded</dfn>
  1232    <li><dfn id=expanded>expanded</dfn>
  1234    <li><dfn id=extra-expanded>extra-expanded</dfn>
  1236    <li><dfn id=ultra-expanded>ultra-expanded</dfn>
  1237   </ul>
  1239   <p>When a face does not exist for a given width, normal or condensed values
  1240    map to a narrower face, otherwise a wider face. Conversely, expanded
  1241    values map to a wider face, otherwise a narrower face. The figure below
  1242    shows how the nine font-stretch property settings affect font selection
  1243    for font family containing a variety of widths, grey indicates a width for
  1244    which no face exists and a different width is substituted:
  1246   <div class=figure><img alt="width mappings for a family with condensed,
  1247    normal and expanded faces" src=universwidths.png>
  1248    <p class=caption>Width mappings for a font family with condensed, normal
  1249     and expanded width faces
  1250   </div>
  1252   <p id=font-stretch-animation>Animation of font stretch: Font stretch is
  1253    interpolated in discrete steps. The interpolation happens as though the
  1254    ordered values are equally spaced real numbers. The interpolation result
  1255    is rounded to the nearest value, with values exactly halfway between two
  1256    values rounded towards the later value in the list above.</p>
  1257   <!-- prop: font-style -->
  1259   <h3 id=font-style-prop><span class=secno>3.4 </span>Font style: the <a
  1260    href="#propdef-font-style">font-style</a> property</h3>
  1262   <table class=propdef id=namefont-stylevaluenormal-italic-oblique>
  1263    <tbody>
  1264     <tr>
  1265      <td>Name:
  1267      <td><dfn id=propdef-font-style
  1268       title="font-style!!property">font-style</dfn>
  1270     <tr>
  1271      <td>Value:
  1273      <td><a href="#font-style-normal-value"
  1274       title="normal!!font-style">normal</a> | <a href="#italic">italic</a> |
  1275       <a href="#oblique">oblique</a>
  1277     <tr>
  1278      <td>Initial:
  1280      <td>normal
  1282     <tr>
  1283      <td>Applies to:
  1285      <td>all elements
  1287     <tr>
  1288      <td>Inherited:
  1290      <td>yes
  1292     <tr>
  1293      <td>Percentages:
  1295      <td>N/A
  1297     <tr>
  1298      <td>Media:
  1300      <td>visual
  1302     <tr>
  1303      <td>Computed value:
  1305      <td>as specified
  1307     <tr>
  1308      <td>Animatable:
  1310      <td>no
  1311   </table>
  1313   <p>The <a href="#propdef-font-style" title="font-style!!property">‘<code
  1314    class=property>font-style</code>’</a> property allows italic or oblique
  1315    faces to be selected. Italic forms are generally cursive in nature while
  1316    oblique faces are typically sloped versions of the regular face. Oblique
  1317    faces can be simulated by artificially sloping the glyphs of the regular
  1318    face. Compare the artificially sloped renderings of Palatino ‘<code
  1319    class=property>a</code>’ and Baskerville ‘<code
  1320    class=property>N</code>’ in grey with the actual italic versions:
  1322   <div class=figure><img alt="artificial sloping vs. real italics"
  1323    src=realvsfakeitalics.png>
  1324    <p class=caption>Artificial sloping versus real italics
  1325   </div>
  1327   <p>Values have the following meanings:
  1329   <dl>
  1330    <dt><dfn id=font-style-normal-value
  1331     title="normal!!font-style">normal</dfn>
  1333    <dd>selects a face that is classified as a normal face, one that is
  1334     neither italic or obliqued
  1336    <dt><dfn id=italic>italic</dfn>
  1338    <dd>selects a font that is labeled as an italic face, or an oblique face
  1339     if one is not
  1341    <dt><dfn id=oblique>oblique</dfn>
  1343    <dd>selects a font that is labeled as an oblique face, or an italic face
  1344     if one is not
  1345   </dl>
  1347   <p>If no italic or oblique face is available, oblique faces can be
  1348    synthesized by rendering non-obliqued faces with an artificial obliquing
  1349    operation. The use of these artificially obliqued faces can be disabled
  1350    using the ‘<a href="#propdef-font-synthesis"><code
  1351    class=property>font-synthesis</code></a>’ property. The details of the
  1352    obliquing operation are not explicitly defined.</p>
  1353   <!-- resolution on the "undefined" nature of synthetics: http://www.w3.org/2013/06/06-css-minutes.html#item03 -->
  1355   <p>Many scripts lack the tradition of mixing a cursive form within text
  1356    rendered with a normal face. Chinese, Japanese and Korean fonts almost
  1357    always lack italic or oblique faces. Fonts that support a mixture of
  1358    scripts will sometimes omit specific scripts such as Arabic from the set
  1359    of glyphs supported in the italic face. User agents should be careful
  1360    about making <a href="#character-map"><em>character map</em></a>
  1361    assumptions across faces when implementing support for <a
  1362    href="#system-font-fallback"><em>system font fallback</em></a>.</p>
  1363   <!-- prop: font-size -->
  1365   <h3 id=font-size-prop><span class=secno>3.5 </span>Font size: the <a
  1366    href="#propdef-font-size">font-size</a> property</h3>
  1368   <table class=propdef id=namefont-sizevalueltabsolute-sizegt-ltre>
  1369    <tbody>
  1370     <tr>
  1371      <td>Name:
  1373      <td><dfn id=propdef-font-size>font-size</dfn>
  1375     <tr>
  1376      <td>Value:
  1378      <td><a href="#absolute-size-value"><var>&lt;absolute-size&gt;</var></a>
  1379       | <a href="#relative-size-value"><var>&lt;relative-size&gt;</var></a> |
  1380       <a href="#length-size-value"><var>&lt;length&gt;</var></a> | <a
  1381       href="#percentage-size-value"><var>&lt;percentage&gt;</var></a>
  1383     <tr>
  1384      <td>Initial:
  1386      <td>medium
  1388     <tr>
  1389      <td>Applies to:
  1391      <td>all elements
  1393     <tr>
  1394      <td>Inherited:
  1396      <td>yes
  1398     <tr>
  1399      <td>Percentages:
  1401      <td>refer to parent element's font size
  1403     <tr>
  1404      <td>Media:
  1406      <td>visual
  1408     <tr>
  1409      <td>Computed value:
  1411      <td>absolute length
  1413     <tr>
  1414      <td>Animatable:
  1416      <td>as <a
  1417       href="http://dev.w3.org/csswg/css3-transitions/#animtype-length">length</a>
  1418   </table>
  1420   <p>This property indicates the desired height of glyphs from the font. For
  1421    scalable fonts, the font-size is a scale factor applied to the EM unit of
  1422    the font. (Note that certain glyphs may bleed outside their EM box.) For
  1423    non-scalable fonts, the font-size is converted into absolute units and
  1424    matched against the declared font-size of the font, using the same
  1425    absolute coordinate space for both of the matched values. Values have the
  1426    following meanings:
  1428   <dl>
  1429    <dt><dfn id=absolute-size-value><var>&lt;absolute-size&gt;</var></dfn>
  1431    <dd> An <a
  1432     href="#absolute-size-value"><var>&lt;absolute-size&gt;</var></a> keyword
  1433     refers to an entry in a table of font sizes computed and kept by the user
  1434     agent. Possible values are:
  1435     <p> [ xx-small | x-small | small | medium | large | x-large | xx-large ]</p>
  1437    <dt><dfn id=relative-size-value><var>&lt;relative-size&gt;</var></dfn>
  1439    <dd> A <a href="#relative-size-value"><var>&lt;relative-size&gt;</var></a>
  1440     keyword is interpreted relative to the table of font sizes and the
  1441     computed ‘<a href="#propdef-font-size"><code
  1442     class=property>font-size</code></a>’ of the parent element. Possible
  1443     values are:
  1444     <p> [ larger | smaller ]
  1446     <p> For example, if the parent element has a font size of ‘<code
  1447      class=property>medium</code>’, a value of ‘<code
  1448      class=property>larger</code>’ will make the font size of the current
  1449      element be ‘<code class=property>large</code>’. If the parent
  1450      element's size is not close to a table entry, the user agent is free to
  1451      interpolate between table entries or round off to the closest one. The
  1452      user agent may have to extrapolate table values if the numerical value
  1453      goes beyond the keywords.
  1455    <dt><dfn id=length-size-value><var>&lt;length&gt;</var></dfn>
  1457    <dd>A length value specifies an absolute font size (independent of the
  1458     user agent's font table). Negative lengths are illegal.
  1460    <dt><dfn id=percentage-size-value><var>&lt;percentage&gt;</var></dfn>
  1462    <dd>A percentage value specifies an absolute font size relative to the
  1463     parent element's font size. Use of percentage values, or values in
  1464     ‘<code class=property>em</code>’s, leads to more robust and
  1465     cascadable style sheets.
  1466   </dl>
  1468   <p>The following table provides user agent guidelines for the absolute-size
  1469    scaling factor and their mapping to HTML heading and absolute font-sizes.
  1470    The ‘<code class=property>medium</code>’ value is used as the
  1471    reference middle value. The user agent may fine-tune these values for
  1472    different fonts or different types of display devices.
  1474   <table class=data>
  1475    <thead>
  1476     <tr>
  1477      <th>CSS absolute-size values
  1479      <th>xx-small
  1481      <th>x-small
  1483      <th>small
  1485      <th>medium
  1487      <th>large
  1489      <th>x-large
  1491      <th>xx-large
  1493      <th> 
  1495    <tbody>
  1496     <tr>
  1497      <th>scaling factor
  1499      <td>3/5
  1501      <td>3/4
  1503      <td>8/9
  1505      <td>1
  1507      <td>6/5
  1509      <td>3/2
  1511      <td>2/1
  1513      <td>3/1
  1515     <tr>
  1516      <th>HTML headings
  1518      <td>h6
  1520      <td> 
  1522      <td>h5
  1524      <td>h4
  1526      <td>h3
  1528      <td>h2
  1530      <td>h1
  1532      <td> 
  1534     <tr>
  1535      <th>HTML font sizes
  1537      <td>1
  1539      <td> 
  1541      <td>2
  1543      <td>3
  1545      <td>4
  1547      <td>5
  1549      <td>6
  1551      <td>7
  1552   </table>
  1554   <p class=note><em><strong>Note 1.</strong> To preserve readability, an UA
  1555    applying these guidelines should nevertheless avoid creating font-size
  1556    resulting in less than 9 device pixels per EM unit on a computer
  1557    display.</em>
  1559   <p class=note><em><strong>Note 2.</strong> In CSS1, the suggested scaling
  1560    factor between adjacent indexes was 1.5 which user experience proved to be
  1561    too large. In CSS2, the suggested scaling factor for computer screen
  1562    between adjacent indexes was 1.2 which still created issues for the small
  1563    sizes. The new scaling factor varies between each index to provide a
  1564    better readability.</em>
  1566   <p>The actual value of this property may differ from the computed value due
  1567    a numerical value on ‘<a href="#propdef-font-size-adjust"><code
  1568    class=property>font-size-adjust</code></a>’ and the unavailability of
  1569    certain font sizes.
  1571   <p>Child elements inherit the computed <a class=noxref
  1572    href="#font-size-prop"> <span class=property>‘<code
  1573    class=property>font-size</code>’</span></a> value (otherwise, the effect
  1574    of <a class=noxref href="#font-size-adjust-prop"><span
  1575    class=property>‘<code
  1576    class=property>font-size-adjust</code>’</span></a> would compound).
  1578   <div class=example>
  1579    <p style="display:none">Example(s):
  1581    <p>
  1583    <pre>p { font-size: 12pt; }
  1584 blockquote { font-size: larger }
  1585 em { font-size: 150% }
  1586 em { font-size: 1.5em }
  1587 </pre>
  1588   </div>
  1589   <!-- prop: font-size-adjust -->
  1591   <h3 id=font-size-adjust-prop><span class=secno>3.6 </span>Relative sizing:
  1592    the <a href="#propdef-font-size-adjust">font-size-adjust</a> property</h3>
  1594   <table class=propdef id=namefont-size-adjustvaluenone-auto-ltnum>
  1595    <tbody>
  1596     <tr>
  1597      <td>Name:
  1599      <td><dfn id=propdef-font-size-adjust>font-size-adjust</dfn>
  1601     <tr>
  1602      <td>Value:
  1604      <td><a href="#font-size-adjust-none-value"
  1605       title="none!!font-size-adjust">none</a> | <a
  1606       href="#font-size-adjust-auto-value"
  1607       title="auto!!font-size-adjust">auto</a> | <a
  1608       href="#aspect-ratio-value"><var>&lt;number&gt;</var></a>
  1610     <tr>
  1611      <td>Initial:
  1613      <td>none
  1615     <tr>
  1616      <td>Applies to:
  1618      <td>all elements
  1620     <tr>
  1621      <td>Inherited:
  1623      <td>yes
  1625     <tr>
  1626      <td>Percentages:
  1628      <td>N/A
  1630     <tr>
  1631      <td>Media:
  1633      <td>visual
  1635     <tr>
  1636      <td>Computed value:
  1638      <td>as specified
  1640     <tr>
  1641      <td>Animatable:
  1643      <td>as <a
  1644       href="http://dev.w3.org/csswg/css3-transitions/#animtype-number">number</a>
  1645   </table>
  1647   <p>For any given font size, the apparent size and legibility of text varies
  1648    across fonts. For scripts such as Latin or Cyrillic that distinguish
  1649    between upper and lowercase letters, the relative height of lowercase
  1650    letters compared to their uppercase counterparts is a determining factor
  1651    of legibility. This is commonly referred to as the <a class=index-def
  1652    href="#aspect-value" id=aspect-value0 title="aspect value"><dfn
  1653    id=aspect-value>aspect value</dfn></a>. Precisely defined, it is equal to
  1654    the x-height of a font divided by the font size.
  1656   <p>In situations where font fallback occurs, fallback fonts may not share
  1657    the same aspect ratio as the desired font family and will thus appear less
  1658    readable. The font-size-adjust property is a way to preserve the
  1659    readability of text when font fallback occurs. It does this by adjusting
  1660    the font-size so that the x-height is the same regardless of the font
  1661    used.
  1663   <div class=example>
  1664    <p>The style defined below defines Verdana as the desired font family, but
  1665     if Verdana is not available Futura or Times will be used.</p>
  1667    <pre>p {
  1668     font-family: Verdana, Futura, Times;
  1671 &lt;p>Lorem ipsum dolor sit amet, ...&lt;/p>
  1672 </pre>
  1674    <p>Verdana has a relatively high aspect ratio, lowercase letters are
  1675     relatively tall compared to uppercase letters, so at small sizes text
  1676     appears legible. Times has a lower aspect ratio and so if fallback
  1677     occurs, the text will be less legible at small sizes than Verdana.</p>
  1678   </div>
  1680   <p>How text rendered in each of these fonts compares is shown below, the
  1681    columns show text rendered in Verdana, Futura and Times. The same
  1682    font-size value is used across cells within each row and red lines are
  1683    included to show the differences in x-height. In the upper half each row
  1684    is rendered in the same font-size value. The same is true for the lower
  1685    half but in this half the font-size-adjust property is also set so that
  1686    the actual font size is adjusted to preserve the x-height across each row.
  1687    Note how small text remains relatively legible across each row in the
  1688    lower half.
  1690   <div class=figure><img alt="text with and without font-size-adjust"
  1691    src=fontsizeadjust.png>
  1692    <p class=caption>Text with and without the use of font-size-adjust
  1693   </div>
  1695   <p>This property allows authors to specify an <a
  1696    href="#aspect-value"><i>aspect value</i></a> for an element that will
  1697    effectively preserve the x-height of the first choice font, whether it is
  1698    substituted or not. Values have the following meanings:
  1700   <dl>
  1701    <dt><dfn id=font-size-adjust-none-value
  1702     title="none!!font-size-adjust">none</dfn>
  1704    <dd>Do not preserve the font's x-height.
  1706    <dt><dfn id=font-size-adjust-auto-value
  1707     title="auto!!font-size-adjust">auto</dfn>
  1709    <dd>Behaves just like &lt;number>, except the number used is the <a
  1710     href="#aspect-value"><i>aspect value</i></a> calculated by user agents
  1711     for the first font in the list of fonts defined for the initial value of
  1712     the <a href="#propdef-font-family" title="font-family!!property">‘<code
  1713     class=property>font-family</code>’</a> property. Effectively this is
  1714     the default font used when <a href="#propdef-font-family"
  1715     title="font-family!!property">‘<code
  1716     class=property>font-family</code>’</a> is not otherwise specified.
  1717     <p>Authors can use this value to specify that font size should be
  1718      normalized across fonts based on the x-height without the need to
  1719      specify the aspect ratio explicitly.</p>
  1721    <dt><dfn id=aspect-ratio-value><var>&lt;number&gt;</var></dfn>
  1723    <dd>Specifies the <a href="#aspect-value"><i>aspect value</i></a> used in
  1724     the calculation below to calculate the adjusted font size:
  1725     <pre>c  =  ( a / a' ) s
  1726 </pre>
  1728     <p>where:</p>
  1730     <pre>s  =  font-size value
  1731 a  =  <a href="#aspect-value"><i>aspect value</i></a> as specified by the font-size-adjust property
  1732 a' =  <a href="#aspect-value"><i>aspect value</i></a> of actual font
  1733 c  =  adjusted font-size to use
  1734 </pre>
  1736     <p>This value applies to any font that is selected but in typical usage
  1737      it should be based on the <a href="#aspect-value"><i>aspect
  1738      value</i></a> of the first font in the font-family list. If this is
  1739      specified accurately, the <tt>(a/a')</tt> term in the formula above is
  1740      effectively 1 for the first font and no adjustment occurs. If the value
  1741      is specified inaccurately, text rendered using the first font in the
  1742      family list will display differently in older user agents that don't
  1743      support font-size-adjust.</p>
  1744   </dl>
  1746   <p>The value of ‘<a href="#propdef-font-size-adjust"><code
  1747    class=property>font-size-adjust</code></a>’ affects the size of relative
  1748    units that are based on font metrics of the <a
  1749    href="#first-available-font"><i>first available font</i></a> such as
  1750    <code>ex</code> and <code>ch</code> but does not affect the size of
  1751    <code>em</code> units.
  1753   <p>Authors can calculate the <a href="#aspect-value"><i>aspect
  1754    value</i></a> for a given font by comparing spans with the same content
  1755    but different font-size-adjust properties. If the same font-size is used,
  1756    the spans will match when the font-size-adjust value is accurate for the
  1757    given font.
  1759   <div class=example>
  1760    <p>Two spans with borders are used to determine the <a
  1761     href="#aspect-value"><i>aspect value</i></a> of a font. The font-size is
  1762     the same for both spans but the font-size-adjust property is specified
  1763     only for the right span. Starting with a value of 0.5, the aspect value
  1764     can be adjusted until the borders around the two letters line up.</p>
  1766    <pre>p {
  1767     font-family: Futura;
  1768     font-size: 500px;
  1771 span {
  1772     border: solid 1px red;
  1775 .adjust {
  1776     font-size-adjust: 0.5;
  1779 &lt;p>&lt;span>b&lt;/span>&lt;span class="adjust">b&lt;/span>&lt;/p>
  1780 </pre>
  1782    <div class=figure><img alt="Futura with an <i>aspect value</i> of 0.5"
  1783     src=beforefontsizeadjust.png>
  1784     <p class=caption>Futura with an <a href="#aspect-value"><i>aspect
  1785      value</i></a> of 0.5
  1786    </div>
  1788    <p>The box on the right is a bit bigger than the one on the left, so the
  1789     <a href="#aspect-value"><i>aspect value</i></a> of this font is something
  1790     less than 0.5. Adjust the value until the boxes align.</p>
  1791   </div>
  1792   <!-- prop: font -->
  1794   <h3 id=font-prop><span class=secno>3.7 </span>Shorthand font property: the
  1795    <a href="#propdef-font">font</a> property</h3>
  1797   <table class=propdef id=namefontvalue-ltlsquofont-stylersquogt-l>
  1798    <tbody>
  1799     <tr>
  1800      <td>Name:
  1802      <td><dfn id=propdef-font>font</dfn>
  1804     <tr>
  1805      <td>Value:
  1807      <td>[ [ <var>&lt;<a href="#propdef-font-style"
  1808       title="font-style!!property">‘<code
  1809       class=property>font-style</code>’</a>&gt;</var> || <a
  1810       href="#font-variant-css21-values"><var>&lt;font-variant-css21&gt;</var></a>
  1811       || <var>&lt;<a href="#propdef-font-weight"
  1812       title="font-weight!!property">‘<code
  1813       class=property>font-weight</code>’</a>&gt;</var> || <var>&lt;<a
  1814       href="#propdef-font-stretch" title="font-stretch!!property">‘<code
  1815       class=property>font-stretch</code>’</a></var> ]? <var>&lt;‘<a
  1816       href="#propdef-font-size"><code
  1817       class=property>font-size</code></a>’&gt;</var> [ / <var>&lt;‘<code
  1818       class=property>line-height</code>’&gt;</var> ]? <var>&lt;<a
  1819       href="#propdef-font-family" title="font-family!!property">‘<code
  1820       class=property>font-family</code>’</a>&gt;</var> ] | caption | icon |
  1821       menu | message-box | small-caption | status-bar
  1823     <tr>
  1824      <td>Initial:
  1826      <td>see individual properties
  1828     <tr>
  1829      <td>Applies to:
  1831      <td>all elements
  1833     <tr>
  1834      <td>Inherited:
  1836      <td>yes
  1838     <tr>
  1839      <td>Percentages:
  1841      <td>see individual properties
  1843     <tr>
  1844      <td>Media:
  1846      <td>visual
  1848     <tr>
  1849      <td>Computed value:
  1851      <td>see individual properties
  1853     <tr>
  1854      <td>Animatable:
  1856      <td>see individual properties
  1857   </table>
  1859   <p>The <span class=property>‘<a href="#propdef-font"><code
  1860    class=property>font</code></a>’</span> property is, except as described
  1861    below, a shorthand property for setting <a href="#propdef-font-style"
  1862    title="font-style!!property">‘<code
  1863    class=property>font-style</code>’</a>, <a href="#propdef-font-variant"
  1864    title="font-variant!!property">‘<code
  1865    class=property>font-variant</code>’</a>, <a href="#propdef-font-weight"
  1866    title="font-weight!!property">‘<code
  1867    class=property>font-weight</code>’</a>, <a href="#propdef-font-stretch"
  1868    title="font-stretch!!property">‘<code
  1869    class=property>font-stretch</code>’</a>, <span class=property>‘<a
  1870    href="#propdef-font-size"><code
  1871    class=property>font-size</code></a>’</span>, <a class=property
  1872    href="http://www.w3.org/TR/CSS2/visudet.html#propdef-line-height">‘<code
  1873    class=property>line-height</code>’</a>, <a href="#propdef-font-family"
  1874    title="font-family!!property">‘<code
  1875    class=property>font-family</code>’</a> at the same place in the
  1876    stylesheet. Values for the <a href="#propdef-font-variant"
  1877    title="font-variant!!property">‘<code
  1878    class=property>font-variant</code>’</a> property may also be included
  1879    but only those supported in CSS 2.1, none of the <a
  1880    href="#propdef-font-variant" title="font-variant!!property">‘<code
  1881    class=property>font-variant</code>’</a> values added in this
  1882    specification can be used in the <span class=property>‘<a
  1883    href="#propdef-font"><code class=property>font</code></a>’</span>
  1884    shorthand:
  1886   <pre
  1887    class=prod><dfn id=font-variant-css21-values><var>&lt;font-variant-css21&gt;</var></dfn> = [normal | small-caps]</pre>
  1889   <p>The syntax of this property is based on a traditional typographical
  1890    shorthand notation to set multiple properties related to fonts.
  1892   <p>All subproperties of the ‘<a href="#propdef-font"><code
  1893    class=property>font</code></a>’ property are first reset to their
  1894    initial values, including those listed above plus <span
  1895    class=property>‘<a href="#propdef-font-size-adjust"><code
  1896    class=property>font-size-adjust</code></a>’</span>, <span
  1897    class=property>‘<a href="#propdef-font-kerning"><code
  1898    class=property>font-kerning</code></a>’</span>, subproperties of <a
  1899    href="#propdef-font-variant" title="font-variant!!property">‘<code
  1900    class=property>font-variant</code>’</a> and and <span>‘<a
  1901    href="#propdef-font-language-override"><code
  1902    class=property>font-language-override</code></a>’</span>. Then, those
  1903    properties that are given explicit values in the <span
  1904    class=property>‘<a href="#propdef-font"><code
  1905    class=property>font</code></a>’</span> shorthand are set to those
  1906    values. For a definition of allowed and initial values, see the previously
  1907    defined properties. For reasons of backwards compatibility, it is not
  1908    possible to set <span class=property>‘<a
  1909    href="#propdef-font-size-adjust"><code
  1910    class=property>font-size-adjust</code></a>’</span> to anything other
  1911    than its initial value using the <span class=property>‘<a
  1912    href="#propdef-font"><code class=property>font</code></a>’</span>
  1913    shorthand property; instead, use the individual property.
  1915   <div class=example>
  1916    <p style="display:none">Example(s):
  1918    <p>
  1920    <pre>p { font: 12pt/14pt sans-serif }
  1921 p { font: 80% sans-serif }
  1922 p { font: x-large/110% &quot;new century schoolbook&quot;, serif }
  1923 p { font: bold italic large Palatino, serif }
  1924 p { font: normal small-caps 120%/120% fantasy }
  1925 p { font: condensed oblique 12pt &quot;Helvetica Neue&quot;, serif; }
  1926 </pre>
  1928    <p> In the second rule, the font size percentage value (‘<code
  1929     class=css>80%</code>’) refers to the computed ‘<a
  1930     href="#propdef-font-size"><code class=property>font-size</code></a>’ of
  1931     the parent element. In the third rule, the line height percentage
  1932     (‘<code class=css>110%</code>’) refers to the font size of the
  1933     element itself.
  1935    <p>The first three rules do not specify the <a
  1936     href="#propdef-font-variant" title="font-variant!!property">‘<code
  1937     class=property>font-variant</code>’</a> and <a
  1938     href="#propdef-font-weight" title="font-weight!!property">‘<code
  1939     class=property>font-weight</code>’</a> explicitly, so these properties
  1940     receive their initial values (<span title="normal value">‘<code
  1941     class=property>normal</code>’</span>). Notice that the font family name
  1942     "new century schoolbook", which contains spaces, is enclosed in quotes.
  1943     The fourth rule sets the <a href="#propdef-font-weight"
  1944     title="font-weight!!property">‘<code
  1945     class=property>font-weight</code>’</a> to ‘<a href="#bold"><code
  1946     class=property>bold</code></a>’, the <a href="#propdef-font-style"
  1947     title="font-style!!property">‘<code
  1948     class=property>font-style</code>’</a> to ‘<a href="#italic"><code
  1949     class=property>italic</code></a>’, and implicitly sets <a
  1950     href="#propdef-font-variant" title="font-variant!!property">‘<code
  1951     class=property>font-variant</code>’</a> to <a
  1952     href="#font-variant-normal-value" title="normal!!font-variant">‘<code
  1953     class=property>normal</code>’</a>.
  1955    <p> The fifth rule sets the <a href="#propdef-font-variant"
  1956     title="font-variant!!property">‘<code
  1957     class=property>font-variant</code>’</a> (‘<a href="#small-caps"><code
  1958     class=property>small-caps</code></a>’), the <span class=property>‘<a
  1959     href="#propdef-font-size"><code
  1960     class=property>font-size</code></a>’</span> (120% of the parent's font
  1961     size), the <a class=property
  1962     href="http://www.w3.org/TR/CSS2/visudet.html#propdef-line-height">‘<code
  1963     class=property>line-height</code>’</a> (120% of the font size) and the
  1964     <a href="#propdef-font-family" title="font-family!!property">‘<code
  1965     class=property>font-family</code>’</a> (‘<a href="#fantasy"><code
  1966     class=property>fantasy</code></a>’). It follows that the keyword <span
  1967     title="normal value">‘<code class=property>normal</code>’</span>
  1968     applies to the two remaining properties: <a href="#propdef-font-style"
  1969     title="font-style!!property">‘<code
  1970     class=property>font-style</code>’</a> and <a
  1971     href="#propdef-font-weight" title="font-weight!!property">‘<code
  1972     class=property>font-weight</code>’</a>.
  1974    <p>The sixth rule sets the <a href="#propdef-font-style"
  1975     title="font-style!!property">‘<code
  1976     class=property>font-style</code>’</a>, <a href="#propdef-font-stretch"
  1977     title="font-stretch!!property">‘<code
  1978     class=property>font-stretch</code>’</a>, <span class=property>‘<a
  1979     href="#propdef-font-size"><code
  1980     class=property>font-size</code></a>’</span>, and <a
  1981     href="#propdef-font-family" title="font-family!!property">‘<code
  1982     class=property>font-family</code>’</a>, the other font properties being
  1983     set to their initial values.
  1984   </div>
  1986   <p>Since the <a href="#propdef-font-stretch"
  1987    title="font-stretch!!property">‘<code
  1988    class=property>font-stretch</code>’</a> property was not defined in CSS
  1989    2.1, when using <a href="#propdef-font-stretch"
  1990    title="font-stretch!!property">‘<code
  1991    class=property>font-stretch</code>’</a> values within ‘<a
  1992    href="#propdef-font"><code class=property>font</code></a>’ rules,
  1993    authors should include a extra version compatible with older user agents:
  1995   <pre>p {
  1996   font: 80% sans-serif;   /* for older user agents */
  1997   font: condensed 80% sans-serif;
  1998 }</pre>
  2000   <p>The following values refer to system fonts:
  2002   <dl>
  2003    <dt><strong>caption</strong>
  2005    <dd>The font used for captioned controls (e.g., buttons, drop-downs,
  2006     etc.).
  2008    <dt><strong>icon</strong>
  2010    <dd>The font used to label icons.
  2012    <dt><strong>menu</strong>
  2014    <dd>The font used in menus (e.g., dropdown menus and menu lists).
  2016    <dt><strong>message-box</strong>
  2018    <dd>The font used in dialog boxes.
  2020    <dt><strong>small-caption</strong>
  2022    <dd>The font used for labeling small controls.
  2024    <dt><strong>status-bar</strong>
  2026    <dd>The font used in window status bars.
  2027   </dl>
  2029   <p>System fonts may only be set as a whole; that is, the font family, size,
  2030    weight, style, etc. are all set at the same time. These values may then be
  2031    altered individually if desired. If no font with the indicated
  2032    characteristics exists on a given platform, the user agent should either
  2033    intelligently substitute (e.g., a smaller version of the ‘<code
  2034    class=property>caption</code>’ font might be used for the ‘<code
  2035    class=property>small-caption</code>’ font), or substitute a user agent
  2036    default font. As for regular fonts, if, for a system font, any of the
  2037    individual properties are not part of the operating system's available
  2038    user preferences, those properties should be set to their initial values.
  2040   <p>That is why this property is "almost" a shorthand property: system fonts
  2041    can only be specified with this property, not with <a
  2042    href="#propdef-font-family" title="font-family!!property">‘<code
  2043    class=property>font-family</code>’</a> itself, so <span
  2044    class=property>‘<a href="#propdef-font"><code
  2045    class=property>font</code></a>’</span> allows authors to do more than
  2046    the sum of its subproperties. However, the individual properties such as
  2047    <a href="#propdef-font-weight" title="font-weight!!property">‘<code
  2048    class=property>font-weight</code>’</a> are still given values taken from
  2049    the system font, which can be independently varied.
  2051   <p>Note that the keywords used for the system fonts listed above are only
  2052    treated as keywords when they occur in the initial position, in other
  2053    positions the same string is treated as part of the font family name:
  2055   <pre>  font: menu;        /* use the font settings for system menus */
  2056   font: large menu;  /* use a font family named "menu" */</pre>
  2058   <div class=example>
  2059    <p style="display:none">Example(s):
  2061    <p>
  2063    <pre>button { font: 300 italic 1.3em/1.7em &quot;FB Armada&quot;, sans-serif }
  2064 button p { font: menu }
  2065 button p em { font-weight: bolder }
  2066 </pre>
  2068    <p>If the font used for dropdown menus on a particular system happened to
  2069     be, for example, 9-point Charcoal, with a weight of 600, then P elements
  2070     that were descendants of BUTTON would be displayed as if this rule were
  2071     in effect:
  2073    <pre>button p { font: 600 9pt Charcoal }
  2074 </pre>
  2076    <p>Because the <span class=property>‘<a href="#propdef-font"><code
  2077     class=property>font</code></a>’</span> shorthand resets to its initial
  2078     value any property not explicitly given a value, this has the same effect
  2079     as this declaration:
  2081    <pre>button p {
  2082   font-style: normal;
  2083   font-variant: normal;
  2084   font-weight: 600;
  2085   font-size: 9pt;
  2086   line-height: normal;
  2087   font-family: Charcoal
  2089 </pre>
  2090   </div>
  2091   <!-- prop: font-synthesis -->
  2093   <h3 id=font-synthesis-prop><span class=secno>3.8 </span>Controlling
  2094    synthetic faces: the <a href="#propdef-font-synthesis">font-synthesis</a>
  2095    property</h3>
  2097   <table class=propdef id=namefont-synthesisvaluenone-weight-style>
  2098    <tbody>
  2099     <tr>
  2100      <td>Name:
  2102      <td><dfn id=propdef-font-synthesis>font-synthesis</dfn>
  2104     <tr>
  2105      <td>Value:
  2107      <td>none | [ weight || style ]
  2109     <tr>
  2110      <td>Initial:
  2112      <td>weight style
  2114     <tr>
  2115      <td>Applies to:
  2117      <td>all elements
  2119     <tr>
  2120      <td>Inherited:
  2122      <td>yes
  2124     <tr>
  2125      <td>Percentages:
  2127      <td>N/A
  2129     <tr>
  2130      <td>Media:
  2132      <td>visual
  2134     <tr>
  2135      <td>Computed value:
  2137      <td>as specified
  2139     <tr>
  2140      <td>Animatable:
  2142      <td>no
  2143   </table>
  2145   <p>This property controls whether user agents are allowed to synthesize
  2146    bold or oblique font faces when a font family lacks bold or italic faces.
  2147    If ‘<a href="#weight"><code class=property>weight</code></a>’ is not
  2148    specified, user agents must not synthesize bold faces and if ‘<code
  2149    class=property>style</code>’ is not specified user agents must not
  2150    synthesize italic faces. A value of ‘<code class=property>none</code>’
  2151    disallows all synthetic faces.
  2153   <div class=example>
  2154    <p>The style rule below disables the use of synthetically obliqued Arabic:</p>
  2156    <pre>*:lang(ar) { font-synthesis: none; }
  2157 </pre>
  2158   </div>
  2160   <h2 id=font-resources><span class=secno>4 </span>Font Resources</h2>
  2162   <h3 id=font-face-rule><span class=secno>4.1 </span>The <dfn
  2163    id=at-font-face-rule style="font-weight: inherit; font-style:
  2164    inherit"><code>@font-face</code></dfn> rule</h3>
  2166   <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule allows
  2167    for linking to fonts that are automatically fetched and activated when
  2168    needed. This allows authors to select a font that closely matches the
  2169    design goals for a given page rather than limiting the font choice to a
  2170    set of fonts available on all platforms. A set of font descriptors define
  2171    the location of a font resource, either locally or externally, along with
  2172    the style characteristics of an individual face. Multiple <a
  2173    href="#at-font-face-rule"><code>@font-face</code></a> rules can be used to
  2174    construct font families with a variety of faces. Using CSS font matching
  2175    rules, a user agent can selectively download only those faces that are
  2176    needed for a given piece of text.
  2178   <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule
  2179    consists of the <a href="#at-font-face-rule"><code>@font-face</code></a>
  2180    at-keyword followed by a block of descriptor declarations. In terms of the
  2181    grammar, this specification defines the following productions:
  2183   <pre><dfn id=fontfacerule>font_face_rule</dfn>
  2184   : <a href="#fontfacesym"><i>FONT_FACE_SYM</i></a> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* '{' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="#descriptordeclaration"><i>descriptor_declaration</i></a>? [ ';' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="#descriptordeclaration"><i>descriptor_declaration</i></a>? ]* '}' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>*
  2187 <dfn id=descriptordeclaration>descriptor_declaration</dfn>
  2188   : <a href="http://www.w3.org/TR/CSS21/grammar.html#grammar"><i>property</i></a> ':' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="http://www.w3.org/TR/CSS21/grammar.html#grammar"><i>expr</i></a>
  2189   ;</pre>
  2191   <p>The following new definitions are introduced:
  2193   <pre>-    -|\\0{0,4}2d(\r\n|[ \t\r\n\f])?
  2194 F    f|\\0{0,4}(46|66)(\r\n|[ \t\r\n\f])?</pre>
  2196   <p>The following new token is introduced:
  2198   <pre>@{F}{O}{N}{T}{-}{F}{A}{C}{E} {return <dfn id=fontfacesym>FONT_FACE_SYM</dfn>;}</pre>
  2200   <p>Each <a href="#at-font-face-rule"><code>@font-face</code></a> rule
  2201    specifies a value for every font descriptor, either implicitly or
  2202    explicitly. Those not given explicit values in the rule take the initial
  2203    value listed with each descriptor in this specification. These descriptors
  2204    apply solely within the context of the <a
  2205    href="#at-font-face-rule"><code>@font-face</code></a> rule in which they
  2206    are defined, and do not apply to document language elements. There is no
  2207    notion of which elements the descriptors apply to or whether the values
  2208    are inherited by child elements. When a given descriptor occurs multiple
  2209    times in a given <a href="#at-font-face-rule"><code>@font-face</code></a>
  2210    rule, only the last descriptor declaration is used and all prior
  2211    declarations for that descriptor are ignored.
  2213   <div class=example>
  2214    <p>To use a downloadable font called Gentium:</p>
  2216    <pre>
  2217 @font-face {
  2218   font-family: Gentium;
  2219   src: url(http://example.com/fonts/Gentium.ttf);
  2222 p { font-family: Gentium, serif; }
  2223 </pre>
  2225    <p>The user agent will download Gentium and use it when rendering text
  2226     within paragraph elements. If for some reason the site serving the font
  2227     is unavailable, the default serif font will be used.</p>
  2228   </div>
  2230   <p>A given set of <a href="#at-font-face-rule"><code>@font-face</code></a>
  2231    rules define a set of fonts available for use within the documents that
  2232    contain these rules. When font matching is done, fonts defined using these
  2233    rules are considered before other available fonts on a system.
  2235   <p>Downloaded fonts are only available to documents that reference them.
  2236    The process of activating these fonts must not make them available to
  2237    other applications or to documents that don't directly link to the same
  2238    font. User agent implementers might consider it convenient to use
  2239    downloaded fonts when rendering characters in other documents for which no
  2240    other available font exists as part of the <a
  2241    href="#system-font-fallback"><em>system font fallback</em></a> procedure.
  2242    However, this would cause a security leak since the contents of one page
  2243    would be able to affect other pages, something an attacker could use as an
  2244    attack vector. These restrictions do not affect caching behavior, fonts
  2245    are cached the same way other web resources are cached.
  2247   <p>This at-rule follows the forward-compatible parsing rules of CSS. Like
  2248    properties in a declaration block, declarations of any descriptors that
  2249    are not supported by the user agent must be ignored. <a
  2250    href="#at-font-face-rule"><code>@font-face</code></a> rules require a
  2251    font-family and src descriptor; if either of these are missing, the <a
  2252    href="#at-font-face-rule"><code>@font-face</code></a> rule is invalid and
  2253    must be ignored entirely.
  2255   <p>In cases where user agents have limited platform resources or implement
  2256    the ability to disable downloadable font resources, <a
  2257    href="#at-font-face-rule"><code>@font-face</code></a> rules must simply be
  2258    ignored; the behavior of individual descriptors as defined in this
  2259    specification should not be altered.
  2261   <h3 id=font-family-desc><span class=secno>4.2 </span>Font family: the <a
  2262    href="#descdef-font-family">font-family</a> descriptor</h3>
  2264   <table class=descdef>
  2265    <tbody>
  2266     <tr>
  2267      <td>Name:
  2269      <td><dfn id=descdef-font-family
  2270       title="font-family!!descriptor">font-family</dfn>
  2272     <tr>
  2273      <td>Value:
  2275      <td><a href="#family-name-value"><var>&lt;family-name&gt;</var></a>
  2277     <tr>
  2278      <td><em>Initial:</em>
  2280      <td>N/A
  2281   </table>
  2283   <p>This descriptor defines the font family name that will be used in all
  2284    CSS font family name matching. It is required for the <a
  2285    href="#at-font-face-rule"><code>@font-face</code></a> rule to be valid. It
  2286    overrides the font family names contained in the underlying font data. If
  2287    the font family name is the same as a font family available in a given
  2288    user's environment, it effectively hides the underlying font for documents
  2289    that use the stylesheet. This permits a web author to freely choose
  2290    font-family names without worrying about conflicts with font family names
  2291    present in a given user's environment. Likewise, platform substitutions
  2292    for a given font family name must not be used.
  2294   <h3 id=src-desc><span class=secno>4.3 </span>Font reference: the <a
  2295    href="#descdef-src">src</a> descriptor</h3>
  2297   <table class=descdef>
  2298    <tbody>
  2299     <tr>
  2300      <td>Name:
  2302      <td><dfn id=descdef-src>src</dfn>
  2304     <tr>
  2305      <td>Value:
  2307      <td>[ &lt;url> [format(&lt;string> #)]? | <a
  2308       href="#font-face-name-value"><var>&lt;font-face-name&gt;</var></a> ] #
  2310     <tr>
  2311      <td><em>Initial:</em>
  2313      <td>N/A
  2314   </table>
  2316   <p>This descriptor specifies the resource containing font data. It is
  2317    required for the <a href="#at-font-face-rule"><code>@font-face</code></a>
  2318    rule to be valid. Its value is a prioritized, comma-separated list of
  2319    external references or locally-installed font face names. When a font is
  2320    needed the user agent iterates over the set of references listed, using
  2321    the first one it can successfully activate. Fonts containing invalid data
  2322    or local font faces that are not found are ignored and the user agent
  2323    loads the next font in the list.
  2325   <p>As with other URLs in CSS, the URL may be relative, in which case it is
  2326    resolved relative to the location of the style sheet containing the <a
  2327    href="#at-font-face-rule"><code>@font-face</code></a> rule. In the case of
  2328    SVG fonts, the URL points to an element within a document containing SVG
  2329    font definitions. If the element reference is omitted, a reference to the
  2330    first defined font is implied. Similarly, font container formats that can
  2331    contain more than one font must load one and only one of the fonts for a
  2332    given <a href="#at-font-face-rule"><code>@font-face</code></a> rule.
  2333    Fragment identifiers are used to indicate which font to load. If a
  2334    container format lacks a defined fragment identifier scheme,
  2335    implementations should use a simple 1-based indexing scheme (e.g.
  2336    "font-collection#1" for the first font, "font-collection#2" for the second
  2337    font).
  2339   <pre>
  2340 src: url(fonts/simple.ttf);   /* load simple.ttf relative to stylesheet location */
  2341 src: url(/fonts/simple.ttf);  /* load simple.ttf from absolute location */
  2342 src: url(fonts.svg#simple);   /* load SVG font with id 'simple' */
  2343 </pre>
  2345   <p>External references consist of a URL, followed by an optional hint
  2346    describing the format of the font resource referenced by that URL. The
  2347    format hint contains a comma-separated list of format strings that denote
  2348    well-known font formats. Conformant user agents must skip downloading a
  2349    font resource if the format hints indicate only unsupported or unknown
  2350    font formats. If no format hints are supplied, the user agent should
  2351    download the font resource.
  2353   <pre>
  2354 /* load WOFF font if possible, otherwise use OpenType font */
  2355 @font-face {
  2356   font-family: bodytext;
  2357   src: url(ideal-sans-serif.woff) format("woff"),
  2358        url(basic-sans-serif.ttf) format("opentype");
  2360 </pre>
  2362   <p>Format strings defined by this specification:
  2364   <table class=data id=fontformats>
  2365    <thead>
  2366     <tr>
  2367      <th>String
  2369      <th>Font Format
  2371      <th>Common extensions
  2373    <tbody>
  2374     <tr>
  2375      <th>"woff"
  2377      <td><a href="http://www.w3.org/TR/WOFF/">WOFF (Web Open Font Format)</a>
  2379      <td>.woff
  2381     <tr>
  2382      <th>"truetype"
  2384      <td><a
  2385       href="http://www.microsoft.com/typography/otspec/default.htm">TrueType</a>
  2387      <td>.ttf
  2389     <tr>
  2390      <th>"opentype"
  2392      <td><a
  2393       href="http://www.microsoft.com/typography/otspec/default.htm">OpenType</a>
  2395      <td>.ttf, .otf
  2397     <tr>
  2398      <th>"embedded-opentype"
  2400      <td><a
  2401       href="http://www.w3.org/Submission/2008/SUBM-EOT-20080305/">Embedded
  2402       OpenType</a>
  2404      <td>.eot
  2406     <tr>
  2407      <th>"svg"
  2409      <td><a href="http://www.w3.org/TR/SVG/fonts.html">SVG Font</a>
  2411      <td>.svg, .svgz
  2412   </table>
  2414   <p>Given the overlap in common usage between TrueType and OpenType, the
  2415    format hints "truetype" and "opentype" must be considered as synonymous; a
  2416    format hint of "opentype" does not imply that the font contains Postscript
  2417    CFF style glyph data or that it contains OpenType layout information (see
  2418    <a href="#platform-props-to-css">Appendix A</a> for more background on
  2419    this).
  2421   <p>When authors would prefer to use a locally available copy of a given
  2422    font and download it if it's not, <code>local()</code> can be used. The
  2423    locally-installed <dfn
  2424    id=font-face-name-value><var>&lt;font-face-name&gt;</var></dfn> argument
  2425    to <code>local()</code> is a format-specific string that uniquely
  2426    identifies a single font face within a larger family. The syntax for a <a
  2427    href="#font-face-name-value"><var>&lt;font-face-name&gt;</var></a> is a
  2428    unique font face name enclosed by "local(" and ")". The name can
  2429    optionally be enclosed in quotes. If unquoted, the unquoted font family
  2430    name processing conventions apply; the name must be a sequence of
  2431    identifiers separated by whitespace which is converted to a string by
  2432    joining the identifiers together separated by a single space.
  2434   <pre>
  2435 /* regular face of Gentium */
  2436 @font-face {
  2437   font-family: MyGentium;
  2438   src: local(Gentium),   /* use locally available Gentium */
  2439        url(Gentium.ttf); /* otherwise, download it */
  2441 </pre>
  2443   <p>For OpenType and TrueType fonts, this string is used to match only the
  2444    Postscript name or the full font name in the name table of locally
  2445    available fonts. Which type of name is used varies by platform and font,
  2446    so authors should include both of these names to assure proper matching
  2447    across platforms. Platform substitutions for a given font name must not be
  2448    used.
  2450   <pre>
  2451 /* bold face of Gentium */
  2452 @font-face {
  2453   font-family: MyGentium;
  2454   src: local(Gentium Bold),   /* full font name */
  2455        local(Gentium-Bold),   /* Postscript name */
  2456        url(GentiumBold.ttf);  /* otherwise, download it */
  2457   font-weight: bold;
  2459 </pre>
  2461   <p>Just as a <a href="#at-font-face-rule"><code>@font-face</code></a> rule
  2462    specifies the characteristics of a single font within a family, the unique
  2463    name used with <code>local()</code> specifies a single font, not an entire
  2464    font family. Defined in terms of OpenType font data, the Postscript name
  2465    is found in the font's <a
  2466    href="http://www.microsoft.com/typography/otspec/name.htm">name table</a>,
  2467    in the name record with nameID = 6 (see <a href="#OPENTYPE"
  2468    rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a> for more details). The
  2469    Postscript name is the commonly used key for all fonts on OSX and for
  2470    Postscript CFF fonts under Windows. The full font name (nameID = 4) is
  2471    used as a unique key for fonts with TrueType glyphs on Windows.
  2473   <p>For OpenType fonts with multiple localizations of the full font name,
  2474    the US English version is used (language ID = 0x409 for Windows and
  2475    language ID = 0 for Macintosh) or the first localization when a US English
  2476    full font name is not available (the OpenType specification recommends
  2477    that <a href="http://www.microsoft.com/typography/otspec/recom.htm">all
  2478    fonts minimally include US English names</a>). User agents that also match
  2479    other full font names, e.g. matching the Dutch name when the current
  2480    system locale is set to Dutch, are considered non-conformant. This is done
  2481    not to prefer English but to avoid matching inconsistencies across font
  2482    versions and OS localizations, since font style names (e.g. "Bold") are
  2483    frequently localized into many languages and the set of localizations
  2484    available varies widely across platform and font version. User agents that
  2485    match a concatenation of family name (nameID = 1) with style name (nameID
  2486    = 2) are considered non-conformant.
  2488   <p>This also allows for referencing faces that belong to larger families
  2489    that cannot otherwise be referenced.
  2491   <div class=example>
  2492    <p>Use a local font or reference an SVG font in another document:</p>
  2494    <pre>
  2495 @font-face {
  2496   font-family: Headline;
  2497   src: local(Futura-Medium),
  2498        url(fonts.svg#MyGeometricModern) format("svg");
  2500 </pre>
  2502    <p>Create an alias for local Japanese fonts on different platforms:</p>
  2504    <pre>
  2505 @font-face {
  2506   font-family: jpgothic;
  2507   src: local(HiraKakuPro-W3), local(Meiryo), local(IPAPGothic);
  2509 </pre>
  2511    <p>Reference a font face that cannot be matched within a larger family:</p>
  2513    <pre>
  2514 @font-face {
  2515   font-family: Hoefler Text Ornaments;
  2516   /* has the same font properties as Hoefler Text Regular */
  2517   src: local(HoeflerText-Ornaments);
  2519 </pre>
  2521    <p>Since localized fullnames never match, a document with the header style
  2522     rules below would always render using the default serif font, regardless
  2523     whether a particular system locale parameter is set to Finnish or not:</p>
  2525    <pre>
  2526 @font-face {
  2527   font-family: SectionHeader;
  2528   src: local("Arial Lihavoitu");  /* Finnish fullname for Arial Bold, should fail */
  2529   font-weight: bold;
  2532 h2 { font-family: SectionHeader, serif; }
  2533 </pre>
  2535    <p>A conformant user agent would never load the font ‘<code
  2536     class=css>gentium.eot</code>’ in the example below, since it is
  2537     included in the first definition of the ‘<a href="#descdef-src"><code
  2538     class=property>src</code></a>’ descriptor which is overridden by the
  2539     second definition in the same <a
  2540     href="#at-font-face-rule"><code>@font-face</code></a> rule:</p>
  2542    <pre>
  2543 @font-face {
  2544   font-family: MainText;
  2545   src: url(gentium.eot); /* for use with older non-conformant user agents */
  2546   src: local("Gentium"), url(gentium.ttf);  /* Overrides src definition */
  2548 </pre>
  2549   </div>
  2551   <h3 id=font-prop-desc><span class=secno>4.4 </span>Font property
  2552    descriptors: the <a href="#descdef-font-style">font-style</a>, <a
  2553    href="#descdef-font-weight">font-weight</a>, <a
  2554    href="#descdef-font-stretch">font-stretch</a> descriptors</h3>
  2556   <table class=descdef>
  2557    <tbody>
  2558     <tr>
  2559      <td>Name:
  2561      <td><dfn id=descdef-font-style
  2562       title="font-style!!descriptor">font-style</dfn>
  2564     <tr>
  2565      <td>Value:
  2567      <td>normal | italic | oblique
  2569     <tr>
  2570      <td><em>Initial:</em>
  2572      <td>normal
  2573   </table>
  2575   <table class=descdef>
  2576    <tbody>
  2577     <tr>
  2578      <td>Name:
  2580      <td><dfn id=descdef-font-weight
  2581       title="font-weight!!descriptor">font-weight</dfn>
  2583     <tr>
  2584      <td>Value:
  2586      <td>normal | bold | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900
  2588     <tr>
  2589      <td><em>Initial:</em>
  2591      <td>normal
  2592   </table>
  2594   <table class=descdef>
  2595    <tbody>
  2596     <tr>
  2597      <td>Name:
  2599      <td><dfn id=descdef-font-stretch
  2600       title="font-stretch!!descriptor">font-stretch</dfn>
  2602     <tr>
  2603      <td>Value:
  2605      <td>normal | ultra-condensed | extra-condensed | condensed |
  2606       semi-condensed | semi-expanded | expanded | extra-expanded |
  2607       ultra-expanded
  2609     <tr>
  2610      <td><em>Initial:</em>
  2612      <td>normal
  2613   </table>
  2615   <p>These descriptors define the characteristics of a font face and are used
  2616    in the process of matching styles to specific faces. For a font family
  2617    defined with several <a
  2618    href="#at-font-face-rule"><code>@font-face</code></a> rules, user agents
  2619    can either download all faces in the family or use these descriptors to
  2620    selectively download font faces that match actual styles used in document.
  2621    The values for these descriptors are the same as those for the
  2622    corresponding font properties except that relative keywords are not
  2623    allowed, ‘<a href="#bolder"><code class=property>bolder</code></a>’
  2624    and ‘<a href="#lighter"><code class=property>lighter</code></a>’. If
  2625    these descriptors are omitted, initial values are assumed.
  2627   <p>The value for these font face style attributes is used in place of the
  2628    style implied by the underlying font data. This allows authors to combine
  2629    faces in flexible combinations, even in situations where the original font
  2630    data was arranged differently. User agents that implement synthetic
  2631    bolding and obliquing must only apply synthetic styling in cases where the
  2632    font descriptors imply this is needed, rather than based on the style
  2633    attributes implied by the font data.
  2635   <h3 id=unicode-range-desc><span class=secno>4.5 </span>Character range: the
  2636    <a href="#descdef-unicode-range">unicode-range</a> descriptor</h3>
  2638   <table class=descdef>
  2639    <tbody>
  2640     <tr>
  2641      <td>Name:
  2643      <td><dfn id=descdef-unicode-range>unicode-range</dfn>
  2645     <tr>
  2646      <td>Value:
  2648      <td><a href="#urange-value"><var>&lt;urange&gt;</var></a> #
  2650     <tr>
  2651      <td><em>Initial:</em>
  2653      <td>U+0-10FFFF
  2654   </table>
  2656   <p>This descriptor defines the set of Unicode codepoints that may be
  2657    supported by the font face for which it is declared. The descriptor value
  2658    is a comma-delimited list of Unicode range (<a
  2659    href="#urange-value"><var>&lt;urange&gt;</var></a>) values. The union of
  2660    these ranges defines the set of codepoints that serves as a hint for user
  2661    agents when deciding whether or not to download a font resource for a
  2662    given text run.
  2664   <p>Each <dfn id=urange-value><var>&lt;urange&gt;</var></dfn> value is a <a
  2665    href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><code
  2666    title="UNICODE-RANGE token">UNICODE-RANGE</code></a> token made up of a
  2667    "U+" or "u+" prefix followed by a codepoint range in one of the three
  2668    forms listed below. Ranges that do not fit one of the these forms are
  2669    invalid and cause the declaration to be ignored.
  2671   <dl>
  2672    <dt>single codepoint (e.g. U+416)
  2674    <dd>a valid Unicode codepoint, represented as one to six hexadecimal
  2675     digits
  2677    <dt>interval range (e.g. U+400-4ff)
  2679    <dd>represented as two hyphen-separated valid Unicode codepoints
  2680     indicating the inclusive start and end codepoints of a range
  2682    <dt>wildcard range (e.g. U+4??)
  2684    <dd>defined by the set of codepoints implied when trailing ‘<code
  2685     class=css>?</code>’ characters signify any hexadeximal digit
  2686   </dl>
  2688   <p>Individual codepoints are written using hexadecimal values that
  2689    correspond to <a href="http://www.unicode.org/charts/">Unicode character
  2690    codepoints</a>. Valid Unicode codepoint values vary between 0 and 10FFFF
  2691    inclusive. Digit values of codepoints are ASCII case-insensitive. For
  2692    interval ranges, the start and end codepoints are valid Unicode values and
  2693    the end codepoint is greater than or equal to the start codepoint.
  2695   <p>Wildcard ranges specified with ‘?’ that lack an initial digit (e.g.
  2696    "U+???") are valid and equivalent to a wildcard range with an initial zero
  2697    digit (e.g. "U+0???" = "U+0000-0FFF"). Wildcard ranges that extend beyond
  2698    the range of valid Unicode codepoints are invalid. Because of this, the
  2699    maximum number of trailing ‘<code class=css>?</code>’ wildcard
  2700    characters is five, even though the <a
  2701    href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><code
  2702    title="UNICODE-RANGE token">UNICODE-RANGE</code></a> token accepts six.
  2704   <p>Within the comma-delimited list of Unicode ranges in a ‘<a
  2705    href="#descdef-unicode-range"><code
  2706    class=property>unicode-range</code></a>’ descriptor declaration, ranges
  2707    may overlap. The union of these ranges defines the set of codepoints for
  2708    which the corresponding font may be used. User agents must not download or
  2709    use the font for codepoints outside this set. User agents may normalize
  2710    the list of ranges into a list that is different but represents the same
  2711    set of codepoints.
  2713   <p>The associated font might not contain glyphs for the entire set of
  2714    codepoints defined by the ‘<a href="#descdef-unicode-range"><code
  2715    class=property>unicode-range</code></a>’ descriptor. When the font is
  2716    used, the <dfn id=effective-character-map>effective character map</dfn> is
  2717    the intersection of the codepoints defined by ‘<a
  2718    href="#descdef-unicode-range"><code
  2719    class=property>unicode-range</code></a>’ with the font's <a
  2720    href="#character-map"><em>character map</em></a>. This allows authors to
  2721    define supported ranges in terms of broad ranges without worrying about
  2722    the precise codepoint ranges supported by the underlying font.
  2724   <h3 id=composite-fonts><span class=secno>4.6 </span>Using character ranges
  2725    to define composite fonts</h3>
  2727   <p>Multiple <a href="#at-font-face-rule"><code>@font-face</code></a> rules
  2728    with different unicode ranges for the same family and style descriptor
  2729    values can be used to create composite fonts that mix the glyphs from
  2730    different fonts for different scripts. This can be used to combine fonts
  2731    that only contain glyphs for a single script (e.g. Latin, Greek, Cyrillic)
  2732    or it can be used by authors as a way of segmenting a font into fonts for
  2733    commonly used characters and less frequently used characters. Since the
  2734    user agent will only pull down the fonts it needs this helps reduce page
  2735    bandwidth.
  2737   <p>If the unicode ranges overlap for a set of <a
  2738    href="#at-font-face-rule"><code>@font-face</code></a> rules with the same
  2739    family and style descriptor values, the rules are ordered in the reverse
  2740    order they were defined; the last rule defined is the first to be checked
  2741    for a given character.
  2743   <p>Example ranges for specific languages or characters:
  2745   <dl>
  2746    <dt>unicode-range: U+A5;
  2748    <dd>a single code point, the yen/yuan symbol
  2750    <dt>unicode-range: U+0-7F;
  2752    <dd>code range for basic ASCII characters
  2754    <dt>unicode-range: U+590-5ff;
  2756    <dd>code range for Hebrew characters
  2758    <dt>unicode-range: U+A5, U+4E00-9FFF, U+30??, U+FF00-FF9F;
  2760    <dd>code range for Japanese kanji, hiragana and katakana characters plus
  2761     yen/yuan symbol
  2762   </dl>
  2764   <div class=example>
  2765    <p>The BBC provides news services in a wide variety of languages, many
  2766     that are not well supported across all platforms. Using an <a
  2767     href="#at-font-face-rule"><code>@font-face</code></a> rule, the BBC could
  2768     provide a font for any of these languages, as it already does via a
  2769     manual font download.</p>
  2771    <pre>
  2772 @font-face {
  2773   font-family: BBCBengali;
  2774   src: url(fonts/BBCBengali.ttf) format("opentype");
  2775   unicode-range: U+00-FF, U+980-9FF;
  2777 </pre>
  2778   </div>
  2780   <div class=example>
  2781    <p>Technical documents often require a wide range of symbols. The STIX
  2782     Fonts project is one project aimed at providing fonts to support a wide
  2783     range of technical typesetting in a standardized way. The example below
  2784     shows the use of a font that provides glyphs for many of the mathematical
  2785     and technical symbol ranges within Unicode:</p>
  2787    <pre>
  2788 @font-face {
  2789   font-family: STIXGeneral;
  2790   src: local(STIXGeneral), url(/stixfonts/STIXGeneral.otf);
  2791   unicode-range: U+000-49F, U+2000-27FF, U+2900-2BFF, U+1D400-1D7FF;
  2793 </pre>
  2794   </div>
  2796   <div class=example>
  2797    <p>This example shows how an author can override the glyphs used for Latin
  2798     characters in a Japanese font with glyphs from a different font. The
  2799     first rule specifies no range so it defaults to the entire range. The
  2800     range specified in the second rule overlaps but takes precedence because
  2801     it is defined later.</p>
  2803    <pre>
  2804 @font-face {
  2805   font-family: JapaneseWithGentium;
  2806   src: local(MSMincho);
  2807   /* no range specified, defaults to entire range */
  2810 @font-face {
  2811   font-family: JapaneseWithGentium;
  2812   src: url(../fonts/Gentium.ttf);
  2813   unicode-range: U+0-2FF;
  2815 </pre>
  2816   </div>
  2818   <div class=example>
  2819    <p>Consider a family constructed to optimize bandwidth by separating out
  2820     Latin, Japanese and other characters into different font files:</p>
  2822    <pre>
  2823 /* fallback font - size: 4.5MB */
  2824 @font-face {
  2825   font-family: DroidSans;
  2826   src: url(DroidSansFallback.ttf);
  2827   /* no range specified, defaults to entire range */
  2830 /* Japanese glyphs - size: 1.2MB */
  2831 @font-face {
  2832   font-family: DroidSans;
  2833   src: url(DroidSansJapanese.ttf);
  2834   unicode-range: U+3000-9FFF, U+ff??;
  2837 /* Latin, Greek, Cyrillic along with some
  2838    punctuation and symbols - size: 190KB */
  2839 @font-face {
  2840   font-family: DroidSans;
  2841   src: url(DroidSans.ttf);
  2842   unicode-range: U+000-5FF, U+1e00-1fff, U+2000-2300;
  2844 </pre>
  2846    <p>For simple Latin text, only the font for Latin characters is
  2847     downloaded:</p>
  2849    <pre>
  2850 body { font-family: DroidSans; }
  2852 &lt;p>This is that&lt;/p>
  2853 </pre>
  2855    <p>In this case the user agent first checks the unicode-range for the font
  2856     containing Latin characters (DroidSans.ttf). Since all the characters
  2857     above are in the range U+0-5FF, the user agent downloads the font and
  2858     renders the text with that font.</p>
  2860    <p>Next, consider text that makes use of an arrow character (⇨):</p>
  2862    <pre>
  2863 &lt;p>This &amp;#x21e8; that&lt;p>
  2864 </pre>
  2866    <p>The user agent again first checks the unicode-range of the font
  2867     containing Latin characters. Since U+2000-2300 includes the arrow code
  2868     point (U+21E8), the user agent downloads the font. For this character
  2869     however the Latin font does not have a matching glyph, so the effective
  2870     unicode-range used for font matching excludes this code point. Next, the
  2871     user agent evaluates the Japanese font. The unicode-range for the
  2872     Japanese font, U+3000-9FFF and U+ff??, does not include U+21E8, so the
  2873     user agent does not download the Japanese font. Next the fallback font is
  2874     considered. The <a href="#at-font-face-rule"><code>@font-face</code></a>
  2875     rule for the fallback font does not define unicode-range so its value
  2876     defaults to the range of all Unicode code points. The fallback font is
  2877     downloaded and used to render the arrow character.</p>
  2878   </div>
  2880   <h3 id=font-rend-desc><span class=secno>4.7 </span>Font features: the <a
  2881    href="#descdef-font-variant">font-variant</a> and <a
  2882    href="#descdef-font-feature-settings">font-feature-settings</a>
  2883    descriptors</h3>
  2885   <table class=descdef>
  2886    <tbody>
  2887     <tr>
  2888      <td>Name:
  2890      <td><dfn id=descdef-font-variant
  2891       title="font-variant!!descriptor">font-variant</dfn>
  2893     <tr>
  2894      <td>Value:
  2896      <td><a href="#font-variant-normal-value"
  2897       title="normal!!font-variant">normal</a> | <a
  2898       href="#font-variant-none-value" title="none!!font-variant">none</a> | [
  2899       <a href="#common-lig-values"><var>&lt;common-lig-values&gt;</var></a>
  2900       || <a
  2901       href="#discretionary-lig-values"><var>&lt;discretionary-lig-values&gt;</var></a>
  2902       || <a
  2903       href="#historical-lig-values"><var>&lt;historical-lig-values&gt;</var></a>
  2904       || <a
  2905       href="#contextual-alt-values"><var>&lt;contextual-alt-values&gt;</var></a>
  2906       || <a href="#stylistic"><var
  2907       title=stylistic>stylistic(&lt;feature-value-name&gt;)</var></a> || <a
  2908       href="#historical-forms"><var>historical-forms</var></a> || <a
  2909       href="#styleset"><var
  2910       title=styleset>styleset(&lt;feature-value-name&gt; #)</var></a> || <a
  2911       href="#character-variant"><var
  2912       title=character-variant>character-variant(&lt;feature-value-name&gt;
  2913       #)</var></a> || <a href="#swash"><var
  2914       title=swash>swash(&lt;feature-value-name&gt;)</var></a> || <a
  2915       href="#ornaments"><var
  2916       title=ornaments>ornaments(&lt;feature-value-name&gt;)</var></a> || <a
  2917       href="#annotation"><var
  2918       title=annotation>annotation(&lt;feature-value-name&gt;)</var></a> || [
  2919       <a href="#small-caps"><i>small-caps</i></a> | <a
  2920       href="#all-small-caps"><i>all-small-caps</i></a> | <a
  2921       href="#petite-caps"><i>petite-caps</i></a> | <a
  2922       href="#all-petite-caps"><i>all-petite-caps</i></a> | <a
  2923       href="#unicase"><i>unicase</i></a> | <a
  2924       href="#titling-caps"><i>titling-caps</i></a> ] || <a
  2925       href="#numeric-figure-values"><var>&lt;numeric-figure-values&gt;</var></a>
  2926       || <a
  2927       href="#numeric-spacing-values"><var>&lt;numeric-spacing-values&gt;</var></a>
  2928       || <a
  2929       href="#numeric-fraction-values"><var>&lt;numeric-fraction-values&gt;</var></a>
  2930       || <a href="#ordinal"><i>ordinal</i></a> || <a
  2931       href="#slashed-zero"><i>slashed-zero</i></a> || <a
  2932       href="#east-asian-variant-values"><var>&lt;east-asian-variant-values&gt;</var></a>
  2933       || <a
  2934       href="#east-asian-width-values"><var>&lt;east-asian-width-values&gt;</var></a>
  2935       || <a href="#ruby"><i>ruby</i></a> ]
  2937     <tr>
  2938      <td><em>Initial:</em>
  2940      <td>normal
  2941   </table>
  2943   <table class=descdef>
  2944    <tbody>
  2945     <tr>
  2946      <td>Name:
  2948      <td><dfn id=descdef-font-feature-settings
  2949       title="font-feature-settings!!descriptor">font-feature-settings</dfn>
  2951     <tr>
  2952      <td>Value:
  2954      <td><a href="#font-feature-settings-normal-value"
  2955       title="normal!!font-feature-settings">normal</a> | <a
  2956       href="#feature-tag-value"><var>&lt;feature-tag-value&gt;</var></a> #
  2958     <tr>
  2959      <td><em>Initial:</em>
  2961      <td>normal
  2962   </table>
  2964   <p>These descriptors define initial settings that apply when the font
  2965    defined by an <a href="#at-font-face-rule"><code>@font-face</code></a>
  2966    rule is rendered. They do not affect font selection. Values are identical
  2967    to those defined for the corresponding <a href="#propdef-font-variant"
  2968    title="font-variant!!property">‘<code
  2969    class=property>font-variant</code>’</a> and <a
  2970    href="#propdef-font-feature-settings"
  2971    title="font-feature-settings!!property">‘<code
  2972    class=property>font-feature-settings</code>’</a> properties defined
  2973    below except that the value ‘<code class=property>inherit</code>’ is
  2974    omitted. When multiple font feature descriptors or properties are used,
  2975    the cumulative effect on text rendering is detailed in the section <a
  2976    href="#font-feature-resolution">Font Feature Resolution</a> below. In
  2977    cases where specific values define synthesized fallback for certain <a
  2978    href="#propdef-font-variant" title="font-variant!!property">‘<code
  2979    class=property>font-variant</code>’</a> subproperties, the same
  2980    synthesized fallback applies when used within those values are used with
  2981    the <a href="#descdef-font-style" title="font-style!!descriptor">‘<code
  2982    class=property>font-variant</code>’</a> descriptor.
  2984   <h3 id=font-face-loading><span class=secno>4.8 </span>Font loading
  2985    guidelines</h3>
  2987   <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule is
  2988    designed to allow lazy loading of font resources that are only downloaded
  2989    when used within a document. A stylesheet can include <a
  2990    href="#at-font-face-rule"><code>@font-face</code></a> rules for a library
  2991    of fonts of which only a select set are used; user agents must only
  2992    download those fonts that are referred to within the style rules
  2993    applicable to a given page. User agents that download all fonts defined in
  2994    <a href="#at-font-face-rule"><code>@font-face</code></a> rules without
  2995    considering whether those fonts are in fact used within a page are
  2996    considered non-conformant. In cases where a font might be downloaded in
  2997    character fallback cases, user agents may download a font if it's
  2998    contained within the computed value of <a href="#propdef-font-family"
  2999    title="font-family!!property">‘<code
  3000    class=property>font-family</code>’</a> for a given text run.
  3002   <pre>
  3003 @font-face {
  3004   font-family: GeometricModern;
  3005   src: url(font.ttf);
  3008 p {
  3009   /* font will be downloaded for pages with p elements */
  3010   font-family: GeometricModern, sans-serif;
  3013 h2 {
  3014   /* font may be downloaded for pages with h2 elements, even if Futura is available locally */
  3015   font-family: Futura, GeometricModern, sans-serif;
  3017 </pre>
  3019   <p>In cases where textual content is loaded before downloadable fonts are
  3020    available, user agents may render text as it would be rendered if
  3021    downloadable font resources are not available or they may render text
  3022    transparently with fallback fonts to avoid a flash of text using a
  3023    fallback font. In cases where the font download fails user agents must
  3024    display text, simply leaving transparent text is considered non-conformant
  3025    behavior. Authors are advised to use fallback fonts in their font lists
  3026    that closely match the metrics of the downloadable fonts to avoid large
  3027    page reflows where possible.
  3029   <h3 id=same-origin-restriction><span class=secno>4.9 </span>Same-origin
  3030    restriction for fonts</h3>
  3032   <h4 id=default-same-origin-restriction><span class=secno>4.9.1
  3033    </span>Default same-origin restriction</h4>
  3034   <!-- TPAC 2011 Resolution to require same-origin restriction for loading fonts:
  3035   http://lists.w3.org/Archives/Public/www-style/2011Nov/0711.html
  3036   http://www.w3.org/2011/10/31-webapps-minutes.html#item02
  3037 -->
  3039   <p>User agents must implement a same-origin restriction when loading fonts
  3040    via the <a href="#at-font-face-rule"><code>@font-face</code></a>
  3041    mechanism. This restriction limits the loading of fonts for a given
  3042    document to fonts loaded from the same origin. Fonts can only be loaded
  3043    via the same host, port, and method combination as the containing
  3044    document, using the <a
  3045    href="http://www.w3.org/TR/html5/browsers.html#origin">origin matching
  3046    algorithm</a> described in the <a href="#HTML5"
  3047    rel=biblioentry>[HTML5]<!--{{!HTML5}}--></a> specification. The origin of
  3048    the stylesheet containing <a
  3049    href="#at-font-face-rule"><code>@font-face</code></a> rules is not used
  3050    when deciding whether a font is same origin or not, only the origin of the
  3051    containing document is used. The restriction applies to all font types.
  3053   <p>Given a document located at http://example.com/page.html, fonts defined
  3054    with ‘<a href="#descdef-src"><code class=property>src</code></a>’
  3055    definitions considered cross origin must not be loaded:
  3057   <pre>
  3058 /* same origin (i.e. domain, scheme, port match document) */
  3059 src: url(fonts/simple.ttf);
  3060 src: url(//fonts/simple.ttf);
  3062 /* cross origin, different scheme */
  3063 src: url(https://example.com/fonts/simple.ttf);
  3065 /* cross origin, different domain */
  3066 src: url(http://another.example.com/fonts/simple.ttf);
  3067 </pre>
  3069   <h4 id=allowing-cross-origin-font-loading><span class=secno>4.9.2
  3070    </span>Allowing cross-origin font loading</h4>
  3072   <p>User agents must also implement the ability to relax this restriction
  3073    using cross-site origin controls <a href="#CORS"
  3074    rel=biblioentry>[CORS]<!--{{!CORS}}--></a> for fonts loaded via HTTP.
  3075    Sites can explicitly allow cross-site downloading of font data using the
  3076    <code>Access-Control-Allow-Origin</code> HTTP header. For other schemes,
  3077    no explicit relaxation mechanism is defined or required.
  3079   <p>For font loads, user agents must use the <a
  3080    href="http://www.w3.org/TR/html5/infrastructure.html#cors-enabled-fetch">potentially
  3081    CORS-enabled fetch</a> method defined by the <a href="#HTML5"
  3082    rel=biblioentry>[HTML5]<!--{{!HTML5}}--></a> specification for URL's
  3083    defined within @font-face rules. When fetching, user agents must use
  3084    "Anonymous" mode, set the referrer source to the stylesheet's URL and set
  3085    the origin to the URL of the containing document.
  3087   <h2 id=font-matching-algorithm><span class=secno>5 </span>Font Matching
  3088    Algorithm</h2>
  3090   <p>The algorithm below describes how fonts are associated with individual
  3091    runs of text. For each character in the run a font family is chosen and a
  3092    particular font face is selected containing a glyph for that character.
  3094   <h3 id=font-family-casing><span class=secno>5.1 </span>Case sensitivity of
  3095    font family names</h3>
  3097   <p>As part of the font matching algorithm outlined below, user agents must
  3098    match font family names used in style rules with actual font family names
  3099    contained in fonts available in a given environment or with font family
  3100    names defined in <a href="#at-font-face-rule"><code>@font-face</code></a>
  3101    rules. User agents must match these names case insensitively, using the
  3102    "Default Caseless Matching" algorithm outlined in the Unicode
  3103    specification <a href="#UNICODE6"
  3104    rel=biblioentry>[UNICODE6]<!--{{!UNICODE6}}--></a>. This algorithm is
  3105    detailed in section 3.13 entitled "Default Case Algorithms". Specifically,
  3106    the algorithm must be applied without normalizing the strings involved and
  3107    without applying any language-specific tailorings. The case folding method
  3108    specified by this algorithm uses the case mappings with status field
  3109    ‘<code class=property>C</code>’ or ‘<code class=property>F</code>’
  3110    in the CaseFolding.txt file of the Unicode Character Database.
  3112   <p class=note> For authors this means that font family names are matched
  3113    case insensitively, whether those names exist in a platform font or in the
  3114    <a href="#at-font-face-rule"><code>@font-face</code></a> rules contained
  3115    in a stylesheet. Authors should take care to ensure that names use a
  3116    character sequence consistent with the actual font family name,
  3117    particularly when using combining characters such as diacritical marks.
  3118    For example, a family name that contains an uppercase A (U+0041) followed
  3119    by a combining ring (U+030A) will <strong>not</strong> match a name that
  3120    looks identical but which uses the precomposed lowercase a-ring character
  3121    (U+00E5) instead of the combining sequence.
  3123   <p class=note> Implementors should take care to verify that a given
  3124    caseless string comparison implementation uses this precise algorithm and
  3125    not assume that a given platform string matching routine follows it, as
  3126    many of these have locale-specific behavior or use some level of string
  3127    normalization.
  3129   <h3 id=font-style-matching><span class=secno>5.2 </span>Matching font
  3130    styles</h3>
  3132   <p>The procedure for choosing a font for a given character in a run of text
  3133    consists of iterating over the font families named by the <a
  3134    href="#propdef-font-family" title="font-family!!property">‘<code
  3135    class=property>font-family</code>’</a> property, selecting a font face
  3136    with the appropriate style based on other font properties and then
  3137    determining whether a glyph exists for the given character. This is done
  3138    using the <dfn id=character-map>character map</dfn> of the font, data
  3139    which maps characters to the default glyph for that character. A font is
  3140    considered to <dfn id=support>support</dfn> a given character if (1) the
  3141    character is contained in the font's <a
  3142    href="#character-map"><em>character map</em></a> and (2) if required by
  3143    the containing script, shaping information is available for that
  3144    character.
  3146   <p>Some legacy fonts may include a given character in the <a
  3147    href="#character-map"><em>character map</em></a> but lack the shaping
  3148    information (e.g. <a
  3149    href="http://www.microsoft.com/typography/otspec/ttochap1.htm">OpenType
  3150    layout tables</a> or <a
  3151    href="http://scripts.sil.org/cms/scripts/page.php?site_id=projects&amp;item_id=graphite_techAbout">Graphite
  3152    tables</a>) necessary for correctly rendering text runs containing that
  3153    character.
  3155   <p>Codepoint sequences consisting of a base character followed by a
  3156    sequence of combining characters are treated slightly differently, see the
  3157    section on <a href="#cluster-matching">cluster matching</a> below.
  3159   <p>For this procedure, the <dfn id=default-face>default face</dfn> for a
  3160    given font family is defined to be the face that would be selected if all
  3161    font style properties were set to their initial value.
  3163   <ol id=fontmatchingalg>
  3164    <li>Using the computed font property values for a given element, the user
  3165     agent starts with the first family name specified by the <a
  3166     href="#propdef-font-family" title="font-family!!property">‘<code
  3167     class=property>font-family</code>’</a> property.
  3169    <li>If the family name is a generic family keyword, the user agent looks
  3170     up the appropriate font family name to be used. User agents may choose
  3171     the generic font family to use based on the language of the containing
  3172     element or the Unicode range of the character.
  3174    <li>For other family names, the user agent attempts to find the family
  3175     name among fonts defined via <a
  3176     href="#at-font-face-rule"><code>@font-face</code></a> rules and then
  3177     among available system fonts, matching names with a <a
  3178     href="#font-family-casing">case-insensitive comparison</a> as outlined in
  3179     the section above. On systems containing fonts with multiple localized
  3180     font family names, user agents must match any of these names independent
  3181     of the underlying system locale or platform API used. If the font
  3182     resources defined for a given face in an <a
  3183     href="#at-font-face-rule"><code>@font-face</code></a> rule are either not
  3184     available or contain invalid font data, then the face should be treated
  3185     as not present in the family. If no faces are present for a family
  3186     defined via <a href="#at-font-face-rule"><code>@font-face</code></a>
  3187     rules, the family should be treated as missing; matching a platform font
  3188     with the same name must not occur in this case.
  3190    <li>If a font family match occurs, the user agent assembles the set of
  3191     font faces in that family and then narrows the set to a single face using
  3192     other font properties in the order given below. A group of faces defined
  3193     via <a href="#at-font-face-rule"><code>@font-face</code></a> rules with
  3194     identical font descriptor values but differing ‘<a
  3195     href="#descdef-unicode-range"><code
  3196     class=property>unicode-range</code></a>’ values are considered to be a
  3197     single <dfn id=composite-face>composite face</dfn> for this step:
  3198     <ol id=fontstylematchingalg>
  3199      <li><a href="#propdef-font-stretch"
  3200       title="font-stretch!!property">‘<code
  3201       class=property>font-stretch</code>’</a> is tried first. If the
  3202       matching set contains faces with width values matching the <a
  3203       href="#propdef-font-stretch" title="font-stretch!!property">‘<code
  3204       class=property>font-stretch</code>’</a> value, faces with other width
  3205       values are removed from the matching set. If there is no face that
  3206       exactly matches the width value the nearest width is used instead. If
  3207       the value of <a href="#propdef-font-stretch"
  3208       title="font-stretch!!property">‘<code
  3209       class=property>font-stretch</code>’</a> is <a
  3210       href="#font-stretch-normal-value" title="normal!!font-stretch">‘<code
  3211       class=property>normal</code>’</a> or one of the condensed values,
  3212       narrower width values are checked first, then wider values. If the
  3213       value of <a href="#propdef-font-stretch"
  3214       title="font-stretch!!property">‘<code
  3215       class=property>font-stretch</code>’</a> is one of the expanded
  3216       values, wider values are checked first, followed by narrower values.
  3217       Once the closest matching width has been determined by this process,
  3218       faces with other widths are removed from the matching set.
  3220      <li><a href="#propdef-font-style" title="font-style!!property">‘<code
  3221       class=property>font-style</code>’</a> is tried next. If the value of
  3222       <a href="#propdef-font-style" title="font-style!!property">‘<code
  3223       class=property>font-style</code>’</a> is ‘<a href="#italic"><code
  3224       class=property>italic</code></a>’, italic faces are checked first,
  3225       then oblique, then normal faces. If the value is ‘<a
  3226       href="#oblique"><code class=property>oblique</code></a>’, oblique
  3227       faces are checked first, then italic faces and then normal faces. If
  3228       the value is <a href="#font-style-normal-value"
  3229       title="normal!!font-style">‘<code
  3230       class=property>normal</code>’</a>, normal faces are checked first,
  3231       then oblique faces, then italic faces. Faces with other style values
  3232       are excluded from the matching set. User agents are permitted to
  3233       distinguish between italic and oblique faces within platform font
  3234       families but this is not required, so all italic or oblique faces may
  3235       be treated as italic faces. However, within font families defined via
  3236       <a href="#at-font-face-rule"><code>@font-face</code></a> rules, italic
  3237       and oblique faces must be distinguished using the value of the <a
  3238       href="#descdef-font-style" title="font-style!!descriptor">‘<code
  3239       class=property>font-style</code>’</a> descriptor. For families that
  3240       lack any italic or oblique faces, users agents may create artificial
  3241       oblique faces, if this is permitted by the value of the ‘<a
  3242       href="#propdef-font-synthesis"><code
  3243       class=property>font-synthesis</code></a>’ property.
  3245      <li><a href="#propdef-font-weight"
  3246       title="font-weight!!property">‘<code
  3247       class=property>font-weight</code>’</a> is matched next, so it will
  3248       always reduce the matching set to a single font face. If bolder/lighter
  3249       relative weights are used, the effective weight is calculated based on
  3250       the inherited weight value, as described in the definition of the <a
  3251       href="#propdef-font-weight" title="font-weight!!property">‘<code
  3252       class=property>font-weight</code>’</a> property. Given the desired
  3253       weight and the weights of faces in the matching set after the steps
  3254       above, if the desired weight is available that face matches. Otherwise,
  3255       a weight is chosen using the rules below:
  3256       <ul>
  3257        <li>If the desired weight is less than 400, weights below the desired
  3258         weight are checked in descending order followed by weights above the
  3259         desired weight in ascending order until a match is found.
  3261        <li>If the desired weight is greater than 500, weights above the
  3262         desired weight are checked in ascending order followed by weights
  3263         below the desired weight in descending order until a match is found.
  3265        <li>If the desired weight is 400, 500 is checked first and then the
  3266         rule for desired weights less than 400 is used.
  3268        <li>If the desired weight is 500, 400 is checked first and then the
  3269         rule for desired weights less than 400 is used.
  3270       </ul>
  3272      <li><span class=property>‘<a href="#propdef-font-size"><code
  3273       class=property>font-size</code></a>’</span> must be matched within a
  3274       UA-dependent margin of tolerance. (Typically, sizes for scalable fonts
  3275       are rounded to the nearest whole pixel, while the tolerance for
  3276       bitmapped fonts could be as large as 20%.) Further computations, e.g.,
  3277       by ‘<code class=property>em</code>’ values in other properties, are
  3278       based on the <span class=property>‘<a href="#propdef-font-size"><code
  3279       class=property>font-size</code></a>’</span> value that is used, not
  3280       the one that is specified.
  3281     </ol>
  3283    <li>
  3284     <p>If the matched face is defined via <a
  3285      href="#at-font-face-rule"><code>@font-face</code></a> rules, user agents
  3286      must use the procedure below to select a single font:
  3288     <ol>
  3289      <li>If the font resource has not been loaded and the range of characters
  3290       defined by the ‘<a href="#descdef-unicode-range"><code
  3291       class=property>unicode-range</code></a>’ descriptor value includes
  3292       the character in question, load the font.
  3294      <li>After downloading, if the <a
  3295       href="#effective-character-map"><em>effective character map</em></a>
  3296       supports the character in question, select that font.
  3297     </ol>
  3299     <p>When the matched face is a <a href="#composite-face"><em>composite
  3300      face</em></a>, user agents must use the procedure above on each of the
  3301      faces in the <a href="#composite-face"><em>composite face</em></a> in
  3302      reverse order of <a
  3303      href="#at-font-face-rule"><code>@font-face</code></a> rule definition.</p>
  3305     <p>While the download occurs, user agents may either wait until the font
  3306      is downloaded or render once with substituted font metrics and render
  3307      again once the font is downloaded.</p>
  3309    <li>
  3310     <p>If no matching face exists or the matched face does not contain a
  3311      glyph for the character to be rendered, the next family name is selected
  3312      and the previous three steps repeated. Glyphs from other faces in the
  3313      family are not considered. The only exception is that user agents may
  3314      optionally substitute a synthetically obliqued version of the <a
  3315      href="#default-face"><em>default face</em></a> if that face supports a
  3316      given glyph and synthesis of these faces is permitted by the value of
  3317      the ‘<a href="#propdef-font-synthesis"><code
  3318      class=property>font-synthesis</code></a>’ property. For example, a
  3319      synthetic italic version of the regular face may be used if the italic
  3320      face doesn't support glyphs for Arabic.</p>
  3321     <!-- resolution on the above: http://lists.w3.org/Archives/Public/www-style/2012Nov/0292.html -->
  3324    <li>If there are no more font families to be evaluated and no matching
  3325     face has been found, then the user agent performs a <dfn
  3326     id=system-font-fallback>system font fallback</dfn> procedure to find the
  3327     best match for the character to be rendered. The result of this procedure
  3328     may vary across user agents.
  3330    <li>If a particular character cannot be displayed using any font, the user
  3331     agent should indicate by some means that a character is not being
  3332     displayed, displaying either a symbolic representation of the missing
  3333     glyph (e.g. using a <a
  3334     href="http://en.wikipedia.org/wiki/Last_resort_font">Last Resort
  3335     Font</a>) or using the missing character glyph from a default font.
  3336   </ol>
  3338   <p>Optimizations of this process are allowed provided that an
  3339    implementation behaves as if the algorithm had been followed exactly.
  3340    Matching occurs in a well-defined order to insure that the results are as
  3341    consistent as possible across user agents, given an identical set of
  3342    available fonts and rendering technology.
  3344   <p>The <dfn id=first-available-font>first available font</dfn>, used in the
  3345    definition of <a
  3346    href="http://www.w3.org/TR/css3-values/#font-relative-lengths"><em>font-relative
  3347    lengths</em></a> such as ‘<code class=property>ex</code>’ and ‘<code
  3348    class=property>ch</code>’, is defined to be the first available font
  3349    that would match any character given font families in the ‘<code
  3350    class=property>font-family</code>’ list (or a user agent's default font
  3351    if none are available).
  3353   <h3 id=cluster-matching><span class=secno>5.3 </span>Cluster matching</h3>
  3355   <p>When text contains characters such as combining marks, ideally the base
  3356    character should be rendered using the same font as the mark, this assures
  3357    proper placement of the mark. For this reason, the font matching algorithm
  3358    for clusters is more specialized than the general case of matching a
  3359    single character by itself. For sequences containing variation selectors,
  3360    which indicate the precise glyph to be used for a given character, user
  3361    agents always attempt <a href="#system-font-fallback"><em>system font
  3362    fallback</em></a> to find the appropriate glyph before using the default
  3363    glyph of the base character.
  3365   <p>A sequence of codepoints containing combining mark or other modifiers is
  3366    termed a grapheme cluster (see <a href="#CSS3TEXT"
  3367    rel=biblioentry>[CSS3TEXT]<!--{{CSS3TEXT}}--></a> for a more complete
  3368    description). For a given cluster containing a base character, <em>b</em>
  3369    and a sequence of combining characters <em>c1, c2…</em>, the entire
  3370    cluster is matched using these steps:
  3372   <ol>
  3373    <li>For each family in the font list, a face is chosen using the style
  3374     selection rules defined in the previous section.
  3375     <ol>
  3376      <li>If all characters in the sequence <em>b + c1 + c2 …</em> are
  3377       completely supported by the font, select this font for the sequence.
  3379      <li>If a sequence of multiple codepoints is canonically equivalent to a
  3380       single character and the font <a href="#support"><em
  3381       title=support>supports</em></a> that character, select this font for
  3382       the sequence.
  3383     </ol>
  3385    <li>If no font was found in the font list in step 1:
  3386     <ol>
  3387      <li>If <em>c1</em> is a variation selector, system fallback must be used
  3388       to find a font that <a href="#support"><em
  3389       title=support>supports</em></a> the full sequence of <em>b + c1</em>.
  3390       If no font on the system <a href="#support"><em
  3391       title=support>supports</em></a> the full sequence, match the single
  3392       character <em>b</em> using the normal procedure for matching single
  3393       characters and ignore the variation selector. Note: a sequence with
  3394       more than one variation selector must be treated as an encoding error
  3395       and the trailing selectors must be ignored. <a href="#UNICODE6"
  3396       rel=biblioentry>[UNICODE6]<!--{{!UNICODE6}}--></a>
  3398      <li>Otherwise, the user agent may optionally use system font fallback to
  3399       match a font that <a href="#support"><em
  3400       title=support>supports</em></a> the entire cluster.
  3401     </ol>
  3403    <li>If no font is found in step 2, use the matching sequence from step 1
  3404     to determine the longest sequence that is completely <a
  3405     href="#support"><em title=support>supported</em></a> by a font in the
  3406     font list and attempt to match the remaining combining characters
  3407     separately using the rules for single characters.
  3408   </ol>
  3410   <h3 id=char-handling-issues><span class=secno>5.4 </span>Character handling
  3411    issues</h3>
  3413   <p>CSS font matching is always performed on text runs containing Unicode
  3414    characters, so documents using legacy encodings are assumed to have been
  3415    transcoded before matching fonts. For fonts containing <a
  3416    href="#character-map"><em title="character map">character maps</em></a>
  3417    for both legacy encodings and Unicode, the contents of the legacy encoding
  3418    <a href="#character-map"><em>character map</em></a> must have no effect on
  3419    the results of the font matching process.
  3421   <p>The font matching process does not assume that text runs are in either
  3422    normalized or denormalized form (see <a href="#CHARMOD-NORM"
  3423    rel=biblioentry>[CHARMOD-NORM]<!--{{CHARMOD-NORM}}--></a> for more
  3424    details). Fonts may only support precomposed forms and not the decomposed
  3425    sequence of base character plus combining marks. Authors should always
  3426    tailor their choice of fonts to their content, including whether that
  3427    content contains normalized or denormalized character streams.
  3429   <p>If a given character is a Private-Use Area Unicode codepoint, user
  3430    agents must only match font families named in the ‘<code
  3431    class=property>font-family</code>’ list that are not generic families.
  3432    If none of the families named in the ‘<code
  3433    class=property>font-family</code>’ list contain a glyph for that
  3434    codepoint, user agents must display some form of missing glyph symbol for
  3435    that character rather than attempting <a
  3436    href="#system-font-fallback"><em>system font fallback</em></a> for that
  3437    codepoint. When matching the replacement character U+FFFD, user agents may
  3438    skip the font matching process and immediately display some form of
  3439    missing glyph symbol, they are not required to display the glyph from the
  3440    font that would be selected by the font matching process.
  3442   <p>In general, the fonts for a given family will all have the same or
  3443    similar <a href="#character-map"><em title="character map">character
  3444    maps</em></a>. The process outlined here is designed to handle even font
  3445    families containing faces with widely variant <a href="#character-map"><em
  3446    title="character map">character maps</em></a>. However, authors are
  3447    cautioned that the use of such families can lead to unexpected results.
  3449   <h3 id=font-matching-changes><span class=secno>5.5 </span>Font matching
  3450    changes since CSS 2.1</h3>
  3452   <p>The algorithm above is different from CSS 2.1 in a number of key places.
  3453    These changes were made to better reflect actual font matching behavior
  3454    across user agent implementations.
  3456   <p>Differences compared to the font matching algorithm in CSS 2.1:
  3458   <ul>
  3459    <li>The algorithm includes font-stretch matching.
  3461    <li>All possible font-style matching scenarios are delineated.
  3463    <li>Small-caps fonts are not matched as part of the font matching process,
  3464     they are now handled via font features.
  3466    <li>Unicode variation selector matching is required.
  3468    <li>Cluster sequences are matched as a unit.
  3469   </ul>
  3471   <h3 id=font-matching-examples><span class=secno>5.6 </span>Font matching
  3472    examples</h3>
  3474   <div class=example>
  3475    <p>It's useful to note that the CSS selector syntax may be used to create
  3476     language-sensitive typography. For example, some Chinese and Japanese
  3477     characters are unified to have the same Unicode code point, although the
  3478     abstract glyphs are not the same in the two languages.
  3480    <pre>*:lang(ja-jp) { font: 900 14pt/16pt &quot;Heisei Mincho W9&quot;, serif; }
  3481 *:lang(zh-tw) { font: 800 14pt/16.5pt &quot;Li Sung&quot;, serif; }
  3482 </pre>
  3484    <p>This selects any element that has the given language — Japanese or
  3485     Traditional Chinese — and uses the appropriate font.
  3486   </div>
  3488   <h2 id=font-rend-props><span class=secno>6 </span>Font Feature Properties</h2>
  3490   <p>Modern font technologies support a variety of advanced typographic and
  3491    language-specific font features. Using these features, a single font can
  3492    provide glyphs for a wide range of ligatures, contextual and stylistic
  3493    alternates, tabular and old-style figures, small capitals, automatic
  3494    fractions, swashes, and alternates specific to a given language. To allow
  3495    authors control over these font capabilities, the ‘<code
  3496    class=property>font-variant</code>’ property has been expanded for CSS3.
  3497    It now functions as a shorthand for a set of properties that provide
  3498    control over stylistic font features.
  3500   <h3 id=glyph-selection-positioning><span class=secno>6.1 </span>Glyph
  3501    selection and positioning</h3>
  3503   <p>Simple fonts used for displaying Latin text use a very basic processing
  3504    model. Fonts contain a <a href="#character-map"><em>character map</em></a>
  3505    which maps each character to a glyph for that character. Glyphs for
  3506    subsequent characters are simply placed one after the other along a run of
  3507    text. Modern font formats such as OpenType and AAT (Apple Advanced
  3508    Typography) use a richer processing model. The glyph for a given character
  3509    can be chosen and positioned not just based on the codepoint of the
  3510    character itself, but also on adjacent characters as well as the language,
  3511    script, and features enabled for the text. Font features may be required
  3512    for specific scripts, or recommended as enabled by default or they might
  3513    be stylistic features meant to be used under author control.
  3515   <p>For a good visual overview of these features, see the <a
  3516    href="#OPENTYPE-FONT-GUIDE"
  3517    rel=biblioentry>[OPENTYPE-FONT-GUIDE]<!--{{OPENTYPE-FONT-GUIDE}}--></a>.
  3518    For a detailed description of glyph processing for OpenType fonts, see <a
  3519    href="#WINDOWS-GLYPH-PROC"
  3520    rel=biblioentry>[WINDOWS-GLYPH-PROC]<!--{{WINDOWS-GLYPH-PROC}}--></a>.
  3522   <p>Stylistic font features can be classified into two broad categories:
  3523    ones that affect the harmonization of glyph shapes with the surrounding
  3524    context, such as kerning and ligature features, and ones such as the
  3525    small-caps, subscript/superscript and alternate features that affect shape
  3526    selection.
  3528   <p>The subproperties of <a href="#propdef-font-variant"
  3529    title="font-variant!!property">‘<code
  3530    class=property>font-variant</code>’</a> listed below are used to control
  3531    these stylistic font features. They do not control features that are
  3532    required for displaying certain scripts, such as the OpenType features
  3533    used when displaying Arabic or Indic language text. They affect glyph
  3534    selection and positioning, but do not affect font selection as described
  3535    in the font matching section (except in cases required for compatibility
  3536    with CSS 2.1).
  3538   <p>To assure consistent behavior across user agents, the equivalent
  3539    OpenType property settings are listed for individual properties and are
  3540    normative. When using other font formats these should be used as a
  3541    guideline to map CSS font feature property values to specific font
  3542    features.
  3544   <h3 id=language-specific-support><span class=secno>6.2
  3545    </span>Language-specific display</h3>
  3547   <p>OpenType also supports language-specific glyph selection and
  3548    positioning, so that text can be displayed correctly in cases where the
  3549    language dictates a specific display behavior. Many languages share a
  3550    common script, but the shape of certain letters can vary across those
  3551    languages. For example, certain Cyrillic letters have different shapes in
  3552    Russian text than in Bulgarian. In Latin text, it's common to render "fi"
  3553    with an explicit fi-ligature that lacks a dot on the "i". However, in
  3554    languages such as Turkish which uses both a dotted-i and a dotless-i, it's
  3555    important to not use this ligature or use a specialized version that
  3556    contains a dot over the "i". The example below shows language-specific
  3557    variations based on stylistic traditions found in Spanish, Italian and
  3558    French orthography:
  3560   <div class=featex><img alt="language specific forms, spanish"
  3561    src=locl-1.png></div>
  3563   <div class=featex><img alt="language specific forms, italian"
  3564    src=locl-2.png></div>
  3566   <div class=featex><img alt="language specific forms, french"
  3567    src=locl-3.png></div>
  3569   <p>If the content language of the element is known according to the rules
  3570    of the <a
  3571    href="http://www.w3.org/TR/CSS21/conform.html#doclanguage">document
  3572    language</a>, user agents are required to infer the OpenType language
  3573    system from the content language and use that when selecting and
  3574    positioning glyphs using an OpenType font.
  3576   <p>For OpenType fonts, in some cases it may be necessary to explicitly
  3577    declare the OpenType language to be used, for example when displaying text
  3578    in a given language that uses the typographic conventions of another
  3579    language or when the font does not explicitly support a given language but
  3580    supports a language that shares common typographic conventions. The ‘<a
  3581    href="#propdef-font-language-override"><code
  3582    class=property>font-language-override</code></a>’ property is used for
  3583    this purpose.</p>
  3584   <!-- prop: font-kerning -->
  3586   <h3 id=font-kerning-prop><span class=secno>6.3 </span>Kerning: the <a
  3587    href="#propdef-font-kerning">font-kerning</a> property</h3>
  3589   <table class=propdef id=namefont-kerningvalueauto-normal-noneini>
  3590    <tbody>
  3591     <tr>
  3592      <td>Name:
  3594      <td><dfn id=propdef-font-kerning>font-kerning</dfn>
  3596     <tr>
  3597      <td>Value:
  3599      <td><a href="#font-kerning-auto-value"
  3600       title="auto!!font-kerning">auto</a> | <a
  3601       href="#font-kerning-normal-value"
  3602       title="normal!!font-kerning">normal</a> | <a
  3603       href="#font-kerning-none-value" title="none!!font-kerning">none</a>
  3605     <tr>
  3606      <td>Initial:
  3608      <td>auto
  3610     <tr>
  3611      <td>Applies to:
  3613      <td>all elements
  3615     <tr>
  3616      <td>Inherited:
  3618      <td>yes
  3620     <tr>
  3621      <td>Percentages:
  3623      <td>N/A
  3625     <tr>
  3626      <td>Media:
  3628      <td>visual
  3630     <tr>
  3631      <td>Computed value:
  3633      <td>as specified
  3635     <tr>
  3636      <td>Animatable:
  3638      <td>no
  3639   </table>
  3641   <p>Kerning is the contextual adjustment of inter-glyph spacing. This
  3642    property controls metric kerning, kerning that utilizes adjustment data
  3643    contained in the font.
  3645   <dl>
  3646    <dt><dfn id=font-kerning-auto-value title="auto!!font-kerning">auto</dfn>
  3648    <dd>Specifies that kerning is applied at the discretion of the user agent
  3650    <dt><dfn id=font-kerning-normal-value
  3651     title="normal!!font-kerning">normal</dfn>
  3653    <dd>Specifies that kerning is applied
  3655    <dt><dfn id=font-kerning-none-value title="none!!font-kerning">none</dfn>
  3657    <dd>Specifies that kerning is not applied
  3658   </dl>
  3660   <p>For fonts that do not include kerning data this property will have no
  3661    visible effect. When rendering with OpenType fonts, the <a
  3662    href="#OPENTYPE" rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a>
  3663    specification suggests that kerning be enabled by default. When kerning is
  3664    enabled, the OpenType <span class=tag>kern</span> feature is enabled (for
  3665    vertical text runs the <span class=tag>vkrn</span> feature is enabled
  3666    instead). User agents must also support fonts that only support kerning
  3667    via data contained in a <span class=tag>kern</span> font table, as
  3668    detailed in the OpenType specification. If the ‘<code
  3669    class=property>letter-spacing</code>’ property is defined, kerning
  3670    adjustments are considered part of the default spacing and letter spacing
  3671    adjustments are made after kerning has been applied.
  3673   <p>When set to ‘<code class=property>auto</code>’, user agents can
  3674    determine whether to apply kerning or not based on a number of factors:
  3675    text size, script, or other factors that influence text processing speed.
  3676    Authors who want proper kerning should use <a
  3677    href="#font-kerning-normal-value" title="normal!!font-kerning">‘<code
  3678    class=property>normal</code>’</a> to explicitly enable kerning.
  3679    Likewise, some authors may prefer to disable kerning in situations where
  3680    performance is more important than precise appearance. However, in
  3681    well-designed modern implementations the use of kerning generally does not
  3682    have a large impact on text rendering speed.</p>
  3683   <!-- prop: font-variant-ligatures -->
  3685   <h3 id=font-variant-ligatures-prop><span class=secno>6.4 </span>Ligatures:
  3686    the <a href="#propdef-font-variant-ligatures">font-variant-ligatures</a>
  3687    property</h3>
  3689   <table class=propdef id=namefont-variant-ligaturesvaluenormal-no>
  3690    <tbody>
  3691     <tr>
  3692      <td>Name:
  3694      <td><dfn id=propdef-font-variant-ligatures>font-variant-ligatures</dfn>
  3696     <tr>
  3697      <td>Value:
  3699      <td><a href="#font-variant-ligatures-normal-value"
  3700       title="normal!!font-variant-ligatures">normal</a> | <a
  3701       href="#font-variant-ligatures-none-value"
  3702       title="none!!font-variant-ligatures">none</a> | [ <a
  3703       href="#common-lig-values"><var>&lt;common-lig-values&gt;</var></a> ||
  3704       <a
  3705       href="#discretionary-lig-values"><var>&lt;discretionary-lig-values&gt;</var></a>
  3706       || <a
  3707       href="#historical-lig-values"><var>&lt;historical-lig-values&gt;</var></a>
  3708       || <a
  3709       href="#contextual-alt-values"><var>&lt;contextual-alt-values&gt;</var></a>
  3712     <tr>
  3713      <td>Initial:
  3715      <td>normal
  3717     <tr>
  3718      <td>Applies to:
  3720      <td>all elements
  3722     <tr>
  3723      <td>Inherited:
  3725      <td>yes
  3727     <tr>
  3728      <td>Percentages:
  3730      <td>N/A
  3732     <tr>
  3733      <td>Media:
  3735      <td>visual
  3737     <tr>
  3738      <td>Computed value:
  3740      <td>as specified
  3742     <tr>
  3743      <td>Animatable:
  3745      <td>no
  3746   </table>
  3748   <p>Ligatures and contextual forms are ways of combining glyphs to produce
  3749    more harmonized forms.
  3751   <pre
  3752    class=prod><dfn id=common-lig-values><var>&lt;common-lig-values&gt;</var></dfn>        = [ <a href="#common-ligatures">common-ligatures</a> | <a href="#no-common-ligatures">no-common-ligatures</a> ]</pre>
  3754   <pre
  3755    class=prod><dfn id=discretionary-lig-values><var>&lt;discretionary-lig-values&gt;</var></dfn> = [ <a href="#discretionary-ligatures">discretionary-ligatures</a> | <a href="#no-discretionary-ligatures">no-discretionary-ligatures</a> ]</pre>
  3757   <pre
  3758    class=prod><dfn id=historical-lig-values><var>&lt;historical-lig-values&gt;</var></dfn>    = [ <a href="#historical-ligatures">historical-ligatures</a> | <a href="#no-historical-ligatures">no-historical-ligatures</a> ]</pre>
  3760   <pre
  3761    class=prod><dfn id=contextual-alt-values><var>&lt;contextual-alt-values&gt;</var></dfn>    = [ <a href="#contextual">contextual</a> | <a href="#no-contextual">no-contextual</a> ]</pre>
  3763   <p>Individual values have the following meanings:
  3765   <dl>
  3766    <dt><dfn id=font-variant-ligatures-normal-value
  3767     title="normal!!font-variant-ligatures">normal</dfn>
  3769    <dd>A value of <a href="#font-variant-ligatures-normal-value"
  3770     title="normal!!font-variant-ligatures">‘<code
  3771     class=property>normal</code>’</a> specifies that common default
  3772     features are enabled, <a href="#font-feature-resolution">as described in
  3773     detail in the next section</a>. For OpenType fonts, common ligatures and
  3774     contextual forms are on by default, discretionary and historical
  3775     ligatures are not.
  3777    <dt><dfn id=font-variant-ligatures-none-value
  3778     title="none!!font-variant-ligatures">none</dfn>
  3780    <dd>Specifies that all types of ligatures and contextual forms covered by
  3781     this property are explicitly disabled. In situations where ligatures are
  3782     not considered necessary, this may improve the speed of text rendering.
  3784    <dt><dfn id=common-ligatures>common-ligatures</dfn>
  3786    <dd>Enables display of common ligatures (OpenType features: <span
  3787     class=tag>liga, clig</span>). For OpenType fonts, common ligatures are
  3788     enabled by default.
  3789   </dl>
  3791   <div class=featex><img alt="common ligature example" src=liga.png></div>
  3793   <dl>
  3794    <dt><dfn id=no-common-ligatures>no-common-ligatures</dfn>
  3796    <dd>Disables display of common ligatures (OpenType features: <span
  3797     class=tag>liga, clig</span>).
  3799    <dt><dfn id=discretionary-ligatures>discretionary-ligatures</dfn>
  3801    <dd>Enables display of discretionary ligatures (OpenType feature: <span
  3802     class=tag>dlig</span>). Which ligatures are discretionary or optional is
  3803     decided by the type designer, so authors will need to refer to the
  3804     documentation of a given font to understand which ligatures are
  3805     considered discretionary.
  3806   </dl>
  3808   <div class=featex><img alt="discretionary ligature example" src=dlig.png></div>
  3810   <dl>
  3811    <dt><dfn id=no-discretionary-ligatures>no-discretionary-ligatures</dfn>
  3813    <dd>Disables display of discretionary ligatures (OpenType feature: <span
  3814     class=tag>dlig</span>).
  3816    <dt><dfn id=historical-ligatures>historical-ligatures</dfn>
  3818    <dd>Enables display of historical ligatures (OpenType feature: <span
  3819     class=tag>hlig</span>).
  3820   </dl>
  3822   <div class=featex><img alt="historical ligature example" src=hlig.png></div>
  3824   <dl>
  3825    <dt><dfn id=no-historical-ligatures>no-historical-ligatures</dfn>
  3827    <dd>Disables display of historical ligatures (OpenType feature: <span
  3828     class=tag>hlig</span>).
  3830    <dt><dfn id=contextual>contextual</dfn>
  3832    <dd>Enables display of contextual alternates (OpenType feature: <span
  3833     class=tag>calt</span>). Although not strictly a ligature feature, like
  3834     ligatures this feature is commonly used to harmonize the shapes of glyphs
  3835     with the surrounding context. For OpenType fonts, this feature is on by
  3836     default.
  3837   </dl>
  3839   <div class=featex><img alt="contextual alternate example" src=calt.png></div>
  3841   <dl>
  3842    <dt><dfn id=no-contextual>no-contextual</dfn>
  3844    <dd>Disables display of contextual alternates (OpenType feature: <span
  3845     class=tag>calt</span>).
  3846   </dl>
  3848   <p>Required ligatures, needed for correctly rendering complex scripts, are
  3849    not affected by the settings above, including ‘<code
  3850    class=property>none</code>’ (OpenType feature: <span
  3851    class=tag>rlig</span>).</p>
  3852   <!-- prop: font-variant-position -->
  3854   <h3 id=font-variant-position-prop><span class=secno>6.5 </span>Subscript
  3855    and superscript forms: the <a
  3856    href="#propdef-font-variant-position">font-variant-position</a> property</h3>
  3858   <table class=propdef id=namefont-variant-positionvaluenormal-sub>
  3859    <tbody>
  3860     <tr>
  3861      <td>Name:
  3863      <td><dfn id=propdef-font-variant-position>font-variant-position</dfn>
  3865     <tr>
  3866      <td>Value:
  3868      <td><a href="#font-variant-position-normal-value"
  3869       title="normal!!font-variant-position">normal</a> | <a
  3870       href="#sub">sub</a> | <a href="#super">super</a>
  3872     <tr>
  3873      <td>Initial:
  3875      <td>normal
  3877     <tr>
  3878      <td>Applies to:
  3880      <td>all elements
  3882     <tr>
  3883      <td>Inherited:
  3885      <td>yes
  3887     <tr>
  3888      <td>Percentages:
  3890      <td>N/A
  3892     <tr>
  3893      <td>Media:
  3895      <td>visual
  3897     <tr>
  3898      <td>Computed value:
  3900      <td>as specified
  3902     <tr>
  3903      <td>Animatable:
  3905      <td>no
  3906   </table>
  3908   <p>This property is used to enable typographic subscript and superscript
  3909    glyphs. These are alternate glyphs designed within the same em-box as
  3910    default glyphs and are intended to be laid out on the same baseline as the
  3911    default glyphs, with no resizing or repositioning of the baseline. They
  3912    are explicitly designed to match the surrounding text and to be more
  3913    readable without affecting the line height.
  3915   <div class=figure><img alt="comparison between real subscript glyphs and
  3916    synthesized ones" src=realsubscripts.png>
  3917    <p class=caption>Subscript glyphs (top) vs. typical synthesized subscripts
  3918     (bottom)
  3919   </div>
  3921   <p>Individual values have the following meanings:
  3923   <dl>
  3924    <dt><dfn id=font-variant-position-normal-value
  3925     title="normal!!font-variant-position">normal</dfn>
  3927    <dd>None of the features listed below are enabled.
  3929    <dt><dfn id=sub>sub</dfn>
  3931    <dd>Enables display of subscript variants (OpenType feature: <span
  3932     class=tag>subs</span>).
  3934    <dt><dfn id=super>super</dfn>
  3936    <dd>Enables display of superscript variants (OpenType feature: <span
  3937     class=tag>sups</span>).
  3938   </dl>
  3940   <p>Because of the semantic nature of subscripts and superscripts, when the
  3941    value is either ‘<a href="#sub"><code class=property>sub</code></a>’
  3942    or ‘<a href="#super"><code class=property>super</code></a>’ for a
  3943    given contiguous run of text, if a variant glyph is not available for all
  3944    the characters in the run, simulated glyphs must be synthesized for all
  3945    characters using reduced forms of the glyphs that would be used without
  3946    this feature applied. This is done per run to avoid a mixture of variant
  3947    glyphs and synthesized ones that would not align correctly. In the case of
  3948    OpenType fonts that lack subscript or superscript glyphs for a given
  3949    character, user agents must use the appropriate subscript and superscript
  3950    metrics specified in the selected font's <a
  3951    href="http://www.microsoft.com/typography/otspec/os2.htm#subxs">OS/2
  3952    table</a> <a href="#OPENTYPE"
  3953    rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a> to calculate the size
  3954    and offset of the synthesized substitutes.
  3956   <div class=figure><img alt="alternate superscripts vs. glyphs synthesized
  3957    using superscript metrics" src=superscript-alt-synth.png>
  3958    <p class=caption>Superscript alternate glyph (left), synthesized
  3959     superscript glyphs (middle), and incorrect mixture of the two (right)
  3960   </div>
  3962   <p>In situations where text decorations are only applied to runs of text
  3963    containing superscript or subscript glyphs, the synthesized glyphs must be
  3964    used to avoid problems with the placement of decorations.
  3966   <p>In the past, user agents have used font-size and vertical-align to
  3967    simulate subscripts and superscripts for the <code title="HTML sub
  3968    element">sub</code> and <code title="HTML sup element">sup</code>
  3969    elements. To allow a backwards compatible way of defining subscripts and
  3970    superscripts, it is recommended that authors use conditional rules <a
  3971    href="#CSS3-CONDITIONAL"
  3972    rel=biblioentry>[CSS3-CONDITIONAL]<!--{{CSS3-CONDITIONAL}}--></a> so that
  3973    older user agents will still render subscripts and superscripts via the
  3974    older mechanism.
  3976   <p>Authors should note that fonts typically only provide subscript and
  3977    superscript glyphs for a subset of all characters supported by the font.
  3978    For example, while subscript and superscript glyphs are often available
  3979    for Latin numbers, glyphs for punctuation and letter characters are less
  3980    frequently provided. The synthetic fallback rules defined for this
  3981    property assure that subscripts and superscripts will always appear but
  3982    the appearance may not match author expectations if the font used does not
  3983    provide the appropriate alternate glyph for all characters contained in a
  3984    subscript or superscript.
  3986   <p>This property is not cumulative. Applying it to elements within a
  3987    subscript or superscript won't nest the placement of a subscript or
  3988    superscript glyph. Images contained within text runs where the value of
  3989    this property is ‘<a href="#sub"><code class=property>sub</code></a>’
  3990    or ‘<a href="#super"><code class=property>super</code></a>’ will be
  3991    drawn just as they would if the value was <a
  3992    href="#font-variant-position-normal-value"
  3993    title="normal!!font-variant-position">‘<code
  3994    class=property>normal</code>’</a>.</p>
  3995   <!-- due to lack of consensus, couldn't resolve on exact positioning of text decorations:
  3996 http://www.w3.org/2013/06/06-css-minutes.html#item03 -->
  3998   <p>Because of these limitations, ‘<a
  3999    href="#propdef-font-variant-position"><code
  4000    class=property>font-variant-position</code></a>’ is not recommended for
  4001    use in user agent stylesheets. Authors should use it in cases where
  4002    subscripts or superscripts will only contain the narrow range of
  4003    characters supported by the fonts specified.
  4005   <p class=note>The variant glyphs use the same baseline as the default
  4006    glyphs would use. There is no shift in the placement along the baseline,
  4007    so the use of variant glyphs doesn't affect the height of the inline box
  4008    or alter the height of the linebox. This makes superscript and subscript
  4009    variants ideal for situations where it's important that leading remain
  4010    constant, such as in multi-column layout.
  4012   <div class=example>
  4013    <p>A typical user agent default style for the <a class=tag
  4014     href="#sub">sub</a> element:</p>
  4016    <pre>sub {
  4017   vertical-align: sub;
  4018   font-size: smaller;
  4019   line-height: normal;
  4021 </pre>
  4023    <p>Using font-variant-position to specify typographic subscripts in a way
  4024     that will still show subscripts in older user agents:</p>
  4026    <pre>@supports ( font-variant-position: sub ) {
  4028   sub {
  4029     vertical-align: baseline;
  4030     font-size: 100%;
  4031     line-height: inherit;
  4032     font-variant-position: sub;
  4036 </pre>
  4038    <p>User agents that support the ‘<a
  4039     href="#propdef-font-variant-position"><code
  4040     class=property>font-variant-position</code></a>’ property will select a
  4041     subscript variant glyph and render this without adjusting the baseline or
  4042     font-size. Older user agents will ignore the ‘<a
  4043     href="#propdef-font-variant-position"><code
  4044     class=property>font-variant-position</code></a>’ property definition
  4045     and use the standard defaults for subscripts.</p>
  4046   </div>
  4047   <!-- prop: font-variant-caps -->
  4049   <h3 id=font-variant-caps-prop><span class=secno>6.6 </span>Capitalization:
  4050    the <a href="#propdef-font-variant-caps">font-variant-caps</a> property</h3>
  4052   <table class=propdef id=namefont-variant-capsvaluenormal-small-c>
  4053    <tbody>
  4054     <tr>
  4055      <td>Name:
  4057      <td><dfn id=propdef-font-variant-caps>font-variant-caps</dfn>
  4059     <tr>
  4060      <td>Value:
  4062      <td><a href="#font-variant-caps-normal-value"
  4063       title="normal!!font-variant-caps">normal</a> | <a
  4064       href="#small-caps">small-caps</a> | <a
  4065       href="#all-small-caps">all-small-caps</a> | <a
  4066       href="#petite-caps">petite-caps</a> | <a
  4067       href="#all-petite-caps">all-petite-caps</a> | <a
  4068       href="#unicase">unicase</a> | <a href="#titling-caps">titling-caps</a>
  4070     <tr>
  4071      <td>Initial:
  4073      <td>normal
  4075     <tr>
  4076      <td>Applies to:
  4078      <td>all elements
  4080     <tr>
  4081      <td>Inherited:
  4083      <td>yes
  4085     <tr>
  4086      <td>Percentages:
  4088      <td>N/A
  4090     <tr>
  4091      <td>Media:
  4093      <td>visual
  4095     <tr>
  4096      <td>Computed value:
  4098      <td>as specified
  4100     <tr>
  4101      <td>Animatable:
  4103      <td>no
  4104   </table>
  4106   <p>This property allows the selection of alternate glyphs used for small or
  4107    petite capitals or for titling. These glyphs are specifically designed to
  4108    blend well with the surrounding normal glyphs, to maintain the weight and
  4109    readability which suffers when text is simply resized to fit this purpose.
  4111   <p>Individual values have the following meanings:
  4113   <dl>
  4114    <dt><dfn id=font-variant-caps-normal-value
  4115     title="normal!!font-variant-caps">normal</dfn>
  4117    <dd>None of the features listed below are enabled.
  4119    <dt><dfn id=small-caps>small-caps</dfn>
  4121    <dd>Enables display of small capitals (OpenType feature: <span
  4122     class=tag>smcp</span>). Small-caps glyphs typically use the form of
  4123     uppercase letters but are reduced to the size of lowercase letters.
  4124   </dl>
  4126   <div class=featex><img alt="small-caps example" src=smcp.png></div>
  4128   <dl>
  4129    <dt><dfn id=all-small-caps>all-small-caps</dfn>
  4131    <dd>Enables display of small capitals for both upper and lowercase letters
  4132     (OpenType features: <span class=tag>c2sc, smcp</span>).
  4134    <dt><dfn id=petite-caps>petite-caps</dfn>
  4136    <dd>Enables display of petite capitals (OpenType feature: <span
  4137     class=tag>pcap</span>).
  4139    <dt><dfn id=all-petite-caps>all-petite-caps</dfn>
  4141    <dd>Enables display of petite capitals for both upper and lowercase
  4142     letters (OpenType features: <span class=tag>c2pc, pcap</span>).
  4144    <dt><dfn id=unicase>unicase</dfn>
  4146    <dd>Enables display of mixture of small capitals for uppercase letters
  4147     with normal lowercase letters (OpenType feature: <span
  4148     class=tag>unic</span>).
  4150    <dt><dfn id=titling-caps>titling-caps</dfn>
  4152    <dd>Enables display of titling capitals (OpenType feature: <span
  4153     class=tag>titl</span>). Uppercase letter glyphs are often designed for
  4154     use with lowercase letters. When used in all uppercase titling sequences
  4155     they can appear too strong. Titling capitals are designed specifically
  4156     for this situation.
  4157   </dl>
  4159   <p>The availability of these glyphs is based on whether a given feature is
  4160    defined or not in the feature list of the font. User agents can optionally
  4161    decide this on a per-script basis but should explicitly not decide this on
  4162    a per-character basis.
  4164   <p>Some fonts may only support a subset or none of the features described
  4165    for this property. For backwards compatibility with CSS 2.1, if ‘<a
  4166    href="#small-caps"><code class=property>small-caps</code></a>’ or ‘<a
  4167    href="#all-small-caps"><code class=property>all-small-caps</code></a>’
  4168    is specified but small-caps glyphs are not available for a given font,
  4169    user agents should simulate a small-caps font, for example by taking a
  4170    normal font and replacing the glyphs for lowercase letters with scaled
  4171    versions of the glyphs for uppercase characters (replacing the glyphs for
  4172    both upper and lowercase letters in the case of ‘<a
  4173    href="#all-small-caps"><code class=property>all-small-caps</code></a>’).
  4175   <div class=figure style="padding: 0; margin: auto;"><img alt="synthetic vs.
  4176    real small-caps" class=hires src=synthetic-vs-real-small-caps.png
  4177    width=512px>
  4178    <p class=caption>Synthetic vs. real small-caps
  4179   </div>
  4181   <p>To match the surrounding text, a font may provide alternate glyphs for
  4182    caseless characters when these features are enabled but when a user agent
  4183    simulates small capitals, it must not attempt to simulate alternates for
  4184    codepoints which are considered caseless.
  4186   <div class=figure style="padding: 0; margin: auto;"><img alt="caseless
  4187    characters with small-caps, all-small-caps enabled" class=hires
  4188    src=small-capitals-variations.png width=418px>
  4189    <p class=caption>Caseless characters with small-caps, all-small-caps
  4190     enabled
  4191   </div>
  4193   <p>If either ‘<a href="#petite-caps"><code
  4194    class=property>petite-caps</code></a>’ or ‘<a
  4195    href="#all-petite-caps"><code class=property>all-petite-caps</code></a>’
  4196    is specified for a font that doesn't support these features, the property
  4197    behaves as if ‘<a href="#small-caps"><code
  4198    class=property>small-caps</code></a>’ or ‘<a
  4199    href="#all-small-caps"><code class=property>all-small-caps</code></a>’,
  4200    respectively, had been specified. If ‘<a href="#unicase"><code
  4201    class=property>unicase</code></a>’ is specified for a font that doesn't
  4202    support that feature, the property behaves as if ‘<a
  4203    href="#small-caps"><code class=property>small-caps</code></a>’ was
  4204    applied only to lowercased uppercase letters. If ‘<a
  4205    href="#titling-caps"><code class=property>titling-caps</code></a>’ is
  4206    specified with a font that does not support this feature, this property
  4207    has no visible effect. When simulated small capital glyphs are used, for
  4208    scripts that lack uppercase and lowercase letters, ‘<a
  4209    href="#small-caps"><code class=property>small-caps</code></a>’, ‘<a
  4210    href="#all-small-caps"><code class=property>all-small-caps</code></a>’,
  4211    ‘<a href="#petite-caps"><code class=property>petite-caps</code></a>’,
  4212    ‘<a href="#all-petite-caps"><code
  4213    class=property>all-petite-caps</code></a>’ and ‘<a
  4214    href="#unicase"><code class=property>unicase</code></a>’ have no visible
  4215    effect.
  4217   <p>When casing transforms are used to simulate small capitals, the casing
  4218    transformations must match those used for the <span
  4219    class=property>‘<code class=property>text-transform</code>’</span>
  4220    property.
  4222   <p>As a last resort, unscaled uppercase letter glyphs in a normal font may
  4223    replace glyphs in a small-caps font so that the text appears in all
  4224    uppercase letters.
  4226   <div class=figure style="padding: 0; margin: auto;"><img alt="using
  4227    all-small-caps in acronym-laden text" class=hires
  4228    src=acronym-laden-text.png width=596px>
  4229    <p class=caption>Using small capitals to improve readability in
  4230     acronym-laden text
  4231   </div>
  4233   <div class=example>
  4234    <p>Quotes rendered italicised, with small-caps on the first line:</p>
  4236    <pre>blockquote            { font-style: italic; }
  4237 blockquote:first-line { font-variant: small-caps; }
  4239 &lt;blockquote><a href="http://lists.w3.org/Archives/Public/www-style/2009Dec/0036.html" style="text-decoration: none; border: none;">I'll be honor-bound to slap them like a haddock.</a>&lt;/blockquote>
  4240 </pre>
  4241   </div>
  4242   <!-- prop: font-variant-numeric -->
  4244   <h3 id=font-variant-numeric-prop><span class=secno>6.7 </span>Numerical
  4245    formatting: the <a
  4246    href="#propdef-font-variant-numeric">font-variant-numeric</a> property</h3>
  4248   <table class=propdef id=namefont-variant-numericvaluenormal-ltnu>
  4249    <tbody>
  4250     <tr>
  4251      <td>Name:
  4253      <td><dfn id=propdef-font-variant-numeric>font-variant-numeric</dfn>
  4255     <tr>
  4256      <td>Value:
  4258      <td><a href="#font-variant-numeric-normal-value"
  4259       title="normal!!font-variant-numeric">normal</a> | [ <a
  4260       href="#numeric-figure-values"><var>&lt;numeric-figure-values&gt;</var></a>
  4261       || <a
  4262       href="#numeric-spacing-values"><var>&lt;numeric-spacing-values&gt;</var></a>
  4263       || <a
  4264       href="#numeric-fraction-values"><var>&lt;numeric-fraction-values&gt;</var></a>
  4265       || <a href="#ordinal">ordinal</a> || <a
  4266       href="#slashed-zero">slashed-zero</a> ]
  4268     <tr>
  4269      <td>Initial:
  4271      <td>normal
  4273     <tr>
  4274      <td>Applies to:
  4276      <td>all elements
  4278     <tr>
  4279      <td>Inherited:
  4281      <td>yes
  4283     <tr>
  4284      <td>Percentages:
  4286      <td>N/A
  4288     <tr>
  4289      <td>Media:
  4291      <td>visual
  4293     <tr>
  4294      <td>Computed value:
  4296      <td>as specified
  4298     <tr>
  4299      <td>Animatable:
  4301      <td>no
  4302   </table>
  4304   <p>Specifies control over numerical forms. The example below shows how some
  4305    of these values can be combined to influence the rendering of tabular data
  4306    with fonts that support these features. Within normal paragraph text,
  4307    proportional numbers are used while tabular numbers are used so that
  4308    columns of numbers line up properly:
  4310   <div class=figure style="padding: 0; margin: auto;"><img alt="combining
  4311    number styles" src=numberstyles.png>
  4312    <p class=caption>Using number styles
  4313   </div>
  4315   <p>Possible combinations:
  4317   <pre
  4318    class=prod><dfn id=numeric-figure-values><var>&lt;numeric-figure-values&gt;</var></dfn>   = [ <a href="#lining-nums">lining-nums</a> | <a href="#oldstyle-nums">oldstyle-nums</a> ]</pre>
  4320   <pre
  4321    class=prod><dfn id=numeric-spacing-values><var>&lt;numeric-spacing-values&gt;</var></dfn>  = [ <a href="#proportional-nums">proportional-nums</a> | <a href="#tabular-nums">tabular-nums</a> ]</pre>
  4323   <pre
  4324    class=prod><dfn id=numeric-fraction-values><var>&lt;numeric-fraction-values&gt;</var></dfn> = [ <a href="#diagonal-fractions">diagonal-fractions</a> | <a href="#stacked-fractions">stacked-fractions</a> ]</pre>
  4326   <p>Individual values have the following meanings:
  4328   <dl>
  4329    <dt><dfn id=font-variant-numeric-normal-value
  4330     title="normal!!font-variant-numeric">normal</dfn>
  4332    <dd>None of the features listed below are enabled.
  4334    <dt><dfn id=lining-nums>lining-nums</dfn>
  4336    <dd>Enables display of lining numerals (OpenType feature: <span
  4337     class=tag>lnum</span>).
  4339    <dt><dfn id=oldstyle-nums>oldstyle-nums</dfn>
  4341    <dd>Enables display of old-style numerals (OpenType feature: <span
  4342     class=tag>onum</span>).
  4344    <dt><dfn id=proportional-nums>proportional-nums</dfn>
  4346    <dd>Enables display of proportional numerals (OpenType feature: <span
  4347     class=tag>pnum</span>).
  4349    <dt><dfn id=tabular-nums>tabular-nums</dfn>
  4351    <dd>Enables display of tabular numerals (OpenType feature: <span
  4352     class=tag>tnum</span>).
  4354    <dt><dfn id=diagonal-fractions>diagonal-fractions</dfn>
  4356    <dd>Enables display of lining diagonal fractions (OpenType feature: <span
  4357     class=tag>frac</span>).
  4358   </dl>
  4360   <div class=featex><img alt="diagonal fraction example" src=frac.png></div>
  4362   <dl>
  4363    <dt><dfn id=stacked-fractions>stacked-fractions</dfn>
  4365    <dd>Enables display of lining stacked fractions (OpenType feature: <span
  4366     class=tag>afrc</span>).
  4367   </dl>
  4369   <div class=featex><img alt="stacked fraction example" src=afrc.png></div>
  4371   <dl>
  4372    <dt><dfn id=ordinal>ordinal</dfn>
  4374    <dd>Enables display of forms used with ordinal numbers (OpenType feature:
  4375     <span class=tag>ordn</span>).
  4377    <dt><dfn id=slashed-zero>slashed-zero</dfn>
  4379    <dd>Enables display of slashed zeros (OpenType feature: <span
  4380     class=tag>zero</span>).
  4381   </dl>
  4383   <div class=featex><img alt="slashed zero example" src=zero.png></div>
  4385   <div class=example id=steak-marinade>
  4386    <p>A simple flank steak marinade recipe, rendered with automatic fractions
  4387     and old-style numerals:</p>
  4389    <pre>.amount { font-variant-numeric: oldstyle-nums diagonal-fractions; }
  4391 &lt;h4>Steak marinade:&lt;/h4>
  4392 &lt;ul>
  4393   &lt;li>&lt;span class="amount">2&lt;/span> tbsp olive oil&lt;/li>
  4394   &lt;li>&lt;span class="amount">1&lt;/span> tbsp lemon juice&lt;/li>
  4395   &lt;li>&lt;span class="amount">1&lt;/span> tbsp soy sauce&lt;/li>
  4396   &lt;li>&lt;span class="amount">1 1/2&lt;/span> tbsp dry minced onion&lt;/li>
  4397   &lt;li>&lt;span class="amount">2 1/2&lt;/span> tsp italian seasoning&lt;/li>
  4398   &lt;li>Salt &amp;amp; pepper&lt;/li>
  4399 &lt;/ul>
  4401 &lt;p>Mix the meat with the marinade and let it sit covered in the refrigerator
  4402 for a few hours or overnight.&lt;/p>
  4403 </pre>
  4405    <p>Note that the fraction feature is only applied to values not the entire
  4406     paragraph. Fonts often implement this feature using contextual rules
  4407     based on the use of the slash (‘<code class=css>/</code>’) character.
  4408     As such, it's not suitable for use as a paragraph-level style.</p>
  4409   </div>
  4410   <!-- prop: font-variant-alternates -->
  4412   <h3 id=font-variant-alternates-prop><span class=secno>6.8 </span>Alternates
  4413    and swashes: the <a
  4414    href="#propdef-font-variant-alternates">font-variant-alternates</a>
  4415    property</h3>
  4417   <table class=propdef id=namefont-variant-alternatesvaluenormal-s>
  4418    <tbody>
  4419     <tr>
  4420      <td>Name:
  4422      <td><dfn
  4423       id=propdef-font-variant-alternates>font-variant-alternates</dfn>
  4425     <tr>
  4426      <td>Value:
  4428      <td>normal | [ <a href="#stylistic"
  4429       title=stylistic>stylistic(&lt;feature-value-name&gt;)</a> || <a
  4430       href="#historical-forms">historical-forms</a> || <a href="#styleset"
  4431       title=styleset>styleset(&lt;feature-value-name&gt; #)</a> || <a
  4432       href="#character-variant"
  4433       title=character-variant>character-variant(&lt;feature-value-name&gt;
  4434       #)</a> || <a href="#swash"
  4435       title=swash>swash(&lt;feature-value-name&gt;)</a> || <a
  4436       href="#ornaments"
  4437       title=ornaments>ornaments(&lt;feature-value-name&gt;)</a> || <a
  4438       href="#annotation"
  4439       title=annotation>annotation(&lt;feature-value-name&gt;)</a> ]
  4441     <tr>
  4442      <td>Initial:
  4444      <td>normal
  4446     <tr>
  4447      <td>Applies to:
  4449      <td>all elements
  4451     <tr>
  4452      <td>Inherited:
  4454      <td>yes
  4456     <tr>
  4457      <td>Percentages:
  4459      <td>N/A
  4461     <tr>
  4462      <td>Media:
  4464      <td>visual
  4466     <tr>
  4467      <td>Computed value:
  4469      <td>as specified
  4471     <tr>
  4472      <td>Animatable:
  4474      <td>no
  4475   </table>
  4477   <p>For any given character, fonts can provide a variety of alternate glyphs
  4478    in addition to the default glyph for that character. This property
  4479    provides control over the selection of these alternate glyphs.
  4481   <p>For many of the property values listed below, several different
  4482    alternate glyphs are available. How many alternates are available and what
  4483    they represent is font-specific, so these are each marked <dfn
  4484    id=font-specific>font specific</dfn> in the value definitions below.
  4485    Because the nature of these alternates is font-specific, the <a
  4486    href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
  4487    rule is used to define values for a specific font family or set of
  4488    families that associate a font-specific numeric
  4489    <code>&lt;feature-index&gt;</code> with a custom
  4490    <code>&lt;feature-value-name&gt;</code>, which is then used in this
  4491    property to select specific alternates:
  4493   <pre>@font-feature-values Noble Script { @swash { swishy: 1; flowing: 2; } }
  4495 p {
  4496   font-family: Noble Script;
  4497   font-variant-alternates: swash(flowing); /* use swash alternate #2 */
  4498 }</pre>
  4500   <p>When a particular <code>&lt;feature-value-name&gt;</code> has not been
  4501    defined for a given family or for a particular feature type, the computed
  4502    value must be the same as if it had been defined. However, property values
  4503    that contain these undefined <code>&lt;feature-value-name&gt;</code>
  4504    identifiers must be ignored when choosing glyphs.
  4506   <pre>/* these two style rules are effectively the same */
  4507 p { font-variant-alternates: swash(unknown-value); } /* not a defined value, ignored */
  4508 p { font-variant-alternates: normal; }
  4509 </pre>
  4511   <p>This allows values to be defined and used for a given set of font
  4512    families but ignored if fallback occurs, since the font family name would
  4513    be different. If a given value is outside the range supported by a given
  4514    font, the value is ignored. These values never apply to generic font
  4515    families.
  4517   <p>Individual values have the following meanings:
  4519   <dl>
  4520    <dt><dfn id=font-variant-alternates-normal-value
  4521     title="normal!!font-variant-alternates">normal</dfn>
  4523    <dd>None of the features listed below are enabled.
  4525    <dt><dfn id=historical-forms>historical-forms</dfn>
  4527    <dd>Enables display of historical forms (OpenType feature: <span
  4528     class=tag>hist</span>).
  4529   </dl>
  4531   <div class=featex><img alt="historical form example" src=hist.png></div>
  4533   <dl>
  4534    <dt><dfn id=stylistic
  4535     title=stylistic>stylistic(&lt;feature-value-name&gt;)</dfn>
  4537    <dd>Enables display of stylistic alternates (<a
  4538     href="#font-specific"><em>font specific</em></a>, OpenType feature: <span
  4539     class=tag>salt &lt;feature-index&gt;</span>).
  4540   </dl>
  4542   <div class=featex><img alt="stylistic alternate example" src=salt.png></div>
  4544   <dl>
  4545    <dt><dfn id=styleset title=styleset>styleset(&lt;feature-value-name&gt;
  4546     #)</dfn>
  4548    <dd>Enables display with stylistic sets (<a href="#font-specific"><em>font
  4549     specific</em></a>, OpenType feature: <span
  4550     class=tag>ss&lt;feature-index&gt;</span> OpenType currently defines <span
  4551     class=tag>ss01</span> through <span class=tag>ss20</span>).
  4552   </dl>
  4554   <div class=featex><img alt="styleset example" src=ssnn.png></div>
  4556   <dl>
  4557    <dt><dfn id=character-variant
  4558     title=character-variant>character-variant(&lt;feature-value-name&gt;
  4559     #)</dfn>
  4561    <dd>Enables display of specific character variants (<a
  4562     href="#font-specific"><em>font specific</em></a>, OpenType feature: <span
  4563     class=tag>cv&lt;feature-index&gt;</span> OpenType currently defines <span
  4564     class=tag>cv01</span> through <span class=tag>cv99</span>).
  4566    <dt><dfn id=swash title=swash>swash(&lt;feature-value-name&gt;)</dfn>
  4568    <dd>Enables display of swash glyphs (<a href="#font-specific"><em>font
  4569     specific</em></a>, OpenType feature: <span class=tag>swsh
  4570     &lt;feature-index&gt;, cswh &lt;feature-index&gt;</span>).
  4571   </dl>
  4573   <div class=featex><img alt="swash example" src=swsh.png></div>
  4575   <dl>
  4576    <dt><dfn id=ornaments
  4577     title=ornaments>ornaments(&lt;feature-value-name&gt;)</dfn>
  4579    <dd>Enables replacement of default glyphs with ornaments, if provided in
  4580     the font (<a href="#font-specific"><em>font specific</em></a>, OpenType
  4581     feature: <span class=tag>ornm &lt;feature-index&gt;</span>). Some fonts
  4582     may offer ornament glyphs as alternates for a wide collection of
  4583     characters; however, displaying arbitrary characters (e.g.,
  4584     alphanumerics) as ornaments is poor practice as it distorts the semantics
  4585     of the data. Font designers are encouraged to encode all ornaments
  4586     (except those explicitly encoded in the Unicode Dingbats blocks, etc.) as
  4587     alternates for the bullet character (U+2022) to allow authors to select
  4588     the desired glyph using ‘<a href="#ornaments"><code
  4589     class=property>ornaments</code></a>’.
  4590   </dl>
  4592   <div class=featex><img alt="ornaments example" src=ornm.png></div>
  4594   <dl>
  4595    <dt><dfn id=annotation
  4596     title=annotation>annotation(&lt;feature-value-name&gt;)</dfn>
  4598    <dd>Enables display of alternate annotation forms (<a
  4599     href="#font-specific"><em>font specific</em></a>, OpenType feature: <span
  4600     class=tag>nalt &lt;feature-index&gt;</span>).
  4601   </dl>
  4603   <div class=featex><img alt="alternate annotation form example"
  4604    src=nalt.png></div>
  4606   <h3 id=font-feature-values><span class=secno>6.9 </span>Defining font
  4607    specific alternates: the <dfn id=at-font-feature-values-rule
  4608    style="font-weight: inherit; font-style:
  4609    inherit"><code>@font-feature-values</code></dfn> rule</h3>
  4611   <p>Several of the possible values of ‘<a
  4612    href="#propdef-font-variant-alternates"><code
  4613    class=property>font-variant-alternates</code></a>’ listed above are
  4614    labeled as <a href="#font-specific"><em>font specific</em></a>. For these
  4615    features fonts may define not just a single glyph but a set of alternate
  4616    glyphs with an index to select a given alternate. Since these are font
  4617    family specific, the <a
  4618    href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
  4619    rule is used to define named values for these indices for a given family.
  4621   <p class=note>See the <a href="#om-fontfeaturevalues">object model
  4622    reference section</a> for a description of the interfaces used to modify
  4623    these rules via the CSS Object Model.
  4625   <div class=example>
  4626    <p>In the case of the swash Q in the example shown above, the swash could
  4627     be specified using these style rules:</p>
  4629    <pre>
  4631 @font-feature-values Jupiter Sans {
  4632   @swash {
  4633     delicate: 1;
  4634     flowing: 2;
  4638 h2 { font-family: Jupiter Sans, sans-serif; }
  4640 /* show the second swash variant in h2 headings */
  4641 h2:first-letter { font-variant-alternates: swash(flowing); }
  4643 &lt;h2>Quick&lt;/h2></pre>
  4645    <p>When Jupiter Sans is present, the second alternate swash alternate will
  4646     be displayed. When not present, no swash character will be shown, since
  4647     the specific named value "flowing" is only defined for the Jupiter Sans
  4648     family. The @-mark indicates the name of the property value for which a
  4649     named value can be used. The name "flowing" is chosen by the author. The
  4650     index that represents each alternate is defined within a given font's
  4651     data.</p>
  4652   </div>
  4654   <h4 id=basic-syntax><span class=secno>6.9.1 </span>Basic syntax</h4>
  4656   <p>An <a
  4657    href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
  4658    rule is composed of a list of font families followed by a block containing
  4659    individual <a href="#featurevalueblock"><i
  4660    title="feature_value_block">feature value blocks</i></a> that take the
  4661    form of @-rules. Each block defines a set of named values for a specific
  4662    font feature when a given set of font families is used. Effectively, they
  4663    define a mapping of ⟨family, feature, ident⟩ → ⟨values⟩ where
  4664    ⟨values⟩ are the numeric indices used for specific features defined
  4665    for a given font.
  4667   <p>In terms of the grammar, this specification defines the following
  4668    productions:
  4670   <pre><dfn id=fontfeaturevaluesrule>font_feature_values_rule</dfn>
  4671   : <a href="#fontfeaturevaluessym"><i>FONT_FEATURE_VALUES_SYM</i></a> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="#fontfamilynamelist"><i>font_family_name_list</i></a> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>*
  4672     '{' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="#featurevalueblock"><i>feature_value_block</i></a>? [ <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="#featurevalueblock"><i>feature_value_block</i></a>? ]* '}' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>*
  4675 <dfn id=fontfamilynamelist>font_family_name_list</dfn>
  4676   : <a href="#fontfamilyname"><i>font_family_name</i></a> [ <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* ',' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="#fontfamilyname"><i>font_family_name</i></a> ]*
  4679 <dfn id=fontfamilyname>font_family_name</dfn>
  4680   : <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>STRING</i></a> | [ <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>IDENT</i></a> [ <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>IDENT</i></a> ]* ]
  4683 <dfn id=featurevalueblock>feature_value_block</dfn>
  4684   : <a href="#featuretype"><i>feature_type</i></a> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>*
  4685     '{' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="#featurevaluedefinition"><i>feature_value_definition</i></a>? [ <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* ';' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="#featurevaluedefinition"><i>feature_value_definition</i></a>? ]* '}' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>*
  4688 <dfn id=featuretype>feature_type</dfn>:
  4689   <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>ATKEYWORD</i></a>
  4692 <dfn id=featurevaluedefinition>feature_value_definition</dfn>
  4693   : <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>IDENT</i></a> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* ':' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>NUMBER</i></a> [ <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>NUMBER</i></a> ]*
  4695 </pre>
  4697   <p>The following new token is introduced:
  4699   <pre>@{F}{O}{N}{T}{-}{F}{E}{A}{T}{U}{R}{E}{-}{V}{A}{L}{U}{E}{S}   {return <dfn id=fontfeaturevaluessym>FONT_FEATURE_VALUES_SYM</dfn>;}
  4700 </pre>
  4702   <p><a href="#featurevalueblock"><i title="feature_value_block">Feature
  4703    value blocks</i></a> are handled as <a
  4704    href="http://www.w3.org/TR/CSS2/syndata.html#at-rules">at-rules</a>, they
  4705    consist of everything up to the next block or semi-colon, whichever comes
  4706    first.
  4708   <p>The <a href="#fontfamilynamelist"><i title="font_family_name_list">font
  4709    family list</i></a> is a comma-delimited list of <a
  4710    href="#fontfamilyname"><i title="font_family_name">font family
  4711    names</i></a> that match the definition of <a
  4712    href="#family-name-value"><var>&lt;family-name&gt;</var></a> for the <a
  4713    href="#propdef-font-family" title="font-family!!property">‘<code
  4714    class=property>font-family</code>’</a> property. This means that only
  4715    named font families are allowed, rules that include generic or system
  4716    fonts in the list of font families are syntax errors. However, if a user
  4717    agent defines a generic font to be a specific named font (e.g. Helvetica),
  4718    the settings associated with that family name will be used. If syntax
  4719    errors occur within the font family list, the entire rule must be ignored.
  4721   <p>Within <a href="#featurevalueblock"><i
  4722    title="feature_value_block">feature value blocks</i></a>, the <a
  4723    href="#featuretype"><i title="feature_type">feature type</i></a> is
  4724    ‘<code class=css>@</code>’ followed by the name of one of the <a
  4725    href="#font-specific"><em>font specific</em></a> property values of ‘<a
  4726    href="#propdef-font-variant-alternates"><code
  4727    class=property>font-variant-alternates</code></a>’ (e.g. <a
  4728    href="#swash"><code>@swash</code></a>). The identifiers used within
  4729    feature value definitions follow the rules of CSS user identifiers and are
  4730    case-sensitive. They are unique only for a given set of font families and
  4731    <a href="#featuretype"><i title="feature_type">feature type</i></a>. The
  4732    same identifier used with a different <a href="#featuretype"><i
  4733    title="feature_type">feature type</i></a> is treated as a separate and
  4734    distinct value. If the same identifier is defined mulitple times for a
  4735    given <a href="#featuretype"><i title="feature_type">feature type</i></a>
  4736    and font family, the last defined value is used. Values associated with a
  4737    given identifier are limited to integer values 0 or greater.
  4739   <p>When syntax errors occur within a <a href="#featurevaluedefinition"><i
  4740    title="feature_value_definition">feature value definition</i></a>, such as
  4741    invalid identifiers or values, the entire <a
  4742    href="#featurevaluedefinition"><i title="feature_value_definition">feature
  4743    value definition</i></a> must be omitted, just as syntax errors in style
  4744    declarations are handled. When the <a href="#featuretype"><i
  4745    title="feature_type">feature type</i></a> is invalid, the entire
  4746    associated <a href="#featurevalueblock"><i
  4747    title="feature_value_block">feature value block</i></a> must be ignored.
  4749   <div class=example>
  4750    <p>Rules that are equivalent given syntax error handling:</p>
  4752    <pre>@font-feature-values Bongo {
  4753   @swash { ornate: 1; }
  4754   annotation { boxed: 4; } /* should be @annotation! */
  4755   @swash { double-loops: 1; flowing: -1; } /* negative value */
  4756   @ornaments ; /* incomplete definition */
  4757   @styleset { double-W: 14; sharp-terminals: 16 1 } /* missing ; */
  4758   <a href="http://www.angryalien.com/0504/shiningbunnies.html" style="text-decoration: none; border: none;">redrum</a>  /* random editing mistake */
  4759 }</pre>
  4761    <p>The example above is equivalent to:</p>
  4763    <pre>@font-feature-values Bongo {
  4764   @swash { ornate: 1; }
  4765   @swash { double-loops: 1; }
  4766   @styleset { double-W: 14; sharp-terminals: 16 1; }
  4767 }</pre>
  4768   </div>
  4770   <p>If multiple <a
  4771    href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
  4772    rules are defined for a given family, the resulting values definitions are
  4773    the union of the definitions contained within these rules. This allows a
  4774    set of named values to be defined for a given font family globally for a
  4775    site and specific additions made per-page.
  4777   <div class=example>
  4778    <p>Using both site-wide and per-page feature values:</p>
  4780    <pre>
  4781 site.css:
  4783   @font-feature-values Mercury Serif {
  4784     @styleset {
  4785       stacked-g: 3; /* "two-storey" versions of g, a */
  4786       stacked-a: 4;
  4790 page.css:
  4792   @font-feature-values Mercury Serif {
  4793     @styleset {
  4794       geometric-m: 7; /* alternate version of m */
  4798   body {
  4799     font-family: Mercury Serif, serif;
  4801     /* enable both the use of stacked g and alternate m */
  4802     font-variant-alternates: styleset(stacked-g, geometric-m);
  4803   }</pre>
  4804   </div>
  4806   <div class=example>
  4807    <p>Using a commonly named value allows authors to use a single style rule
  4808     to cover a set of fonts for which the underlying selector is different
  4809     for each font. If either font in the example below is found, a circled
  4810     number glyph will be used:</p>
  4812    <pre>@font-feature-values Taisho Gothic {
  4813   @annotation { boxed: 1; circled: 4; }
  4816 @font-feature-values Otaru Kisa {
  4817   @annotation { circled: 1; black-boxed: 3; }
  4820 h3.title {
  4821   /* circled form defined for both fonts */
  4822   font-family: Taisho Gothic, Otaru Kisa;
  4823   font-variant: annotation(circled);
  4824 }</pre>
  4825   </div>
  4827   <h4 id=multi-valued-feature-value-definitions><span class=secno>6.9.2
  4828    </span>Multi-valued feature value definitions</h4>
  4830   <p>Most <a href="#font-specific"><em>font specific</em></a> ‘<a
  4831    href="#propdef-font-variant-alternates"><code
  4832    class=property>font-variant-alternates</code></a>’ property values take
  4833    a single value (e.g. ‘<a href="#swash"><code
  4834    class=property>swash</code></a>’). The ‘<a
  4835    href="#character-variant"><code
  4836    class=property>character-variant</code></a>’ property value allows two
  4837    values and ‘<a href="#styleset"><code
  4838    class=property>styleset</code></a>’ allows an unlimited number.
  4840   <p>For the styleset property value, multiple values indicate the style sets
  4841    to be enabled. Values between 1 and 99 enable OpenType features <span
  4842    class=tag>ss01</span> through <span class=tag>ss99</span>. However, the
  4843    OpenType standard only officially defines <span class=tag>ss01</span>
  4844    through <span class=tag>ss20</span>. For OpenType fonts, values greater
  4845    than 99 or equal to 0 do not generate a syntax error when parsed but
  4846    enable no OpenType features.
  4848   <pre>@font-feature-values Mars Serif {
  4849   @styleset {
  4850     alt-g: 1;        /* implies ss01 = 1 */
  4851     curly-quotes: 3; /* implies ss03 = 1 */
  4852     code: 4 5;       /* implies ss04 = 1, ss05 = 1 */
  4855   @styleset {
  4856     dumb: 125;        /* &gt;99, ignored */
  4859   @swash {
  4860     swishy: 3 5;     /* more than 1 value for swash, syntax error */
  4864 p.codeblock {
  4865   /* implies ss03 = 1, ss04 = 1, ss05 = 1 */
  4866   font-variant-alternates: styleset(curly-quotes, code);
  4867 }</pre>
  4869   <p>For character-variant, a single value between 1 and 99 indicates the
  4870    enabling of OpenType feature <span class=tag>cv01</span> through <span
  4871    class=tag>cv99</span>. For OpenType fonts, values greater than 99 or equal
  4872    to 0 are ignored but do not generate a syntax error when parsed but enable
  4873    no OpenType features. When two values are listed, the first value
  4874    indicates the feature used and the second the value passed for that
  4875    feature. If more than two values are assigned to a given name, a syntax
  4876    error occurs and the entire <a href="#featurevaluedefinition"><i
  4877    title="feature_value_definition">feature value definition</i></a> is
  4878    ignored.
  4880   <pre>@font-feature-values MM Greek {
  4881   @character-variant { alpha-2: 1 2; }   /* implies cv01 = 2 */
  4882   @character-variant { beta-3: 2 3; }    /* implies cv02 = 3 */
  4883   @character-variant { epsilon: 5 3 6; } /* more than 2 values, syntax error, definition ignored */
  4884   @character-variant { gamma: 12; }      /* implies cv12 = 1 */
  4885   @character-variant { zeta:   20 3; }   /* implies cv20 = 3 */
  4886   @character-variant { zeta-2: 20 2; }   /* implies cv20 = 2 */
  4887   @character-variant { silly: 105; }     /* &gt;99, ignored */
  4888   @character-variant { dumb: 323 3; }    /* &gt;99, ignored */
  4891 #title {
  4892   /* use the third alternate beta, first alternate gamma */
  4893   font-variant-alternates: character-variant(beta-3, gamma);
  4896 p {
  4897   /* zeta-2 follows zeta, implies cv20 = 2  */
  4898   font-variant-alternates: character-variant(zeta, zeta-2);
  4901 .special {
  4902   /* zeta follows zeta-2, implies cv20 = 3  */
  4903   font-variant-alternates: character-variant(zeta-2, zeta);
  4904 }</pre>
  4906   <div class=figure><img alt="Matching text on Byzantine seals using
  4907    character variants" src=byzantineseal.png>
  4908    <p class=caption>Byzantine seal text displayed with character variants
  4909   </div>
  4911   <div class=example>
  4912    <p>In the figure above, the text in red is rendered using a font
  4913     containing character variants that mimic the character forms found on a
  4914     Byzantine seal from the 8th century A.D. Two lines below is the same text
  4915     displayed in a font without variants. Note the two variants for U and N
  4916     used on the seal.</p>
  4918    <pre>@font-feature-values Athena Ruby {
  4919   @character-variant {
  4920     leo-B: 2 1;
  4921     leo-M: 13 3;
  4922     leo-alt-N: 14 1;
  4923     leo-N: 14 2;
  4924     leo-T: 20 1;
  4925     leo-U: 21 2;
  4926     leo-alt-U: 21 4;
  4930 p {
  4931   font-variant: discretionary-ligatures,
  4932                 character-variant(leo-B, leo-M, leo-N, leo-T, leo-U);
  4935 span.alt-N {
  4936   font-variant-alternates: character-variant(leo-alt-N);
  4939 span.alt-U {
  4940   font-variant-alternates: character-variant(leo-alt-U);
  4943 &lt;p>ENO....UP͞RSTU&lt;span class="alt-U">U&lt;/span>͞&lt;span class="alt-U">U&lt;/span>ΚΑΙTỤẠG̣IUPNS&lt;/p>
  4945 &lt;p>LEON|ΚΑΙCONSTA|NTI&lt;span class="alt-N">N&lt;/span>OS..|STOIBAṢ.|LIṢROM|AIO&lt;span class="alt-N">N&lt;/span>&lt;/p>
  4946 </pre>
  4947   </div>
  4949   <h3 id=font-variant-east-asian-prop><span class=secno>6.10 </span>East
  4950    Asian text rendering: the <a
  4951    href="#propdef-font-variant-east-asian">font-variant-east-asian</a>
  4952    property</h3>
  4954   <table class=propdef id=namefont-variant-east-asianvaluenormal-l>
  4955    <tbody>
  4956     <tr>
  4957      <td>Name:
  4959      <td><dfn
  4960       id=propdef-font-variant-east-asian>font-variant-east-asian</dfn>
  4962     <tr>
  4963      <td>Value:
  4965      <td><a href="#font-variant-east-asian-normal-value"
  4966       title="normal!!font-variant-east-asian">normal</a> | [ <a
  4967       href="#east-asian-variant-values"><var>&lt;east-asian-variant-values&gt;</var></a>
  4968       || <a
  4969       href="#east-asian-width-values"><var>&lt;east-asian-width-values&gt;</var></a>
  4970       || <a href="#ruby">ruby</a> ]
  4972     <tr>
  4973      <td>Initial:
  4975      <td>normal
  4977     <tr>
  4978      <td>Applies to:
  4980      <td>all elements
  4982     <tr>
  4983      <td>Inherited:
  4985      <td>yes
  4987     <tr>
  4988      <td>Percentages:
  4990      <td>N/A
  4992     <tr>
  4993      <td>Media:
  4995      <td>visual
  4997     <tr>
  4998      <td>Computed value:
  5000      <td>as specified
  5002     <tr>
  5003      <td>Animatable:
  5005      <td>no
  5006   </table>
  5008   <p>Allows control of glyph substitution and sizing in East Asian text.
  5010   <pre
  5011    class=prod><dfn id=east-asian-variant-values><var>&lt;east-asian-variant-values&gt;</var></dfn> = [ <a href="#jis78">jis78</a> | <a href="#jis83">jis83</a> | <a href="#jis90">jis90</a> | <a href="#jis04">jis04</a> | <a href="#simplified">simplified</a> | <a href="#traditional">traditional</a> ]</pre>
  5013   <pre
  5014    class=prod><dfn id=east-asian-width-values><var>&lt;east-asian-width-values&gt;</var></dfn>   = [ <a href="#full-width">full-width</a> | <a href="#proportional-width">proportional-width</a> ]</pre>
  5016   <p>Individual values have the following meanings:
  5018   <dl>
  5019    <dt><dfn id=font-variant-east-asian-normal-value
  5020     title="normal!!font-variant-east-asian">normal</dfn>
  5022    <dd>None of the features listed below are enabled.
  5024    <dt><dfn id=jis78>jis78</dfn>
  5026    <dd>Enables rendering of JIS78 forms (OpenType feature: <span
  5027     class=tag>jp78</span>).
  5028   </dl>
  5030   <div class=featex><img alt="JIS78 form example" src=jp78.png></div>
  5032   <dl>
  5033    <dt><dfn id=jis83>jis83</dfn>
  5035    <dd>Enables rendering of JIS83 forms (OpenType feature: <span
  5036     class=tag>jp83</span>).
  5038    <dt><dfn id=jis90>jis90</dfn>
  5040    <dd>Enables rendering of JIS90 forms (OpenType feature: <span
  5041     class=tag>jp90</span>).
  5043    <dt><dfn id=jis04>jis04</dfn>
  5045    <dd>Enables rendering of JIS2004 forms (OpenType feature: <span
  5046     class=tag>jp04</span>).
  5047     <p>The various JIS variants reflect the glyph forms defined in different
  5048      Japanese national standards. Fonts generally include glyphs defined by
  5049      the most recent national standard but it's sometimes necessary to use
  5050      older variants, to match signage for example.</p>
  5052    <dt><dfn id=simplified>simplified</dfn>
  5054    <dd>Enables rendering of simplified forms (OpenType feature: <span
  5055     class=tag>smpl</span>).
  5057    <dt><dfn id=traditional>traditional</dfn>
  5059    <dd>Enables rendering of traditional forms (OpenType feature: <span
  5060     class=tag>trad</span>).
  5061   </dl>
  5063   <p>The ‘<a href="#simplified"><code
  5064    class=property>simplified</code></a>’ and ‘<a
  5065    href="#traditional"><code class=property>traditional</code></a>’ values
  5066    allow control over the glyph forms for characters which have been
  5067    simplified over time but for which the older, traditional form is still
  5068    used in some contexts. The exact set of characters and glyph forms will
  5069    vary to some degree by context for which a given font was designed.
  5071   <div class=featex><img alt="tradtional form example" src=trad.png></div>
  5073   <dl>
  5074    <dt><dfn id=full-width>full-width</dfn>
  5076    <dd>Enables rendering of full-width variants (OpenType feature: <span
  5077     class=tag>fwid</span>).
  5079    <dt><dfn id=proportional-width>proportional-width</dfn>
  5081    <dd>Enables rendering of proportionally-spaced variants (OpenType feature:
  5082     <span class=tag>pwid</span>).
  5083   </dl>
  5085   <div class=featex><img alt="proportionally spaced Japanese example"
  5086    src=pwid.png></div>
  5088   <dl>
  5089    <dt><dfn id=ruby>ruby</dfn>
  5091    <dd>Enables display of ruby variant glyphs (OpenType feature: <span
  5092     class=tag>ruby</span>). Since ruby text is generally smaller than the
  5093     associated body text, font designers can design special glyphs for use
  5094     with ruby that are more readable than scaled down versions of the default
  5095     glyphs. Only glyph selection is affected, there is no associated font
  5096     scaling or other change that affects line layout. The red ruby text below
  5097     is shown with default glyphs (top) and with ruby variant glyphs (bottom).
  5098     Note the slight difference in stroke thickness.
  5099   </dl>
  5101   <div class=featex><img alt="ruby variant example" src=rubyshinkansen.png></div>
  5103   <h3 id=font-variant-prop><span class=secno>6.11 </span>Overall shorthand
  5104    for font rendering: the <a href="#propdef-font-variant">font-variant</a>
  5105    property</h3>
  5107   <table class=propdef id=namefont-variantvaluenormal-none-ltcommo>
  5108    <tbody>
  5109     <tr>
  5110      <td>Name:
  5112      <td><dfn id=propdef-font-variant
  5113       title="font-variant!!property">font-variant</dfn>
  5115     <tr>
  5116      <td>Value:
  5118      <td><a href="#font-variant-normal-value"
  5119       title="normal!!font-variant">normal</a> | <a
  5120       href="#font-variant-none-value" title="none!!font-variant">none</a> | [
  5121       <a href="#common-lig-values"><var>&lt;common-lig-values&gt;</var></a>
  5122       || <a
  5123       href="#discretionary-lig-values"><var>&lt;discretionary-lig-values&gt;</var></a>
  5124       || <a
  5125       href="#historical-lig-values"><var>&lt;historical-lig-values&gt;</var></a>
  5126       || <a
  5127       href="#contextual-alt-values"><var>&lt;contextual-alt-values&gt;</var></a>
  5128       || <a href="#stylistic"><var
  5129       title=stylistic>stylistic(&lt;feature-value-name&gt;)</var></a> || <a
  5130       href="#historical-forms"><var>historical-forms</var></a> || <a
  5131       href="#styleset"><var
  5132       title=styleset>styleset(&lt;feature-value-name&gt; #)</var></a> || <a
  5133       href="#character-variant"><var
  5134       title=character-variant>character-variant(&lt;feature-value-name&gt;
  5135       #)</var></a> || <a href="#swash"><var
  5136       title=swash>swash(&lt;feature-value-name&gt;)</var></a> || <a
  5137       href="#ornaments"><var
  5138       title=ornaments>ornaments(&lt;feature-value-name&gt;)</var></a> || <a
  5139       href="#annotation"><var
  5140       title=annotation>annotation(&lt;feature-value-name&gt;)</var></a> || [
  5141       <a href="#small-caps"><i>small-caps</i></a> | <a
  5142       href="#all-small-caps"><i>all-small-caps</i></a> | <a
  5143       href="#petite-caps"><i>petite-caps</i></a> | <a
  5144       href="#all-petite-caps"><i>all-petite-caps</i></a> | <a
  5145       href="#unicase"><i>unicase</i></a> | <a
  5146       href="#titling-caps"><i>titling-caps</i></a> ] || <a
  5147       href="#numeric-figure-values"><var>&lt;numeric-figure-values&gt;</var></a>
  5148       || <a
  5149       href="#numeric-spacing-values"><var>&lt;numeric-spacing-values&gt;</var></a>
  5150       || <a
  5151       href="#numeric-fraction-values"><var>&lt;numeric-fraction-values&gt;</var></a>
  5152       || <a href="#ordinal"><i>ordinal</i></a> || <a
  5153       href="#slashed-zero"><i>slashed-zero</i></a> || <a
  5154       href="#east-asian-variant-values"><var>&lt;east-asian-variant-values&gt;</var></a>
  5155       || <a
  5156       href="#east-asian-width-values"><var>&lt;east-asian-width-values&gt;</var></a>
  5157       || <a href="#ruby"><i>ruby</i></a> ]
  5159     <tr>
  5160      <td>Initial:
  5162      <td>normal
  5164     <tr>
  5165      <td>Applies to:
  5167      <td>all elements
  5169     <tr>
  5170      <td>Inherited:
  5172      <td>yes
  5174     <tr>
  5175      <td>Percentages:
  5177      <td>see individual properties
  5179     <tr>
  5180      <td>Media:
  5182      <td>visual
  5184     <tr>
  5185      <td>Computed value:
  5187      <td>see individual properties
  5189     <tr>
  5190      <td>Animatable:
  5192      <td>see individual properties
  5193   </table>
  5195   <p>The <a href="#propdef-font-variant"
  5196    title="font-variant!!property">‘<code
  5197    class=property>font-variant</code>’</a> property is a shorthand for all
  5198    font-variant subproperties. The value <dfn id=font-variant-normal-value
  5199    title="normal!!font-variant">‘<code
  5200    class=property>normal</code>’</dfn> resets all subproperties of <a
  5201    href="#propdef-font-variant" title="font-variant!!property">‘<code
  5202    class=property>font-variant</code>’</a> to their inital value. The <dfn
  5203    id=font-variant-none-value title="none!!font-variant">‘<code
  5204    class=property>none</code>’</dfn> value sets ‘<a
  5205    href="#propdef-font-variant-ligatures"><code
  5206    class=property>font-variant-ligatures</code></a>’ to ‘<code
  5207    class=property>none</code>’ and resets all other font feature properties
  5208    to their initial value. Like other shorthands, using <a
  5209    href="#propdef-font-variant" title="font-variant!!property">‘<code
  5210    class=property>font-variant</code>’</a> resets unspecified <a
  5211    href="#propdef-font-variant" title="font-variant!!property">‘<code
  5212    class=property>font-variant</code>’</a> subproperties to their initial
  5213    values. It does not reset the values of either ‘<a
  5214    href="#propdef-font-language-override"><code
  5215    class=property>font-language-override</code></a>’ or <a
  5216    href="#propdef-font-feature-settings"
  5217    title="font-feature-settings!!property">‘<code
  5218    class=property>font-feature-settings</code>’</a>.
  5220   <h3 id=font-feature-settings-prop><span class=secno>6.12 </span>Low-level
  5221    font feature settings control: the <a
  5222    href="#propdef-font-feature-settings">font-feature-settings</a> property</h3>
  5224   <table class=propdef id=namefont-feature-settingsvaluenormal-ltf>
  5225    <tbody>
  5226     <tr>
  5227      <td>Name:
  5229      <td><dfn id=propdef-font-feature-settings
  5230       title="font-feature-settings!!property">font-feature-settings</dfn>
  5232     <tr>
  5233      <td>Value:
  5235      <td><a href="#font-feature-settings-normal-value"
  5236       title="normal!!font-feature-settings">normal</a> | <a
  5237       href="#feature-tag-value"><var>&lt;feature-tag-value&gt;</var></a> #
  5239     <tr>
  5240      <td>Initial:
  5242      <td>normal
  5244     <tr>
  5245      <td>Applies to:
  5247      <td>all elements
  5249     <tr>
  5250      <td>Inherited:
  5252      <td>yes
  5254     <tr>
  5255      <td>Percentages:
  5257      <td>N/A
  5259     <tr>
  5260      <td>Media:
  5262      <td>visual
  5264     <tr>
  5265      <td>Computed value:
  5267      <td>as specified
  5269     <tr>
  5270      <td>Animatable:
  5272      <td>no
  5273   </table>
  5275   <p>This property provides low-level control over OpenType font features. It
  5276    is intended as a way of providing access to font features that are not
  5277    widely used but are needed for a particular use case.
  5279   <p>Authors should generally use <a href="#propdef-font-variant"
  5280    title="font-variant!!property">‘<code
  5281    class=property>font-variant</code>’</a> and its related subproperties
  5282    whenever possible and only use this property for special cases where its
  5283    use is the only way of accessing a particular infrequently used font
  5284    feature.
  5286   <pre>/* enable small caps and use second swash alternate */
  5287 font-feature-settings: "smcp", "swsh" 2;</pre>
  5289   <p>A value of <dfn id=font-feature-settings-normal-value
  5290    title="normal!!font-feature-settings">‘<code
  5291    class=property>normal</code>’</dfn> means that no change in glyph
  5292    selection or positioning occurs due to this property.
  5294   <p>Feature tag values have the following syntax:
  5296   <pre
  5297    class=prod><dfn id=feature-tag-value><var>&lt;feature-tag-value&gt;</var></dfn> = &lt;string&gt; [ &lt;integer&gt; | on | off ]?</pre>
  5299   <p>The &lt;string&gt; is a case-sensitive OpenType feature tag. As
  5300    specified in the OpenType specification, feature tags contain four ASCII
  5301    characters. Tag strings longer or shorter than four characters, or
  5302    containing characters outside the U+20–7E codepoint range are invalid.
  5303    Feature tags need only match a feature tag defined in the font, so they
  5304    are not limited to explicitly registered OpenType features. Fonts defining
  5305    custom feature tags should follow the <a
  5306    href="http://www.microsoft.com/typography/otspec/featuretags.htm">tag name
  5307    rules</a> defined in the OpenType specification <a
  5308    href="#OPENTYPE-FEATURES"
  5309    rel=biblioentry>[OPENTYPE-FEATURES]<!--{{!OPENTYPE-FEATURES}}--></a>.
  5310    Feature tags not present in the font are ignored; a user agent must not
  5311    attempt to synthesize fallback behavior based on these feature tags.
  5313   <p>This means that explicitly disabling the <span class=tag>kern</span>
  5314    feature will not affect the application of kerning data found in the
  5315    ‘<code class=property>kern</code>’ table (as opposed to kerning data
  5316    associated with the <span class=tag>kern</span> feature in the ‘<code
  5317    class=property>GPOS</code>’ table). Authors should use the ‘<a
  5318    href="#propdef-font-kerning"><code
  5319    class=property>font-kerning</code></a>’ property to explictly enable or
  5320    disable kerning since this property affects both types of kerning.
  5322   <p>If present, a value indicates an index used for glyph selection. An
  5323    &lt;integer&gt; value must be 0 or greater. A value of 0 indicates that
  5324    the feature is disabled. For boolean features, a value of 1 enables the
  5325    feature. For non-boolean features, a value of 1 or greater enables the
  5326    feature and indicates the feature selection index. A value of ‘<code
  5327    class=property>on</code>’ is synonymous with 1 and ‘<code
  5328    class=property>off</code>’ is synonymous with 0. If the value is
  5329    omitted, a value of 1 is assumed.
  5331   <pre>
  5332 font-feature-settings: "dlig" 1;       /* dlig=1 enable discretionary ligatures */
  5333 font-feature-settings: "smcp" on;      /* smcp=1 enable small caps */
  5334 font-feature-settings: 'c2sc';         /* c2sc=1 enable caps to small caps */
  5335 font-feature-settings: "liga" off;     /* liga=0 no common ligatures */
  5336 font-feature-settings: "tnum", 'hist'; /* tnum=1, hist=1 enable tabular numbers and historical forms */
  5337 font-feature-settings: "tnum" "hist";  /* invalid, need a comma-delimited list */
  5338 font-feature-settings: "palin" off;    /* good idea but invalid tagname */
  5339 font-feature-settings: "PKRN";         /* PKRN=1 enable custom feature */
  5340 font-feature-settings: dlig;           /* invalid, tag must be a string */
  5341 </pre>
  5343   <p>When values greater than the range supported by the font are specified,
  5344    the behavior is explicitly undefined. For boolean features, in general
  5345    these will enable the feature. For non-boolean features, out of range
  5346    values will in general be equivalent to a 0 value. However, in both cases
  5347    the exact behavior will depend upon the way the font is designed
  5348    (specifically, which type of lookup is used to define the feature).
  5350   <p>Although specifically defined for OpenType feature tags, feature tags
  5351    for other modern font formats that support font features may be added in
  5352    the future. Where possible, features defined for other font formats should
  5353    attempt to follow the pattern of registered OpenType tags.
  5355   <div class=example>
  5356    <p>The Japanese text below will be rendered with half-width kana
  5357     characters:</p>
  5359    <pre lang=ja>
  5360 body { font-feature-settings: "hwid"; /* Half-width OpenType feature */ }
  5362 &lt;p>毎日<a href="http://images.google.com/images?q=%E3%82%AB%E3%83%AC%E3%83%BC" style="text-decoration: none;">カレー</a>食べてるのに、飽きない&lt;/p>
  5363 </pre>
  5364   </div>
  5366   <h3 id=font-language-override-prop><span class=secno>6.13 </span>Font
  5367    language override: the <a
  5368    href="#propdef-font-language-override">font-language-override</a> property</h3>
  5370   <table class=propdef id=namefont-language-overridevaluenormal-lt>
  5371    <tbody>
  5372     <tr>
  5373      <td>Name:
  5375      <td><dfn id=propdef-font-language-override>font-language-override</dfn>
  5377     <tr>
  5378      <td>Value:
  5380      <td><a href="#font-language-override-normal-value"
  5381       title="normal!!font-language-override">normal</a> | <a
  5382       href="#font-language-override-string-value"><var>&lt;string&gt;</var></a>
  5384     <tr>
  5385      <td>Initial:
  5387      <td><a href="#font-language-override-normal-value"
  5388       title="normal!!font-language-override">normal</a>
  5390     <tr>
  5391      <td>Applies to:
  5393      <td>all elements
  5395     <tr>
  5396      <td>Inherited:
  5398      <td>yes
  5400     <tr>
  5401      <td>Percentages:
  5403      <td>N/A
  5405     <tr>
  5406      <td>Media:
  5408      <td>visual
  5410     <tr>
  5411      <td>Computed value:
  5413      <td>as specified
  5415     <tr>
  5416      <td>Animatable:
  5418      <td>no
  5419   </table>
  5421   <p>Normally, authors can control the use of language-specific glyph
  5422    substitutions and positioning by setting the content language of an
  5423    element, as <a href="#language-specific-support">described above</a>:
  5425   <pre>&lt;!-- Display text using S'gaw Karen specific features -->
  5426 &lt;p lang="ksw">...&lt;/p></pre>
  5428   <p>In some cases, authors may need to specify a language system that
  5429    differs from the content language, for example due to the need to mimic
  5430    another language's typographic traditions. The ‘<a
  5431    href="#propdef-font-language-override"><code
  5432    class=property>font-language-override</code></a>’ property allows
  5433    authors to explicitly specify the language system of the font, overriding
  5434    the language system implied by the content language.
  5436   <p>Values have the following meanings:
  5438   <dl>
  5439    <dt><dfn id=font-language-override-normal-value
  5440     title="normal!!font-language-override">normal</dfn>
  5442    <dd>specifies that when rendering with OpenType fonts, the content
  5443     language of the element is used to infer the OpenType language system
  5445    <dt><dfn
  5446     id=font-language-override-string-value><var>&lt;string&gt;</var></dfn>
  5448    <dd>single three-letter case-sensitive OpenType <a
  5449     href="http://www.microsoft.com/typography/otspec/languagetags.htm">language
  5450     system tag</a>, specifies the OpenType language system to be used instead
  5451     of the language system implied by the language of the element
  5452   </dl>
  5453   <!-- For this level, string represents a single language code, there's no concept of "fallback" 
  5454 http://www.w3.org/2013/06/07-css-minutes.html#item04 -->
  5456   <p>Use of invalid OpenType language system tags must not generate a parse
  5457    error but must be ignored when doing glyph selection and placement.
  5459   <div class=example>
  5460    <p>The <a href="http://www.un.org/en/documents/udhr/index.shtml">Universal
  5461     Declaration of Human Rights</a> has been translated into a wide variety
  5462     of languages. In Turkish, Article 9 of this document might be marked up
  5463     as below:</p>
  5465    <pre lang=tr>&lt;body lang="tr">
  5467 &lt;h4>Madde 9&lt;/h4>
  5468 &lt;p>Hiç kimse keyfi olarak tutuklanamaz, alıkonulanamaz veya sürülemez.&lt;/p>
  5469 </pre>
  5471    <p>Here the user agent uses the value of the ‘<code
  5472     class=property>lang</code>’ attribute when rendering text and
  5473     appropriately renders this text without ‘<code
  5474     class=property>fi</code>’ ligatures. There is no need to use the ‘<a
  5475     href="#propdef-font-language-override"><code
  5476     class=property>font-language-override</code></a>’ property.</p>
  5478    <p>However, a given font may lack support for a specific language. In this
  5479     situation authors may need to use the typographic conventions of a
  5480     related language that are supported by that font:</p>
  5482    <pre lang=mk>&lt;body lang="mk">     &lt;!-- Macedonian lang code --&gt;
  5484 body { font-language-override: "SRB"; /* Serbian OpenType language tag */ }
  5486 &lt;h4>Члeн 9&lt;/h4>
  5487 &lt;p>Никoj чoвeк нeмa дa бидe пoдлoжeн нa прoизвoлнo aпсeњe, притвoр или прoгoнувaњe.&lt;/p>
  5489 </pre>
  5491    <p>The Macedonian text here will be rendered using Serbian typographic
  5492     conventions, with the assumption that the font specified supports
  5493     Serbian.</p>
  5494   </div>
  5496   <p><a id=rendering-considerations></a>
  5498   <h2 id=font-feature-resolution><span class=secno>7 </span>Font Feature
  5499    Resolution</h2>
  5501   <p>As described in the previous section, font features can be enabled in a
  5502    variety of ways, either via the use of <a href="#propdef-font-variant"
  5503    title="font-variant!!property">‘<code
  5504    class=property>font-variant</code>’</a> or <a
  5505    href="#propdef-font-feature-settings"
  5506    title="font-feature-settings!!property">‘<code
  5507    class=property>font-feature-settings</code>’</a> in a style rule or
  5508    within an <a href="#at-font-face-rule"><code>@font-face</code></a> rule.
  5509    The resolution order for the union of these settings is defined below.
  5510    Features defined via CSS properties are applied on top of layout engine
  5511    default features.
  5513   <h3 id=default-features><span class=secno>7.1 </span>Default features</h3>
  5515   <p>For OpenType fonts, user agents must enable the default features defined
  5516    in the OpenType documentation for a given script and writing mode.
  5517    Required ligatures, common ligatures and contextual forms must be enabled
  5518    by default (OpenType features: <span class=tag>rlig, liga, clig,
  5519    calt</span>), along with localized forms (OpenType feature: <span
  5520    class=tag>locl</span>), and features required for proper display of
  5521    composed characters and marks (OpenType features: <span class=tag>ccmp,
  5522    mark, mkmk</span>). These features must always be enabled, even when the
  5523    value of the <a href="#propdef-font-variant"
  5524    title="font-variant!!property">‘<code
  5525    class=property>font-variant</code>’</a> and <a
  5526    href="#propdef-font-feature-settings"
  5527    title="font-feature-settings!!property">‘<code
  5528    class=property>font-feature-settings</code>’</a> properties is <span
  5529    title="normal value">‘<code class=property>normal</code>’</span>.
  5530    Individual features are only disabled when explicitly overridden by the
  5531    author, as when ‘<a href="#propdef-font-variant-ligatures"><code
  5532    class=property>font-variant-ligatures</code></a>’ is set to ‘<a
  5533    href="#no-common-ligatures"><code
  5534    class=property>no-common-ligatures</code></a>’. For handling complex
  5535    scripts such as <a
  5536    href="http://www.microsoft.com/typography/otfntdev/arabicot/features.aspx">Arabic</a>,
  5537    <a
  5538    href="http://www.microsoft.com/typography/otfntdev/mongolot/features.htm">Mongolian</a>
  5539    or <a
  5540    href="http://www.microsoft.com/typography/otfntdev/devanot/features.aspx">Devanagari</a>
  5541    additional features are required. For upright text within vertical text
  5542    runs, vertical alternates (OpenType feature: <span class=tag>vert</span>)
  5543    must be enabled.
  5545   <h3 id=feature-precedence><span class=secno>7.2 </span>Feature precedence</h3>
  5547   <p>General and <a href="#font-specific"><em>font specific</em></a> font
  5548    feature property settings are resolved in the order below, in ascending
  5549    order of precedence. This ordering is used to construct a combined list of
  5550    font features that affect a given text run.
  5552   <ol>
  5553    <li>Font features enabled by default, including features required for a
  5554     given script.
  5556    <li>If the font is defined via an <a
  5557     href="#at-font-face-rule"><code>@font-face</code></a> rule, the font
  5558     features implied by the font-variant descriptor in the <a
  5559     href="#at-font-face-rule"><code>@font-face</code></a> rule.
  5561    <li>If the font is defined via an <a
  5562     href="#at-font-face-rule"><code>@font-face</code></a> rule, the font
  5563     features implied by the font-feature-settings descriptor in the <a
  5564     href="#at-font-face-rule"><code>@font-face</code></a> rule.
  5566    <li>Feature settings determined by properties other than <a
  5567     href="#propdef-font-variant" title="font-variant!!property">‘<code
  5568     class=property>font-variant</code>’</a> or <a
  5569     href="#propdef-font-feature-settings"
  5570     title="font-feature-settings!!property">‘<code
  5571     class=property>font-feature-settings</code>’</a>. For example, setting
  5572     a non-default value for the ‘<code
  5573     class=property>letter-spacing</code>’ property disables common
  5574     ligatures.
  5576    <li>Font features implied by the value of the <a
  5577     href="#propdef-font-variant" title="font-variant!!property">‘<code
  5578     class=property>font-variant</code>’</a> property, the related <a
  5579     href="#propdef-font-variant" title="font-variant!!property">‘<code
  5580     class=property>font-variant</code>’</a> subproperties and any other CSS
  5581     property that uses OpenType features (e.g. the ‘<a
  5582     href="#propdef-font-kerning"><code
  5583     class=property>font-kerning</code></a>’ property).
  5585    <li>Font features implied by the value of <a
  5586     href="#propdef-font-feature-settings"
  5587     title="font-feature-settings!!property">‘<code
  5588     class=property>font-feature-settings</code>’</a> property.
  5589   </ol>
  5591   <p>This ordering allows authors to set up a general set of defaults for
  5592    fonts within their <a
  5593    href="#at-font-face-rule"><code>@font-face</code></a> rules, then override
  5594    them with property settings for specific elements. General property
  5595    settings override the settings in <a
  5596    href="#at-font-face-rule"><code>@font-face</code></a> rules and low-level
  5597    font feature settings override <a href="#propdef-font-variant"
  5598    title="font-variant!!property">‘<code
  5599    class=property>font-variant</code>’</a> property settings.
  5601   <p>For situations where the combined list of font feature settings contains
  5602    more than one value for the same feature, the last value is used. When a
  5603    font lacks support for a given underlying font feature, text is simply
  5604    rendered as if that font feature was not enabled; font fallback does not
  5605    occur and no attempt is made to synthesize the feature except where
  5606    explicitly defined for specific properties.
  5608   <h3 id=feature-precedence-examples><span class=secno>7.3 </span>Feature
  5609    precedence examples</h3>
  5611   <div class=example>
  5612    <p>With the styles below, numbers are rendered proportionally when used
  5613     within a paragraph but are shown in tabular form within tables of prices:</p>
  5615    <pre>body {
  5616   font-variant-numeric: proportional-nums;
  5619 table.prices td {
  5620   font-variant-numeric: tabular-nums;
  5622 </pre>
  5623   </div>
  5625   <div class=example>
  5626    <p>When the <a href="#descdef-font-variant"
  5627     title="font-variant!!descriptor">font-variant</a> descriptor is used
  5628     within an <a href="#at-font-face-rule"><code>@font-face</code></a> rule,
  5629     it only applies to the font defined by that rule.</p>
  5631    <pre>@font-face {
  5632   font-family: MainText;
  5633   src: url(http://example.com/font.ttf);
  5634   font-variant: oldstyle-nums proportional-nums styleset(1,3);
  5637 body {
  5638   font-family: MainText, Helvetica;
  5641 table.prices td {
  5642   font-variant-numeric: tabular-nums;
  5644 </pre>
  5646    <p>In this case, old-style numerals will be used throughout but only where
  5647     the font "MainText" is used. Just as in the previous example, tabular
  5648     values will be used in price tables since ‘<a
  5649     href="#tabular-nums"><code class=property>tabular-nums</code></a>’
  5650     appears in a general style rule and its use is mutually exclusive with
  5651     ‘<a href="#proportional-nums"><code
  5652     class=property>proportional-nums</code></a>’. Stylistic alternate sets
  5653     will only be used where MainText is used.</p>
  5654   </div>
  5656   <div class=example>
  5657    <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule can
  5658     also be used to access font features in locally available fonts via the
  5659     use of <code>local()</code> in the ‘<a href="#descdef-src"><code
  5660     class=property>src</code></a>’ descriptor of the <a
  5661     href="#at-font-face-rule"><code>@font-face</code></a> definition:</p>
  5663    <pre>@font-face {
  5664   font-family: BodyText;
  5665   src: local("HiraMaruPro-W4");
  5666   font-variant: proportional-width;
  5667   font-feature-settings: "ital"; /* Latin italics within CJK text feature */
  5670 body { font-family: BodyText, serif; }
  5671 </pre>
  5673    <p>If available, a Japanese font "Hiragino Maru Gothic" will be used. When
  5674     text rendering occurs, Japanese kana will be proportionally spaced and
  5675     Latin text will be italicised. Text rendered with the fallback serif font
  5676     will use default rendering properties.</p>
  5677   </div>
  5679   <div class=example>
  5680    <p>In the example below, discretionary ligatures are enabled only for a
  5681     downloadable font but are disabled within spans of class "special":</p>
  5683    <pre>@font-face {
  5684   font-family: main;
  5685   src: url(fonts/ffmeta.woff) format("woff");
  5686   font-variant: discretionary-ligatures;
  5689 body         { font-family: main, Helvetica; }
  5690 span.special { font-variant-ligatures: no-discretionary-ligatures; }
  5691 </pre>
  5693    <p>Suppose one adds a rule using ‘<code
  5694     class=property>font-feature-settings</code>’ to enable discretionary
  5695     ligatures:</p>
  5697    <pre>body         { font-family: main, Helvetica; }
  5698 span         { font-feature-settings: "dlig"; }
  5699 span.special { font-variant-ligatures: no-discretionary-ligatures; }
  5700 </pre>
  5702    <p>In this case, discretionary ligatures <em>will</em> be rendered within
  5703     spans of class "special". This is because both the <a
  5704     href="#propdef-font-feature-settings"
  5705     title="font-feature-settings!!property">‘<code
  5706     class=property>font-feature-settings</code>’</a> and ‘<a
  5707     href="#propdef-font-variant-ligatures"><code
  5708     class=property>font-variant-ligatures</code></a>’ properties apply to
  5709     these spans. Although the ‘<code class=css>no-discretionary
  5710     ligatures</code>’ setting of ‘<a
  5711     href="#propdef-font-variant-ligatures"><code
  5712     class=property>font-variant-ligatures</code></a>’ effectively disables
  5713     the OpenType <span class=tag>dlig</span> feature, because the <a
  5714     href="#propdef-font-feature-settings"
  5715     title="font-feature-settings!!property">‘<code
  5716     class=property>font-feature-settings</code>’</a> is resolved after
  5717     that, the ‘<code class=property>dlig</code>’ value reenables
  5718     discretionary ligatures.</p>
  5719   </div>
  5721   <h2 id=object-model><span class=secno>8 </span>Object Model</h2>
  5723   <p>The contents of <a href="#at-font-face-rule"><code>@font-face</code></a>
  5724    and <a
  5725    href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
  5726    rules can be accessed via the following extensions to the CSS Object
  5727    Model.
  5729   <h3 id=om-fontface><span class=secno>8.1 </span>The <a
  5730    href="#cssfontfacerule"><code>CSSFontFaceRule</code></a> interface</h3>
  5732   <p>The <dfn id=cssfontfacerule>CSSFontFaceRule</dfn> interface represents a
  5733    <a href="#at-font-face-rule"><code>@font-face</code></a> rule.
  5735   <pre class=idl>
  5736 interface CSSFontFaceRule : CSSRule {
  5737   attribute DOMString family;
  5738   attribute DOMString src;
  5739   attribute DOMString style;
  5740   attribute DOMString weight;
  5741   attribute DOMString stretch;
  5742   attribute DOMString unicodeRange;
  5743   attribute DOMString variant;
  5744   attribute DOMString featureSettings;
  5745 }</pre>
  5747   <p>The DOM Level 2 Style specification <a href="#DOM-LEVEL-2-STYLE"
  5748    rel=biblioentry>[DOM-LEVEL-2-STYLE]<!--{{DOM-LEVEL-2-STYLE}}--></a>
  5749    defined a different variant of this rule. This definition supercedes that
  5750    one.
  5752   <h3 id=om-fontfeaturevalues><span class=secno>8.2 </span>The <a
  5753    href="#cssfontfeaturevaluesrule"><code>CSSFontFeatureValuesRule</code></a>
  5754    interface</h3>
  5756   <p>The <code>CSSRule</code> interface is extended as follows:
  5758   <pre class=idl>partial interface CSSRule {
  5759   const unsigned short FONT_FEATURE_VALUES_RULE = 14;
  5760 }</pre>
  5762   <p>The <dfn id=cssfontfeaturevaluesrule>CSSFontFeatureValuesRule</dfn>
  5763    interface represents a <a
  5764    href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
  5765    rule.
  5767   <pre class=idl>interface CSSFontFeatureValuesRule : CSSRule {
  5768   attribute DOMString fontFamily;
  5769   readonly attribute CSSFontFeatureValuesMap annotation;
  5770   readonly attribute CSSFontFeatureValuesMap ornaments;
  5771   readonly attribute CSSFontFeatureValuesMap stylistic;
  5772   readonly attribute CSSFontFeatureValuesMap swash;
  5773   readonly attribute CSSFontFeatureValuesMap characterVariant;
  5774   readonly attribute CSSFontFeatureValuesMap styleset;
  5777 [MapClass(DOMString, sequence&lt;unsigned long&gt;)]
  5778 interface CSSFontFeatureValuesMap {
  5779   void set(DOMString featureValueName,
  5780            (unsigned long or sequence&lt;unsigned long&gt;) values);
  5781 }</pre>
  5783   <dl class=idl-attributes>
  5784    <dt><var>fontFamily</var> of type <code>DOMString</code>
  5786    <dd>The list of one or more font families for which a given set of feature
  5787     values is defined.
  5789    <dt>value maps of type <code>CSSFontFeatureValuesMap</code>, readonly
  5791    <dd>Maps of feature values associated with feature value names for a given
  5792     ‘<a href="#propdef-font-variant-alternates"><code
  5793     class=property>font-variant-alternates</code></a>’ value type
  5794   </dl>
  5796   <p>Each value map attribute of <a
  5797    href="#cssfontfeaturevaluesrule"><code>CSSFontFeatureValuesRule</code></a>
  5798    reflects the values defined via a corresponding <a
  5799    href="#featurevalueblock"><i title="feature_value_block">feature value
  5800    block</i></a>. Thus, the <var title="annotation
  5801    attribute">annotation</var> attribute contains the values contained within
  5802    a <code title="@annotation">@annotation</code> <a
  5803    href="#featurevalueblock"><i title="feature_value_block">feature value
  5804    block</i></a>, the <var title="ornaments attribute">ornaments</var>
  5805    attribute contains the values contained with a <code
  5806    title="@ornaments">@ornaments</code> <a href="#featurevalueblock"><i
  5807    title="feature_value_block">feature value block</i></a> and so forth.
  5809   <p>The <code>CSSFontFeatureValuesMap</code> interface uses the <a
  5810    href="http://dev.w3.org/2006/webapi/WebIDL/#es-map-members">default
  5811    methods of map class</a> but the <code>set</code> method takes a sequence
  5812    of unsigned integers and associates it with a given
  5813    <code>featureValueName</code>. The method behaves the same as the default
  5814    map class method except that a single unsigned long value is treated as a
  5815    sequence of a single value. The method throws an exception if an invalid
  5816    number of values is passed in. If the associated <a
  5817    href="#featurevalueblock"><i title="feature_value_block">feature value
  5818    block</i></a> only allows a limited number of values, the <code>set</code>
  5819    method throws an <code>InvalidAccessError</code> exception when the input
  5820    sequence to <code>set</code> contains more than the limited number of
  5821    values. See the description of <a
  5822    href="#multi-valued-feature-value-definitions">multi-valued feature value
  5823    definitions</a> for details on the maximum number of values allowed for a
  5824    given type of <a href="#featurevalueblock"><i
  5825    title="feature_value_block">feature value block</i></a>. The
  5826    <code>get</code> method always returns a sequence of values, even if the
  5827    sequence only contains a single value.
  5829   <h2 class=no-num id=platform-props-to-css>Appendix A: Mapping platform font
  5830    properties to CSS properties</h2>
  5832   <p><em>This appendix is included as background for some of the problems and
  5833    situations that are described in other sections. It should be viewed as
  5834    informative only.</em>
  5836   <p>Font properties in CSS are designed to be independent of the underlying
  5837    font formats used; they can be used to specify bitmap fonts, Type1 fonts,
  5838    SVG fonts in addition to the common TrueType and OpenType fonts. But there
  5839    are facets of the TrueType and OpenType formats that often cause confusion
  5840    for authors and present challenges to implementers on different platforms.
  5842   <p>Originally developed at Apple, TrueType was designed as an outline font
  5843    format for both screen and print. Microsoft joined Apple in developing the
  5844    TrueType format and both platforms have supported TrueType fonts since
  5845    then. Font data in the TrueType format consists of a set of tables
  5846    distinguished with common four-letter tag names, each containing a
  5847    specific type of data. For example, naming information, including
  5848    copyright and license information, is stored in the ‘<code
  5849    class=property>name</code>’ table. The <a
  5850    href="#character-map"><em>character map</em></a> (‘<code
  5851    class=property>cmap</code>’) table contains a mapping of character
  5852    encodings to glyphs. Apple later added additional tables for supporting
  5853    enhanced typographic functionality; these are now called Apple Advanced
  5854    Typography, or AAT, fonts. Microsoft and Adobe developed a separate set of
  5855    tables for advanced typography and called their format OpenType <a
  5856    href="#OPENTYPE" rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a>.
  5858   <p>In many cases the font data used under Microsoft Windows or Linux is
  5859    slightly different from the data used under Apple's Mac OS X because the
  5860    TrueType format allowed for explicit variation across platforms. This
  5861    includes font metrics, names and <a href="#character-map"><em>character
  5862    map</em></a> data.
  5864   <p>Specifically, font family name data is handled differently across
  5865    platforms. For TrueType and OpenType fonts these names are contained in
  5866    the ‘<code class=property>name</code>’ table, in name records with
  5867    name ID 1. Mulitple names can be stored for different locales, but
  5868    Microsoft recommends fonts always include at least a US English version of
  5869    the name. On Windows, Microsoft made the decision for backwards
  5870    compatibility to limit this family name to a maximum of four faces; for
  5871    larger groupings the "preferred family" (name ID 16) or "WWS family" (name
  5872    ID 21) can be used. Other platforms such as OSX don't have this
  5873    limitation, so the family name is used to define all possible groupings.
  5875   <p>Other name table data provides names used to uniquely identify a
  5876    specific face within a family. The full font name (name ID 4) and the
  5877    Postscript name (name ID 6) describe a single face uniquely. For example,
  5878    the bold face of the Gill Sans family has a fullname of "Gill Sans Bold"
  5879    and a Postscript name of "GillSans-Bold". There can be multiple localized
  5880    versions of the fullname for a given face, but the Postscript name is
  5881    always a unique name made from a limited set of ASCII characters.
  5883   <p>On various platforms, different names are used to search for a font. For
  5884    example, with the Windows GDI CreateIndirectFont API, either a family or
  5885    fullname can be used to lookup a face, while on Mac OS X the
  5886    CTFontCreateWithName API call is used to lookup a given face using the
  5887    fullname and Postscript name. Under Linux, the fontconfig API allows fonts
  5888    to be searched using any of these names. In situations where platform
  5889    API's automatically substitute other font choices, it may be necessary to
  5890    verify a returned font matches a given name.
  5892   <p>The weight of a given face can be determined via the usWeightClass field
  5893    of the OS/2 table or inferred from the style name (name ID 2). Likewise,
  5894    the width can be determined via the usWidthClass of the OS/2 table or
  5895    inferred from the style name. For historical reasons related to synthetic
  5896    bolding at weights 200 or lower with the Windows GDI API, font designers
  5897    have sometimes skewed values in the OS/2 table to avoid these weights.
  5899   <p>Rendering complex scripts that use contextual shaping such as Thai,
  5900    Arabic and Devanagari requires features present only in OpenType or AAT
  5901    fonts. Currently, complex script rendering is supported on Windows and
  5902    Linux using OpenType font features while both OpenType and AAT font
  5903    features are used under Mac OS X.
  5905   <h2 class=no-num id=ch-ch-ch-changes>Changes</h2>
  5907   <h3 class=no-num id=recent-changes> Changes from the <a
  5908    href="http://www.w3.org/TR/2013/WD-css3-fonts-20130212/">February 2013
  5909    CSS3 Fonts Working Draft</a></h3>
  5911   <p>Major changes include:
  5913   <ul>
  5914    <li>Moved font load events into a separate <a
  5915     href="http://dev.w3.org/csswg/css3-font-load-events/">spec</a>
  5917    <li>Tightened syntax rules for <a
  5918     href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
  5919     rules
  5921    <li>Added grammar productions for <a
  5922     href="#at-font-face-rule"><code>@font-face</code></a> and <a
  5923     href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
  5924     rules
  5926    <li>Revised definition of ‘<a href="#descdef-unicode-range"><code
  5927     class=property>unicode-range</code></a>’ descriptor
  5929    <li>Detailed font matching of composite faces
  5931    <li>Revised object model interface of CSSFontFeatureValuesRule
  5933    <li>Detailed effect of ‘<a href="#propdef-font-size-adjust"><code
  5934     class=property>font-size-adjust</code></a>’ on relative unit sizes
  5936    <li>Reference the potentially CORS-enabled fetch method defined in HTML5
  5937   </ul>
  5939   <h2 class=no-num id=acknowledgments>Acknowledgments</h2>
  5941   <p>I'd like to thank Tal Leming, Jonathan Kew and Christopher Slye for all
  5942    their help and feedback. John Hudson was kind enough to take the time to
  5943    explain the subtleties of OpenType language tags and provided the example
  5944    of character variant usage for displaying text on Byzantine seals. Ken
  5945    Lunde and Eric Muller provided valuable feedback on CJK OpenType features
  5946    and Unicode variation selectors. The idea for supporting font features by
  5947    using <a href="#propdef-font-variant"
  5948    title="font-variant!!property">‘<code
  5949    class=property>font-variant</code>’</a> subproperties originated with
  5950    Håkon Wium Lie, Adam Twardoch and Tal Leming. Elika Etemad supplied some
  5951    of the initial design ideas for the <a
  5952    href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
  5953    rule. Thanks also to House Industries for allowing the use of Ed Interlock
  5954    in the discretionary ligatures example.
  5956   <p>A special thanks to Robert Bringhurst for the sublime mind expansion
  5957    that is <em>The Elements of Typographic Style</em>.
  5959   <h2 class=no-num id=conformance> Conformance</h2>
  5961   <h3 class=no-num id=conventions> Document Conventions</h3>
  5963   <p>Conformance requirements are expressed with a combination of descriptive
  5964    assertions and RFC 2119 terminology. The key words “MUST”, “MUST
  5965    NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”,
  5966    “SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL” in the
  5967    normative parts of this document are to be interpreted as described in RFC
  5968    2119. However, for readability, these words do not appear in all uppercase
  5969    letters in this specification.
  5971   <p>All of the text of this specification is normative except sections
  5972    explicitly marked as non-normative, examples, and notes. <a
  5973    href="#RFC2119" rel=biblioentry>[RFC2119]<!--{{!RFC2119}}--></a>
  5975   <p>Examples in this specification are introduced with the words “for
  5976    example” or are set apart from the normative text with
  5977    <code>class="example"</code>, like this:
  5979   <div class=example>
  5980    <p>This is an example of an informative example.
  5981   </div>
  5983   <p>Informative notes begin with the word “Note” and are set apart from
  5984    the normative text with <code>class="note"</code>, like this:
  5986   <p class=note>Note, this is an informative note.
  5988   <h3 class=no-num id=conformance-classes> Conformance Classes</h3>
  5990   <p>Conformance to CSS Fonts Level 3 Module is defined for three conformance
  5991    classes:
  5993   <dl>
  5994    <dt><dfn id=style-sheet title="style sheet!!as conformance class">style
  5995     sheet</dfn>
  5997    <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#style-sheet">CSS
  5998     style sheet</a>.
  6000    <dt><dfn id=renderer>renderer</dfn>
  6002    <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
  6003     that interprets the semantics of a style sheet and renders documents that
  6004     use them.
  6006    <dt><dfn id=authoring-tool>authoring tool</dfn>
  6008    <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
  6009     that writes a style sheet.
  6010   </dl>
  6012   <p>A style sheet is conformant to CSS Fonts Level 3 Module if all of its
  6013    declarations that use properties defined in this module have values that
  6014    are valid according to the generic CSS grammar and the individual grammars
  6015    of each property as given in this module.
  6017   <p>A renderer is conformant to CSS Fonts Level 3 Module if, in addition to
  6018    interpreting the style sheet as defined by the appropriate specifications,
  6019    it supports all the features defined by CSS Fonts Level 3 Module by
  6020    parsing them correctly and rendering the document accordingly. However,
  6021    the inability of a UA to correctly render a document due to limitations of
  6022    the device does not make the UA non-conformant. (For example, a UA is not
  6023    required to render color on a monochrome monitor.)
  6025   <p>An authoring tool is conformant to CSS Fonts Level 3 Module if it writes
  6026    style sheets that are syntactically correct according to the generic CSS
  6027    grammar and the individual grammars of each feature in this module, and
  6028    meet all other conformance requirements of style sheets as described in
  6029    this module.
  6031   <h3 class=no-num id=partial> Partial Implementations</h3>
  6033   <p>So that authors can exploit the forward-compatible parsing rules to
  6034    assign fallback values, CSS renderers <strong>must</strong> treat as
  6035    invalid (and <a
  6036    href="http://www.w3.org/TR/CSS21/conform.html#ignore">ignore as
  6037    appropriate</a>) any at-rules, properties, property values, keywords, and
  6038    other syntactic constructs for which they have no usable level of support.
  6039    In particular, user agents <strong>must not</strong> selectively ignore
  6040    unsupported component values and honor supported values in a single
  6041    multi-value property declaration: if any value is considered invalid (as
  6042    unsupported values must be), CSS requires that the entire declaration be
  6043    ignored.
  6045   <h3 class=no-num id=experimental> Experimental Implementations</h3>
  6047   <p>To avoid clashes with future CSS features, the CSS2.1 specification
  6048    reserves a <a
  6049    href="http://www.w3.org/TR/CSS21/syndata.html#vendor-keywords">prefixed
  6050    syntax</a> for proprietary and experimental extensions to CSS.
  6052   <p>Prior to a specification reaching the Candidate Recommendation stage in
  6053    the W3C process, all implementations of a CSS feature are considered
  6054    experimental. The CSS Working Group recommends that implementations use a
  6055    vendor-prefixed syntax for such features, including those in W3C Working
  6056    Drafts. This avoids incompatibilities with future changes in the draft.
  6058   <h3 class=no-num id=testing> Non-Experimental Implementations</h3>
  6060   <p>Once a specification reaches the Candidate Recommendation stage,
  6061    non-experimental implementations are possible, and implementors should
  6062    release an unprefixed implementation of any CR-level feature they can
  6063    demonstrate to be correctly implemented according to spec.
  6065   <p>To establish and maintain the interoperability of CSS across
  6066    implementations, the CSS Working Group requests that non-experimental CSS
  6067    renderers submit an implementation report (and, if necessary, the
  6068    testcases used for that implementation report) to the W3C before releasing
  6069    an unprefixed implementation of any CSS features. Testcases submitted to
  6070    W3C are subject to review and correction by the CSS Working Group.
  6072   <p>Further information on submitting testcases and implementation reports
  6073    can be found from on the CSS Working Group's website at <a
  6074    href="http://www.w3.org/Style/CSS/Test/">http://www.w3.org/Style/CSS/Test/</a>.
  6075    Questions should be directed to the <a
  6076    href="http://lists.w3.org/Archives/Public/public-css-testsuite">public-css-testsuite@w3.org</a>
  6077    mailing list.
  6079   <h2 class=no-num id=references>References</h2>
  6081   <h3 class=no-num id=normative-references>Normative References</h3>
  6082   <!--begin-normative-->
  6083   <!-- Sorted by label -->
  6085   <dl class=bibliography>
  6086    <dd style="display: none"><!-- keeps the doc valid if the DL is empty -->
  6087     <!---->
  6089    <dt id=CHARMOD>[CHARMOD]
  6091    <dd>Martin J. Dürst; et al. <a
  6092     href="http://www.w3.org/TR/2005/REC-charmod-20050215/"><cite>Character
  6093     Model for the World Wide Web 1.0: Fundamentals.</cite></a> 15 February
  6094     2005. W3C Recommendation. URL: <a
  6095     href="http://www.w3.org/TR/2005/REC-charmod-20050215/">http://www.w3.org/TR/2005/REC-charmod-20050215/</a>
  6096     </dd>
  6097    <!---->
  6099    <dt id=CORS>[CORS]
  6101    <dd>Anne van Kesteren. <a
  6102     href="http://www.w3.org/TR/2013/CR-cors-20130129/"><cite>Cross-Origin
  6103     Resource Sharing.</cite></a> 29 January 2013. W3C Candidate
  6104     Recommendation. (Work in progress.) URL: <a
  6105     href="http://www.w3.org/TR/2013/CR-cors-20130129/">http://www.w3.org/TR/2013/CR-cors-20130129/</a>
  6106     </dd>
  6107    <!---->
  6109    <dt id=CSS21>[CSS21]
  6111    <dd>Bert Bos; et al. <a
  6112     href="http://www.w3.org/TR/2011/REC-CSS2-20110607"><cite>Cascading Style
  6113     Sheets Level 2 Revision 1 (CSS 2.1) Specification.</cite></a> 7 June
  6114     2011. W3C Recommendation. URL: <a
  6115     href="http://www.w3.org/TR/2011/REC-CSS2-20110607">http://www.w3.org/TR/2011/REC-CSS2-20110607</a>
  6116     </dd>
  6117    <!---->
  6119    <dt id=CSS3VAL>[CSS3VAL]
  6121    <dd>Håkon Wium Lie; Tab Atkins; Elika J. Etemad. <a
  6122     href="http://www.w3.org/TR/2013/CR-css3-values-20130404/"><cite>CSS
  6123     Values and Units Module Level 3.</cite></a> 4 April 2013. W3C Candidate
  6124     Recommendation. (Work in progress.) URL: <a
  6125     href="http://www.w3.org/TR/2013/CR-css3-values-20130404/">http://www.w3.org/TR/2013/CR-css3-values-20130404/</a>
  6126     </dd>
  6127    <!---->
  6129    <dt id=HTML5>[HTML5]
  6131    <dd>Ian Hickson. <a
  6132     href="http://www.w3.org/TR/2012/CR-html5-20121217/"><cite>HTML5.</cite></a>
  6133     17 December 2012. W3C Candidate Recommendation. (Work in progress.) URL:
  6134     <a
  6135     href="http://www.w3.org/TR/2012/CR-html5-20121217/">http://www.w3.org/TR/2012/CR-html5-20121217/</a>
  6136     </dd>
  6137    <!---->
  6139    <dt id=OPEN-FONT-FORMAT>[OPEN-FONT-FORMAT]
  6141    <dd><a
  6142     href="http://standards.iso.org/ittf/PubliclyAvailableStandards/c052136_ISO_IEC_14496-22_2009(E).zip"><cite>Information
  6143     technology — Coding of audio-visual objects — Part 22: Open Font
  6144     Format.</cite></a> International Organization for Standardization.
  6145     ISO/IEC 14496-22:2009. URL: <a
  6146     href="http://standards.iso.org/ittf/PubliclyAvailableStandards/c052136_ISO_IEC_14496-22_2009(E).zip">http://standards.iso.org/ittf/PubliclyAvailableStandards/c052136_ISO_IEC_14496-22_2009(E).zip</a>
  6147     </dd>
  6148    <!---->
  6150    <dt id=OPENTYPE>[OPENTYPE]
  6152    <dd><a
  6153     href="http://www.microsoft.com/typography/otspec/default.htm"><cite>OpenType
  6154     specification.</cite></a> Microsoft. URL: <a
  6155     href="http://www.microsoft.com/typography/otspec/default.htm">http://www.microsoft.com/typography/otspec/default.htm</a>
  6156     </dd>
  6157    <!---->
  6159    <dt id=OPENTYPE-FEATURES>[OPENTYPE-FEATURES]
  6161    <dd><a
  6162     href="http://www.microsoft.com/typography/otspec/featurelist.htm"><cite>OpenType
  6163     feature registry.</cite></a> Microsoft. URL: <a
  6164     href="http://www.microsoft.com/typography/otspec/featurelist.htm">http://www.microsoft.com/typography/otspec/featurelist.htm</a>
  6165     </dd>
  6166    <!---->
  6168    <dt id=RFC2119>[RFC2119]
  6170    <dd>S. Bradner. <a href="http://www.ietf.org/rfc/rfc2119.txt"><cite>Key
  6171     words for use in RFCs to Indicate Requirement Levels.</cite></a> Internet
  6172     RFC 2119. URL: <a
  6173     href="http://www.ietf.org/rfc/rfc2119.txt">http://www.ietf.org/rfc/rfc2119.txt</a>
  6174     </dd>
  6175    <!---->
  6177    <dt id=UAX15>[UAX15]
  6179    <dd>Mark Davis; Ken Whistler. <a
  6180     href="http://www.unicode.org/reports/tr15/"><cite>Unicode Normalization
  6181     Forms.</cite></a> 31 August 2012. Unicode Standard Annex #15. URL: <a
  6182     href="http://www.unicode.org/reports/tr15/">http://www.unicode.org/reports/tr15/</a>
  6183     </dd>
  6184    <!---->
  6186    <dt id=UAX29>[UAX29]
  6188    <dd>Mark Davis. <a
  6189     href="http://www.unicode.org/reports/tr29/"><cite>Unicode Text
  6190     Segmentation.</cite></a> 12 September 2012. Unicode Standard Annex #29.
  6191     URL: <a
  6192     href="http://www.unicode.org/reports/tr29/">http://www.unicode.org/reports/tr29/</a>
  6193     </dd>
  6194    <!---->
  6196    <dt id=UNICODE6>[UNICODE6]
  6198    <dd>The Unicode Consortium. <a
  6199     href="http://www.unicode.org/versions/Unicode6.2.0/"><cite>The Unicode
  6200     Standard, Version 6.2.0.</cite></a> Defined by: The Unicode Standard,
  6201     Version 6.2.0 URL: <a
  6202     href="http://www.unicode.org/versions/Unicode6.2.0/">http://www.unicode.org/versions/Unicode6.2.0/</a>
  6203     </dd>
  6204    <!---->
  6205   </dl>
  6206   <!--end-normative-->
  6207   <!--{{!CSS21}}-->
  6208   <!--{{!CSS3VAL}}-->
  6209   <!--{{!OPENTYPE}}-->
  6210   <!--{{!OPENTYPE-FEATURES}}-->
  6211   <!--{{!OPEN-FONT-FORMAT}}-->
  6212   <!--{{!UNICODE6}}-->
  6213   <!--{{!UAX15}}-->
  6214   <!--{{!UAX29}}-->
  6215   <!--{{!CORS}}-->
  6216   <!--{{!HTML5}}-->
  6217   <!--{{!CHARMOD}}-->
  6219   <h3 class=no-num id=other-references>Other References</h3>
  6220   <!--begin-informative-->
  6221   <!-- Sorted by label -->
  6223   <dl class=bibliography>
  6224    <dd style="display: none"><!-- keeps the doc valid if the DL is empty -->
  6225     <!---->
  6227    <dt id=AAT-FEATURES>[AAT-FEATURES]
  6229    <dd><a href="http://developer.apple.com/fonts/registry/"><cite>Apple
  6230     Advanced Typography font feature registry.</cite></a> Apple. URL: <a
  6231     href="http://developer.apple.com/fonts/registry/">http://developer.apple.com/fonts/registry/</a>
  6232     </dd>
  6233    <!---->
  6235    <dt id=ARABIC-TYPO>[ARABIC-TYPO]
  6237    <dd>Huda Smitshuijzen AbiFares. <cite>Arabic Typography: A Comprehensive
  6238     Sourcebook.</cite> Saqi Books. 2001. ISBN 0-86356-347-3.</dd>
  6239    <!---->
  6241    <dt id=CHARMOD-NORM>[CHARMOD-NORM]
  6243    <dd>François Yergeau; et al. <a
  6244     href="http://www.w3.org/TR/2012/WD-charmod-norm-20120501/"><cite>Character
  6245     Model for the World Wide Web 1.0: Normalization.</cite></a> 1 May 2012.
  6246     W3C Working Draft. (Work in progress.) URL: <a
  6247     href="http://www.w3.org/TR/2012/WD-charmod-norm-20120501/">http://www.w3.org/TR/2012/WD-charmod-norm-20120501/</a>
  6248     </dd>
  6249    <!---->
  6251    <dt id=CJKV-INFO-PROCESSING>[CJKV-INFO-PROCESSING]
  6253    <dd>Ken Lunde. <cite>CJKV Information Processing, Second Edition.</cite>
  6254     O'Reilly Media, Inc. 2009. ISBN 0-596-51447-1.</dd>
  6255    <!---->
  6257    <dt id=CSS3-CONDITIONAL>[CSS3-CONDITIONAL]
  6259    <dd>L. David Baron. <a
  6260     href="http://www.w3.org/TR/2013/CR-css3-conditional-20130404/"><cite>CSS
  6261     Conditional Rules Module Level 3.</cite></a> 4 April 2013. W3C Candidate
  6262     Recommendation. (Work in progress.) URL: <a
  6263     href="http://www.w3.org/TR/2013/CR-css3-conditional-20130404/">http://www.w3.org/TR/2013/CR-css3-conditional-20130404/</a>
  6264     </dd>
  6265    <!---->
  6267    <dt id=CSS3TEXT>[CSS3TEXT]
  6269    <dd>Elika J. Etemad; Koji Ishii. <a
  6270     href="http://www.w3.org/TR/2012/WD-css3-text-20121113/"><cite>CSS Text
  6271     Module Level 3.</cite></a> 13 November 2012. W3C Working Draft. (Work in
  6272     progress.) URL: <a
  6273     href="http://www.w3.org/TR/2012/WD-css3-text-20121113/">http://www.w3.org/TR/2012/WD-css3-text-20121113/</a>
  6274     </dd>
  6275    <!---->
  6277    <dt id=DIGITAL-TYPOGRAPHY>[DIGITAL-TYPOGRAPHY]
  6279    <dd>Richard Rubinstein. <cite>Digital Typography, An Introduction to Type
  6280     and Composition for Computer System Design.</cite> Addison-Wesley. 1988.
  6281     ISBN 0-201-17633-5.</dd>
  6282    <!---->
  6284    <dt id=DOM-LEVEL-2-STYLE>[DOM-LEVEL-2-STYLE]
  6286    <dd>Chris Wilson; Philippe Le Hégaret; Vidur Apparao. <a
  6287     href="http://www.w3.org/TR/2000/REC-DOM-Level-2-Style-20001113/"><cite>Document
  6288     Object Model (DOM) Level 2 Style Specification.</cite></a> 13 November
  6289     2000. W3C Recommendation. URL: <a
  6290     href="http://www.w3.org/TR/2000/REC-DOM-Level-2-Style-20001113/">http://www.w3.org/TR/2000/REC-DOM-Level-2-Style-20001113/</a>
  6291     </dd>
  6292    <!---->
  6294    <dt id=ELEMTYPO>[ELEMTYPO]
  6296    <dd>Robert Bringhurst. <cite>The Elements of Typographic Style, Version
  6297     4.</cite> Hartley &amp; Marks. 2013. ISBN 0-88179-212-8.</dd>
  6298    <!---->
  6300    <dt id=LANGCULTTYPE>[LANGCULTTYPE]
  6302    <dd>John D. Berry, Ed. <cite>Language Culture Type.</cite> Graphis. 2001.
  6303     ISBN 1-932026-01-0.</dd>
  6304    <!---->
  6306    <dt id=OPENTYPE-FONT-GUIDE>[OPENTYPE-FONT-GUIDE]
  6308    <dd><a
  6309     href="https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf"><cite>OpenType
  6310     User Guide.</cite></a> FontShop International. URL: <a
  6311     href="https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf">https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf</a>
  6312     </dd>
  6313    <!---->
  6315    <dt id=RASTER-TRAGEDY>[RASTER-TRAGEDY]
  6317    <dd>Beat Stamm. <a href="http://www.rastertragedy.com/"><cite>The Raster
  6318     Tragedy at Low-Resolution Revisited.</cite></a> 7 December 2011. URL: <a
  6319     href="http://www.rastertragedy.com/">http://www.rastertragedy.com/</a></dd>
  6320    <!---->
  6322    <dt id=WINDOWS-GLYPH-PROC>[WINDOWS-GLYPH-PROC]
  6324    <dd>John Hudson. <a
  6325     href="http://www.microsoft.com/typography/developers/opentype/default.htm"><cite>Windows
  6326     Glyph Processing.</cite></a> Microsoft Typogrraphy. URL: <a
  6327     href="http://www.microsoft.com/typography/developers/opentype/default.htm">http://www.microsoft.com/typography/developers/opentype/default.htm</a>
  6328     </dd>
  6329    <!---->
  6330   </dl>
  6331   <!--end-informative-->
  6332   <!--{{ARABIC-TYPO}}-->
  6333   <!--{{CJKV-INFO-PROCESSING}}-->
  6334   <!--{{DIGITAL-TYPOGRAPHY}}-->
  6335   <!--{{DOM-LEVEL-2-STYLE}}-->
  6336   <!--{{ELEMTYPO}}-->
  6337   <!--{{LANGCULTTYPE}}-->
  6338   <!--{{OPENTYPE-FONT-GUIDE}}-->
  6339   <!--{{RASTER-TRAGEDY}}-->
  6340   <!--{{WINDOWS-GLYPH-PROC}}-->
  6341   <!--{{CHARMOD-NORM}}-->
  6342   <!--{{AAT-FEATURES}}-->
  6343   <!--{{CSS3-CONDITIONAL}}-->
  6344   <!--{{CSS3TEXT}}-->
  6346   <h2 class=no-num id=index>Index</h2>
  6347   <!--begin-index-->
  6349   <ul class=indexlist>
  6350    <li>100...900 weight values, <a href="#font-weight-numeric-values"
  6351     title="100...900 weight values"><strong>3.2</strong></a>
  6353    <li><var>&lt;absolute-size&gt;</var>, <a href="#absolute-size-value"
  6354     title="&lt;absolute-size&gt;"><strong>3.5</strong></a>
  6356    <li><var>&lt;common-lig-values&gt;</var>, <a href="#common-lig-values"
  6357     title="&lt;common-lig-values&gt;"><strong>6.4</strong></a>
  6359    <li><var>&lt;contextual-alt-values&gt;</var>, <a
  6360     href="#contextual-alt-values"
  6361     title="&lt;contextual-alt-values&gt;"><strong>6.4</strong></a>
  6363    <li><var>&lt;discretionary-lig-values&gt;</var>, <a
  6364     href="#discretionary-lig-values"
  6365     title="&lt;discretionary-lig-values&gt;"><strong>6.4</strong></a>
  6367    <li><var>&lt;east-asian-variant-values&gt;</var>, <a
  6368     href="#east-asian-variant-values"
  6369     title="&lt;east-asian-variant-values&gt;"><strong>6.10</strong></a>
  6371    <li><var>&lt;east-asian-width-values&gt;</var>, <a
  6372     href="#east-asian-width-values"
  6373     title="&lt;east-asian-width-values&gt;"><strong>6.10</strong></a>
  6375    <li><var>&lt;family-name&gt;</var>, <a href="#family-name-value"
  6376     title="&lt;family-name&gt;"><strong>3.1</strong></a>
  6378    <li><var>&lt;feature-tag-value&gt;</var>, <a href="#feature-tag-value"
  6379     title="&lt;feature-tag-value&gt;"><strong>6.12</strong></a>
  6381    <li><var>&lt;font-face-name&gt;</var>, <a href="#font-face-name-value"
  6382     title="&lt;font-face-name&gt;"><strong>4.3</strong></a>
  6384    <li><var>&lt;font-variant-css21&gt;</var>, <a
  6385     href="#font-variant-css21-values"
  6386     title="&lt;font-variant-css21&gt;"><strong>3.7</strong></a>
  6388    <li><var>&lt;generic-family&gt;</var>, <a href="#generic-family-value"
  6389     title="&lt;generic-family&gt;"><strong>3.1</strong></a>
  6391    <li><var>&lt;historical-lig-values&gt;</var>, <a
  6392     href="#historical-lig-values"
  6393     title="&lt;historical-lig-values&gt;"><strong>6.4</strong></a>
  6395    <li><var>&lt;length&gt;</var>, <a href="#length-size-value"
  6396     title="&lt;length&gt;"><strong>3.5</strong></a>
  6398    <li><var>&lt;number&gt;</var>, <a href="#aspect-ratio-value"
  6399     title="&lt;number&gt;"><strong>3.6</strong></a>
  6401    <li><var>&lt;numeric-figure-values&gt;</var>, <a
  6402     href="#numeric-figure-values"
  6403     title="&lt;numeric-figure-values&gt;"><strong>6.7</strong></a>
  6405    <li><var>&lt;numeric-fraction-values&gt;</var>, <a
  6406     href="#numeric-fraction-values"
  6407     title="&lt;numeric-fraction-values&gt;"><strong>6.7</strong></a>
  6409    <li><var>&lt;numeric-spacing-values&gt;</var>, <a
  6410     href="#numeric-spacing-values"
  6411     title="&lt;numeric-spacing-values&gt;"><strong>6.7</strong></a>
  6413    <li><var>&lt;percentage&gt;</var>, <a href="#percentage-size-value"
  6414     title="&lt;percentage&gt;"><strong>3.5</strong></a>
  6416    <li><var>&lt;relative-size&gt;</var>, <a href="#relative-size-value"
  6417     title="&lt;relative-size&gt;"><strong>3.5</strong></a>
  6419    <li><var>&lt;string&gt;</var>, <a
  6420     href="#font-language-override-string-value"
  6421     title="&lt;string&gt;"><strong>6.13</strong></a>
  6423    <li><var>&lt;urange&gt;</var>, <a href="#urange-value"
  6424     title="&lt;urange&gt;"><strong>4.5</strong></a>
  6426    <li><code>@font-face</code>, <a href="#at-font-face-rule"
  6427     title="@font-face"><strong>4.1</strong></a>
  6429    <li><code>@font-feature-values</code>, <a
  6430     href="#at-font-feature-values-rule"
  6431     title="@font-feature-values"><strong>6.9</strong></a>
  6433    <li>all-petite-caps, <a href="#all-petite-caps"
  6434     title=all-petite-caps><strong>6.6</strong></a>
  6436    <li>all-small-caps, <a href="#all-small-caps"
  6437     title=all-small-caps><strong>6.6</strong></a>
  6439    <li>annotation, <a href="#annotation"
  6440     title=annotation><strong>6.8</strong></a>
  6442    <li>aspect value, <a href="#aspect-value0" title="aspect
  6443     value"><strong>3.6</strong></a>
  6445    <li>authoring tool, <a href="#authoring-tool" title="authoring
  6446     tool"><strong>#</strong></a>
  6448    <li>auto
  6449     <ul>
  6450      <li>font-kerning, <a href="#font-kerning-auto-value" title="auto,
  6451       font-kerning"><strong>6.3</strong></a>
  6453      <li>font-size-adjust, <a href="#font-size-adjust-auto-value"
  6454       title="auto, font-size-adjust"><strong>3.6</strong></a>
  6455     </ul>
  6457    <li>bold, <a href="#bold" title=bold><strong>3.2</strong></a>
  6459    <li>bolder, <a href="#bolder" title=bolder><strong>3.2</strong></a>
  6461    <li>character map, <a href="#character-map" title="character
  6462     map"><strong>5.2</strong></a>
  6464    <li>character-variant, <a href="#character-variant"
  6465     title=character-variant><strong>6.8</strong></a>
  6467    <li>common-ligatures, <a href="#common-ligatures"
  6468     title=common-ligatures><strong>6.4</strong></a>
  6470    <li>composite face, <a href="#composite-face" title="composite
  6471     face"><strong>5.2</strong></a>
  6473    <li>condensed, <a href="#condensed"
  6474     title=condensed><strong>3.3</strong></a>
  6476    <li>contextual, <a href="#contextual"
  6477     title=contextual><strong>6.4</strong></a>
  6479    <li>CSSFontFaceRule, <a href="#cssfontfacerule"
  6480     title=CSSFontFaceRule><strong>8.1</strong></a>
  6482    <li>CSSFontFeatureValuesRule, <a href="#cssfontfeaturevaluesrule"
  6483     title=CSSFontFeatureValuesRule><strong>8.2</strong></a>
  6485    <li>cursive, definition of, <a href="#cursive0" title="cursive, definition
  6486     of"><strong>#</strong></a>
  6488    <li>default face, <a href="#default-face" title="default
  6489     face"><strong>5.2</strong></a>
  6491    <li>descriptor_declaration, <a href="#descriptordeclaration"
  6492     title="descriptor_declaration"><strong>4.1</strong></a>
  6494    <li>diagonal-fractions, <a href="#diagonal-fractions"
  6495     title=diagonal-fractions><strong>6.7</strong></a>
  6497    <li>discretionary-ligatures, <a href="#discretionary-ligatures"
  6498     title=discretionary-ligatures><strong>6.4</strong></a>
  6500    <li>effective character map, <a href="#effective-character-map"
  6501     title="effective character map"><strong>4.5</strong></a>
  6503    <li>expanded, <a href="#expanded" title=expanded><strong>3.3</strong></a>
  6505    <li>extra-condensed, <a href="#extra-condensed"
  6506     title=extra-condensed><strong>3.3</strong></a>
  6508    <li>extra-expanded, <a href="#extra-expanded"
  6509     title=extra-expanded><strong>3.3</strong></a>
  6511    <li>fantasy, definition of, <a href="#fantasy0" title="fantasy, definition
  6512     of"><strong>#</strong></a>
  6514    <li>feature_type, <a href="#featuretype"
  6515     title="feature_type"><strong>6.9.1</strong></a>
  6517    <li>feature_value_block, <a href="#featurevalueblock"
  6518     title="feature_value_block"><strong>6.9.1</strong></a>
  6520    <li>feature_value_definition, <a href="#featurevaluedefinition"
  6521     title="feature_value_definition"><strong>6.9.1</strong></a>
  6523    <li>first available font, <a href="#first-available-font" title="first
  6524     available font"><strong>5.2</strong></a>
  6526    <li>font, <a href="#propdef-font" title=font><strong>3.7</strong></a>
  6528    <li>font specific, <a href="#font-specific" title="font
  6529     specific"><strong>6.8</strong></a>
  6531    <li>font-family
  6532     <ul>
  6533      <li>descriptor, <a href="#descdef-font-family" title="font-family,
  6534       descriptor"><strong>4.2</strong></a>
  6536      <li>property, <a href="#propdef-font-family" title="font-family,
  6537       property"><strong>3.1</strong></a>
  6538     </ul>
  6540    <li>font-feature-settings
  6541     <ul>
  6542      <li>descriptor, <a href="#descdef-font-feature-settings"
  6543       title="font-feature-settings, descriptor"><strong>4.7</strong></a>
  6545      <li>property, <a href="#propdef-font-feature-settings"
  6546       title="font-feature-settings, property"><strong>6.12</strong></a>
  6547     </ul>
  6549    <li>font-kerning, <a href="#propdef-font-kerning"
  6550     title=font-kerning><strong>6.3</strong></a>
  6552    <li>font-language-override, <a href="#propdef-font-language-override"
  6553     title=font-language-override><strong>6.13</strong></a>
  6555    <li>font-size, <a href="#propdef-font-size"
  6556     title=font-size><strong>3.5</strong></a>
  6558    <li>font-size-adjust, <a href="#propdef-font-size-adjust"
  6559     title=font-size-adjust><strong>3.6</strong></a>
  6561    <li>font-stretch
  6562     <ul>
  6563      <li>descriptor, <a href="#descdef-font-stretch" title="font-stretch,
  6564       descriptor"><strong>4.4</strong></a>
  6566      <li>property, <a href="#propdef-font-stretch" title="font-stretch,
  6567       property"><strong>3.3</strong></a>
  6568     </ul>
  6570    <li>font-style
  6571     <ul>
  6572      <li>descriptor, <a href="#descdef-font-style" title="font-style,
  6573       descriptor"><strong>4.4</strong></a>
  6575      <li>property, <a href="#propdef-font-style" title="font-style,
  6576       property"><strong>3.4</strong></a>
  6577     </ul>
  6579    <li>font-synthesis, <a href="#propdef-font-synthesis"
  6580     title=font-synthesis><strong>3.8</strong></a>
  6582    <li>font-variant
  6583     <ul>
  6584      <li>descriptor, <a href="#descdef-font-variant" title="font-variant,
  6585       descriptor"><strong>4.7</strong></a>
  6587      <li>property, <a href="#propdef-font-variant" title="font-variant,
  6588       property"><strong>6.11</strong></a>
  6589     </ul>
  6591    <li>font-variant-alternates, <a href="#propdef-font-variant-alternates"
  6592     title=font-variant-alternates><strong>6.8</strong></a>
  6594    <li>font-variant-caps, <a href="#propdef-font-variant-caps"
  6595     title=font-variant-caps><strong>6.6</strong></a>
  6597    <li>font-variant-east-asian, <a href="#propdef-font-variant-east-asian"
  6598     title=font-variant-east-asian><strong>6.10</strong></a>
  6600    <li>font-variant-ligatures, <a href="#propdef-font-variant-ligatures"
  6601     title=font-variant-ligatures><strong>6.4</strong></a>
  6603    <li>font-variant-numeric, <a href="#propdef-font-variant-numeric"
  6604     title=font-variant-numeric><strong>6.7</strong></a>
  6606    <li>font-variant-position, <a href="#propdef-font-variant-position"
  6607     title=font-variant-position><strong>6.5</strong></a>
  6609    <li>font-weight
  6610     <ul>
  6611      <li>descriptor, <a href="#descdef-font-weight" title="font-weight,
  6612       descriptor"><strong>4.4</strong></a>
  6614      <li>property, <a href="#propdef-font-weight" title="font-weight,
  6615       property"><strong>3.2</strong></a>
  6616     </ul>
  6618    <li>font_face_rule, <a href="#fontfacerule"
  6619     title="font_face_rule"><strong>4.1</strong></a>
  6621    <li>FONT_FACE_SYM, <a href="#fontfacesym"
  6622     title="FONT_FACE_SYM"><strong>4.1</strong></a>
  6624    <li>font_family_name, <a href="#fontfamilyname"
  6625     title="font_family_name"><strong>6.9.1</strong></a>
  6627    <li>font_family_name_list, <a href="#fontfamilynamelist"
  6628     title="font_family_name_list"><strong>6.9.1</strong></a>
  6630    <li>font_feature_values_rule, <a href="#fontfeaturevaluesrule"
  6631     title="font_feature_values_rule"><strong>6.9.1</strong></a>
  6633    <li>FONT_FEATURE_VALUES_SYM, <a href="#fontfeaturevaluessym"
  6634     title="FONT_FEATURE_VALUES_SYM"><strong>6.9.1</strong></a>
  6636    <li>full-width, <a href="#full-width"
  6637     title=full-width><strong>6.10</strong></a>
  6639    <li>historical-forms, <a href="#historical-forms"
  6640     title=historical-forms><strong>6.8</strong></a>
  6642    <li>historical-ligatures, <a href="#historical-ligatures"
  6643     title=historical-ligatures><strong>6.4</strong></a>
  6645    <li>italic, <a href="#italic" title=italic><strong>3.4</strong></a>
  6647    <li>jis04, <a href="#jis04" title=jis04><strong>6.10</strong></a>
  6649    <li>jis78, <a href="#jis78" title=jis78><strong>6.10</strong></a>
  6651    <li>jis83, <a href="#jis83" title=jis83><strong>6.10</strong></a>
  6653    <li>jis90, <a href="#jis90" title=jis90><strong>6.10</strong></a>
  6655    <li>lighter, <a href="#lighter" title=lighter><strong>3.2</strong></a>
  6657    <li>lining-nums, <a href="#lining-nums"
  6658     title=lining-nums><strong>6.7</strong></a>
  6660    <li>monospace, definition of, <a href="#monospace0" title="monospace,
  6661     definition of"><strong>#</strong></a>
  6663    <li>no-common-ligatures, <a href="#no-common-ligatures"
  6664     title=no-common-ligatures><strong>6.4</strong></a>
  6666    <li>no-contextual, <a href="#no-contextual"
  6667     title=no-contextual><strong>6.4</strong></a>
  6669    <li>no-discretionary-ligatures, <a href="#no-discretionary-ligatures"
  6670     title=no-discretionary-ligatures><strong>6.4</strong></a>
  6672    <li>no-historical-ligatures, <a href="#no-historical-ligatures"
  6673     title=no-historical-ligatures><strong>6.4</strong></a>
  6675    <li>none
  6676     <ul>
  6677      <li>font-kerning, <a href="#font-kerning-none-value" title="none,
  6678       font-kerning"><strong>6.3</strong></a>
  6680      <li>font-size-adjust, <a href="#font-size-adjust-none-value"
  6681       title="none, font-size-adjust"><strong>3.6</strong></a>
  6683      <li>font-variant, <a href="#font-variant-none-value" title="none,
  6684       font-variant"><strong>6.11</strong></a>
  6686      <li>font-variant-ligatures, <a href="#font-variant-ligatures-none-value"
  6687       title="none, font-variant-ligatures"><strong>6.4</strong></a>
  6688     </ul>
  6690    <li>normal
  6691     <ul>
  6692      <li>font-feature-settings, <a href="#font-feature-settings-normal-value"
  6693       title="normal, font-feature-settings"><strong>6.12</strong></a>
  6695      <li>font-kerning, <a href="#font-kerning-normal-value" title="normal,
  6696       font-kerning"><strong>6.3</strong></a>
  6698      <li>font-language-override, <a
  6699       href="#font-language-override-normal-value" title="normal,
  6700       font-language-override"><strong>6.13</strong></a>
  6702      <li>font-stretch, <a href="#font-stretch-normal-value" title="normal,
  6703       font-stretch"><strong>3.3</strong></a>
  6705      <li>font-style, <a href="#font-style-normal-value" title="normal,
  6706       font-style"><strong>3.4</strong></a>
  6708      <li>font-variant, <a href="#font-variant-normal-value" title="normal,
  6709       font-variant"><strong>6.11</strong></a>
  6711      <li>font-variant-alternates, <a
  6712       href="#font-variant-alternates-normal-value" title="normal,
  6713       font-variant-alternates"><strong>6.8</strong></a>
  6715      <li>font-variant-caps, <a href="#font-variant-caps-normal-value"
  6716       title="normal, font-variant-caps"><strong>6.6</strong></a>
  6718      <li>font-variant-east-asian, <a
  6719       href="#font-variant-east-asian-normal-value" title="normal,
  6720       font-variant-east-asian"><strong>6.10</strong></a>
  6722      <li>font-variant-ligatures, <a
  6723       href="#font-variant-ligatures-normal-value" title="normal,
  6724       font-variant-ligatures"><strong>6.4</strong></a>
  6726      <li>font-variant-numeric, <a href="#font-variant-numeric-normal-value"
  6727       title="normal, font-variant-numeric"><strong>6.7</strong></a>
  6729      <li>font-variant-position, <a href="#font-variant-position-normal-value"
  6730       title="normal, font-variant-position"><strong>6.5</strong></a>
  6732      <li>font-weight, <a href="#font-weight-normal-value" title="normal,
  6733       font-weight"><strong>3.2</strong></a>
  6734     </ul>
  6736    <li>oblique, <a href="#oblique" title=oblique><strong>3.4</strong></a>
  6738    <li>oldstyle-nums, <a href="#oldstyle-nums"
  6739     title=oldstyle-nums><strong>6.7</strong></a>
  6741    <li>ordinal, <a href="#ordinal" title=ordinal><strong>6.7</strong></a>
  6743    <li>ornaments, <a href="#ornaments"
  6744     title=ornaments><strong>6.8</strong></a>
  6746    <li>petite-caps, <a href="#petite-caps"
  6747     title=petite-caps><strong>6.6</strong></a>
  6749    <li>proportional-nums, <a href="#proportional-nums"
  6750     title=proportional-nums><strong>6.7</strong></a>
  6752    <li>proportional-width, <a href="#proportional-width"
  6753     title=proportional-width><strong>6.10</strong></a>
  6755    <li>renderer, <a href="#renderer" title=renderer><strong>#</strong></a>
  6757    <li>ruby, <a href="#ruby" title=ruby><strong>6.10</strong></a>
  6759    <li>sans-serif, definition of, <a href="#sans-serif0" title="sans-serif,
  6760     definition of"><strong>#</strong></a>
  6762    <li>semi-condensed, <a href="#semi-condensed-"
  6763     title=semi-condensed><strong>3.3</strong></a>
  6765    <li>semi-expanded, <a href="#semi-expanded"
  6766     title=semi-expanded><strong>3.3</strong></a>
  6768    <li>serif, definition of, <a href="#serif0" title="serif, definition
  6769     of"><strong>#</strong></a>
  6771    <li>simplified, <a href="#simplified"
  6772     title=simplified><strong>6.10</strong></a>
  6774    <li>slashed-zero, <a href="#slashed-zero"
  6775     title=slashed-zero><strong>6.7</strong></a>
  6777    <li>small-caps, <a href="#small-caps"
  6778     title=small-caps><strong>6.6</strong></a>
  6780    <li>src, <a href="#descdef-src" title=src><strong>4.3</strong></a>
  6782    <li>stacked-fractions, <a href="#stacked-fractions"
  6783     title=stacked-fractions><strong>6.7</strong></a>
  6785    <li>style sheet
  6786     <ul>
  6787      <li>as conformance class, <a href="#style-sheet" title="style sheet, as
  6788       conformance class"><strong>#</strong></a>
  6789     </ul>
  6791    <li>styleset, <a href="#styleset" title=styleset><strong>6.8</strong></a>
  6793    <li>stylistic, <a href="#stylistic"
  6794     title=stylistic><strong>6.8</strong></a>
  6796    <li>sub, <a href="#sub" title=sub><strong>6.5</strong></a>
  6798    <li>super, <a href="#super" title=super><strong>6.5</strong></a>
  6800    <li>support, <a href="#support" title=support><strong>5.2</strong></a>
  6802    <li>swash, <a href="#swash" title=swash><strong>6.8</strong></a>
  6804    <li>system font fallback, <a href="#system-font-fallback" title="system
  6805     font fallback"><strong>5.2</strong></a>
  6807    <li>tabular-nums, <a href="#tabular-nums"
  6808     title=tabular-nums><strong>6.7</strong></a>
  6810    <li>titling-caps, <a href="#titling-caps"
  6811     title=titling-caps><strong>6.6</strong></a>
  6813    <li>traditional, <a href="#traditional"
  6814     title=traditional><strong>6.10</strong></a>
  6816    <li>ultra-condensed, <a href="#ultra-condensed"
  6817     title=ultra-condensed><strong>3.3</strong></a>
  6819    <li>ultra-expanded, <a href="#ultra-expanded"
  6820     title=ultra-expanded><strong>3.3</strong></a>
  6822    <li>unicase, <a href="#unicase" title=unicase><strong>6.6</strong></a>
  6824    <li>unicode-range, <a href="#descdef-unicode-range"
  6825     title=unicode-range><strong>4.5</strong></a>
  6827    <li>weight, <a href="#weight" title=weight><strong>2</strong></a>
  6829    <li>width, <a href="#width" title=width><strong>2</strong></a>
  6830   </ul>
  6831   <!--end-index-->
  6833   <h2 class=no-num id=property-index>Property index</h2>
  6834   <!--begin-properties-->
  6836   <table class=proptable>
  6837    <thead>
  6838     <tr>
  6839      <th>Property
  6841      <th>Values
  6843      <th>Initial
  6845      <th>Applies to
  6847      <th>Inh.
  6849      <th>Percentages
  6851      <th>Media
  6853    <tbody>
  6854     <tr>
  6855      <th><a class=property href="#propdef-font">font</a>
  6857      <td>[ [ &lt;‘font-style’&gt; || &lt;font-variant-css21&gt; ||
  6858       &lt;‘font-weight’&gt; || &lt;‘font-stretch’ ]?
  6859       &lt;‘font-size’&gt; [ / &lt;‘line-height’&gt; ]?
  6860       &lt;‘font-family’&gt; ] | caption | icon | menu | message-box |
  6861       small-caption | status-bar
  6863      <td>see individual properties
  6865      <td>all elements
  6867      <td>yes
  6869      <td>see individual properties
  6871      <td>visual
  6873     <tr>
  6874      <th><span class=property>font-family</span>
  6876      <td>[ &lt;family-name&gt; | &lt;generic-family&gt; ] #
  6878      <td>depends on user agent
  6880      <td>all elements
  6882      <td>yes
  6884      <td>N/A
  6886      <td>visual
  6888     <tr>
  6889      <th><span class=property>font-feature-settings</span>
  6891      <td>normal | &lt;feature-tag-value&gt; #
  6893      <td>normal
  6895      <td>all elements
  6897      <td>yes
  6899      <td>N/A
  6901      <td>visual
  6903     <tr>
  6904      <th><a class=property href="#propdef-font-kerning">font-kerning</a>
  6906      <td>auto | normal | none
  6908      <td>auto
  6910      <td>all elements
  6912      <td>yes
  6914      <td>N/A
  6916      <td>visual
  6918     <tr>
  6919      <th><a class=property
  6920       href="#propdef-font-language-override">font-language-override</a>
  6922      <td>normal | &lt;string&gt;
  6924      <td>normal
  6926      <td>all elements
  6928      <td>yes
  6930      <td>N/A
  6932      <td>visual
  6934     <tr>
  6935      <th><a class=property href="#propdef-font-size">font-size</a>
  6937      <td>&lt;absolute-size&gt; | &lt;relative-size&gt; | &lt;length&gt; |
  6938       &lt;percentage&gt;
  6940      <td>medium
  6942      <td>all elements
  6944      <td>yes
  6946      <td>refer to parent element's font size
  6948      <td>visual
  6950     <tr>
  6951      <th><a class=property
  6952       href="#propdef-font-size-adjust">font-size-adjust</a>
  6954      <td>none | auto | &lt;number&gt;
  6956      <td>none
  6958      <td>all elements
  6960      <td>yes
  6962      <td>N/A
  6964      <td>visual
  6966     <tr>
  6967      <th><span class=property>font-stretch</span>
  6969      <td>normal | ultra-condensed | extra-condensed | condensed |
  6970       semi-condensed | semi-expanded | expanded | extra-expanded |
  6971       ultra-expanded
  6973      <td>normal
  6975      <td>all elements
  6977      <td>yes
  6979      <td>N/A
  6981      <td>visual
  6983     <tr>
  6984      <th><span class=property>font-style</span>
  6986      <td>normal | italic | oblique
  6988      <td>normal
  6990      <td>all elements
  6992      <td>yes
  6994      <td>N/A
  6996      <td>visual
  6998     <tr>
  6999      <th><a class=property href="#propdef-font-synthesis">font-synthesis</a>
  7001      <td>none | [ weight || style ]
  7003      <td>weight style
  7005      <td>all elements
  7007      <td>yes
  7009      <td>N/A
  7011      <td>visual
  7013     <tr>
  7014      <th><span class=property>font-variant</span>
  7016      <td>normal | none | [ &lt;common-lig-values&gt; ||
  7017       &lt;discretionary-lig-values&gt; || &lt;historical-lig-values&gt; ||
  7018       &lt;contextual-alt-values&gt; || stylistic(&lt;feature-value-name&gt;)
  7019       || historical-forms || styleset(&lt;feature-value-name&gt; #) ||
  7020       character-variant(&lt;feature-value-name&gt; #) ||
  7021       swash(&lt;feature-value-name&gt;) ||
  7022       ornaments(&lt;feature-value-name&gt;) ||
  7023       annotation(&lt;feature-value-name&gt;) || [ small-caps | all-small-caps
  7024       | petite-caps | all-petite-caps | unicase | titling-caps ] ||
  7025       &lt;numeric-figure-values&gt; || &lt;numeric-spacing-values&gt; ||
  7026       &lt;numeric-fraction-values&gt; || ordinal || slashed-zero ||
  7027       &lt;east-asian-variant-values&gt; || &lt;east-asian-width-values&gt; ||
  7028       ruby ]
  7030      <td>normal
  7032      <td>all elements
  7034      <td>yes
  7036      <td>see individual properties
  7038      <td>visual
  7040     <tr>
  7041      <th><a class=property
  7042       href="#propdef-font-variant-alternates">font-variant-alternates</a>
  7044      <td>normal | [ stylistic(&lt;feature-value-name&gt;) || historical-forms
  7045       || styleset(&lt;feature-value-name&gt; #) ||
  7046       character-variant(&lt;feature-value-name&gt; #) ||
  7047       swash(&lt;feature-value-name&gt;) ||
  7048       ornaments(&lt;feature-value-name&gt;) ||
  7049       annotation(&lt;feature-value-name&gt;) ]
  7051      <td>normal
  7053      <td>all elements
  7055      <td>yes
  7057      <td>N/A
  7059      <td>visual
  7061     <tr>
  7062      <th><a class=property
  7063       href="#propdef-font-variant-caps">font-variant-caps</a>
  7065      <td>normal | small-caps | all-small-caps | petite-caps | all-petite-caps
  7066       | unicase | titling-caps
  7068      <td>normal
  7070      <td>all elements
  7072      <td>yes
  7074      <td>N/A
  7076      <td>visual
  7078     <tr>
  7079      <th><a class=property
  7080       href="#propdef-font-variant-east-asian">font-variant-east-asian</a>
  7082      <td>normal | [ &lt;east-asian-variant-values&gt; ||
  7083       &lt;east-asian-width-values&gt; || ruby ]
  7085      <td>normal
  7087      <td>all elements
  7089      <td>yes
  7091      <td>N/A
  7093      <td>visual
  7095     <tr>
  7096      <th><a class=property
  7097       href="#propdef-font-variant-ligatures">font-variant-ligatures</a>
  7099      <td>normal | none | [ &lt;common-lig-values&gt; ||
  7100       &lt;discretionary-lig-values&gt; || &lt;historical-lig-values&gt; ||
  7101       &lt;contextual-alt-values&gt; ]
  7103      <td>normal
  7105      <td>all elements
  7107      <td>yes
  7109      <td>N/A
  7111      <td>visual
  7113     <tr>
  7114      <th><a class=property
  7115       href="#propdef-font-variant-numeric">font-variant-numeric</a>
  7117      <td>normal | [ &lt;numeric-figure-values&gt; ||
  7118       &lt;numeric-spacing-values&gt; || &lt;numeric-fraction-values&gt; ||
  7119       ordinal || slashed-zero ]
  7121      <td>normal
  7123      <td>all elements
  7125      <td>yes
  7127      <td>N/A
  7129      <td>visual
  7131     <tr>
  7132      <th><a class=property
  7133       href="#propdef-font-variant-position">font-variant-position</a>
  7135      <td>normal | sub | super
  7137      <td>normal
  7139      <td>all elements
  7141      <td>yes
  7143      <td>N/A
  7145      <td>visual
  7147     <tr>
  7148      <th><span class=property>font-weight</span>
  7150      <td>normal | bold | bolder | lighter | 100 | 200 | 300 | 400 | 500 | 600
  7151       | 700 | 800 | 900
  7153      <td>normal
  7155      <td>all elements
  7157      <td>yes
  7159      <td>N/A
  7161      <td>visual
  7162   </table>
  7163   <!--end-properties-->
  7164   <!--begin-descriptors-->
  7166   <table class=proptable>
  7167    <thead>
  7168     <tr>
  7169      <th>Descriptor
  7171      <th>Value
  7173      <th>Initial
  7175      <th>Percentages
  7177      <th>Media
  7179    <tbody>
  7180     <tr>
  7181      <th><span class=property>font-family</span>
  7183      <td>&lt;family-name&gt;
  7185      <td>N/A
  7187     <tr>
  7188      <th><span class=property>font-feature-settings</span>
  7190      <td>normal | &lt;feature-tag-value&gt; #
  7192      <td>normal
  7194     <tr>
  7195      <th><span class=property>font-stretch</span>
  7197      <td>normal | ultra-condensed | extra-condensed | condensed |
  7198       semi-condensed | semi-expanded | expanded | extra-expanded |
  7199       ultra-expanded
  7201      <td>normal
  7203     <tr>
  7204      <th><span class=property>font-style</span>
  7206      <td>normal | italic | oblique
  7208      <td>normal
  7210     <tr>
  7211      <th><span class=property>font-variant</span>
  7213      <td>normal | none | [ &lt;common-lig-values&gt; ||
  7214       &lt;discretionary-lig-values&gt; || &lt;historical-lig-values&gt; ||
  7215       &lt;contextual-alt-values&gt; || stylistic(&lt;feature-value-name&gt;)
  7216       || historical-forms || styleset(&lt;feature-value-name&gt; #) ||
  7217       character-variant(&lt;feature-value-name&gt; #) ||
  7218       swash(&lt;feature-value-name&gt;) ||
  7219       ornaments(&lt;feature-value-name&gt;) ||
  7220       annotation(&lt;feature-value-name&gt;) || [ small-caps | all-small-caps
  7221       | petite-caps | all-petite-caps | unicase | titling-caps ] ||
  7222       &lt;numeric-figure-values&gt; || &lt;numeric-spacing-values&gt; ||
  7223       &lt;numeric-fraction-values&gt; || ordinal || slashed-zero ||
  7224       &lt;east-asian-variant-values&gt; || &lt;east-asian-width-values&gt; ||
  7225       ruby ]
  7227      <td>normal
  7229     <tr>
  7230      <th><span class=property>font-weight</span>
  7232      <td>normal | bold | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900
  7234      <td>normal
  7236     <tr>
  7237      <th><a class=property href="#descdef-src">src</a>
  7239      <td>[ &lt;url> [format(&lt;string> #)]? | &lt;font-face-name&gt; ] #
  7241      <td>N/A
  7243     <tr>
  7244      <th><a class=property href="#descdef-unicode-range">unicode-range</a>
  7246      <td>&lt;urange&gt; #
  7248      <td>U+0-10FFFF
  7249   </table>
  7250   <!--end-descriptors-->
  7251   <script type="text/javascript">
  7252 window.onload = function () {
  7253   if (!("devicePixelRatio" in window && window.devicePixelRatio > 1)) return;
  7254   var i, hiresElements = document.getElementsByClassName("hires");
  7255   for (i = 0; i < hiresElements.length; i++) {
  7256     var h = hiresElements[i];
  7257     if (h.tagName != "IMG") continue;
  7258     var src = h.getAttribute("src");
  7259     var src2x = src.replace(/\.\w+$/, function(m) { return "@2x" + m; });
  7260     h.src = src2x;
  7263 </script>
  7264 </html>
  7265 <!-- Keep this comment at the end of the file
  7266 Local variables:
  7267 mode: sgml
  7268 sgml-declaration:"~/SGML/HTML4.decl"
  7269 sgml-default-doctype-name:"html"
  7270 sgml-minimize-attributes:t
  7271 sgml-nofill-elements:("pre" "style" "br")
  7272 sgml-live-element-indicator:t
  7273 sgml-omittag:nil
  7274 sgml-shorttag:nil
  7275 sgml-namecase-general:t
  7276 sgml-general-insert-case:lower
  7277 sgml-always-quote-attributes:t
  7278 sgml-indent-step:nil
  7279 sgml-indent-data:t
  7280 sgml-parent-document:nil
  7281 sgml-exposed-tags:nil
  7282 sgml-local-catalogs:nil
  7283 sgml-local-ecat-files:nil
  7284 End:
  7285 -->
  7286 <!--
  7288 to do:
  7290 - wording of OpenType family name handling
  7291 - handling combining sequences in the font matching algorithm
  7292 - fix-up fi ligature example
  7294 -->

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