css-fonts/Fonts.html

Tue, 11 Jun 2013 16:52:35 +0900

author
John Daggett <jdaggett@mozilla.com>
date
Tue, 11 Jun 2013 16:52:35 +0900
changeset 8431
16e837f77ef5
parent 8430
330ae631cc35
child 8640
82e75c734096
permissions
-rw-r--r--

[css3-fonts] define first available font

     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-11-june-2013>Editor's Draft 11
   119     June 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-css3-fonts-20130611/">http://www.w3.org/TR/2013/ED-css3-fonts-20130611/</a> -->
   129     <dt>Latest version:
   131     <dd><a
   132      href="http://www.w3.org/TR/css3-fonts/">http://www.w3.org/TR/css3-fonts/</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/css3-font-load-events/">CSS3 Font
   199    Load 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.
   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 class=issue>How does the use of ‘<a
  1657    href="#propdef-font-size-adjust"><code
  1658    class=property>font-size-adjust</code></a>’ affect <a
  1659    href="http://www.w3.org/TR/css3-values/#font-relative-lengths"><em>font-relative</em></a>
  1660    unit sizes? Are all units affected the same way, i.e. including the
  1661    definition of ‘<code class=property>em</code>’?
  1663   <p>In situations where font fallback occurs, fallback fonts may not share
  1664    the same aspect ratio as the desired font family and will thus appear less
  1665    readable. The font-size-adjust property is a way to preserve the
  1666    readability of text when font fallback occurs. It does this by adjusting
  1667    the font-size so that the x-height is the same regardless of the font
  1668    used.
  1670   <div class=example>
  1671    <p>The style defined below defines Verdana as the desired font family, but
  1672     if Verdana is not available Futura or Times will be used.</p>
  1674    <pre>p {
  1675     font-family: Verdana, Futura, Times;
  1678 &lt;p>Lorem ipsum dolor sit amet, ...&lt;/p>
  1679 </pre>
  1681    <p>Verdana has a relatively high aspect ratio, lowercase letters are
  1682     relatively tall compared to uppercase letters, so at small sizes text
  1683     appears legible. Times has a lower aspect ratio and so if fallback
  1684     occurs, the text will be less legible at small sizes than Verdana.</p>
  1685   </div>
  1687   <p>How text rendered in each of these fonts compares is shown below, the
  1688    columns show text rendered in Verdana, Futura and Times. The same
  1689    font-size value is used across cells within each row and red lines are
  1690    included to show the differences in x-height. In the upper half each row
  1691    is rendered in the same font-size value. The same is true for the lower
  1692    half but in this half the font-size-adjust property is also set so that
  1693    the actual font size is adjusted to preserve the x-height across each row.
  1694    Note how small text remains relatively legible across each row in the
  1695    lower half.
  1697   <div class=figure><img alt="text with and without font-size-adjust"
  1698    src=fontsizeadjust.png>
  1699    <p class=caption>Text with and without the use of font-size-adjust
  1700   </div>
  1702   <p>This property allows authors to specify an aspect value for an element
  1703    that will effectively preserve the x-height of the first choice font,
  1704    whether it is substituted or not. Values have the following meanings:
  1706   <dl>
  1707    <dt><dfn id=font-size-adjust-none-value
  1708     title="none!!font-size-adjust">none</dfn>
  1710    <dd>Do not preserve the font's x-height.
  1712    <dt><dfn id=font-size-adjust-auto-value
  1713     title="auto!!font-size-adjust">auto</dfn>
  1715    <dd>Behaves just like &lt;number>, except the number used is the aspect
  1716     value calculated by user agents for the first font in the list of fonts
  1717     defined for the initial value of the <a href="#propdef-font-family"
  1718     title="font-family!!property">‘<code
  1719     class=property>font-family</code>’</a> property. Effectively this is
  1720     the default font used when <a href="#propdef-font-family"
  1721     title="font-family!!property">‘<code
  1722     class=property>font-family</code>’</a> is not otherwise specified.
  1723     <p>Authors can use this value to specify that font size should be
  1724      normalized across fonts based on the x-height without the need to
  1725      specify the aspect ratio explicitly.</p>
  1727    <dt><dfn id=aspect-ratio-value><var>&lt;number&gt;</var></dfn>
  1729    <dd>Specifies the aspect value used in the calculation below to calculate
  1730     the adjusted font size:
  1731     <pre>c  =  ( a / a' ) s
  1732 </pre>
  1734     <p>where:</p>
  1736     <pre>s  =  font-size value
  1737 a  =  aspect value as specified by the font-size-adjust property
  1738 a' =  aspect value of actual font
  1739 c  =  adjusted font-size to use
  1740 </pre>
  1742     <p>This value applies to any font that is selected but in typical usage
  1743      it should be based on the aspect value of the first font in the
  1744      font-family list. If this is specified accurately, the <tt>(a/a')</tt>
  1745      term in the formula above is effectively 1 for the first font and no
  1746      adjustment occurs. If the value is specified inaccurately, text rendered
  1747      using the first font in the family list will display differently in
  1748      older user agents that don't support font-size-adjust.</p>
  1749   </dl>
  1751   <p>Authors can calculate the aspect value for a given font by comparing
  1752    spans with the same content but different font-size-adjust properties. If
  1753    the same font-size is used, the spans will match when the font-size-adjust
  1754    value is accurate for the given font.
  1756   <div class=example>
  1757    <p>Two spans with borders are used to determine the aspect value of a
  1758     font. The font-size is the same for both spans but the font-size-adjust
  1759     property is specified only for the right span. Starting with a value of
  1760     0.5, the aspect value can be adjusted until the borders around the two
  1761     letters line up.</p>
  1763    <pre>p {
  1764     font-family: Futura;
  1765     font-size: 500px;
  1768 span {
  1769     border: solid 1px red;
  1772 .adjust {
  1773     font-size-adjust: 0.5;
  1776 &lt;p>&lt;span>b&lt;/span>&lt;span class="adjust">b&lt;/span>&lt;/p>
  1777 </pre>
  1779    <div class=figure><img alt="Futura with an aspect value of 0.5"
  1780     src=beforefontsizeadjust.png>
  1781     <p class=caption>Futura with an aspect value of 0.5
  1782    </div>
  1784    <p>The box on the right is a bit bigger than the one on the left, so the
  1785     aspect value of this font is something less than 0.5. Adjust the value
  1786     until the boxes align.</p>
  1787   </div>
  1788   <!-- prop: font -->
  1790   <h3 id=font-prop><span class=secno>3.7 </span>Shorthand font property: the
  1791    <a href="#propdef-font">font</a> property</h3>
  1793   <table class=propdef id=namefontvalue-ltlsquofont-stylersquogt-l>
  1794    <tbody>
  1795     <tr>
  1796      <td>Name:
  1798      <td><dfn id=propdef-font>font</dfn>
  1800     <tr>
  1801      <td>Value:
  1803      <td>[ [ <var>&lt;<a href="#propdef-font-style"
  1804       title="font-style!!property">‘<code
  1805       class=property>font-style</code>’</a>&gt;</var> || <a
  1806       href="#font-variant-css21-values"><var>&lt;font-variant-css21&gt;</var></a>
  1807       || <var>&lt;<a href="#propdef-font-weight"
  1808       title="font-weight!!property">‘<code
  1809       class=property>font-weight</code>’</a>&gt;</var> || <var>&lt;<a
  1810       href="#propdef-font-stretch" title="font-stretch!!property">‘<code
  1811       class=property>font-stretch</code>’</a></var> ]? <var>&lt;‘<a
  1812       href="#propdef-font-size"><code
  1813       class=property>font-size</code></a>’&gt;</var> [ / <var>&lt;‘<code
  1814       class=property>line-height</code>’&gt;</var> ]? <var>&lt;<a
  1815       href="#propdef-font-family" title="font-family!!property">‘<code
  1816       class=property>font-family</code>’</a>&gt;</var> ] | caption | icon |
  1817       menu | message-box | small-caption | status-bar
  1819     <tr>
  1820      <td>Initial:
  1822      <td>see individual properties
  1824     <tr>
  1825      <td>Applies to:
  1827      <td>all elements
  1829     <tr>
  1830      <td>Inherited:
  1832      <td>yes
  1834     <tr>
  1835      <td>Percentages:
  1837      <td>see individual properties
  1839     <tr>
  1840      <td>Media:
  1842      <td>visual
  1844     <tr>
  1845      <td>Computed value:
  1847      <td>see individual properties
  1849     <tr>
  1850      <td>Animatable:
  1852      <td>see individual properties
  1853   </table>
  1855   <p>The <span class=property>‘<a href="#propdef-font"><code
  1856    class=property>font</code></a>’</span> property is, except as described
  1857    below, a shorthand property for setting <a href="#propdef-font-style"
  1858    title="font-style!!property">‘<code
  1859    class=property>font-style</code>’</a>, <a href="#propdef-font-variant"
  1860    title="font-variant!!property">‘<code
  1861    class=property>font-variant</code>’</a>, <a href="#propdef-font-weight"
  1862    title="font-weight!!property">‘<code
  1863    class=property>font-weight</code>’</a>, <a href="#propdef-font-stretch"
  1864    title="font-stretch!!property">‘<code
  1865    class=property>font-stretch</code>’</a>, <span class=property>‘<a
  1866    href="#propdef-font-size"><code
  1867    class=property>font-size</code></a>’</span>, <a class=property
  1868    href="http://www.w3.org/TR/CSS2/visudet.html#propdef-line-height">‘<code
  1869    class=property>line-height</code>’</a>, <a href="#propdef-font-family"
  1870    title="font-family!!property">‘<code
  1871    class=property>font-family</code>’</a> at the same place in the
  1872    stylesheet. Values for the <a href="#propdef-font-variant"
  1873    title="font-variant!!property">‘<code
  1874    class=property>font-variant</code>’</a> property may also be included
  1875    but only those supported in CSS 2.1, none of the <a
  1876    href="#propdef-font-variant" title="font-variant!!property">‘<code
  1877    class=property>font-variant</code>’</a> values added in this
  1878    specification can be used in the <span class=property>‘<a
  1879    href="#propdef-font"><code class=property>font</code></a>’</span>
  1880    shorthand:
  1882   <pre
  1883    class=prod><dfn id=font-variant-css21-values><var>&lt;font-variant-css21&gt;</var></dfn> = [normal | small-caps]</pre>
  1885   <p>The syntax of this property is based on a traditional typographical
  1886    shorthand notation to set multiple properties related to fonts.
  1888   <p>All subproperties of the ‘<a href="#propdef-font"><code
  1889    class=property>font</code></a>’ property are first reset to their
  1890    initial values, including those listed above plus <span
  1891    class=property>‘<a href="#propdef-font-size-adjust"><code
  1892    class=property>font-size-adjust</code></a>’</span>, <span
  1893    class=property>‘<a href="#propdef-font-kerning"><code
  1894    class=property>font-kerning</code></a>’</span>, subproperties of <a
  1895    href="#propdef-font-variant" title="font-variant!!property">‘<code
  1896    class=property>font-variant</code>’</a> and and <span>‘<a
  1897    href="#propdef-font-language-override"><code
  1898    class=property>font-language-override</code></a>’</span>. Then, those
  1899    properties that are given explicit values in the <span
  1900    class=property>‘<a href="#propdef-font"><code
  1901    class=property>font</code></a>’</span> shorthand are set to those
  1902    values. For a definition of allowed and initial values, see the previously
  1903    defined properties. For reasons of backwards compatibility, it is not
  1904    possible to set <span class=property>‘<a
  1905    href="#propdef-font-size-adjust"><code
  1906    class=property>font-size-adjust</code></a>’</span> to anything other
  1907    than its initial value using the <span class=property>‘<a
  1908    href="#propdef-font"><code class=property>font</code></a>’</span>
  1909    shorthand property; instead, use the individual property.
  1911   <div class=example>
  1912    <p style="display:none">Example(s):
  1914    <p>
  1916    <pre>p { font: 12pt/14pt sans-serif }
  1917 p { font: 80% sans-serif }
  1918 p { font: x-large/110% &quot;new century schoolbook&quot;, serif }
  1919 p { font: bold italic large Palatino, serif }
  1920 p { font: normal small-caps 120%/120% fantasy }
  1921 p { font: condensed oblique 12pt &quot;Helvetica Neue&quot;, serif; }
  1922 </pre>
  1924    <p> In the second rule, the font size percentage value (‘<code
  1925     class=css>80%</code>’) refers to the computed ‘<a
  1926     href="#propdef-font-size"><code class=property>font-size</code></a>’ of
  1927     the parent element. In the third rule, the line height percentage
  1928     (‘<code class=css>110%</code>’) refers to the font size of the
  1929     element itself.
  1931    <p>The first three rules do not specify the <a
  1932     href="#propdef-font-variant" title="font-variant!!property">‘<code
  1933     class=property>font-variant</code>’</a> and <a
  1934     href="#propdef-font-weight" title="font-weight!!property">‘<code
  1935     class=property>font-weight</code>’</a> explicitly, so these properties
  1936     receive their initial values (<span title="normal value">‘<code
  1937     class=property>normal</code>’</span>). Notice that the font family name
  1938     "new century schoolbook", which contains spaces, is enclosed in quotes.
  1939     The fourth rule sets the <a href="#propdef-font-weight"
  1940     title="font-weight!!property">‘<code
  1941     class=property>font-weight</code>’</a> to ‘<a href="#bold"><code
  1942     class=property>bold</code></a>’, the <a href="#propdef-font-style"
  1943     title="font-style!!property">‘<code
  1944     class=property>font-style</code>’</a> to ‘<a href="#italic"><code
  1945     class=property>italic</code></a>’, and implicitly sets <a
  1946     href="#propdef-font-variant" title="font-variant!!property">‘<code
  1947     class=property>font-variant</code>’</a> to <a
  1948     href="#font-variant-normal-value" title="normal!!font-variant">‘<code
  1949     class=property>normal</code>’</a>.
  1951    <p> The fifth rule sets the <a href="#propdef-font-variant"
  1952     title="font-variant!!property">‘<code
  1953     class=property>font-variant</code>’</a> (‘<a href="#small-caps"><code
  1954     class=property>small-caps</code></a>’), the <span class=property>‘<a
  1955     href="#propdef-font-size"><code
  1956     class=property>font-size</code></a>’</span> (120% of the parent's font
  1957     size), the <a class=property
  1958     href="http://www.w3.org/TR/CSS2/visudet.html#propdef-line-height">‘<code
  1959     class=property>line-height</code>’</a> (120% of the font size) and the
  1960     <a href="#propdef-font-family" title="font-family!!property">‘<code
  1961     class=property>font-family</code>’</a> (‘<a href="#fantasy"><code
  1962     class=property>fantasy</code></a>’). It follows that the keyword <span
  1963     title="normal value">‘<code class=property>normal</code>’</span>
  1964     applies to the two remaining properties: <a href="#propdef-font-style"
  1965     title="font-style!!property">‘<code
  1966     class=property>font-style</code>’</a> and <a
  1967     href="#propdef-font-weight" title="font-weight!!property">‘<code
  1968     class=property>font-weight</code>’</a>.
  1970    <p>The sixth rule sets the <a href="#propdef-font-style"
  1971     title="font-style!!property">‘<code
  1972     class=property>font-style</code>’</a>, <a href="#propdef-font-stretch"
  1973     title="font-stretch!!property">‘<code
  1974     class=property>font-stretch</code>’</a>, <span class=property>‘<a
  1975     href="#propdef-font-size"><code
  1976     class=property>font-size</code></a>’</span>, and <a
  1977     href="#propdef-font-family" title="font-family!!property">‘<code
  1978     class=property>font-family</code>’</a>, the other font properties being
  1979     set to their initial values.
  1980   </div>
  1982   <p>Since the <a href="#propdef-font-stretch"
  1983    title="font-stretch!!property">‘<code
  1984    class=property>font-stretch</code>’</a> property was not defined in CSS
  1985    2.1, when using <a href="#propdef-font-stretch"
  1986    title="font-stretch!!property">‘<code
  1987    class=property>font-stretch</code>’</a> values within ‘<a
  1988    href="#propdef-font"><code class=property>font</code></a>’ rules,
  1989    authors should include a extra version compatible with older user agents:
  1991   <pre>p {
  1992   font: 80% sans-serif;   /* for older user agents */
  1993   font: condensed 80% sans-serif;
  1994 }</pre>
  1996   <p>The following values refer to system fonts:
  1998   <dl>
  1999    <dt><strong>caption</strong>
  2001    <dd>The font used for captioned controls (e.g., buttons, drop-downs,
  2002     etc.).
  2004    <dt><strong>icon</strong>
  2006    <dd>The font used to label icons.
  2008    <dt><strong>menu</strong>
  2010    <dd>The font used in menus (e.g., dropdown menus and menu lists).
  2012    <dt><strong>message-box</strong>
  2014    <dd>The font used in dialog boxes.
  2016    <dt><strong>small-caption</strong>
  2018    <dd>The font used for labeling small controls.
  2020    <dt><strong>status-bar</strong>
  2022    <dd>The font used in window status bars.
  2023   </dl>
  2025   <p>System fonts may only be set as a whole; that is, the font family, size,
  2026    weight, style, etc. are all set at the same time. These values may then be
  2027    altered individually if desired. If no font with the indicated
  2028    characteristics exists on a given platform, the user agent should either
  2029    intelligently substitute (e.g., a smaller version of the ‘<code
  2030    class=property>caption</code>’ font might be used for the ‘<code
  2031    class=property>small-caption</code>’ font), or substitute a user agent
  2032    default font. As for regular fonts, if, for a system font, any of the
  2033    individual properties are not part of the operating system's available
  2034    user preferences, those properties should be set to their initial values.
  2036   <p>That is why this property is "almost" a shorthand property: system fonts
  2037    can only be specified with this property, not with <a
  2038    href="#propdef-font-family" title="font-family!!property">‘<code
  2039    class=property>font-family</code>’</a> itself, so <span
  2040    class=property>‘<a href="#propdef-font"><code
  2041    class=property>font</code></a>’</span> allows authors to do more than
  2042    the sum of its subproperties. However, the individual properties such as
  2043    <a href="#propdef-font-weight" title="font-weight!!property">‘<code
  2044    class=property>font-weight</code>’</a> are still given values taken from
  2045    the system font, which can be independently varied.
  2047   <p>Note that the keywords used for the system fonts listed above are only
  2048    treated as keywords when they occur in the initial position, in other
  2049    positions the same string is treated as part of the font family name:
  2051   <pre>  font: menu;        /* use the font settings for system menus */
  2052   font: large menu;  /* use a font family named "menu" */</pre>
  2054   <div class=example>
  2055    <p style="display:none">Example(s):
  2057    <p>
  2059    <pre>button { font: 300 italic 1.3em/1.7em &quot;FB Armada&quot;, sans-serif }
  2060 button p { font: menu }
  2061 button p em { font-weight: bolder }
  2062 </pre>
  2064    <p>If the font used for dropdown menus on a particular system happened to
  2065     be, for example, 9-point Charcoal, with a weight of 600, then P elements
  2066     that were descendants of BUTTON would be displayed as if this rule were
  2067     in effect:
  2069    <pre>button p { font: 600 9pt Charcoal }
  2070 </pre>
  2072    <p>Because the <span class=property>‘<a href="#propdef-font"><code
  2073     class=property>font</code></a>’</span> shorthand resets to its initial
  2074     value any property not explicitly given a value, this has the same effect
  2075     as this declaration:
  2077    <pre>button p {
  2078   font-style: normal;
  2079   font-variant: normal;
  2080   font-weight: 600;
  2081   font-size: 9pt;
  2082   line-height: normal;
  2083   font-family: Charcoal
  2085 </pre>
  2086   </div>
  2087   <!-- prop: font-synthesis -->
  2089   <h3 id=font-synthesis-prop><span class=secno>3.8 </span>Controlling
  2090    synthetic faces: the <a href="#propdef-font-synthesis">font-synthesis</a>
  2091    property</h3>
  2093   <table class=propdef id=namefont-synthesisvaluenone-weight-style>
  2094    <tbody>
  2095     <tr>
  2096      <td>Name:
  2098      <td><dfn id=propdef-font-synthesis>font-synthesis</dfn>
  2100     <tr>
  2101      <td>Value:
  2103      <td>none | [ weight || style ]
  2105     <tr>
  2106      <td>Initial:
  2108      <td>weight style
  2110     <tr>
  2111      <td>Applies to:
  2113      <td>all elements
  2115     <tr>
  2116      <td>Inherited:
  2118      <td>yes
  2120     <tr>
  2121      <td>Percentages:
  2123      <td>N/A
  2125     <tr>
  2126      <td>Media:
  2128      <td>visual
  2130     <tr>
  2131      <td>Computed value:
  2133      <td>as specified
  2135     <tr>
  2136      <td>Animatable:
  2138      <td>no
  2139   </table>
  2141   <p>This property controls whether user agents are allowed to synthesize
  2142    bold or oblique font faces when a font family lacks bold or italic faces.
  2143    If ‘<a href="#weight"><code class=property>weight</code></a>’ is not
  2144    specified, user agents must not synthesize bold faces and if ‘<code
  2145    class=property>style</code>’ is not specified user agents must not
  2146    synthesize italic faces. A value of ‘<code class=property>none</code>’
  2147    disallows all synthetic faces.
  2149   <div class=example>
  2150    <p>The style rule below disables the use of synthetically obliqued Arabic:</p>
  2152    <pre>*:lang(ar) { font-synthesis: none; }
  2153 </pre>
  2154   </div>
  2156   <h2 id=font-resources><span class=secno>4 </span>Font Resources</h2>
  2158   <h3 id=font-face-rule><span class=secno>4.1 </span>The <dfn
  2159    id=at-font-face-rule style="font-weight: inherit; font-style:
  2160    inherit"><code>@font-face</code></dfn> rule</h3>
  2162   <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule allows
  2163    for linking to fonts that are automatically fetched and activated when
  2164    needed. This allows authors to select a font that closely matches the
  2165    design goals for a given page rather than limiting the font choice to a
  2166    set of fonts available on all platforms. A set of font descriptors define
  2167    the location of a font resource, either locally or externally, along with
  2168    the style characteristics of an individual face. Multiple <a
  2169    href="#at-font-face-rule"><code>@font-face</code></a> rules can be used to
  2170    construct font families with a variety of faces. Using CSS font matching
  2171    rules, a user agent can selectively download only those faces that are
  2172    needed for a given piece of text.
  2174   <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule
  2175    consists of the <a href="#at-font-face-rule"><code>@font-face</code></a>
  2176    at-keyword followed by a block of descriptor declarations. In terms of the
  2177    grammar, this specification defines the following productions:
  2179   <pre><dfn id=fontfacerule>font_face_rule</dfn>
  2180   : <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>*
  2183 <dfn id=descriptordeclaration>descriptor_declaration</dfn>
  2184   : <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>
  2185   ;</pre>
  2187   <p>The following new definitions are introduced:
  2189   <pre>-    -|\\0{0,4}2d(\r\n|[ \t\r\n\f])?
  2190 F    f|\\0{0,4}(46|66)(\r\n|[ \t\r\n\f])?</pre>
  2192   <p>The following new token is introduced:
  2194   <pre>@{F}{O}{N}{T}{-}{F}{A}{C}{E} {return <dfn id=fontfacesym>FONT_FACE_SYM</dfn>;}</pre>
  2196   <p>Each <a href="#at-font-face-rule"><code>@font-face</code></a> rule
  2197    specifies a value for every font descriptor, either implicitly or
  2198    explicitly. Those not given explicit values in the rule take the initial
  2199    value listed with each descriptor in this specification. These descriptors
  2200    apply solely within the context of the <a
  2201    href="#at-font-face-rule"><code>@font-face</code></a> rule in which they
  2202    are defined, and do not apply to document language elements. There is no
  2203    notion of which elements the descriptors apply to or whether the values
  2204    are inherited by child elements. When a given descriptor occurs multiple
  2205    times in a given <a href="#at-font-face-rule"><code>@font-face</code></a>
  2206    rule, only the last descriptor declaration is used and all prior
  2207    declarations for that descriptor are ignored.
  2209   <div class=example>
  2210    <p>To use a downloadable font called Gentium:</p>
  2212    <pre>
  2213 @font-face {
  2214   font-family: Gentium;
  2215   src: url(http://example.com/fonts/Gentium.ttf);
  2218 p { font-family: Gentium, serif; }
  2219 </pre>
  2221    <p>The user agent will download Gentium and use it when rendering text
  2222     within paragraph elements. If for some reason the site serving the font
  2223     is unavailable, the default serif font will be used.</p>
  2224   </div>
  2226   <p>A given set of <a href="#at-font-face-rule"><code>@font-face</code></a>
  2227    rules define a set of fonts available for use within the documents that
  2228    contain these rules. When font matching is done, fonts defined using these
  2229    rules are considered before other available fonts on a system.
  2231   <p>Downloaded fonts are only available to documents that reference them.
  2232    The process of activating these fonts must not make them available to
  2233    other applications or to documents that don't directly link to the same
  2234    font. User agent implementers might consider it convenient to use
  2235    downloaded fonts when rendering characters in other documents for which no
  2236    other available font exists as part of the <a
  2237    href="#system-font-fallback"><em>system font fallback</em></a> procedure.
  2238    However, this would cause a security leak since the contents of one page
  2239    would be able to affect other pages, something an attacker could use as an
  2240    attack vector. These restrictions do not affect caching behavior, fonts
  2241    are cached the same way other web resources are cached.
  2243   <p>This at-rule follows the forward-compatible parsing rules of CSS. Like
  2244    properties in a declaration block, declarations of any descriptors that
  2245    are not supported by the user agent must be ignored. <a
  2246    href="#at-font-face-rule"><code>@font-face</code></a> rules require a
  2247    font-family and src descriptor; if either of these are missing, the <a
  2248    href="#at-font-face-rule"><code>@font-face</code></a> rule is invalid and
  2249    must be ignored entirely.
  2251   <p>In cases where user agents have limited platform resources or implement
  2252    the ability to disable downloadable font resources, <a
  2253    href="#at-font-face-rule"><code>@font-face</code></a> rules must simply be
  2254    ignored; the behavior of individual descriptors as defined in this
  2255    specification should not be altered.
  2257   <h3 id=font-family-desc><span class=secno>4.2 </span>Font family: the <a
  2258    href="#descdef-font-family">font-family</a> descriptor</h3>
  2260   <table class=descdef>
  2261    <tbody>
  2262     <tr>
  2263      <td>Name:
  2265      <td><dfn id=descdef-font-family
  2266       title="font-family!!descriptor">font-family</dfn>
  2268     <tr>
  2269      <td>Value:
  2271      <td><a href="#family-name-value"><var>&lt;family-name&gt;</var></a>
  2273     <tr>
  2274      <td><em>Initial:</em>
  2276      <td>N/A
  2277   </table>
  2279   <p>This descriptor defines the font family name that will be used in all
  2280    CSS font family name matching. It is required for the <a
  2281    href="#at-font-face-rule"><code>@font-face</code></a> rule to be valid. It
  2282    overrides the font family names contained in the underlying font data. If
  2283    the font family name is the same as a font family available in a given
  2284    user's environment, it effectively hides the underlying font for documents
  2285    that use the stylesheet. This permits a web author to freely choose
  2286    font-family names without worrying about conflicts with font family names
  2287    present in a given user's environment. Likewise, platform substitutions
  2288    for a given font family name must not be used.
  2290   <h3 id=src-desc><span class=secno>4.3 </span>Font reference: the <a
  2291    href="#descdef-src">src</a> descriptor</h3>
  2293   <table class=descdef>
  2294    <tbody>
  2295     <tr>
  2296      <td>Name:
  2298      <td><dfn id=descdef-src>src</dfn>
  2300     <tr>
  2301      <td>Value:
  2303      <td>[ &lt;url> [format(&lt;string> #)]? | <a
  2304       href="#font-face-name-value"><var>&lt;font-face-name&gt;</var></a> ] #
  2306     <tr>
  2307      <td><em>Initial:</em>
  2309      <td>N/A
  2310   </table>
  2312   <p>This descriptor specifies the resource containing font data. It is
  2313    required for the <a href="#at-font-face-rule"><code>@font-face</code></a>
  2314    rule to be valid. Its value is a prioritized, comma-separated list of
  2315    external references or locally-installed font face names. When a font is
  2316    needed the user agent iterates over the set of references listed, using
  2317    the first one it can successfully activate. Fonts containing invalid data
  2318    or local font faces that are not found are ignored and the user agent
  2319    loads the next font in the list.
  2321   <p>As with other URLs in CSS, the URL may be relative, in which case it is
  2322    resolved relative to the location of the style sheet containing the <a
  2323    href="#at-font-face-rule"><code>@font-face</code></a> rule. In the case of
  2324    SVG fonts, the URL points to an element within a document containing SVG
  2325    font definitions. If the element reference is omitted, a reference to the
  2326    first defined font is implied. Similarly, font container formats that can
  2327    contain more than one font must load one and only one of the fonts for a
  2328    given <a href="#at-font-face-rule"><code>@font-face</code></a> rule.
  2329    Fragment identifiers are used to indicate which font to load. If a
  2330    container format lacks a defined fragment identifier scheme,
  2331    implementations should use a simple 1-based indexing scheme (e.g.
  2332    "font-collection#1" for the first font, "font-collection#2" for the second
  2333    font).
  2335   <pre>
  2336 src: url(fonts/simple.ttf);   /* load simple.ttf relative to stylesheet location */
  2337 src: url(/fonts/simple.ttf);  /* load simple.ttf from absolute location */
  2338 src: url(fonts.svg#simple);   /* load SVG font with id 'simple' */
  2339 </pre>
  2341   <p>External references consist of a URL, followed by an optional hint
  2342    describing the format of the font resource referenced by that URL. The
  2343    format hint contains a comma-separated list of format strings that denote
  2344    well-known font formats. Conformant user agents must skip downloading a
  2345    font resource if the format hints indicate only unsupported or unknown
  2346    font formats. If no format hints are supplied, the user agent should
  2347    download the font resource.
  2349   <pre>
  2350 /* load WOFF font if possible, otherwise use OpenType font */
  2351 @font-face {
  2352   font-family: bodytext;
  2353   src: url(ideal-sans-serif.woff) format("woff"),
  2354        url(basic-sans-serif.ttf) format("opentype");
  2356 </pre>
  2358   <p>Format strings defined by this specification:
  2360   <table class=data id=fontformats>
  2361    <thead>
  2362     <tr>
  2363      <th>String
  2365      <th>Font Format
  2367      <th>Common extensions
  2369    <tbody>
  2370     <tr>
  2371      <th>"woff"
  2373      <td><a href="http://www.w3.org/TR/WOFF/">WOFF (Web Open Font Format)</a>
  2375      <td>.woff
  2377     <tr>
  2378      <th>"truetype"
  2380      <td><a
  2381       href="http://www.microsoft.com/typography/otspec/default.htm">TrueType</a>
  2383      <td>.ttf
  2385     <tr>
  2386      <th>"opentype"
  2388      <td><a
  2389       href="http://www.microsoft.com/typography/otspec/default.htm">OpenType</a>
  2391      <td>.ttf, .otf
  2393     <tr>
  2394      <th>"embedded-opentype"
  2396      <td><a
  2397       href="http://www.w3.org/Submission/2008/SUBM-EOT-20080305/">Embedded
  2398       OpenType</a>
  2400      <td>.eot
  2402     <tr>
  2403      <th>"svg"
  2405      <td><a href="http://www.w3.org/TR/SVG/fonts.html">SVG Font</a>
  2407      <td>.svg, .svgz
  2408   </table>
  2410   <p>Given the overlap in common usage between TrueType and OpenType, the
  2411    format hints "truetype" and "opentype" must be considered as synonymous; a
  2412    format hint of "opentype" does not imply that the font contains Postscript
  2413    CFF style glyph data or that it contains OpenType layout information (see
  2414    <a href="#platform-props-to-css">Appendix A</a> for more background on
  2415    this).
  2417   <p>When authors would prefer to use a locally available copy of a given
  2418    font and download it if it's not, <code>local()</code> can be used. The
  2419    locally-installed <dfn
  2420    id=font-face-name-value><var>&lt;font-face-name&gt;</var></dfn> argument
  2421    to <code>local()</code> is a format-specific string that uniquely
  2422    identifies a single font face within a larger family. The syntax for a <a
  2423    href="#font-face-name-value"><var>&lt;font-face-name&gt;</var></a> is a
  2424    unique font face name enclosed by "local(" and ")". The name can
  2425    optionally be enclosed in quotes. If unquoted, the unquoted font family
  2426    name processing conventions apply; the name must be a sequence of
  2427    identifiers separated by whitespace which is converted to a string by
  2428    joining the identifiers together separated by a single space.
  2430   <pre>
  2431 /* regular face of Gentium */
  2432 @font-face {
  2433   font-family: MyGentium;
  2434   src: local(Gentium),   /* use locally available Gentium */
  2435        url(Gentium.ttf); /* otherwise, download it */
  2437 </pre>
  2439   <p>For OpenType and TrueType fonts, this string is used to match only the
  2440    Postscript name or the full font name in the name table of locally
  2441    available fonts. Which type of name is used varies by platform and font,
  2442    so authors should include both of these names to assure proper matching
  2443    across platforms. Platform substitutions for a given font name must not be
  2444    used.
  2446   <pre>
  2447 /* bold face of Gentium */
  2448 @font-face {
  2449   font-family: MyGentium;
  2450   src: local(Gentium Bold),   /* full font name */
  2451        local(Gentium-Bold),   /* Postscript name */
  2452        url(GentiumBold.ttf);  /* otherwise, download it */
  2453   font-weight: bold;
  2455 </pre>
  2457   <p>Just as a <a href="#at-font-face-rule"><code>@font-face</code></a> rule
  2458    specifies the characteristics of a single font within a family, the unique
  2459    name used with <code>local()</code> specifies a single font, not an entire
  2460    font family. Defined in terms of OpenType font data, the Postscript name
  2461    is found in the font's <a
  2462    href="http://www.microsoft.com/typography/otspec/name.htm">name table</a>,
  2463    in the name record with nameID = 6 (see <a href="#OPENTYPE"
  2464    rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a> for more details). The
  2465    Postscript name is the commonly used key for all fonts on OSX and for
  2466    Postscript CFF fonts under Windows. The full font name (nameID = 4) is
  2467    used as a unique key for fonts with TrueType glyphs on Windows.
  2469   <p>For OpenType fonts with multiple localizations of the full font name,
  2470    the US English version is used (language ID = 0x409 for Windows and
  2471    language ID = 0 for Macintosh) or the first localization when a US English
  2472    full font name is not available (the OpenType specification recommends
  2473    that <a href="http://www.microsoft.com/typography/otspec/recom.htm">all
  2474    fonts minimally include US English names</a>). User agents that also match
  2475    other full font names, e.g. matching the Dutch name when the current
  2476    system locale is set to Dutch, are considered non-conformant. This is done
  2477    not to prefer English but to avoid matching inconsistencies across font
  2478    versions and OS localizations, since font style names (e.g. "Bold") are
  2479    frequently localized into many languages and the set of localizations
  2480    available varies widely across platform and font version. User agents that
  2481    match a concatenation of family name (nameID = 1) with style name (nameID
  2482    = 2) are considered non-conformant.
  2484   <p>This also allows for referencing faces that belong to larger families
  2485    that cannot otherwise be referenced.
  2487   <div class=example>
  2488    <p>Use a local font or reference an SVG font in another document:</p>
  2490    <pre>
  2491 @font-face {
  2492   font-family: Headline;
  2493   src: local(Futura-Medium),
  2494        url(fonts.svg#MyGeometricModern) format("svg");
  2496 </pre>
  2498    <p>Create an alias for local Japanese fonts on different platforms:</p>
  2500    <pre>
  2501 @font-face {
  2502   font-family: jpgothic;
  2503   src: local(HiraKakuPro-W3), local(Meiryo), local(IPAPGothic);
  2505 </pre>
  2507    <p>Reference a font face that cannot be matched within a larger family:</p>
  2509    <pre>
  2510 @font-face {
  2511   font-family: Hoefler Text Ornaments;
  2512   /* has the same font properties as Hoefler Text Regular */
  2513   src: local(HoeflerText-Ornaments);
  2515 </pre>
  2517    <p>Since localized fullnames never match, a document with the header style
  2518     rules below would always render using the default serif font, regardless
  2519     whether a particular system locale parameter is set to Finnish or not:</p>
  2521    <pre>
  2522 @font-face {
  2523   font-family: SectionHeader;
  2524   src: local("Arial Lihavoitu");  /* Finnish fullname for Arial Bold, should fail */
  2525   font-weight: bold;
  2528 h2 { font-family: SectionHeader, serif; }
  2529 </pre>
  2531    <p>A conformant user agent would never load the font ‘<code
  2532     class=css>gentium.eot</code>’ in the example below, since it is
  2533     included in the first definition of the ‘<a href="#descdef-src"><code
  2534     class=property>src</code></a>’ descriptor which is overridden by the
  2535     second definition in the same <a
  2536     href="#at-font-face-rule"><code>@font-face</code></a> rule:</p>
  2538    <pre>
  2539 @font-face {
  2540   font-family: MainText;
  2541   src: url(gentium.eot); /* for use with older non-conformant user agents */
  2542   src: local("Gentium"), url(gentium.ttf);  /* Overrides src definition */
  2544 </pre>
  2545   </div>
  2547   <h3 id=font-prop-desc><span class=secno>4.4 </span>Font property
  2548    descriptors: the <a href="#descdef-font-style">font-style</a>, <a
  2549    href="#descdef-font-weight">font-weight</a>, <a
  2550    href="#descdef-font-stretch">font-stretch</a> descriptors</h3>
  2552   <table class=descdef>
  2553    <tbody>
  2554     <tr>
  2555      <td>Name:
  2557      <td><dfn id=descdef-font-style
  2558       title="font-style!!descriptor">font-style</dfn>
  2560     <tr>
  2561      <td>Value:
  2563      <td>normal | italic | oblique
  2565     <tr>
  2566      <td><em>Initial:</em>
  2568      <td>normal
  2569   </table>
  2571   <table class=descdef>
  2572    <tbody>
  2573     <tr>
  2574      <td>Name:
  2576      <td><dfn id=descdef-font-weight
  2577       title="font-weight!!descriptor">font-weight</dfn>
  2579     <tr>
  2580      <td>Value:
  2582      <td>normal | bold | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900
  2584     <tr>
  2585      <td><em>Initial:</em>
  2587      <td>normal
  2588   </table>
  2590   <table class=descdef>
  2591    <tbody>
  2592     <tr>
  2593      <td>Name:
  2595      <td><dfn id=descdef-font-stretch
  2596       title="font-stretch!!descriptor">font-stretch</dfn>
  2598     <tr>
  2599      <td>Value:
  2601      <td>normal | ultra-condensed | extra-condensed | condensed |
  2602       semi-condensed | semi-expanded | expanded | extra-expanded |
  2603       ultra-expanded
  2605     <tr>
  2606      <td><em>Initial:</em>
  2608      <td>normal
  2609   </table>
  2611   <p>These descriptors define the characteristics of a font face and are used
  2612    in the process of matching styles to specific faces. For a font family
  2613    defined with several <a
  2614    href="#at-font-face-rule"><code>@font-face</code></a> rules, user agents
  2615    can either download all faces in the family or use these descriptors to
  2616    selectively download font faces that match actual styles used in document.
  2617    The values for these descriptors are the same as those for the
  2618    corresponding font properties except that relative keywords are not
  2619    allowed, ‘<a href="#bolder"><code class=property>bolder</code></a>’
  2620    and ‘<a href="#lighter"><code class=property>lighter</code></a>’. If
  2621    these descriptors are omitted, initial values are assumed.
  2623   <p>The value for these font face style attributes is used in place of the
  2624    style implied by the underlying font data. This allows authors to combine
  2625    faces in flexible combinations, even in situations where the original font
  2626    data was arranged differently. User agents that implement synthetic
  2627    bolding and obliquing must only apply synthetic styling in cases where the
  2628    font descriptors imply this is needed, rather than based on the style
  2629    attributes implied by the font data.
  2631   <h3 id=unicode-range-desc><span class=secno>4.5 </span>Character range: the
  2632    <a href="#descdef-unicode-range">unicode-range</a> descriptor</h3>
  2634   <table class=descdef>
  2635    <tbody>
  2636     <tr>
  2637      <td>Name:
  2639      <td><dfn id=descdef-unicode-range>unicode-range</dfn>
  2641     <tr>
  2642      <td>Value:
  2644      <td><a href="#urange-value"><var>&lt;urange&gt;</var></a> #
  2646     <tr>
  2647      <td><em>Initial:</em>
  2649      <td>U+0-10FFFF
  2650   </table>
  2652   <p>This descriptor defines the set of Unicode codepoints that may be
  2653    supported by the font face for which it is declared. The descriptor value
  2654    is a comma-delimited list of Unicode range (<a
  2655    href="#urange-value"><var>&lt;urange&gt;</var></a>) values. The union of
  2656    these ranges defines the set of codepoints that serves as a hint for user
  2657    agents when deciding whether or not to download a font resource for a
  2658    given text run.
  2660   <p>Each <dfn id=urange-value><var>&lt;urange&gt;</var></dfn> value is a <a
  2661    href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><code
  2662    title="UNICODE-RANGE token">UNICODE-RANGE</code></a> token made up of a
  2663    "U+" or "u+" prefix followed by a codepoint range in one of the three
  2664    forms listed below. Ranges that do not fit one of the these forms are
  2665    invalid and cause the declaration to be ignored.
  2667   <dl>
  2668    <dt>single codepoint (e.g. U+416)
  2670    <dd>a valid Unicode codepoint, represented as one to six hexadecimal
  2671     digits
  2673    <dt>interval range (e.g. U+400-4ff)
  2675    <dd>represented as two hyphen-separated valid Unicode codepoints
  2676     indicating the inclusive start and end codepoints of a range
  2678    <dt>wildcard range (e.g. U+4??)
  2680    <dd>defined by the set of codepoints implied when trailing ‘<code
  2681     class=css>?</code>’ characters signify any hexadeximal digit
  2682   </dl>
  2684   <p>Individual codepoints are written using hexadecimal values that
  2685    correspond to <a href="http://www.unicode.org/charts/">Unicode character
  2686    codepoints</a>. Valid Unicode codepoint values vary between 0 and 10FFFF
  2687    inclusive. Digit values of codepoints are ASCII case-insensitive. For
  2688    interval ranges, the start and end codepoints are valid Unicode values and
  2689    the end codepoint is greater than or equal to the start codepoint.
  2691   <p>Wildcard ranges specified with ‘?’ that lack an initial digit (e.g.
  2692    "U+???") are valid and equivalent to a wildcard range with an initial zero
  2693    digit (e.g. "U+0???" = "U+0000-0FFF"). Wildcard ranges that extend beyond
  2694    the range of valid Unicode codepoints are invalid. Because of this, the
  2695    maximum number of trailing ‘<code class=css>?</code>’ wildcard
  2696    characters is five, even though the <a
  2697    href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><code
  2698    title="UNICODE-RANGE token">UNICODE-RANGE</code></a> token accepts six.
  2700   <p>Within the comma-delimited list of Unicode ranges in a ‘<a
  2701    href="#descdef-unicode-range"><code
  2702    class=property>unicode-range</code></a>’ descriptor declaration, ranges
  2703    may overlap. The union of these ranges defines the set of codepoints for
  2704    which the corresponding font may be used. User agents must not download or
  2705    use the font for codepoints outside this set. User agents may normalize
  2706    the list of ranges into a list that is different but represents the same
  2707    set of codepoints.
  2709   <p>The associated font might not contain glyphs for the entire set of
  2710    codepoints defined by the ‘<a href="#descdef-unicode-range"><code
  2711    class=property>unicode-range</code></a>’ descriptor. When the font is
  2712    used, the <dfn id=effective-character-map>effective character map</dfn> is
  2713    the intersection of the codepoints defined by ‘<a
  2714    href="#descdef-unicode-range"><code
  2715    class=property>unicode-range</code></a>’ with the font's <a
  2716    href="#character-map"><em>character map</em></a>. This allows authors to
  2717    define supported ranges in terms of broad ranges without worrying about
  2718    the precise codepoint ranges supported by the underlying font.
  2720   <h3 id=composite-fonts><span class=secno>4.6 </span>Using character ranges
  2721    to define composite fonts</h3>
  2723   <p>Multiple <a href="#at-font-face-rule"><code>@font-face</code></a> rules
  2724    with different unicode ranges for the same family and style descriptor
  2725    values can be used to create composite fonts that mix the glyphs from
  2726    different fonts for different scripts. This can be used to combine fonts
  2727    that only contain glyphs for a single script (e.g. Latin, Greek, Cyrillic)
  2728    or it can be used by authors as a way of segmenting a font into fonts for
  2729    commonly used characters and less frequently used characters. Since the
  2730    user agent will only pull down the fonts it needs this helps reduce page
  2731    bandwidth.
  2733   <p>If the unicode ranges overlap for a set of <a
  2734    href="#at-font-face-rule"><code>@font-face</code></a> rules with the same
  2735    family and style descriptor values, the rules are ordered in the reverse
  2736    order they were defined; the last rule defined is the first to be checked
  2737    for a given character.
  2739   <p>Example ranges for specific languages or characters:
  2741   <dl>
  2742    <dt>unicode-range: U+A5;
  2744    <dd>a single code point, the yen/yuan symbol
  2746    <dt>unicode-range: U+0-7F;
  2748    <dd>code range for basic ASCII characters
  2750    <dt>unicode-range: U+590-5ff;
  2752    <dd>code range for Hebrew characters
  2754    <dt>unicode-range: U+A5, U+4E00-9FFF, U+30??, U+FF00-FF9F;
  2756    <dd>code range for Japanese kanji, hiragana and katakana characters plus
  2757     yen/yuan symbol
  2758   </dl>
  2760   <div class=example>
  2761    <p>The BBC provides news services in a wide variety of languages, many
  2762     that are not well supported across all platforms. Using an <a
  2763     href="#at-font-face-rule"><code>@font-face</code></a> rule, the BBC could
  2764     provide a font for any of these languages, as it already does via a
  2765     manual font download.</p>
  2767    <pre>
  2768 @font-face {
  2769   font-family: BBCBengali;
  2770   src: url(fonts/BBCBengali.ttf) format("opentype");
  2771   unicode-range: U+00-FF, U+980-9FF;
  2773 </pre>
  2774   </div>
  2776   <div class=example>
  2777    <p>Technical documents often require a wide range of symbols. The STIX
  2778     Fonts project is one project aimed at providing fonts to support a wide
  2779     range of technical typesetting in a standardized way. The example below
  2780     shows the use of a font that provides glyphs for many of the mathematical
  2781     and technical symbol ranges within Unicode:</p>
  2783    <pre>
  2784 @font-face {
  2785   font-family: STIXGeneral;
  2786   src: local(STIXGeneral), url(/stixfonts/STIXGeneral.otf);
  2787   unicode-range: U+000-49F, U+2000-27FF, U+2900-2BFF, U+1D400-1D7FF;
  2789 </pre>
  2790   </div>
  2792   <div class=example>
  2793    <p>This example shows how an author can override the glyphs used for Latin
  2794     characters in a Japanese font with glyphs from a different font. The
  2795     first rule specifies no range so it defaults to the entire range. The
  2796     range specified in the second rule overlaps but takes precedence because
  2797     it is defined later.</p>
  2799    <pre>
  2800 @font-face {
  2801   font-family: JapaneseWithGentium;
  2802   src: local(MSMincho);
  2803   /* no range specified, defaults to entire range */
  2806 @font-face {
  2807   font-family: JapaneseWithGentium;
  2808   src: url(../fonts/Gentium.ttf);
  2809   unicode-range: U+0-2FF;
  2811 </pre>
  2812   </div>
  2814   <div class=example>
  2815    <p>Consider a family constructed to optimize bandwidth by separating out
  2816     Latin, Japanese and other characters into different font files:</p>
  2818    <pre>
  2819 /* fallback font - size: 4.5MB */
  2820 @font-face {
  2821   font-family: DroidSans;
  2822   src: url(DroidSansFallback.ttf);
  2823   /* no range specified, defaults to entire range */
  2826 /* Japanese glyphs - size: 1.2MB */
  2827 @font-face {
  2828   font-family: DroidSans;
  2829   src: url(DroidSansJapanese.ttf);
  2830   unicode-range: U+3000-9FFF, U+ff??;
  2833 /* Latin, Greek, Cyrillic along with some
  2834    punctuation and symbols - size: 190KB */
  2835 @font-face {
  2836   font-family: DroidSans;
  2837   src: url(DroidSans.ttf);
  2838   unicode-range: U+000-5FF, U+1e00-1fff, U+2000-2300;
  2840 </pre>
  2842    <p>For simple Latin text, only the font for Latin characters is
  2843     downloaded:</p>
  2845    <pre>
  2846 body { font-family: DroidSans; }
  2848 &lt;p>This is that&lt;/p>
  2849 </pre>
  2851    <p>In this case the user agent first checks the unicode-range for the font
  2852     containing Latin characters (DroidSans.ttf). Since all the characters
  2853     above are in the range U+0-5FF, the user agent downloads the font and
  2854     renders the text with that font.</p>
  2856    <p>Next, consider text that makes use of an arrow character (⇨):</p>
  2858    <pre>
  2859 &lt;p>This &amp;#x21e8; that&lt;p>
  2860 </pre>
  2862    <p>The user agent again first checks the unicode-range of the font
  2863     containing Latin characters. Since U+2000-2300 includes the arrow code
  2864     point (U+21E8), the user agent downloads the font. For this character
  2865     however the Latin font does not have a matching glyph, so the effective
  2866     unicode-range used for font matching excludes this code point. Next, the
  2867     user agent evaluates the Japanese font. The unicode-range for the
  2868     Japanese font, U+3000-9FFF and U+ff??, does not include U+21E8, so the
  2869     user agent does not download the Japanese font. Next the fallback font is
  2870     considered. The <a href="#at-font-face-rule"><code>@font-face</code></a>
  2871     rule for the fallback font does not define unicode-range so its value
  2872     defaults to the range of all Unicode code points. The fallback font is
  2873     downloaded and used to render the arrow character.</p>
  2874   </div>
  2876   <h3 id=font-rend-desc><span class=secno>4.7 </span>Font features: the <a
  2877    href="#descdef-font-variant">font-variant</a> and <a
  2878    href="#descdef-font-feature-settings">font-feature-settings</a>
  2879    descriptors</h3>
  2881   <table class=descdef>
  2882    <tbody>
  2883     <tr>
  2884      <td>Name:
  2886      <td><dfn id=descdef-font-variant
  2887       title="font-variant!!descriptor">font-variant</dfn>
  2889     <tr>
  2890      <td>Value:
  2892      <td><a href="#font-variant-normal-value"
  2893       title="normal!!font-variant">normal</a> | <a
  2894       href="#font-variant-none-value" title="none!!font-variant">none</a> | [
  2895       <a href="#common-lig-values"><var>&lt;common-lig-values&gt;</var></a>
  2896       || <a
  2897       href="#discretionary-lig-values"><var>&lt;discretionary-lig-values&gt;</var></a>
  2898       || <a
  2899       href="#historical-lig-values"><var>&lt;historical-lig-values&gt;</var></a>
  2900       || <a
  2901       href="#contextual-alt-values"><var>&lt;contextual-alt-values&gt;</var></a>
  2902       || <a href="#stylistic"><var
  2903       title=stylistic>stylistic(&lt;feature-value-name&gt;)</var></a> || <a
  2904       href="#historical-forms"><var>historical-forms</var></a> || <a
  2905       href="#styleset"><var
  2906       title=styleset>styleset(&lt;feature-value-name&gt; #)</var></a> || <a
  2907       href="#character-variant"><var
  2908       title=character-variant>character-variant(&lt;feature-value-name&gt;
  2909       #)</var></a> || <a href="#swash"><var
  2910       title=swash>swash(&lt;feature-value-name&gt;)</var></a> || <a
  2911       href="#ornaments"><var
  2912       title=ornaments>ornaments(&lt;feature-value-name&gt;)</var></a> || <a
  2913       href="#annotation"><var
  2914       title=annotation>annotation(&lt;feature-value-name&gt;)</var></a> || [
  2915       <a href="#small-caps"><i>small-caps</i></a> | <a
  2916       href="#all-small-caps"><i>all-small-caps</i></a> | <a
  2917       href="#petite-caps"><i>petite-caps</i></a> | <a
  2918       href="#all-petite-caps"><i>all-petite-caps</i></a> | <a
  2919       href="#unicase"><i>unicase</i></a> | <a
  2920       href="#titling-caps"><i>titling-caps</i></a> ] || <a
  2921       href="#numeric-figure-values"><var>&lt;numeric-figure-values&gt;</var></a>
  2922       || <a
  2923       href="#numeric-spacing-values"><var>&lt;numeric-spacing-values&gt;</var></a>
  2924       || <a
  2925       href="#numeric-fraction-values"><var>&lt;numeric-fraction-values&gt;</var></a>
  2926       || <a href="#ordinal"><i>ordinal</i></a> || <a
  2927       href="#slashed-zero"><i>slashed-zero</i></a> || <a
  2928       href="#east-asian-variant-values"><var>&lt;east-asian-variant-values&gt;</var></a>
  2929       || <a
  2930       href="#east-asian-width-values"><var>&lt;east-asian-width-values&gt;</var></a>
  2931       || <a href="#ruby"><i>ruby</i></a> ]
  2933     <tr>
  2934      <td><em>Initial:</em>
  2936      <td>normal
  2937   </table>
  2939   <table class=descdef>
  2940    <tbody>
  2941     <tr>
  2942      <td>Name:
  2944      <td><dfn id=descdef-font-feature-settings
  2945       title="font-feature-settings!!descriptor">font-feature-settings</dfn>
  2947     <tr>
  2948      <td>Value:
  2950      <td><a href="#font-feature-settings-normal-value"
  2951       title="normal!!font-feature-settings">normal</a> | <a
  2952       href="#feature-tag-value"><var>&lt;feature-tag-value&gt;</var></a> #
  2954     <tr>
  2955      <td><em>Initial:</em>
  2957      <td>normal
  2958   </table>
  2960   <p>These descriptors define initial settings that apply when the font
  2961    defined by an <a href="#at-font-face-rule"><code>@font-face</code></a>
  2962    rule is rendered. They do not affect font selection. Values are identical
  2963    to those defined for the corresponding <a href="#propdef-font-variant"
  2964    title="font-variant!!property">‘<code
  2965    class=property>font-variant</code>’</a> and <a
  2966    href="#propdef-font-feature-settings"
  2967    title="font-feature-settings!!property">‘<code
  2968    class=property>font-feature-settings</code>’</a> properties defined
  2969    below except that the value ‘<code class=property>inherit</code>’ is
  2970    omitted. When multiple font feature descriptors or properties are used,
  2971    the cumulative effect on text rendering is detailed in the section <a
  2972    href="#font-feature-resolution">Font Feature Resolution</a> below. In
  2973    cases where specific values define synthesized fallback for certain <a
  2974    href="#propdef-font-variant" title="font-variant!!property">‘<code
  2975    class=property>font-variant</code>’</a> subproperties, the same
  2976    synthesized fallback applies when used within those values are used with
  2977    the <a href="#descdef-font-style" title="font-style!!descriptor">‘<code
  2978    class=property>font-variant</code>’</a> descriptor.
  2980   <h3 id=font-face-loading><span class=secno>4.8 </span>Font loading
  2981    guidelines</h3>
  2983   <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule is
  2984    designed to allow lazy loading of font resources that are only downloaded
  2985    when used within a document. A stylesheet can include <a
  2986    href="#at-font-face-rule"><code>@font-face</code></a> rules for a library
  2987    of fonts of which only a select set are used; user agents must only
  2988    download those fonts that are referred to within the style rules
  2989    applicable to a given page. User agents that download all fonts defined in
  2990    <a href="#at-font-face-rule"><code>@font-face</code></a> rules without
  2991    considering whether those fonts are in fact used within a page are
  2992    considered non-conformant. In cases where a font might be downloaded in
  2993    character fallback cases, user agents may download a font if it's
  2994    contained within the computed value of <a href="#propdef-font-family"
  2995    title="font-family!!property">‘<code
  2996    class=property>font-family</code>’</a> for a given text run.
  2998   <pre>
  2999 @font-face {
  3000   font-family: GeometricModern;
  3001   src: url(font.ttf);
  3004 p {
  3005   /* font will be downloaded for pages with p elements */
  3006   font-family: GeometricModern, sans-serif;
  3009 h2 {
  3010   /* font may be downloaded for pages with h2 elements, even if Futura is available locally */
  3011   font-family: Futura, GeometricModern, sans-serif;
  3013 </pre>
  3015   <p>In cases where textual content is loaded before downloadable fonts are
  3016    available, user agents may render text as it would be rendered if
  3017    downloadable font resources are not available or they may render text
  3018    transparently with fallback fonts to avoid a flash of text using a
  3019    fallback font. In cases where the font download fails user agents must
  3020    display text, simply leaving transparent text is considered non-conformant
  3021    behavior. Authors are advised to use fallback fonts in their font lists
  3022    that closely match the metrics of the downloadable fonts to avoid large
  3023    page reflows where possible.
  3025   <h3 id=same-origin-restriction><span class=secno>4.9 </span>Same-origin
  3026    restriction for fonts</h3>
  3028   <h4 id=default-same-origin-restriction><span class=secno>4.9.1
  3029    </span>Default same-origin restriction</h4>
  3030   <!-- TPAC 2011 Resolution to require same-origin restriction for loading fonts:
  3031   http://lists.w3.org/Archives/Public/www-style/2011Nov/0711.html
  3032   http://www.w3.org/2011/10/31-webapps-minutes.html#item02
  3033 -->
  3035   <p>User agents must implement a same-origin restriction when loading fonts
  3036    via the <a href="#at-font-face-rule"><code>@font-face</code></a>
  3037    mechanism. This restriction limits the loading of fonts for a given
  3038    document to fonts loaded from the same origin. Fonts can only be loaded
  3039    via the same host, port, and method combination as the containing
  3040    document, using the <a
  3041    href="http://www.w3.org/TR/html5/browsers.html#origin">origin matching
  3042    algorithm</a> described in the <a href="#HTML5"
  3043    rel=biblioentry>[HTML5]<!--{{!HTML5}}--></a> specification. The origin of
  3044    the stylesheet containing <a
  3045    href="#at-font-face-rule"><code>@font-face</code></a> rules is not used
  3046    when deciding whether a font is same origin or not, only the origin of the
  3047    containing document is used. The restriction applies to all font types.
  3049   <p>Given a document located at http://example.com/page.html, fonts defined
  3050    with ‘<a href="#descdef-src"><code class=property>src</code></a>’
  3051    definitions considered cross origin must not be loaded:
  3053   <pre>
  3054 /* same origin (i.e. domain, protocol, port match document) */
  3055 src: url(fonts/simple.ttf);
  3056 src: url(//fonts/simple.ttf);
  3058 /* cross origin, different protocol */
  3059 src: url(https://example.com/fonts/simple.ttf);
  3061 /* cross origin, different domain */
  3062 src: url(http://another.example.com/fonts/simple.ttf);
  3063 </pre>
  3065   <h4 id=allowing-cross-origin-font-loading><span class=secno>4.9.2
  3066    </span>Allowing cross-origin font loading</h4>
  3068   <p>User agents must also implement the ability to relax this restriction
  3069    using cross-site origin controls <a href="#CORS"
  3070    rel=biblioentry>[CORS]<!--{{!CORS}}--></a> for fonts loaded via HTTP.
  3071    Sites can explicitly allow cross-site downloading of font data using the
  3072    <code>Access-Control-Allow-Origin</code> HTTP header. For other protocols,
  3073    no explicit relaxation mechanism is defined or required.
  3075   <p>For font loads over HTTP, cross-origin requests must be made with the
  3076    following parameter settings which are used in conjunction with the <a
  3077    href="http://www.w3.org/TR/cors/#cross-origin-request-0"> <em>cross-origin
  3078    request algorithm</em></a> <a href="#CORS"
  3079    rel=biblioentry>[CORS]<!--{{!CORS}}--></a>:
  3081   <ul>
  3082    <li><em>request URL</em> — the URL of the font resource in the <a
  3083     href="#descdef-src"><code>src</code></a> descriptor
  3085    <li><em>request method</em> — GET
  3087    <li><em>author request headers</em> — none
  3089    <li><em>request entity body</em> — empty
  3091    <li><em>source origin</em> — the origin of the page which linked to the
  3092     stylesheet
  3094    <li><em>manual redirect flag</em> — false
  3096    <li><em>omit credentials flag</em> — true
  3098    <li><em>force preflight flag</em> — false
  3099   </ul>
  3101   <h2 id=font-matching-algorithm><span class=secno>5 </span>Font Matching
  3102    Algorithm</h2>
  3104   <p>The algorithm below describes how fonts are associated with individual
  3105    runs of text. For each character in the run a font family is chosen and a
  3106    particular font face is selected containing a glyph for that character.
  3108   <h3 id=font-family-casing><span class=secno>5.1 </span>Case sensitivity of
  3109    font family names</h3>
  3111   <p>As part of the font matching algorithm outlined below, user agents must
  3112    match font family names used in style rules with actual font family names
  3113    contained in fonts available in a given environment or with font family
  3114    names defined in <a href="#at-font-face-rule"><code>@font-face</code></a>
  3115    rules. User agents must match these names case insensitively, using the
  3116    "Default Caseless Matching" algorithm outlined in the Unicode
  3117    specification <a href="#UNICODE6"
  3118    rel=biblioentry>[UNICODE6]<!--{{!UNICODE6}}--></a>. This algorithm is
  3119    detailed in section 3.13 entitled "Default Case Algorithms". Specifically,
  3120    the algorithm must be applied without normalizing the strings involved and
  3121    without applying any language-specific tailorings. The case folding method
  3122    specified by this algorithm uses the case mappings with status field
  3123    ‘<code class=property>C</code>’ or ‘<code class=property>F</code>’
  3124    in the CaseFolding.txt file of the Unicode Character Database.
  3126   <p class=note> For authors this means that font family names are matched
  3127    case insensitively, whether those names exist in a platform font or in the
  3128    <a href="#at-font-face-rule"><code>@font-face</code></a> rules contained
  3129    in a stylesheet. Authors should take care to ensure that names use a
  3130    character sequence consistent with the actual font family name,
  3131    particularly when using combining characters such as diacritical marks.
  3132    For example, a family name that contains an uppercase A (U+0041) followed
  3133    by a combining ring (U+030A) will <strong>not</strong> match a name that
  3134    looks identical but which uses the precomposed lowercase a-ring character
  3135    (U+00E5) instead of the combining sequence.
  3137   <p class=note> Implementors should take care to verify that a given
  3138    caseless string comparison implementation uses this precise algorithm and
  3139    not assume that a given platform string matching routine follows it, as
  3140    many of these have locale-specific behavior or use some level of string
  3141    normalization.
  3143   <h3 id=font-style-matching><span class=secno>5.2 </span>Matching font
  3144    styles</h3>
  3146   <p>The procedure for choosing a font for a given character in a run of text
  3147    consists of iterating over the font families named by the <a
  3148    href="#propdef-font-family" title="font-family!!property">‘<code
  3149    class=property>font-family</code>’</a> property, selecting a font face
  3150    with the appropriate style based on other font properties and then
  3151    determining whether a glyph exists for the given character. This is done
  3152    using the <dfn id=character-map>character map</dfn> of the font, data
  3153    which maps characters to the default glyph for that character. A font is
  3154    considered to <dfn id=support>support</dfn> a given character if (1) the
  3155    character is contained in the font's <a
  3156    href="#character-map"><em>character map</em></a> and (2) if required by
  3157    the containing script, shaping information is available for that
  3158    character.
  3160   <p>Some legacy fonts may include a given character in the <a
  3161    href="#character-map"><em>character map</em></a> but lack the shaping
  3162    information (e.g. <a
  3163    href="http://www.microsoft.com/typography/otspec/ttochap1.htm">OpenType
  3164    layout tables</a> or <a
  3165    href="http://scripts.sil.org/cms/scripts/page.php?site_id=projects&amp;item_id=graphite_techAbout">Graphite
  3166    tables</a>) necessary for correctly rendering text runs containing that
  3167    character.
  3169   <p>Codepoint sequences consisting of a base character followed by a
  3170    sequence of combining characters are treated slightly differently, see the
  3171    section on <a href="#cluster-matching">cluster matching</a> below.
  3173   <p>For this procedure, the <dfn id=default-face>default face</dfn> for a
  3174    given font family is defined to be the face that would be selected if all
  3175    font style properties were set to their initial value.
  3177   <ol id=fontmatchingalg>
  3178    <li>Using the computed font property values for a given element, the user
  3179     agent starts with the first family name specified by the <a
  3180     href="#propdef-font-family" title="font-family!!property">‘<code
  3181     class=property>font-family</code>’</a> property.
  3183    <li>If the family name is a generic family keyword, the user agent looks
  3184     up the appropriate font family name to be used. User agents may choose
  3185     the generic font family to use based on the language of the containing
  3186     element or the Unicode range of the character.
  3188    <li>For other family names, the user agent attempts to find the family
  3189     name among fonts defined via <a
  3190     href="#at-font-face-rule"><code>@font-face</code></a> rules and then
  3191     among available system fonts, matching names with a <a
  3192     href="#font-family-casing">case-insensitive comparison</a> as outlined in
  3193     the section above. On systems containing fonts with multiple localized
  3194     font family names, user agents must match any of these names independent
  3195     of the underlying system locale or platform API used. If the font
  3196     resources defined for a given face in an <a
  3197     href="#at-font-face-rule"><code>@font-face</code></a> rule are either not
  3198     available or contain invalid font data, then the face should be treated
  3199     as not present in the family. If no faces are present for a family
  3200     defined via <a href="#at-font-face-rule"><code>@font-face</code></a>
  3201     rules, the family should be treated as missing; matching a platform font
  3202     with the same name must not occur in this case.
  3204    <li>If a font family match occurs, the user agent assembles the set of
  3205     font faces in that family and then narrows the set to a single face using
  3206     other font properties in the order given below. A group of faces defined
  3207     via <a href="#at-font-face-rule"><code>@font-face</code></a> rules with
  3208     identical font descriptor values but differing ‘<a
  3209     href="#descdef-unicode-range"><code
  3210     class=property>unicode-range</code></a>’ values are considered to be a
  3211     single <dfn id=composite-face>composite face</dfn> for this step:
  3212     <ol id=fontstylematchingalg>
  3213      <li><a href="#propdef-font-stretch"
  3214       title="font-stretch!!property">‘<code
  3215       class=property>font-stretch</code>’</a> is tried first. If the
  3216       matching set contains faces with width values matching the <a
  3217       href="#propdef-font-stretch" title="font-stretch!!property">‘<code
  3218       class=property>font-stretch</code>’</a> value, faces with other width
  3219       values are removed from the matching set. If there is no face that
  3220       exactly matches the width value the nearest width is used instead. If
  3221       the value of <a href="#propdef-font-stretch"
  3222       title="font-stretch!!property">‘<code
  3223       class=property>font-stretch</code>’</a> is <a
  3224       href="#font-stretch-normal-value" title="normal!!font-stretch">‘<code
  3225       class=property>normal</code>’</a> or one of the condensed values,
  3226       narrower width values are checked first, then wider values. If the
  3227       value of <a href="#propdef-font-stretch"
  3228       title="font-stretch!!property">‘<code
  3229       class=property>font-stretch</code>’</a> is one of the expanded
  3230       values, wider values are checked first, followed by narrower values.
  3231       Once the closest matching width has been determined by this process,
  3232       faces with other widths are removed from the matching set.
  3234      <li><a href="#propdef-font-style" title="font-style!!property">‘<code
  3235       class=property>font-style</code>’</a> is tried next. If the value of
  3236       <a href="#propdef-font-style" title="font-style!!property">‘<code
  3237       class=property>font-style</code>’</a> is ‘<a href="#italic"><code
  3238       class=property>italic</code></a>’, italic faces are checked first,
  3239       then oblique, then normal faces. If the value is ‘<a
  3240       href="#oblique"><code class=property>oblique</code></a>’, oblique
  3241       faces are checked first, then italic faces and then normal faces. If
  3242       the value is <a href="#font-style-normal-value"
  3243       title="normal!!font-style">‘<code
  3244       class=property>normal</code>’</a>, normal faces are checked first,
  3245       then oblique faces, then italic faces. Faces with other style values
  3246       are excluded from the matching set. User agents are permitted to
  3247       distinguish between italic and oblique faces within platform font
  3248       families but this is not required, so all italic or oblique faces may
  3249       be treated as italic faces. However, within font families defined via
  3250       <a href="#at-font-face-rule"><code>@font-face</code></a> rules, italic
  3251       and oblique faces must be distinguished using the value of the <a
  3252       href="#descdef-font-style" title="font-style!!descriptor">‘<code
  3253       class=property>font-style</code>’</a> descriptor. For families that
  3254       lack any italic or oblique faces, users agents may create artificial
  3255       oblique faces, if this is permitted by the value of the ‘<a
  3256       href="#propdef-font-synthesis"><code
  3257       class=property>font-synthesis</code></a>’ property.
  3259      <li><a href="#propdef-font-weight"
  3260       title="font-weight!!property">‘<code
  3261       class=property>font-weight</code>’</a> is matched next, so it will
  3262       always reduce the matching set to a single font face. If bolder/lighter
  3263       relative weights are used, the effective weight is calculated based on
  3264       the inherited weight value, as described in the definition of the <a
  3265       href="#propdef-font-weight" title="font-weight!!property">‘<code
  3266       class=property>font-weight</code>’</a> property. Given the desired
  3267       weight and the weights of faces in the matching set after the steps
  3268       above, if the desired weight is available that face matches. Otherwise,
  3269       a weight is chosen using the rules below:
  3270       <ul>
  3271        <li>If the desired weight is less than 400, weights below the desired
  3272         weight are checked in descending order followed by weights above the
  3273         desired weight in ascending order until a match is found.
  3275        <li>If the desired weight is greater than 500, weights above the
  3276         desired weight are checked in ascending order followed by weights
  3277         below the desired weight in descending order until a match is found.
  3279        <li>If the desired weight is 400, 500 is checked first and then the
  3280         rule for desired weights less than 400 is used.
  3282        <li>If the desired weight is 500, 400 is checked first and then the
  3283         rule for desired weights less than 400 is used.
  3284       </ul>
  3286      <li><span class=property>‘<a href="#propdef-font-size"><code
  3287       class=property>font-size</code></a>’</span> must be matched within a
  3288       UA-dependent margin of tolerance. (Typically, sizes for scalable fonts
  3289       are rounded to the nearest whole pixel, while the tolerance for
  3290       bitmapped fonts could be as large as 20%.) Further computations, e.g.,
  3291       by ‘<code class=property>em</code>’ values in other properties, are
  3292       based on the <span class=property>‘<a href="#propdef-font-size"><code
  3293       class=property>font-size</code></a>’</span> value that is used, not
  3294       the one that is specified.
  3295     </ol>
  3297    <li>
  3298     <p>If the matched face is defined via <a
  3299      href="#at-font-face-rule"><code>@font-face</code></a> rules, user agents
  3300      must use the procedure below to select a single font:
  3302     <ol>
  3303      <li>If the font resource has not been loaded and the range of characters
  3304       defined by the ‘<a href="#descdef-unicode-range"><code
  3305       class=property>unicode-range</code></a>’ descriptor value includes
  3306       the character in question, load the font.
  3308      <li>After downloading, if the <a
  3309       href="#effective-character-map"><em>effective character map</em></a>
  3310       supports the character in question, select that font.
  3311     </ol>
  3313     <p>When the matched face is a <a href="#composite-face"><em>composite
  3314      face</em></a>, user agents must use the procedure above on each of the
  3315      faces in the <a href="#composite-face"><em>composite face</em></a> in
  3316      reverse order of <a
  3317      href="#at-font-face-rule"><code>@font-face</code></a> rule definition.</p>
  3319     <p>While the download occurs, user agents may either wait until the font
  3320      is downloaded or render once with substituted font metrics and render
  3321      again once the font is downloaded.</p>
  3323    <li>
  3324     <p>If no matching face exists or the matched face does not contain a
  3325      glyph for the character to be rendered, the next family name is selected
  3326      and the previous three steps repeated. Glyphs from other faces in the
  3327      family are not considered. The only exception is that user agents may
  3328      optionally substitute a synthetically obliqued version of the <a
  3329      href="#default-face"><em>default face</em></a> if that face supports a
  3330      given glyph and synthesis of these faces is permitted by the value of
  3331      the ‘<a href="#propdef-font-synthesis"><code
  3332      class=property>font-synthesis</code></a>’ property. For example, a
  3333      synthetic italic version of the regular face may be used if the italic
  3334      face doesn't support glyphs for Arabic.</p>
  3335     <!-- resolution on the above: http://lists.w3.org/Archives/Public/www-style/2012Nov/0292.html -->
  3338    <li>If there are no more font families to be evaluated and no matching
  3339     face has been found, then the user agent performs a <dfn
  3340     id=system-font-fallback>system font fallback</dfn> procedure to find the
  3341     best match for the character to be rendered. The result of this procedure
  3342     may vary across user agents.
  3344    <li>If a particular character cannot be displayed using any font, the user
  3345     agent should indicate by some means that a character is not being
  3346     displayed, displaying either a symbolic representation of the missing
  3347     glyph (e.g. using a <a
  3348     href="http://en.wikipedia.org/wiki/Last_resort_font">Last Resort
  3349     Font</a>) or using the missing character glyph from a default font.
  3350   </ol>
  3352   <p>Optimizations of this process are allowed provided that an
  3353    implementation behaves as if the algorithm had been followed exactly.
  3354    Matching occurs in a well-defined order to insure that the results are as
  3355    consistent as possible across user agents, given an identical set of
  3356    available fonts and rendering technology.
  3358   <p>The <dfn id=first-available-font>first available font</dfn>, used in the
  3359    definition of <a
  3360    href="http://www.w3.org/TR/css3-values/#font-relative-lengths"><em>font-relative
  3361    lengths</em></a> such as ‘<code class=property>ex</code>’ and ‘<code
  3362    class=property>ch</code>’, is defined to be the first available font
  3363    that would match any character given font families in the ‘<code
  3364    class=property>font-family</code>’ list (or a user agent's default font
  3365    if none are available).
  3367   <h3 id=cluster-matching><span class=secno>5.3 </span>Cluster matching</h3>
  3369   <p>When text contains characters such as combining marks, ideally the base
  3370    character should be rendered using the same font as the mark, this assures
  3371    proper placement of the mark. For this reason, the font matching algorithm
  3372    for clusters is more specialized than the general case of matching a
  3373    single character by itself. For sequences containing variation selectors,
  3374    which indicate the precise glyph to be used for a given character, user
  3375    agents always attempt <a href="#system-font-fallback"><em>system font
  3376    fallback</em></a> to find the appropriate glyph before using the default
  3377    glyph of the base character.
  3379   <p>A sequence of codepoints containing combining mark or other modifiers is
  3380    termed a grapheme cluster (see <a href="#CSS3TEXT"
  3381    rel=biblioentry>[CSS3TEXT]<!--{{CSS3TEXT}}--></a> for a more complete
  3382    description). For a given cluster containing a base character, <em>b</em>
  3383    and a sequence of combining characters <em>c1, c2…</em>, the entire
  3384    cluster is matched using these steps:
  3386   <ol>
  3387    <li>For each family in the font list, a face is chosen using the style
  3388     selection rules defined in the previous section.
  3389     <ol>
  3390      <li>If all characters in the sequence <em>b + c1 + c2 …</em> are
  3391       completely supported by the font, select this font for the sequence.
  3393      <li>If a sequence of multiple codepoints is canonically equivalent to a
  3394       single character and the font <a href="#support"><em
  3395       title=support>supports</em></a> that character, select this font for
  3396       the sequence.
  3397     </ol>
  3399    <li>If no font was found in the font list in step 1:
  3400     <ol>
  3401      <li>If <em>c1</em> is a variation selector, system fallback must be used
  3402       to find a font that <a href="#support"><em
  3403       title=support>supports</em></a> the full sequence of <em>b + c1</em>.
  3404       If no font on the system <a href="#support"><em
  3405       title=support>supports</em></a> the full sequence, match the single
  3406       character <em>b</em> using the normal procedure for matching single
  3407       characters and ignore the variation selector. Note: a sequence with
  3408       more than one variation selector must be treated as an encoding error
  3409       and the trailing selectors must be ignored. <a href="#UNICODE6"
  3410       rel=biblioentry>[UNICODE6]<!--{{!UNICODE6}}--></a>
  3412      <li>Otherwise, the user agent may optionally use system font fallback to
  3413       match a font that <a href="#support"><em
  3414       title=support>supports</em></a> the entire cluster.
  3415     </ol>
  3417    <li>If no font is found in step 2, use the matching sequence from step 1
  3418     to determine the longest sequence that is completely <a
  3419     href="#support"><em title=support>supported</em></a> by a font in the
  3420     font list and attempt to match the remaining combining characters
  3421     separately using the rules for single characters.
  3422   </ol>
  3424   <h3 id=char-handling-issues><span class=secno>5.4 </span>Character handling
  3425    issues</h3>
  3427   <p>CSS font matching is always performed on text runs containing Unicode
  3428    characters, so documents using legacy encodings are assumed to have been
  3429    transcoded before matching fonts. For fonts containing <a
  3430    href="#character-map"><em title="character map">character maps</em></a>
  3431    for both legacy encodings and Unicode, the contents of the legacy encoding
  3432    <a href="#character-map"><em>character map</em></a> must have no effect on
  3433    the results of the font matching process.
  3435   <p>The font matching process does not assume that text runs are in either
  3436    normalized or denormalized form (see <a href="#CHARMOD-NORM"
  3437    rel=biblioentry>[CHARMOD-NORM]<!--{{CHARMOD-NORM}}--></a> for more
  3438    details). Fonts may only support precomposed forms and not the decomposed
  3439    sequence of base character plus combining marks. Authors should always
  3440    tailor their choice of fonts to their content, including whether that
  3441    content contains normalized or denormalized character streams.
  3443   <p>If a given character is a Private-Use Area Unicode codepoint, user
  3444    agents must only match font families named in the ‘<code
  3445    class=property>font-family</code>’ list that are not generic families.
  3446    If none of the families named in the ‘<code
  3447    class=property>font-family</code>’ list contain a glyph for that
  3448    codepoint, user agents must display some form of missing glyph symbol for
  3449    that character rather than attempting <a
  3450    href="#system-font-fallback"><em>system font fallback</em></a> for that
  3451    codepoint. When matching the replacement character U+FFFD, user agents may
  3452    skip the font matching process and immediately display some form of
  3453    missing glyph symbol, they are not required to display the glyph from the
  3454    font that would be selected by the font matching process.
  3456   <p>In general, the fonts for a given family will all have the same or
  3457    similar <a href="#character-map"><em title="character map">character
  3458    maps</em></a>. The process outlined here is designed to handle even font
  3459    families containing faces with widely variant <a href="#character-map"><em
  3460    title="character map">character maps</em></a>. However, authors are
  3461    cautioned that the use of such families can lead to unexpected results.
  3463   <h3 id=font-matching-changes><span class=secno>5.5 </span>Font matching
  3464    changes since CSS 2.1</h3>
  3466   <p>The algorithm above is different from CSS 2.1 in a number of key places.
  3467    These changes were made to better reflect actual font matching behavior
  3468    across user agent implementations.
  3470   <p>Differences compared to the font matching algorithm in CSS 2.1:
  3472   <ul>
  3473    <li>The algorithm includes font-stretch matching.
  3475    <li>All possible font-style matching scenarios are delineated.
  3477    <li>Small-caps fonts are not matched as part of the font matching process,
  3478     they are now handled via font features.
  3480    <li>Unicode variation selector matching is required.
  3482    <li>Cluster sequences are matched as a unit.
  3483   </ul>
  3485   <h3 id=font-matching-examples><span class=secno>5.6 </span>Font matching
  3486    examples</h3>
  3488   <div class=example>
  3489    <p>It's useful to note that the CSS selector syntax may be used to create
  3490     language-sensitive typography. For example, some Chinese and Japanese
  3491     characters are unified to have the same Unicode code point, although the
  3492     abstract glyphs are not the same in the two languages.
  3494    <pre>*:lang(ja-jp) { font: 900 14pt/16pt &quot;Heisei Mincho W9&quot;, serif; }
  3495 *:lang(zh-tw) { font: 800 14pt/16.5pt &quot;Li Sung&quot;, serif; }
  3496 </pre>
  3498    <p>This selects any element that has the given language — Japanese or
  3499     Traditional Chinese — and uses the appropriate font.
  3500   </div>
  3502   <h2 id=font-rend-props><span class=secno>6 </span>Font Feature Properties</h2>
  3504   <p>Modern font technologies support a variety of advanced typographic and
  3505    language-specific font features. Using these features, a single font can
  3506    provide glyphs for a wide range of ligatures, contextual and stylistic
  3507    alternates, tabular and old-style figures, small capitals, automatic
  3508    fractions, swashes, and alternates specific to a given language. To allow
  3509    authors control over these font capabilities, the ‘<code
  3510    class=property>font-variant</code>’ property has been expanded for CSS3.
  3511    It now functions as a shorthand for a set of properties that provide
  3512    control over stylistic font features.
  3514   <h3 id=glyph-selection-positioning><span class=secno>6.1 </span>Glyph
  3515    selection and positioning</h3>
  3517   <p>Simple fonts used for displaying Latin text use a very basic processing
  3518    model. Fonts contain a <a href="#character-map"><em>character map</em></a>
  3519    which maps each character to a glyph for that character. Glyphs for
  3520    subsequent characters are simply placed one after the other along a run of
  3521    text. Modern font formats such as OpenType and AAT (Apple Advanced
  3522    Typography) use a richer processing model. The glyph for a given character
  3523    can be chosen and positioned not just based on the codepoint of the
  3524    character itself, but also on adjacent characters as well as the language,
  3525    script, and features enabled for the text. Font features may be required
  3526    for specific scripts, or recommended as enabled by default or they might
  3527    be stylistic features meant to be used under author control.
  3529   <p>For a good visual overview of these features, see the <a
  3530    href="#OPENTYPE-FONT-GUIDE"
  3531    rel=biblioentry>[OPENTYPE-FONT-GUIDE]<!--{{OPENTYPE-FONT-GUIDE}}--></a>.
  3532    For a detailed description of glyph processing for OpenType fonts, see <a
  3533    href="#WINDOWS-GLYPH-PROC"
  3534    rel=biblioentry>[WINDOWS-GLYPH-PROC]<!--{{WINDOWS-GLYPH-PROC}}--></a>.
  3536   <p>Stylistic font features can be classified into two broad categories:
  3537    ones that affect the harmonization of glyph shapes with the surrounding
  3538    context, such as kerning and ligature features, and ones such as the
  3539    small-caps, subscript/superscript and alternate features that affect shape
  3540    selection.
  3542   <p>The subproperties of <a href="#propdef-font-variant"
  3543    title="font-variant!!property">‘<code
  3544    class=property>font-variant</code>’</a> listed below are used to control
  3545    these stylistic font features. They do not control features that are
  3546    required for displaying certain scripts, such as the OpenType features
  3547    used when displaying Arabic or Indic language text. They affect glyph
  3548    selection and positioning, but do not affect font selection as described
  3549    in the font matching section (except in cases required for compatibility
  3550    with CSS 2.1).
  3552   <p>To assure consistent behavior across user agents, the equivalent
  3553    OpenType property settings are listed for individual properties and are
  3554    normative. When using other font formats these should be used as a
  3555    guideline to map CSS font feature property values to specific font
  3556    features.
  3558   <h3 id=language-specific-support><span class=secno>6.2
  3559    </span>Language-specific display</h3>
  3561   <p>OpenType also supports language-specific glyph selection and
  3562    positioning, so that text can be displayed correctly in cases where the
  3563    language dictates a specific display behavior. Many languages share a
  3564    common script, but the shape of certain letters can vary across those
  3565    languages. For example, certain Cyrillic letters have different shapes in
  3566    Russian text than in Bulgarian. In Latin text, it's common to render "fi"
  3567    with an explicit fi-ligature that lacks a dot on the "i". However, in
  3568    languages such as Turkish which uses both a dotted-i and a dotless-i, it's
  3569    important to not use this ligature or use a specialized version that
  3570    contains a dot over the "i". The example below shows language-specific
  3571    variations based on stylistic traditions found in Spanish, Italian and
  3572    French orthography:
  3574   <div class=featex><img alt="language specific forms, spanish"
  3575    src=locl-1.png></div>
  3577   <div class=featex><img alt="language specific forms, italian"
  3578    src=locl-2.png></div>
  3580   <div class=featex><img alt="language specific forms, french"
  3581    src=locl-3.png></div>
  3583   <p>If the content language of the element is known according to the rules
  3584    of the <a
  3585    href="http://www.w3.org/TR/CSS21/conform.html#doclanguage">document
  3586    language</a>, user agents are required to infer the OpenType language
  3587    system from the content language and use that when selecting and
  3588    positioning glyphs using an OpenType font.
  3590   <p>For OpenType fonts, in some cases it may be necessary to explicitly
  3591    declare the OpenType language to be used, for example when displaying text
  3592    in a given language that uses the typographic conventions of another
  3593    language or when the font does not explicitly support a given language but
  3594    supports a language that shares common typographic conventions. The ‘<a
  3595    href="#propdef-font-language-override"><code
  3596    class=property>font-language-override</code></a>’ property is used for
  3597    this purpose.</p>
  3598   <!-- prop: font-kerning -->
  3600   <h3 id=font-kerning-prop><span class=secno>6.3 </span>Kerning: the <a
  3601    href="#propdef-font-kerning">font-kerning</a> property</h3>
  3603   <table class=propdef id=namefont-kerningvalueauto-normal-noneini>
  3604    <tbody>
  3605     <tr>
  3606      <td>Name:
  3608      <td><dfn id=propdef-font-kerning>font-kerning</dfn>
  3610     <tr>
  3611      <td>Value:
  3613      <td><a href="#font-kerning-auto-value"
  3614       title="auto!!font-kerning">auto</a> | <a
  3615       href="#font-kerning-normal-value"
  3616       title="normal!!font-kerning">normal</a> | <a
  3617       href="#font-kerning-none-value" title="none!!font-kerning">none</a>
  3619     <tr>
  3620      <td>Initial:
  3622      <td>auto
  3624     <tr>
  3625      <td>Applies to:
  3627      <td>all elements
  3629     <tr>
  3630      <td>Inherited:
  3632      <td>yes
  3634     <tr>
  3635      <td>Percentages:
  3637      <td>N/A
  3639     <tr>
  3640      <td>Media:
  3642      <td>visual
  3644     <tr>
  3645      <td>Computed value:
  3647      <td>as specified
  3649     <tr>
  3650      <td>Animatable:
  3652      <td>no
  3653   </table>
  3655   <p>Kerning is the contextual adjustment of inter-glyph spacing. This
  3656    property controls metric kerning, kerning that utilizes adjustment data
  3657    contained in the font.
  3659   <dl>
  3660    <dt><dfn id=font-kerning-auto-value title="auto!!font-kerning">auto</dfn>
  3662    <dd>Specifies that kerning is applied at the discretion of the user agent
  3664    <dt><dfn id=font-kerning-normal-value
  3665     title="normal!!font-kerning">normal</dfn>
  3667    <dd>Specifies that kerning is applied
  3669    <dt><dfn id=font-kerning-none-value title="none!!font-kerning">none</dfn>
  3671    <dd>Specifies that kerning is not applied
  3672   </dl>
  3674   <p>For fonts that do not include kerning data this property will have no
  3675    visible effect. When rendering with OpenType fonts, the <a
  3676    href="#OPENTYPE" rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a>
  3677    specification suggests that kerning be enabled by default. When kerning is
  3678    enabled, the OpenType <span class=tag>kern</span> feature is enabled (for
  3679    vertical text runs the <span class=tag>vkrn</span> feature is enabled
  3680    instead). User agents must also support fonts that only support kerning
  3681    via data contained in a <span class=tag>kern</span> font table, as
  3682    detailed in the OpenType specification. If the ‘<code
  3683    class=property>letter-spacing</code>’ property is defined, kerning
  3684    adjustments are considered part of the default spacing and letter spacing
  3685    adjustments are made after kerning has been applied.
  3687   <p>When set to ‘<code class=property>auto</code>’, user agents can
  3688    determine whether to apply kerning or not based on a number of factors:
  3689    text size, script, or other factors that influence text processing speed.
  3690    Authors who want proper kerning should use <a
  3691    href="#font-kerning-normal-value" title="normal!!font-kerning">‘<code
  3692    class=property>normal</code>’</a> to explicitly enable kerning.
  3693    Likewise, some authors may prefer to disable kerning in situations where
  3694    performance is more important than precise appearance. However, in
  3695    well-designed modern implementations the use of kerning generally does not
  3696    have a large impact on text rendering speed.</p>
  3697   <!-- prop: font-variant-ligatures -->
  3699   <h3 id=font-variant-ligatures-prop><span class=secno>6.4 </span>Ligatures:
  3700    the <a href="#propdef-font-variant-ligatures">font-variant-ligatures</a>
  3701    property</h3>
  3703   <table class=propdef id=namefont-variant-ligaturesvaluenormal-no>
  3704    <tbody>
  3705     <tr>
  3706      <td>Name:
  3708      <td><dfn id=propdef-font-variant-ligatures>font-variant-ligatures</dfn>
  3710     <tr>
  3711      <td>Value:
  3713      <td><a href="#font-variant-ligatures-normal-value"
  3714       title="normal!!font-variant-ligatures">normal</a> | <a
  3715       href="#font-variant-ligatures-none-value"
  3716       title="none!!font-variant-ligatures">none</a> | [ <a
  3717       href="#common-lig-values"><var>&lt;common-lig-values&gt;</var></a> ||
  3718       <a
  3719       href="#discretionary-lig-values"><var>&lt;discretionary-lig-values&gt;</var></a>
  3720       || <a
  3721       href="#historical-lig-values"><var>&lt;historical-lig-values&gt;</var></a>
  3722       || <a
  3723       href="#contextual-alt-values"><var>&lt;contextual-alt-values&gt;</var></a>
  3726     <tr>
  3727      <td>Initial:
  3729      <td>normal
  3731     <tr>
  3732      <td>Applies to:
  3734      <td>all elements
  3736     <tr>
  3737      <td>Inherited:
  3739      <td>yes
  3741     <tr>
  3742      <td>Percentages:
  3744      <td>N/A
  3746     <tr>
  3747      <td>Media:
  3749      <td>visual
  3751     <tr>
  3752      <td>Computed value:
  3754      <td>as specified
  3756     <tr>
  3757      <td>Animatable:
  3759      <td>no
  3760   </table>
  3762   <p>Ligatures and contextual forms are ways of combining glyphs to produce
  3763    more harmonized forms.
  3765   <pre
  3766    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>
  3768   <pre
  3769    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>
  3771   <pre
  3772    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>
  3774   <pre
  3775    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>
  3777   <p>Individual values have the following meanings:
  3779   <dl>
  3780    <dt><dfn id=font-variant-ligatures-normal-value
  3781     title="normal!!font-variant-ligatures">normal</dfn>
  3783    <dd>A value of <a href="#font-variant-ligatures-normal-value"
  3784     title="normal!!font-variant-ligatures">‘<code
  3785     class=property>normal</code>’</a> specifies that common default
  3786     features are enabled, <a href="#font-feature-resolution">as described in
  3787     detail in the next section</a>. For OpenType fonts, common ligatures and
  3788     contextual forms are on by default, discretionary and historical
  3789     ligatures are not.
  3791    <dt><dfn id=font-variant-ligatures-none-value
  3792     title="none!!font-variant-ligatures">none</dfn>
  3794    <dd>Specifies that all types of ligatures and contextual forms covered by
  3795     this property are explicitly disabled. In situations where ligatures are
  3796     not considered necessary, this may improve the speed of text rendering.
  3798    <dt><dfn id=common-ligatures>common-ligatures</dfn>
  3800    <dd>Enables display of common ligatures (OpenType features: <span
  3801     class=tag>liga, clig</span>). For OpenType fonts, common ligatures are
  3802     enabled by default.
  3803   </dl>
  3805   <div class=featex><img alt="common ligature example" src=liga.png></div>
  3807   <dl>
  3808    <dt><dfn id=no-common-ligatures>no-common-ligatures</dfn>
  3810    <dd>Disables display of common ligatures (OpenType features: <span
  3811     class=tag>liga, clig</span>).
  3813    <dt><dfn id=discretionary-ligatures>discretionary-ligatures</dfn>
  3815    <dd>Enables display of discretionary ligatures (OpenType feature: <span
  3816     class=tag>dlig</span>). Which ligatures are discretionary or optional is
  3817     decided by the type designer, so authors will need to refer to the
  3818     documentation of a given font to understand which ligatures are
  3819     considered discretionary.
  3820   </dl>
  3822   <div class=featex><img alt="discretionary ligature example" src=dlig.png></div>
  3824   <dl>
  3825    <dt><dfn id=no-discretionary-ligatures>no-discretionary-ligatures</dfn>
  3827    <dd>Disables display of discretionary ligatures (OpenType feature: <span
  3828     class=tag>dlig</span>).
  3830    <dt><dfn id=historical-ligatures>historical-ligatures</dfn>
  3832    <dd>Enables display of historical ligatures (OpenType feature: <span
  3833     class=tag>hlig</span>).
  3834   </dl>
  3836   <div class=featex><img alt="historical ligature example" src=hlig.png></div>
  3838   <dl>
  3839    <dt><dfn id=no-historical-ligatures>no-historical-ligatures</dfn>
  3841    <dd>Disables display of historical ligatures (OpenType feature: <span
  3842     class=tag>hlig</span>).
  3844    <dt><dfn id=contextual>contextual</dfn>
  3846    <dd>Enables display of contextual alternates (OpenType feature: <span
  3847     class=tag>calt</span>). Although not strictly a ligature feature, like
  3848     ligatures this feature is commonly used to harmonize the shapes of glyphs
  3849     with the surrounding context. For OpenType fonts, this feature is on by
  3850     default.
  3851   </dl>
  3853   <div class=featex><img alt="contextual alternate example" src=calt.png></div>
  3855   <dl>
  3856    <dt><dfn id=no-contextual>no-contextual</dfn>
  3858    <dd>Disables display of contextual alternates (OpenType feature: <span
  3859     class=tag>calt</span>).
  3860   </dl>
  3862   <p>Required ligatures, needed for correctly rendering complex scripts, are
  3863    not affected by the settings above, including ‘<code
  3864    class=property>none</code>’ (OpenType feature: <span
  3865    class=tag>rlig</span>).</p>
  3866   <!-- prop: font-variant-position -->
  3868   <h3 id=font-variant-position-prop><span class=secno>6.5 </span>Subscript
  3869    and superscript forms: the <a
  3870    href="#propdef-font-variant-position">font-variant-position</a> property</h3>
  3872   <table class=propdef id=namefont-variant-positionvaluenormal-sub>
  3873    <tbody>
  3874     <tr>
  3875      <td>Name:
  3877      <td><dfn id=propdef-font-variant-position>font-variant-position</dfn>
  3879     <tr>
  3880      <td>Value:
  3882      <td><a href="#font-variant-position-normal-value"
  3883       title="normal!!font-variant-position">normal</a> | <a
  3884       href="#sub">sub</a> | <a href="#super">super</a>
  3886     <tr>
  3887      <td>Initial:
  3889      <td>normal
  3891     <tr>
  3892      <td>Applies to:
  3894      <td>all elements
  3896     <tr>
  3897      <td>Inherited:
  3899      <td>yes
  3901     <tr>
  3902      <td>Percentages:
  3904      <td>N/A
  3906     <tr>
  3907      <td>Media:
  3909      <td>visual
  3911     <tr>
  3912      <td>Computed value:
  3914      <td>as specified
  3916     <tr>
  3917      <td>Animatable:
  3919      <td>no
  3920   </table>
  3922   <p>This property is used to enable typographic subscript and superscript
  3923    glyphs. These are alternate glyphs designed within the same em-box as
  3924    default glyphs and are intended to be laid out on the same baseline as the
  3925    default glyphs, with no resizing or repositioning of the baseline. They
  3926    are explicitly designed to match the surrounding text and to be more
  3927    readable without affecting the line height.
  3929   <div class=figure><img alt="comparison between real subscript glyphs and
  3930    synthesized ones" src=realsubscripts.png>
  3931    <p class=caption>Subscript glyphs (top) vs. typical synthesized subscripts
  3932     (bottom)
  3933   </div>
  3935   <p>Individual values have the following meanings:
  3937   <dl>
  3938    <dt><dfn id=font-variant-position-normal-value
  3939     title="normal!!font-variant-position">normal</dfn>
  3941    <dd>None of the features listed below are enabled.
  3943    <dt><dfn id=sub>sub</dfn>
  3945    <dd>Enables display of subscript variants (OpenType feature: <span
  3946     class=tag>subs</span>).
  3948    <dt><dfn id=super>super</dfn>
  3950    <dd>Enables display of superscript variants (OpenType feature: <span
  3951     class=tag>sups</span>).
  3952   </dl>
  3954   <p>Because of the semantic nature of subscripts and superscripts, when the
  3955    value is either ‘<a href="#sub"><code class=property>sub</code></a>’
  3956    or ‘<a href="#super"><code class=property>super</code></a>’ for a
  3957    given contiguous run of text, if a variant glyph is not available for all
  3958    the characters in the run, simulated glyphs must be synthesized for all
  3959    characters using reduced forms of the glyphs that would be used without
  3960    this feature applied. This is done per run to avoid a mixture of variant
  3961    glyphs and synthesized ones that would not align correctly. In the case of
  3962    OpenType fonts that lack subscript or superscript glyphs for a given
  3963    character, user agents must use the appropriate subscript and superscript
  3964    metrics specified in the selected font's <a
  3965    href="http://www.microsoft.com/typography/otspec/os2.htm#subxs">OS/2
  3966    table</a> <a href="#OPENTYPE"
  3967    rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a> to calculate the size
  3968    and offset of the synthesized substitutes.
  3970   <div class=figure><img alt="alternate superscripts vs. glyphs synthesized
  3971    using superscript metrics" src=superscript-alt-synth.png>
  3972    <p class=caption>Superscript alternate glyph (left), synthesized
  3973     superscript glyphs (middle), and incorrect mixture of the two (right)
  3974   </div>
  3976   <p>In situations where text decorations are only applied to runs of text
  3977    containing superscript or subscript glyphs, the synthesized glyphs must be
  3978    used to avoid problems with the placement of decorations.
  3980   <p>In the past, user agents have used font-size and vertical-align to
  3981    simulate subscripts and superscripts for the <code title="HTML sub
  3982    element">sub</code> and <code title="HTML sup element">sup</code>
  3983    elements. To allow a backwards compatible way of defining subscripts and
  3984    superscripts, it is recommended that authors use conditional rules <a
  3985    href="#CSS3-CONDITIONAL"
  3986    rel=biblioentry>[CSS3-CONDITIONAL]<!--{{CSS3-CONDITIONAL}}--></a> so that
  3987    older user agents will still render subscripts and superscripts via the
  3988    older mechanism.
  3990   <p>Authors should note that fonts typically only provide subscript and
  3991    superscript glyphs for a subset of all characters supported by the font.
  3992    For example, while subscript and superscript glyphs are often available
  3993    for Latin numbers, glyphs for punctuation and letter characters are less
  3994    frequently provided. The synthetic fallback rules defined for this
  3995    property assure that subscripts and superscripts will always appear but
  3996    the appearance may not match author expectations if the font used does not
  3997    provide the appropriate alternate glyph for all characters contained in a
  3998    subscript or superscript.
  4000   <p>This property is not cumulative. Applying it to elements within a
  4001    subscript or superscript won't nest the placement of a subscript or
  4002    superscript glyph. Images contained within text runs where the value of
  4003    this property is ‘<a href="#sub"><code class=property>sub</code></a>’
  4004    or ‘<a href="#super"><code class=property>super</code></a>’ will be
  4005    drawn just as they would if the value was <a
  4006    href="#font-variant-position-normal-value"
  4007    title="normal!!font-variant-position">‘<code
  4008    class=property>normal</code>’</a>.</p>
  4009   <!-- due to lack of consensus, couldn't resolve on exact positioning of text decorations:
  4010 http://www.w3.org/2013/06/06-css-minutes.html#item03 -->
  4012   <p>Because of these limitations, ‘<a
  4013    href="#propdef-font-variant-position"><code
  4014    class=property>font-variant-position</code></a>’ is not recommended for
  4015    use in user agent stylesheets. Authors should use it in cases where
  4016    subscripts or superscripts will only contain the narrow range of
  4017    characters supported by the fonts specified.
  4019   <p class=note>The variant glyphs use the same baseline as the default
  4020    glyphs would use. There is no shift in the placement along the baseline,
  4021    so the use of variant glyphs doesn't affect the height of the inline box
  4022    or alter the height of the linebox. This makes superscript and subscript
  4023    variants ideal for situations where it's important that leading remain
  4024    constant, such as in multi-column layout.
  4026   <div class=example>
  4027    <p>A typical user agent default style for the <a class=tag
  4028     href="#sub">sub</a> element:</p>
  4030    <pre>sub {
  4031   vertical-align: sub;
  4032   font-size: smaller;
  4033   line-height: normal;
  4035 </pre>
  4037    <p>Using font-variant-position to specify typographic subscripts in a way
  4038     that will still show subscripts in older user agents:</p>
  4040    <pre>@supports ( font-variant-position: sub ) {
  4042   sub {
  4043     vertical-align: baseline;
  4044     font-size: 100%;
  4045     line-height: inherit;
  4046     font-variant-position: sub;
  4050 </pre>
  4052    <p>User agents that support the ‘<a
  4053     href="#propdef-font-variant-position"><code
  4054     class=property>font-variant-position</code></a>’ property will select a
  4055     subscript variant glyph and render this without adjusting the baseline or
  4056     font-size. Older user agents will ignore the ‘<a
  4057     href="#propdef-font-variant-position"><code
  4058     class=property>font-variant-position</code></a>’ property definition
  4059     and use the standard defaults for subscripts.</p>
  4060   </div>
  4061   <!-- prop: font-variant-caps -->
  4063   <h3 id=font-variant-caps-prop><span class=secno>6.6 </span>Capitalization:
  4064    the <a href="#propdef-font-variant-caps">font-variant-caps</a> property</h3>
  4066   <table class=propdef id=namefont-variant-capsvaluenormal-small-c>
  4067    <tbody>
  4068     <tr>
  4069      <td>Name:
  4071      <td><dfn id=propdef-font-variant-caps>font-variant-caps</dfn>
  4073     <tr>
  4074      <td>Value:
  4076      <td><a href="#font-variant-caps-normal-value"
  4077       title="normal!!font-variant-caps">normal</a> | <a
  4078       href="#small-caps">small-caps</a> | <a
  4079       href="#all-small-caps">all-small-caps</a> | <a
  4080       href="#petite-caps">petite-caps</a> | <a
  4081       href="#all-petite-caps">all-petite-caps</a> | <a
  4082       href="#unicase">unicase</a> | <a href="#titling-caps">titling-caps</a>
  4084     <tr>
  4085      <td>Initial:
  4087      <td>normal
  4089     <tr>
  4090      <td>Applies to:
  4092      <td>all elements
  4094     <tr>
  4095      <td>Inherited:
  4097      <td>yes
  4099     <tr>
  4100      <td>Percentages:
  4102      <td>N/A
  4104     <tr>
  4105      <td>Media:
  4107      <td>visual
  4109     <tr>
  4110      <td>Computed value:
  4112      <td>as specified
  4114     <tr>
  4115      <td>Animatable:
  4117      <td>no
  4118   </table>
  4120   <p>This property allows the selection of alternate glyphs used for small or
  4121    petite capitals or for titling. These glyphs are specifically designed to
  4122    blend well with the surrounding normal glyphs, to maintain the weight and
  4123    readability which suffers when text is simply resized to fit this purpose.
  4125   <p>Individual values have the following meanings:
  4127   <dl>
  4128    <dt><dfn id=font-variant-caps-normal-value
  4129     title="normal!!font-variant-caps">normal</dfn>
  4131    <dd>None of the features listed below are enabled.
  4133    <dt><dfn id=small-caps>small-caps</dfn>
  4135    <dd>Enables display of small capitals (OpenType feature: <span
  4136     class=tag>smcp</span>). Small-caps glyphs typically use the form of
  4137     uppercase letters but are reduced to the size of lowercase letters.
  4138   </dl>
  4140   <div class=featex><img alt="small-caps example" src=smcp.png></div>
  4142   <dl>
  4143    <dt><dfn id=all-small-caps>all-small-caps</dfn>
  4145    <dd>Enables display of small capitals for both upper and lowercase letters
  4146     (OpenType features: <span class=tag>c2sc, smcp</span>).
  4148    <dt><dfn id=petite-caps>petite-caps</dfn>
  4150    <dd>Enables display of petite capitals (OpenType feature: <span
  4151     class=tag>pcap</span>).
  4153    <dt><dfn id=all-petite-caps>all-petite-caps</dfn>
  4155    <dd>Enables display of petite capitals for both upper and lowercase
  4156     letters (OpenType features: <span class=tag>c2pc, pcap</span>).
  4158    <dt><dfn id=unicase>unicase</dfn>
  4160    <dd>Enables display of mixture of small capitals for uppercase letters
  4161     with normal lowercase letters (OpenType feature: <span
  4162     class=tag>unic</span>).
  4164    <dt><dfn id=titling-caps>titling-caps</dfn>
  4166    <dd>Enables display of titling capitals (OpenType feature: <span
  4167     class=tag>titl</span>). Uppercase letter glyphs are often designed for
  4168     use with lowercase letters. When used in all uppercase titling sequences
  4169     they can appear too strong. Titling capitals are designed specifically
  4170     for this situation.
  4171   </dl>
  4173   <p>The availability of these glyphs is based on whether a given feature is
  4174    defined or not in the feature list of the font. User agents can optionally
  4175    decide this on a per-script basis but should explicitly not decide this on
  4176    a per-character basis.
  4178   <p>Some fonts may only support a subset or none of the features described
  4179    for this property. For backwards compatibility with CSS 2.1, if ‘<a
  4180    href="#small-caps"><code class=property>small-caps</code></a>’ or ‘<a
  4181    href="#all-small-caps"><code class=property>all-small-caps</code></a>’
  4182    is specified but small-caps glyphs are not available for a given font,
  4183    user agents should simulate a small-caps font, for example by taking a
  4184    normal font and replacing the glyphs for lowercase letters with scaled
  4185    versions of the glyphs for uppercase characters (replacing the glyphs for
  4186    both upper and lowercase letters in the case of ‘<a
  4187    href="#all-small-caps"><code class=property>all-small-caps</code></a>’).
  4189   <div class=figure style="padding: 0; margin: auto;"><img alt="synthetic vs.
  4190    real small-caps" class=hires src=synthetic-vs-real-small-caps.png
  4191    width=512px>
  4192    <p class=caption>Synthetic vs. real small-caps
  4193   </div>
  4195   <p>To match the surrounding text, a font may provide alternate glyphs for
  4196    caseless characters when these features are enabled but when a user agent
  4197    simulates small capitals, it must not attempt to simulate alternates for
  4198    codepoints which are considered caseless.
  4200   <div class=figure style="padding: 0; margin: auto;"><img alt="caseless
  4201    characters with small-caps, all-small-caps enabled" class=hires
  4202    src=small-capitals-variations.png width=418px>
  4203    <p class=caption>Caseless characters with small-caps, all-small-caps
  4204     enabled
  4205   </div>
  4207   <p>If either ‘<a href="#petite-caps"><code
  4208    class=property>petite-caps</code></a>’ or ‘<a
  4209    href="#all-petite-caps"><code class=property>all-petite-caps</code></a>’
  4210    is specified for a font that doesn't support these features, the property
  4211    behaves as if ‘<a href="#small-caps"><code
  4212    class=property>small-caps</code></a>’ or ‘<a
  4213    href="#all-small-caps"><code class=property>all-small-caps</code></a>’,
  4214    respectively, had been specified. If ‘<a href="#unicase"><code
  4215    class=property>unicase</code></a>’ is specified for a font that doesn't
  4216    support that feature, the property behaves as if ‘<a
  4217    href="#small-caps"><code class=property>small-caps</code></a>’ was
  4218    applied only to lowercased uppercase letters. If ‘<a
  4219    href="#titling-caps"><code class=property>titling-caps</code></a>’ is
  4220    specified with a font that does not support this feature, this property
  4221    has no visible effect. When simulated small capital glyphs are used, for
  4222    scripts that lack uppercase and lowercase letters, ‘<a
  4223    href="#small-caps"><code class=property>small-caps</code></a>’, ‘<a
  4224    href="#all-small-caps"><code class=property>all-small-caps</code></a>’,
  4225    ‘<a href="#petite-caps"><code class=property>petite-caps</code></a>’,
  4226    ‘<a href="#all-petite-caps"><code
  4227    class=property>all-petite-caps</code></a>’ and ‘<a
  4228    href="#unicase"><code class=property>unicase</code></a>’ have no visible
  4229    effect.
  4231   <p>When casing transforms are used to simulate small capitals, the casing
  4232    transformations must match those used for the <span
  4233    class=property>‘<code class=property>text-transform</code>’</span>
  4234    property.
  4236   <p>As a last resort, unscaled uppercase letter glyphs in a normal font may
  4237    replace glyphs in a small-caps font so that the text appears in all
  4238    uppercase letters.
  4240   <div class=figure style="padding: 0; margin: auto;"><img alt="using
  4241    all-small-caps in acronym-laden text" class=hires
  4242    src=acronym-laden-text.png width=596px>
  4243    <p class=caption>Using small capitals to improve readability in
  4244     acronym-laden text
  4245   </div>
  4247   <div class=example>
  4248    <p>Quotes rendered italicised, with small-caps on the first line:</p>
  4250    <pre>blockquote            { font-style: italic; }
  4251 blockquote:first-line { font-variant: small-caps; }
  4253 &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>
  4254 </pre>
  4255   </div>
  4256   <!-- prop: font-variant-numeric -->
  4258   <h3 id=font-variant-numeric-prop><span class=secno>6.7 </span>Numerical
  4259    formatting: the <a
  4260    href="#propdef-font-variant-numeric">font-variant-numeric</a> property</h3>
  4262   <table class=propdef id=namefont-variant-numericvaluenormal-ltnu>
  4263    <tbody>
  4264     <tr>
  4265      <td>Name:
  4267      <td><dfn id=propdef-font-variant-numeric>font-variant-numeric</dfn>
  4269     <tr>
  4270      <td>Value:
  4272      <td><a href="#font-variant-numeric-normal-value"
  4273       title="normal!!font-variant-numeric">normal</a> | [ <a
  4274       href="#numeric-figure-values"><var>&lt;numeric-figure-values&gt;</var></a>
  4275       || <a
  4276       href="#numeric-spacing-values"><var>&lt;numeric-spacing-values&gt;</var></a>
  4277       || <a
  4278       href="#numeric-fraction-values"><var>&lt;numeric-fraction-values&gt;</var></a>
  4279       || <a href="#ordinal">ordinal</a> || <a
  4280       href="#slashed-zero">slashed-zero</a> ]
  4282     <tr>
  4283      <td>Initial:
  4285      <td>normal
  4287     <tr>
  4288      <td>Applies to:
  4290      <td>all elements
  4292     <tr>
  4293      <td>Inherited:
  4295      <td>yes
  4297     <tr>
  4298      <td>Percentages:
  4300      <td>N/A
  4302     <tr>
  4303      <td>Media:
  4305      <td>visual
  4307     <tr>
  4308      <td>Computed value:
  4310      <td>as specified
  4312     <tr>
  4313      <td>Animatable:
  4315      <td>no
  4316   </table>
  4318   <p>Specifies control over numerical forms. The example below shows how some
  4319    of these values can be combined to influence the rendering of tabular data
  4320    with fonts that support these features. Within normal paragraph text,
  4321    proportional numbers are used while tabular numbers are used so that
  4322    columns of numbers line up properly:
  4324   <div class=figure style="padding: 0; margin: auto;"><img alt="combining
  4325    number styles" src=numberstyles.png>
  4326    <p class=caption>Using number styles
  4327   </div>
  4329   <p>Possible combinations:
  4331   <pre
  4332    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>
  4334   <pre
  4335    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>
  4337   <pre
  4338    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>
  4340   <p>Individual values have the following meanings:
  4342   <dl>
  4343    <dt><dfn id=font-variant-numeric-normal-value
  4344     title="normal!!font-variant-numeric">normal</dfn>
  4346    <dd>None of the features listed below are enabled.
  4348    <dt><dfn id=lining-nums>lining-nums</dfn>
  4350    <dd>Enables display of lining numerals (OpenType feature: <span
  4351     class=tag>lnum</span>).
  4353    <dt><dfn id=oldstyle-nums>oldstyle-nums</dfn>
  4355    <dd>Enables display of old-style numerals (OpenType feature: <span
  4356     class=tag>onum</span>).
  4358    <dt><dfn id=proportional-nums>proportional-nums</dfn>
  4360    <dd>Enables display of proportional numerals (OpenType feature: <span
  4361     class=tag>pnum</span>).
  4363    <dt><dfn id=tabular-nums>tabular-nums</dfn>
  4365    <dd>Enables display of tabular numerals (OpenType feature: <span
  4366     class=tag>tnum</span>).
  4368    <dt><dfn id=diagonal-fractions>diagonal-fractions</dfn>
  4370    <dd>Enables display of lining diagonal fractions (OpenType feature: <span
  4371     class=tag>frac</span>).
  4372   </dl>
  4374   <div class=featex><img alt="diagonal fraction example" src=frac.png></div>
  4376   <dl>
  4377    <dt><dfn id=stacked-fractions>stacked-fractions</dfn>
  4379    <dd>Enables display of lining stacked fractions (OpenType feature: <span
  4380     class=tag>afrc</span>).
  4381   </dl>
  4383   <div class=featex><img alt="stacked fraction example" src=afrc.png></div>
  4385   <dl>
  4386    <dt><dfn id=ordinal>ordinal</dfn>
  4388    <dd>Enables display of forms used with ordinal numbers (OpenType feature:
  4389     <span class=tag>ordn</span>).
  4391    <dt><dfn id=slashed-zero>slashed-zero</dfn>
  4393    <dd>Enables display of slashed zeros (OpenType feature: <span
  4394     class=tag>zero</span>).
  4395   </dl>
  4397   <div class=featex><img alt="slashed zero example" src=zero.png></div>
  4399   <div class=example id=steak-marinade>
  4400    <p>A simple flank steak marinade recipe, rendered with automatic fractions
  4401     and old-style numerals:</p>
  4403    <pre>.amount { font-variant-numeric: oldstyle-nums diagonal-fractions; }
  4405 &lt;h4>Steak marinade:&lt;/h4>
  4406 &lt;ul>
  4407   &lt;li>&lt;span class="amount">2&lt;/span> tbsp olive oil&lt;/li>
  4408   &lt;li>&lt;span class="amount">1&lt;/span> tbsp lemon juice&lt;/li>
  4409   &lt;li>&lt;span class="amount">1&lt;/span> tbsp soy sauce&lt;/li>
  4410   &lt;li>&lt;span class="amount">1 1/2&lt;/span> tbsp dry minced onion&lt;/li>
  4411   &lt;li>&lt;span class="amount">2 1/2&lt;/span> tsp italian seasoning&lt;/li>
  4412   &lt;li>Salt &amp;amp; pepper&lt;/li>
  4413 &lt;/ul>
  4415 &lt;p>Mix the meat with the marinade and let it sit covered in the refrigerator
  4416 for a few hours or overnight.&lt;/p>
  4417 </pre>
  4419    <p>Note that the fraction feature is only applied to values not the entire
  4420     paragraph. Fonts often implement this feature using contextual rules
  4421     based on the use of the slash (‘<code class=css>/</code>’) character.
  4422     As such, it's not suitable for use as a paragraph-level style.</p>
  4423   </div>
  4424   <!-- prop: font-variant-alternates -->
  4426   <h3 id=font-variant-alternates-prop><span class=secno>6.8 </span>Alternates
  4427    and swashes: the <a
  4428    href="#propdef-font-variant-alternates">font-variant-alternates</a>
  4429    property</h3>
  4431   <table class=propdef id=namefont-variant-alternatesvaluenormal-s>
  4432    <tbody>
  4433     <tr>
  4434      <td>Name:
  4436      <td><dfn
  4437       id=propdef-font-variant-alternates>font-variant-alternates</dfn>
  4439     <tr>
  4440      <td>Value:
  4442      <td>normal | [ <a href="#stylistic"
  4443       title=stylistic>stylistic(&lt;feature-value-name&gt;)</a> || <a
  4444       href="#historical-forms">historical-forms</a> || <a href="#styleset"
  4445       title=styleset>styleset(&lt;feature-value-name&gt; #)</a> || <a
  4446       href="#character-variant"
  4447       title=character-variant>character-variant(&lt;feature-value-name&gt;
  4448       #)</a> || <a href="#swash"
  4449       title=swash>swash(&lt;feature-value-name&gt;)</a> || <a
  4450       href="#ornaments"
  4451       title=ornaments>ornaments(&lt;feature-value-name&gt;)</a> || <a
  4452       href="#annotation"
  4453       title=annotation>annotation(&lt;feature-value-name&gt;)</a> ]
  4455     <tr>
  4456      <td>Initial:
  4458      <td>normal
  4460     <tr>
  4461      <td>Applies to:
  4463      <td>all elements
  4465     <tr>
  4466      <td>Inherited:
  4468      <td>yes
  4470     <tr>
  4471      <td>Percentages:
  4473      <td>N/A
  4475     <tr>
  4476      <td>Media:
  4478      <td>visual
  4480     <tr>
  4481      <td>Computed value:
  4483      <td>as specified
  4485     <tr>
  4486      <td>Animatable:
  4488      <td>no
  4489   </table>
  4491   <p>For any given character, fonts can provide a variety of alternate glyphs
  4492    in addition to the default glyph for that character. This property
  4493    provides control over the selection of these alternate glyphs.
  4495   <p>For many of the property values listed below, several different
  4496    alternate glyphs are available. How many alternates are available and what
  4497    they represent is font-specific, so these are each marked <dfn
  4498    id=font-specific>font specific</dfn> in the value definitions below.
  4499    Because the nature of these alternates is font-specific, the <a
  4500    href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
  4501    rule is used to define values for a specific font family or set of
  4502    families that associate a font-specific numeric
  4503    <code>&lt;feature-index&gt;</code> with a custom
  4504    <code>&lt;feature-value-name&gt;</code>, which is then used in this
  4505    property to select specific alternates:
  4507   <pre>@font-feature-values Noble Script { @swash { swishy: 1; flowing: 2; } }
  4509 p {
  4510   font-family: Noble Script;
  4511   font-variant-alternates: swash(flowing); /* use swash alternate #2 */
  4512 }</pre>
  4514   <p>When a particular <code>&lt;feature-value-name&gt;</code> has not been
  4515    defined for a given family or for a particular feature type, the computed
  4516    value must be the same as if it had been defined. However, property values
  4517    that contain these undefined <code>&lt;feature-value-name&gt;</code>
  4518    identifiers must be ignored when choosing glyphs.
  4520   <pre>/* these two style rules are effectively the same */
  4521 p { font-variant-alternates: swash(unknown-value); } /* not a defined value, ignored */
  4522 p { font-variant-alternates: normal; }
  4523 </pre>
  4525   <p>This allows values to be defined and used for a given set of font
  4526    families but ignored if fallback occurs, since the font family name would
  4527    be different. If a given value is outside the range supported by a given
  4528    font, the value is ignored. These values never apply to generic font
  4529    families.
  4531   <p>Individual values have the following meanings:
  4533   <dl>
  4534    <dt><dfn id=font-variant-alternates-normal-value
  4535     title="normal!!font-variant-alternates">normal</dfn>
  4537    <dd>None of the features listed below are enabled.
  4539    <dt><dfn id=historical-forms>historical-forms</dfn>
  4541    <dd>Enables display of historical forms (OpenType feature: <span
  4542     class=tag>hist</span>).
  4543   </dl>
  4545   <div class=featex><img alt="historical form example" src=hist.png></div>
  4547   <dl>
  4548    <dt><dfn id=stylistic
  4549     title=stylistic>stylistic(&lt;feature-value-name&gt;)</dfn>
  4551    <dd>Enables display of stylistic alternates (<a
  4552     href="#font-specific"><em>font specific</em></a>, OpenType feature: <span
  4553     class=tag>salt &lt;feature-index&gt;</span>).
  4554   </dl>
  4556   <div class=featex><img alt="stylistic alternate example" src=salt.png></div>
  4558   <dl>
  4559    <dt><dfn id=styleset title=styleset>styleset(&lt;feature-value-name&gt;
  4560     #)</dfn>
  4562    <dd>Enables display with stylistic sets (<a href="#font-specific"><em>font
  4563     specific</em></a>, OpenType feature: <span
  4564     class=tag>ss&lt;feature-index&gt;</span> OpenType currently defines <span
  4565     class=tag>ss01</span> through <span class=tag>ss20</span>).
  4566   </dl>
  4568   <div class=featex><img alt="styleset example" src=ssnn.png></div>
  4570   <dl>
  4571    <dt><dfn id=character-variant
  4572     title=character-variant>character-variant(&lt;feature-value-name&gt;
  4573     #)</dfn>
  4575    <dd>Enables display of specific character variants (<a
  4576     href="#font-specific"><em>font specific</em></a>, OpenType feature: <span
  4577     class=tag>cv&lt;feature-index&gt;</span> OpenType currently defines <span
  4578     class=tag>cv01</span> through <span class=tag>cv99</span>).
  4580    <dt><dfn id=swash title=swash>swash(&lt;feature-value-name&gt;)</dfn>
  4582    <dd>Enables display of swash glyphs (<a href="#font-specific"><em>font
  4583     specific</em></a>, OpenType feature: <span class=tag>swsh
  4584     &lt;feature-index&gt;, cswh &lt;feature-index&gt;</span>).
  4585   </dl>
  4587   <div class=featex><img alt="swash example" src=swsh.png></div>
  4589   <dl>
  4590    <dt><dfn id=ornaments
  4591     title=ornaments>ornaments(&lt;feature-value-name&gt;)</dfn>
  4593    <dd>Enables replacement of default glyphs with ornaments, if provided in
  4594     the font (<a href="#font-specific"><em>font specific</em></a>, OpenType
  4595     feature: <span class=tag>ornm &lt;feature-index&gt;</span>). Some fonts
  4596     may offer ornament glyphs as alternates for a wide collection of
  4597     characters; however, displaying arbitrary characters (e.g.,
  4598     alphanumerics) as ornaments is poor practice as it distorts the semantics
  4599     of the data. Font designers are encouraged to encode all ornaments
  4600     (except those explicitly encoded in the Unicode Dingbats blocks, etc.) as
  4601     alternates for the bullet character (U+2022) to allow authors to select
  4602     the desired glyph using ‘<a href="#ornaments"><code
  4603     class=property>ornaments</code></a>’.
  4604   </dl>
  4606   <div class=featex><img alt="ornaments example" src=ornm.png></div>
  4608   <dl>
  4609    <dt><dfn id=annotation
  4610     title=annotation>annotation(&lt;feature-value-name&gt;)</dfn>
  4612    <dd>Enables display of alternate annotation forms (<a
  4613     href="#font-specific"><em>font specific</em></a>, OpenType feature: <span
  4614     class=tag>nalt &lt;feature-index&gt;</span>).
  4615   </dl>
  4617   <div class=featex><img alt="alternate annotation form example"
  4618    src=nalt.png></div>
  4620   <h3 id=font-feature-values><span class=secno>6.9 </span>Defining font
  4621    specific alternates: the <dfn id=at-font-feature-values-rule
  4622    style="font-weight: inherit; font-style:
  4623    inherit"><code>@font-feature-values</code></dfn> rule</h3>
  4625   <p>Several of the possible values of ‘<a
  4626    href="#propdef-font-variant-alternates"><code
  4627    class=property>font-variant-alternates</code></a>’ listed above are
  4628    labeled as <a href="#font-specific"><em>font specific</em></a>. For these
  4629    features fonts may define not just a single glyph but a set of alternate
  4630    glyphs with an index to select a given alternate. Since these are font
  4631    family specific, the <a
  4632    href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
  4633    rule is used to define named values for these indices for a given family.
  4635   <p class=note>See the <a href="#om-fontfeaturevalues">object model
  4636    reference section</a> for a description of the interfaces used to modify
  4637    these rules via the CSS Object Model.
  4639   <div class=example>
  4640    <p>In the case of the swash Q in the example shown above, the swash could
  4641     be specified using these style rules:</p>
  4643    <pre>
  4645 @font-feature-values Jupiter Sans {
  4646   @swash {
  4647     delicate: 1;
  4648     flowing: 2;
  4652 h2 { font-family: Jupiter Sans, sans-serif; }
  4654 /* show the second swash variant in h2 headings */
  4655 h2:first-letter { font-variant-alternates: swash(flowing); }
  4657 &lt;h2>Quick&lt;/h2></pre>
  4659    <p>When Jupiter Sans is present, the second alternate swash alternate will
  4660     be displayed. When not present, no swash character will be shown, since
  4661     the specific named value "flowing" is only defined for the Jupiter Sans
  4662     family. The @-mark indicates the name of the property value for which a
  4663     named value can be used. The name "flowing" is chosen by the author. The
  4664     index that represents each alternate is defined within a given font's
  4665     data.</p>
  4666   </div>
  4668   <h4 id=basic-syntax><span class=secno>6.9.1 </span>Basic syntax</h4>
  4670   <p>An <a
  4671    href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
  4672    rule is composed of a list of font families followed by a block containing
  4673    individual <a href="#featurevalueblock"><i
  4674    title="feature_value_block">feature value blocks</i></a> that take the
  4675    form of @-rules. Each block defines a set of named values for a specific
  4676    font feature when a given set of font families is used. Effectively, they
  4677    define a mapping of ⟨family, feature, ident⟩ → ⟨values⟩ where
  4678    ⟨values⟩ are the numeric indices used for specific features defined
  4679    for a given font.
  4681   <p>In terms of the grammar, this specification defines the following
  4682    productions:
  4684   <pre><dfn id=fontfeaturevaluesrule>font_feature_values_rule</dfn>
  4685   : <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>*
  4686     '{' <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>*
  4689 <dfn id=fontfamilynamelist>font_family_name_list</dfn>
  4690   : <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> ]*
  4693 <dfn id=fontfamilyname>font_family_name</dfn>
  4694   : <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> ]* ]
  4697 <dfn id=featurevalueblock>feature_value_block</dfn>
  4698   : <a href="#featuretype"><i>feature_type</i></a> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>*
  4699     '{' <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>*
  4702 <dfn id=featuretype>feature_type</dfn>:
  4703   <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>ATKEYWORD</i></a>
  4706 <dfn id=featurevaluedefinition>feature_value_definition</dfn>
  4707   : <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> ]*
  4709 </pre>
  4711   <p>The following new token is introduced:
  4713   <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>;}
  4714 </pre>
  4716   <p><a href="#featurevalueblock"><i title="feature_value_block">Feature
  4717    value blocks</i></a> are handled as <a
  4718    href="http://www.w3.org/TR/CSS2/syndata.html#at-rules">at-rules</a>, they
  4719    consist of everything up to the next block or semi-colon, whichever comes
  4720    first.
  4722   <p>The <a href="#fontfamilynamelist"><i title="font_family_name_list">font
  4723    family list</i></a> is a comma-delimited list of <a
  4724    href="#fontfamilyname"><i title="font_family_name">font family
  4725    names</i></a> that match the definition of <a
  4726    href="#family-name-value"><var>&lt;family-name&gt;</var></a> for the <a
  4727    href="#propdef-font-family" title="font-family!!property">‘<code
  4728    class=property>font-family</code>’</a> property. This means that only
  4729    named font families are allowed, rules that include generic or system
  4730    fonts in the list of font families are syntax errors. However, if a user
  4731    agent defines a generic font to be a specific named font (e.g. Helvetica),
  4732    the settings associated with that family name will be used. If syntax
  4733    errors occur within the font family list, the entire rule must be ignored.
  4735   <p>Within <a href="#featurevalueblock"><i
  4736    title="feature_value_block">feature value blocks</i></a>, the <a
  4737    href="#featuretype"><i title="feature_type">feature type</i></a> is
  4738    ‘<code class=css>@</code>’ followed by the name of one of the <a
  4739    href="#font-specific"><em>font specific</em></a> property values of ‘<a
  4740    href="#propdef-font-variant-alternates"><code
  4741    class=property>font-variant-alternates</code></a>’ (e.g. <a
  4742    href="#swash"><code>@swash</code></a>). The identifiers used within
  4743    feature value definitions follow the rules of CSS user identifiers and are
  4744    case-sensitive. They are unique only for a given set of font families and
  4745    <a href="#featuretype"><i title="feature_type">feature type</i></a>. The
  4746    same identifier used with a different <a href="#featuretype"><i
  4747    title="feature_type">feature type</i></a> is treated as a separate and
  4748    distinct value. If the same identifier is defined mulitple times for a
  4749    given <a href="#featuretype"><i title="feature_type">feature type</i></a>
  4750    and font family, the last defined value is used. Values associated with a
  4751    given identifier are limited to integer values 0 or greater.
  4753   <p>When syntax errors occur within a <a href="#featurevaluedefinition"><i
  4754    title="feature_value_definition">feature value definition</i></a>, such as
  4755    invalid identifiers or values, the entire <a
  4756    href="#featurevaluedefinition"><i title="feature_value_definition">feature
  4757    value definition</i></a> must be omitted, just as syntax errors in style
  4758    declarations are handled. When the <a href="#featuretype"><i
  4759    title="feature_type">feature type</i></a> is invalid, the entire
  4760    associated <a href="#featurevalueblock"><i
  4761    title="feature_value_block">feature value block</i></a> must be ignored.
  4763   <div class=example>
  4764    <p>Rules that are equivalent given syntax error handling:</p>
  4766    <pre>@font-feature-values Bongo {
  4767   @swash { ornate: 1; }
  4768   annotation { boxed: 4; } /* should be @annotation! */
  4769   @swash { double-loops: 1; flowing: -1; } /* negative value */
  4770   @ornaments ; /* incomplete definition */
  4771   @styleset { double-W: 14; sharp-terminals: 16 1 } /* missing ; */
  4772   <a href="http://www.angryalien.com/0504/shiningbunnies.html" style="text-decoration: none; border: none;">redrum</a>  /* random editing mistake */
  4773 }</pre>
  4775    <p>The example above is equivalent to:</p>
  4777    <pre>@font-feature-values Bongo {
  4778   @swash { ornate: 1; }
  4779   @swash { double-loops: 1; }
  4780   @styleset { double-W: 14; sharp-terminals: 16 1; }
  4781 }</pre>
  4782   </div>
  4784   <p>If multiple <a
  4785    href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
  4786    rules are defined for a given family, the resulting values definitions are
  4787    the union of the definitions contained within these rules. This allows a
  4788    set of named values to be defined for a given font family globally for a
  4789    site and specific additions made per-page.
  4791   <div class=example>
  4792    <p>Using both site-wide and per-page feature values:</p>
  4794    <pre>
  4795 site.css:
  4797   @font-feature-values Mercury Serif {
  4798     @styleset {
  4799       stacked-g: 3; /* "two-storey" versions of g, a */
  4800       stacked-a: 4;
  4804 page.css:
  4806   @font-feature-values Mercury Serif {
  4807     @styleset {
  4808       geometric-m: 7; /* alternate version of m */
  4812   body {
  4813     font-family: Mercury Serif, serif;
  4815     /* enable both the use of stacked g and alternate m */
  4816     font-variant-alternates: styleset(stacked-g, geometric-m);
  4817   }</pre>
  4818   </div>
  4820   <div class=example>
  4821    <p>Using a commonly named value allows authors to use a single style rule
  4822     to cover a set of fonts for which the underlying selector is different
  4823     for each font. If either font in the example below is found, a circled
  4824     number glyph will be used:</p>
  4826    <pre>@font-feature-values Taisho Gothic {
  4827   @annotation { boxed: 1; circled: 4; }
  4830 @font-feature-values Otaru Kisa {
  4831   @annotation { circled: 1; black-boxed: 3; }
  4834 h3.title {
  4835   /* circled form defined for both fonts */
  4836   font-family: Taisho Gothic, Otaru Kisa;
  4837   font-variant: annotation(circled);
  4838 }</pre>
  4839   </div>
  4841   <h4 id=multi-valued-feature-value-definitions><span class=secno>6.9.2
  4842    </span>Multi-valued feature value definitions</h4>
  4844   <p>Most <a href="#font-specific"><em>font specific</em></a> ‘<a
  4845    href="#propdef-font-variant-alternates"><code
  4846    class=property>font-variant-alternates</code></a>’ property values take
  4847    a single value (e.g. ‘<a href="#swash"><code
  4848    class=property>swash</code></a>’). The ‘<a
  4849    href="#character-variant"><code
  4850    class=property>character-variant</code></a>’ property value allows two
  4851    values and ‘<a href="#styleset"><code
  4852    class=property>styleset</code></a>’ allows an unlimited number.
  4854   <p>For the styleset property value, multiple values indicate the style sets
  4855    to be enabled. Values between 1 and 99 enable OpenType features <span
  4856    class=tag>ss01</span> through <span class=tag>ss99</span>. However, the
  4857    OpenType standard only officially defines <span class=tag>ss01</span>
  4858    through <span class=tag>ss20</span>. For OpenType fonts, values greater
  4859    than 99 or equal to 0 do not generate a syntax error when parsed but
  4860    enable no OpenType features.
  4862   <pre>@font-feature-values Mars Serif {
  4863   @styleset {
  4864     alt-g: 1;        /* implies ss01 = 1 */
  4865     curly-quotes: 3; /* implies ss03 = 1 */
  4866     code: 4 5;       /* implies ss04 = 1, ss05 = 1 */
  4869   @styleset {
  4870     dumb: 125;        /* &gt;99, ignored */
  4873   @swash {
  4874     swishy: 3 5;     /* more than 1 value for swash, syntax error */
  4878 p.codeblock {
  4879   /* implies ss03 = 1, ss04 = 1, ss05 = 1 */
  4880   font-variant-alternates: styleset(curly-quotes, code);
  4881 }</pre>
  4883   <p>For character-variant, a single value between 1 and 99 indicates the
  4884    enabling of OpenType feature <span class=tag>cv01</span> through <span
  4885    class=tag>cv99</span>. For OpenType fonts, values greater than 99 or equal
  4886    to 0 are ignored but do not generate a syntax error when parsed but enable
  4887    no OpenType features. When two values are listed, the first value
  4888    indicates the feature used and the second the value passed for that
  4889    feature. If more than two values are assigned to a given name, a syntax
  4890    error occurs and the entire <a href="#featurevaluedefinition"><i
  4891    title="feature_value_definition">feature value definition</i></a> is
  4892    ignored.
  4894   <pre>@font-feature-values MM Greek {
  4895   @character-variant { alpha-2: 1 2; }   /* implies cv01 = 2 */
  4896   @character-variant { beta-3: 2 3; }    /* implies cv02 = 3 */
  4897   @character-variant { epsilon: 5 3 6; } /* more than 2 values, syntax error, definition ignored */
  4898   @character-variant { gamma: 12; }      /* implies cv12 = 1 */
  4899   @character-variant { zeta:   20 3; }   /* implies cv20 = 3 */
  4900   @character-variant { zeta-2: 20 2; }   /* implies cv20 = 2 */
  4901   @character-variant { silly: 105; }     /* &gt;99, ignored */
  4902   @character-variant { dumb: 323 3; }    /* &gt;99, ignored */
  4905 #title {
  4906   /* use the third alternate beta, first alternate gamma */
  4907   font-variant-alternates: character-variant(beta-3, gamma);
  4910 p {
  4911   /* zeta-2 follows zeta, implies cv20 = 2  */
  4912   font-variant-alternates: character-variant(zeta, zeta-2);
  4915 .special {
  4916   /* zeta follows zeta-2, implies cv20 = 3  */
  4917   font-variant-alternates: character-variant(zeta-2, zeta);
  4918 }</pre>
  4920   <div class=figure><img alt="Matching text on Byzantine seals using
  4921    character variants" src=byzantineseal.png>
  4922    <p class=caption>Byzantine seal text displayed with character variants
  4923   </div>
  4925   <div class=example>
  4926    <p>In the figure above, the text in red is rendered using a font
  4927     containing character variants that mimic the character forms found on a
  4928     Byzantine seal from the 8th century A.D. Two lines below is the same text
  4929     displayed in a font without variants. Note the two variants for U and N
  4930     used on the seal.</p>
  4932    <pre>@font-feature-values Athena Ruby {
  4933   @character-variant {
  4934     leo-B: 2 1;
  4935     leo-M: 13 3;
  4936     leo-alt-N: 14 1;
  4937     leo-N: 14 2;
  4938     leo-T: 20 1;
  4939     leo-U: 21 2;
  4940     leo-alt-U: 21 4;
  4944 p {
  4945   font-variant: discretionary-ligatures,
  4946                 character-variant(leo-B, leo-M, leo-N, leo-T, leo-U);
  4949 span.alt-N {
  4950   font-variant-alternates: character-variant(leo-alt-N);
  4953 span.alt-U {
  4954   font-variant-alternates: character-variant(leo-alt-U);
  4957 &lt;p>ENO....UP͞RSTU&lt;span class="alt-U">U&lt;/span>͞&lt;span class="alt-U">U&lt;/span>ΚΑΙTỤẠG̣IUPNS&lt;/p>
  4959 &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>
  4960 </pre>
  4961   </div>
  4963   <h3 id=font-variant-east-asian-prop><span class=secno>6.10 </span>East
  4964    Asian text rendering: the <a
  4965    href="#propdef-font-variant-east-asian">font-variant-east-asian</a>
  4966    property</h3>
  4968   <table class=propdef id=namefont-variant-east-asianvaluenormal-l>
  4969    <tbody>
  4970     <tr>
  4971      <td>Name:
  4973      <td><dfn
  4974       id=propdef-font-variant-east-asian>font-variant-east-asian</dfn>
  4976     <tr>
  4977      <td>Value:
  4979      <td><a href="#font-variant-east-asian-normal-value"
  4980       title="normal!!font-variant-east-asian">normal</a> | [ <a
  4981       href="#east-asian-variant-values"><var>&lt;east-asian-variant-values&gt;</var></a>
  4982       || <a
  4983       href="#east-asian-width-values"><var>&lt;east-asian-width-values&gt;</var></a>
  4984       || <a href="#ruby">ruby</a> ]
  4986     <tr>
  4987      <td>Initial:
  4989      <td>normal
  4991     <tr>
  4992      <td>Applies to:
  4994      <td>all elements
  4996     <tr>
  4997      <td>Inherited:
  4999      <td>yes
  5001     <tr>
  5002      <td>Percentages:
  5004      <td>N/A
  5006     <tr>
  5007      <td>Media:
  5009      <td>visual
  5011     <tr>
  5012      <td>Computed value:
  5014      <td>as specified
  5016     <tr>
  5017      <td>Animatable:
  5019      <td>no
  5020   </table>
  5022   <p>Allows control of glyph substitution and sizing in East Asian text.
  5024   <pre
  5025    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>
  5027   <pre
  5028    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>
  5030   <p>Individual values have the following meanings:
  5032   <dl>
  5033    <dt><dfn id=font-variant-east-asian-normal-value
  5034     title="normal!!font-variant-east-asian">normal</dfn>
  5036    <dd>None of the features listed below are enabled.
  5038    <dt><dfn id=jis78>jis78</dfn>
  5040    <dd>Enables rendering of JIS78 forms (OpenType feature: <span
  5041     class=tag>jp78</span>).
  5042   </dl>
  5044   <div class=featex><img alt="JIS78 form example" src=jp78.png></div>
  5046   <dl>
  5047    <dt><dfn id=jis83>jis83</dfn>
  5049    <dd>Enables rendering of JIS83 forms (OpenType feature: <span
  5050     class=tag>jp83</span>).
  5052    <dt><dfn id=jis90>jis90</dfn>
  5054    <dd>Enables rendering of JIS90 forms (OpenType feature: <span
  5055     class=tag>jp90</span>).
  5057    <dt><dfn id=jis04>jis04</dfn>
  5059    <dd>Enables rendering of JIS2004 forms (OpenType feature: <span
  5060     class=tag>jp04</span>).
  5061     <p>The various JIS variants reflect the glyph forms defined in different
  5062      Japanese national standards. Fonts generally include glyphs defined by
  5063      the most recent national standard but it's sometimes necessary to use
  5064      older variants, to match signage for example.</p>
  5066    <dt><dfn id=simplified>simplified</dfn>
  5068    <dd>Enables rendering of simplified forms (OpenType feature: <span
  5069     class=tag>smpl</span>).
  5071    <dt><dfn id=traditional>traditional</dfn>
  5073    <dd>Enables rendering of traditional forms (OpenType feature: <span
  5074     class=tag>trad</span>).
  5075   </dl>
  5077   <p>The ‘<a href="#simplified"><code
  5078    class=property>simplified</code></a>’ and ‘<a
  5079    href="#traditional"><code class=property>traditional</code></a>’ values
  5080    allow control over the glyph forms for characters which have been
  5081    simplified over time but for which the older, traditional form is still
  5082    used in some contexts. The exact set of characters and glyph forms will
  5083    vary to some degree by context for which a given font was designed.
  5085   <div class=featex><img alt="tradtional form example" src=trad.png></div>
  5087   <dl>
  5088    <dt><dfn id=full-width>full-width</dfn>
  5090    <dd>Enables rendering of full-width variants (OpenType feature: <span
  5091     class=tag>fwid</span>).
  5093    <dt><dfn id=proportional-width>proportional-width</dfn>
  5095    <dd>Enables rendering of proportionally-spaced variants (OpenType feature:
  5096     <span class=tag>pwid</span>).
  5097   </dl>
  5099   <div class=featex><img alt="proportionally spaced Japanese example"
  5100    src=pwid.png></div>
  5102   <dl>
  5103    <dt><dfn id=ruby>ruby</dfn>
  5105    <dd>Enables display of ruby variant glyphs (OpenType feature: <span
  5106     class=tag>ruby</span>). Since ruby text is generally smaller than the
  5107     associated body text, font designers can design special glyphs for use
  5108     with ruby that are more readable than scaled down versions of the default
  5109     glyphs. Only glyph selection is affected, there is no associated font
  5110     scaling or other change that affects line layout. The red ruby text below
  5111     is shown with default glyphs (top) and with ruby variant glyphs (bottom).
  5112     Note the slight difference in stroke thickness.
  5113   </dl>
  5115   <div class=featex><img alt="ruby variant example" src=rubyshinkansen.png></div>
  5117   <h3 id=font-variant-prop><span class=secno>6.11 </span>Overall shorthand
  5118    for font rendering: the <a href="#propdef-font-variant">font-variant</a>
  5119    property</h3>
  5121   <table class=propdef id=namefont-variantvaluenormal-none-ltcommo>
  5122    <tbody>
  5123     <tr>
  5124      <td>Name:
  5126      <td><dfn id=propdef-font-variant
  5127       title="font-variant!!property">font-variant</dfn>
  5129     <tr>
  5130      <td>Value:
  5132      <td><a href="#font-variant-normal-value"
  5133       title="normal!!font-variant">normal</a> | <a
  5134       href="#font-variant-none-value" title="none!!font-variant">none</a> | [
  5135       <a href="#common-lig-values"><var>&lt;common-lig-values&gt;</var></a>
  5136       || <a
  5137       href="#discretionary-lig-values"><var>&lt;discretionary-lig-values&gt;</var></a>
  5138       || <a
  5139       href="#historical-lig-values"><var>&lt;historical-lig-values&gt;</var></a>
  5140       || <a
  5141       href="#contextual-alt-values"><var>&lt;contextual-alt-values&gt;</var></a>
  5142       || <a href="#stylistic"><var
  5143       title=stylistic>stylistic(&lt;feature-value-name&gt;)</var></a> || <a
  5144       href="#historical-forms"><var>historical-forms</var></a> || <a
  5145       href="#styleset"><var
  5146       title=styleset>styleset(&lt;feature-value-name&gt; #)</var></a> || <a
  5147       href="#character-variant"><var
  5148       title=character-variant>character-variant(&lt;feature-value-name&gt;
  5149       #)</var></a> || <a href="#swash"><var
  5150       title=swash>swash(&lt;feature-value-name&gt;)</var></a> || <a
  5151       href="#ornaments"><var
  5152       title=ornaments>ornaments(&lt;feature-value-name&gt;)</var></a> || <a
  5153       href="#annotation"><var
  5154       title=annotation>annotation(&lt;feature-value-name&gt;)</var></a> || [
  5155       <a href="#small-caps"><i>small-caps</i></a> | <a
  5156       href="#all-small-caps"><i>all-small-caps</i></a> | <a
  5157       href="#petite-caps"><i>petite-caps</i></a> | <a
  5158       href="#all-petite-caps"><i>all-petite-caps</i></a> | <a
  5159       href="#unicase"><i>unicase</i></a> | <a
  5160       href="#titling-caps"><i>titling-caps</i></a> ] || <a
  5161       href="#numeric-figure-values"><var>&lt;numeric-figure-values&gt;</var></a>
  5162       || <a
  5163       href="#numeric-spacing-values"><var>&lt;numeric-spacing-values&gt;</var></a>
  5164       || <a
  5165       href="#numeric-fraction-values"><var>&lt;numeric-fraction-values&gt;</var></a>
  5166       || <a href="#ordinal"><i>ordinal</i></a> || <a
  5167       href="#slashed-zero"><i>slashed-zero</i></a> || <a
  5168       href="#east-asian-variant-values"><var>&lt;east-asian-variant-values&gt;</var></a>
  5169       || <a
  5170       href="#east-asian-width-values"><var>&lt;east-asian-width-values&gt;</var></a>
  5171       || <a href="#ruby"><i>ruby</i></a> ]
  5173     <tr>
  5174      <td>Initial:
  5176      <td>normal
  5178     <tr>
  5179      <td>Applies to:
  5181      <td>all elements
  5183     <tr>
  5184      <td>Inherited:
  5186      <td>yes
  5188     <tr>
  5189      <td>Percentages:
  5191      <td>see individual properties
  5193     <tr>
  5194      <td>Media:
  5196      <td>visual
  5198     <tr>
  5199      <td>Computed value:
  5201      <td>see individual properties
  5203     <tr>
  5204      <td>Animatable:
  5206      <td>see individual properties
  5207   </table>
  5209   <p>The <a href="#propdef-font-variant"
  5210    title="font-variant!!property">‘<code
  5211    class=property>font-variant</code>’</a> property is a shorthand for all
  5212    font-variant subproperties. The value <dfn id=font-variant-normal-value
  5213    title="normal!!font-variant">‘<code
  5214    class=property>normal</code>’</dfn> resets all subproperties of <a
  5215    href="#propdef-font-variant" title="font-variant!!property">‘<code
  5216    class=property>font-variant</code>’</a> to their inital value. The <dfn
  5217    id=font-variant-none-value title="none!!font-variant">‘<code
  5218    class=property>none</code>’</dfn> value sets ‘<a
  5219    href="#propdef-font-variant-ligatures"><code
  5220    class=property>font-variant-ligatures</code></a>’ to ‘<code
  5221    class=property>none</code>’ and resets all other font feature properties
  5222    to their initial value. Like other shorthands, using <a
  5223    href="#propdef-font-variant" title="font-variant!!property">‘<code
  5224    class=property>font-variant</code>’</a> resets unspecified <a
  5225    href="#propdef-font-variant" title="font-variant!!property">‘<code
  5226    class=property>font-variant</code>’</a> subproperties to their initial
  5227    values. It does not reset the values of either ‘<a
  5228    href="#propdef-font-language-override"><code
  5229    class=property>font-language-override</code></a>’ or <a
  5230    href="#propdef-font-feature-settings"
  5231    title="font-feature-settings!!property">‘<code
  5232    class=property>font-feature-settings</code>’</a>.
  5234   <h3 id=font-feature-settings-prop><span class=secno>6.12 </span>Low-level
  5235    font feature settings control: the <a
  5236    href="#propdef-font-feature-settings">font-feature-settings</a> property</h3>
  5238   <table class=propdef id=namefont-feature-settingsvaluenormal-ltf>
  5239    <tbody>
  5240     <tr>
  5241      <td>Name:
  5243      <td><dfn id=propdef-font-feature-settings
  5244       title="font-feature-settings!!property">font-feature-settings</dfn>
  5246     <tr>
  5247      <td>Value:
  5249      <td><a href="#font-feature-settings-normal-value"
  5250       title="normal!!font-feature-settings">normal</a> | <a
  5251       href="#feature-tag-value"><var>&lt;feature-tag-value&gt;</var></a> #
  5253     <tr>
  5254      <td>Initial:
  5256      <td>normal
  5258     <tr>
  5259      <td>Applies to:
  5261      <td>all elements
  5263     <tr>
  5264      <td>Inherited:
  5266      <td>yes
  5268     <tr>
  5269      <td>Percentages:
  5271      <td>N/A
  5273     <tr>
  5274      <td>Media:
  5276      <td>visual
  5278     <tr>
  5279      <td>Computed value:
  5281      <td>as specified
  5283     <tr>
  5284      <td>Animatable:
  5286      <td>no
  5287   </table>
  5289   <p>This property provides low-level control over OpenType font features. It
  5290    is intended as a way of providing access to font features that are not
  5291    widely used but are needed for a particular use case.
  5293   <p>Authors should generally use <a href="#propdef-font-variant"
  5294    title="font-variant!!property">‘<code
  5295    class=property>font-variant</code>’</a> and its related subproperties
  5296    whenever possible and only use this property for special cases where its
  5297    use is the only way of accessing a particular infrequently used font
  5298    feature.
  5300   <pre>/* enable small caps and use second swash alternate */
  5301 font-feature-settings: "smcp", "swsh" 2;</pre>
  5303   <p>A value of <dfn id=font-feature-settings-normal-value
  5304    title="normal!!font-feature-settings">‘<code
  5305    class=property>normal</code>’</dfn> means that no change in glyph
  5306    selection or positioning occurs due to this property.
  5308   <p>Feature tag values have the following syntax:
  5310   <pre
  5311    class=prod><dfn id=feature-tag-value><var>&lt;feature-tag-value&gt;</var></dfn> = &lt;string&gt; [ &lt;integer&gt; | on | off ]?</pre>
  5313   <p>The &lt;string&gt; is a case-sensitive OpenType feature tag. As
  5314    specified in the OpenType specification, feature tags contain four ASCII
  5315    characters. Tag strings longer or shorter than four characters, or
  5316    containing characters outside the U+20–7E codepoint range are invalid.
  5317    Feature tags need only match a feature tag defined in the font, so they
  5318    are not limited to explicitly registered OpenType features. Fonts defining
  5319    custom feature tags should follow the <a
  5320    href="http://www.microsoft.com/typography/otspec/featuretags.htm">tag name
  5321    rules</a> defined in the OpenType specification <a
  5322    href="#OPENTYPE-FEATURES"
  5323    rel=biblioentry>[OPENTYPE-FEATURES]<!--{{!OPENTYPE-FEATURES}}--></a>.
  5324    Feature tags not present in the font are ignored; a user agent must not
  5325    attempt to synthesize fallback behavior based on these feature tags.
  5327   <p>This means that explicitly disabling the <span class=tag>kern</span>
  5328    feature will not affect the application of kerning data found in the
  5329    ‘<code class=property>kern</code>’ table (as opposed to kerning data
  5330    associated with the <span class=tag>kern</span> feature in the ‘<code
  5331    class=property>GPOS</code>’ table). Authors should use the ‘<a
  5332    href="#propdef-font-kerning"><code
  5333    class=property>font-kerning</code></a>’ property to explictly enable or
  5334    disable kerning since this property affects both types of kerning.
  5336   <p>If present, a value indicates an index used for glyph selection. An
  5337    &lt;integer&gt; value must be 0 or greater. A value of 0 indicates that
  5338    the feature is disabled. For boolean features, a value of 1 enables the
  5339    feature. For non-boolean features, a value of 1 or greater enables the
  5340    feature and indicates the feature selection index. A value of ‘<code
  5341    class=property>on</code>’ is synonymous with 1 and ‘<code
  5342    class=property>off</code>’ is synonymous with 0. If the value is
  5343    omitted, a value of 1 is assumed.
  5345   <pre>
  5346 font-feature-settings: "dlig" 1;       /* dlig=1 enable discretionary ligatures */
  5347 font-feature-settings: "smcp" on;      /* smcp=1 enable small caps */
  5348 font-feature-settings: 'c2sc';         /* c2sc=1 enable caps to small caps */
  5349 font-feature-settings: "liga" off;     /* liga=0 no common ligatures */
  5350 font-feature-settings: "tnum", 'hist'; /* tnum=1, hist=1 enable tabular numbers and historical forms */
  5351 font-feature-settings: "tnum" "hist";  /* invalid, need a comma-delimited list */
  5352 font-feature-settings: "palin" off;    /* good idea but invalid tagname */
  5353 font-feature-settings: "PKRN";         /* PKRN=1 enable custom feature */
  5354 font-feature-settings: dlig;           /* invalid, tag must be a string */
  5355 </pre>
  5357   <p>When values greater than the range supported by the font are specified,
  5358    the behavior is explicitly undefined. For boolean features, in general
  5359    these will enable the feature. For non-boolean features, out of range
  5360    values will in general be equivalent to a 0 value. However, in both cases
  5361    the exact behavior will depend upon the way the font is designed
  5362    (specifically, which type of lookup is used to define the feature).
  5364   <p>Although specifically defined for OpenType feature tags, feature tags
  5365    for other modern font formats that support font features may be added in
  5366    the future. Where possible, features defined for other font formats should
  5367    attempt to follow the pattern of registered OpenType tags.
  5369   <div class=example>
  5370    <p>The Japanese text below will be rendered with half-width kana
  5371     characters:</p>
  5373    <pre lang=ja>
  5374 body { font-feature-settings: "hwid"; /* Half-width OpenType feature */ }
  5376 &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>
  5377 </pre>
  5378   </div>
  5380   <h3 id=font-language-override-prop><span class=secno>6.13 </span>Font
  5381    language override: the <a
  5382    href="#propdef-font-language-override">font-language-override</a> property</h3>
  5384   <table class=propdef id=namefont-language-overridevaluenormal-lt>
  5385    <tbody>
  5386     <tr>
  5387      <td>Name:
  5389      <td><dfn id=propdef-font-language-override>font-language-override</dfn>
  5391     <tr>
  5392      <td>Value:
  5394      <td><a href="#font-language-override-normal-value"
  5395       title="normal!!font-language-override">normal</a> | <a
  5396       href="#font-language-override-string-value"><var>&lt;string&gt;</var></a>
  5398     <tr>
  5399      <td>Initial:
  5401      <td><a href="#font-language-override-normal-value"
  5402       title="normal!!font-language-override">normal</a>
  5404     <tr>
  5405      <td>Applies to:
  5407      <td>all elements
  5409     <tr>
  5410      <td>Inherited:
  5412      <td>yes
  5414     <tr>
  5415      <td>Percentages:
  5417      <td>N/A
  5419     <tr>
  5420      <td>Media:
  5422      <td>visual
  5424     <tr>
  5425      <td>Computed value:
  5427      <td>as specified
  5429     <tr>
  5430      <td>Animatable:
  5432      <td>no
  5433   </table>
  5435   <p>Normally, authors can control the use of language-specific glyph
  5436    substitutions and positioning by setting the content language of an
  5437    element, as <a href="#language-specific-support">described above</a>:
  5439   <pre>&lt;!-- Display text using S'gaw Karen specific features -->
  5440 &lt;p lang="ksw">...&lt;/p></pre>
  5442   <p>In some cases, authors may need to specify a language system that
  5443    differs from the content language, for example due to the need to mimic
  5444    another language's typographic traditions. The ‘<a
  5445    href="#propdef-font-language-override"><code
  5446    class=property>font-language-override</code></a>’ property allows
  5447    authors to explicitly specify the language system of the font, overriding
  5448    the language system implied by the content language.
  5450   <p>Values have the following meanings:
  5452   <dl>
  5453    <dt><dfn id=font-language-override-normal-value
  5454     title="normal!!font-language-override">normal</dfn>
  5456    <dd>specifies that when rendering with OpenType fonts, the content
  5457     language of the element is used to infer the OpenType language system
  5459    <dt><dfn
  5460     id=font-language-override-string-value><var>&lt;string&gt;</var></dfn>
  5462    <dd>single three-letter case-sensitive OpenType <a
  5463     href="http://www.microsoft.com/typography/otspec/languagetags.htm">language
  5464     system tag</a>, specifies the OpenType language system to be used instead
  5465     of the language system implied by the language of the element
  5466   </dl>
  5467   <!-- For this level, string represents a single language code, there's no concept of "fallback" 
  5468 http://www.w3.org/2013/06/07-css-minutes.html#item04 -->
  5470   <p>Use of invalid OpenType language system tags must not generate a parse
  5471    error but must be ignored when doing glyph selection and placement.
  5473   <div class=example>
  5474    <p>The <a href="http://www.un.org/en/documents/udhr/index.shtml">Universal
  5475     Declaration of Human Rights</a> has been translated into a wide variety
  5476     of languages. In Turkish, Article 9 of this document might be marked up
  5477     as below:</p>
  5479    <pre lang=tr>&lt;body lang="tr">
  5481 &lt;h4>Madde 9&lt;/h4>
  5482 &lt;p>Hiç kimse keyfi olarak tutuklanamaz, alıkonulanamaz veya sürülemez.&lt;/p>
  5483 </pre>
  5485    <p>Here the user agent uses the value of the ‘<code
  5486     class=property>lang</code>’ attribute when rendering text and
  5487     appropriately renders this text without ‘<code
  5488     class=property>fi</code>’ ligatures. There is no need to use the ‘<a
  5489     href="#propdef-font-language-override"><code
  5490     class=property>font-language-override</code></a>’ property.</p>
  5492    <p>However, a given font may lack support for a specific language. In this
  5493     situation authors may need to use the typographic conventions of a
  5494     related language that are supported by that font:</p>
  5496    <pre lang=mk>&lt;body lang="mk">     &lt;!-- Macedonian lang code --&gt;
  5498 body { font-language-override: "SRB"; /* Serbian OpenType language tag */ }
  5500 &lt;h4>Члeн 9&lt;/h4>
  5501 &lt;p>Никoj чoвeк нeмa дa бидe пoдлoжeн нa прoизвoлнo aпсeњe, притвoр или прoгoнувaњe.&lt;/p>
  5503 </pre>
  5505    <p>The Macedonian text here will be rendered using Serbian typographic
  5506     conventions, with the assumption that the font specified supports
  5507     Serbian.</p>
  5508   </div>
  5510   <p><a id=rendering-considerations></a>
  5512   <h2 id=font-feature-resolution><span class=secno>7 </span>Font Feature
  5513    Resolution</h2>
  5515   <p>As described in the previous section, font features can be enabled in a
  5516    variety of ways, either via the use of <a href="#propdef-font-variant"
  5517    title="font-variant!!property">‘<code
  5518    class=property>font-variant</code>’</a> or <a
  5519    href="#propdef-font-feature-settings"
  5520    title="font-feature-settings!!property">‘<code
  5521    class=property>font-feature-settings</code>’</a> in a style rule or
  5522    within an <a href="#at-font-face-rule"><code>@font-face</code></a> rule.
  5523    The resolution order for the union of these settings is defined below.
  5524    Features defined via CSS properties are applied on top of layout engine
  5525    default features.
  5527   <h3 id=default-features><span class=secno>7.1 </span>Default features</h3>
  5529   <p>For OpenType fonts, user agents must enable the default features defined
  5530    in the OpenType documentation for a given script and writing mode.
  5531    Required ligatures, common ligatures and contextual forms must be enabled
  5532    by default (OpenType features: <span class=tag>rlig, liga, clig,
  5533    calt</span>), along with localized forms (OpenType feature: <span
  5534    class=tag>locl</span>), and features required for proper display of
  5535    composed characters and marks (OpenType features: <span class=tag>ccmp,
  5536    mark, mkmk</span>). These features must always be enabled, even when the
  5537    value of the <a href="#propdef-font-variant"
  5538    title="font-variant!!property">‘<code
  5539    class=property>font-variant</code>’</a> and <a
  5540    href="#propdef-font-feature-settings"
  5541    title="font-feature-settings!!property">‘<code
  5542    class=property>font-feature-settings</code>’</a> properties is <span
  5543    title="normal value">‘<code class=property>normal</code>’</span>.
  5544    Individual features are only disabled when explicitly overridden by the
  5545    author, as when ‘<a href="#propdef-font-variant-ligatures"><code
  5546    class=property>font-variant-ligatures</code></a>’ is set to ‘<a
  5547    href="#no-common-ligatures"><code
  5548    class=property>no-common-ligatures</code></a>’. For handling complex
  5549    scripts such as <a
  5550    href="http://www.microsoft.com/typography/otfntdev/arabicot/features.aspx">Arabic</a>,
  5551    <a
  5552    href="http://www.microsoft.com/typography/otfntdev/mongolot/features.htm">Mongolian</a>
  5553    or <a
  5554    href="http://www.microsoft.com/typography/otfntdev/devanot/features.aspx">Devanagari</a>
  5555    additional features are required. For upright text within vertical text
  5556    runs, vertical alternates (OpenType feature: <span class=tag>vert</span>)
  5557    must be enabled.
  5559   <h3 id=feature-precedence><span class=secno>7.2 </span>Feature precedence</h3>
  5561   <p>General and <a href="#font-specific"><em>font specific</em></a> font
  5562    feature property settings are resolved in the order below, in ascending
  5563    order of precedence. This ordering is used to construct a combined list of
  5564    font features that affect a given text run.
  5566   <ol>
  5567    <li>Font features enabled by default, including features required for a
  5568     given script.
  5570    <li>If the font is defined via an <a
  5571     href="#at-font-face-rule"><code>@font-face</code></a> rule, the font
  5572     features implied by the font-variant descriptor in the <a
  5573     href="#at-font-face-rule"><code>@font-face</code></a> rule.
  5575    <li>If the font is defined via an <a
  5576     href="#at-font-face-rule"><code>@font-face</code></a> rule, the font
  5577     features implied by the font-feature-settings descriptor in the <a
  5578     href="#at-font-face-rule"><code>@font-face</code></a> rule.
  5580    <li>Feature settings determined by properties other than <a
  5581     href="#propdef-font-variant" title="font-variant!!property">‘<code
  5582     class=property>font-variant</code>’</a> or <a
  5583     href="#propdef-font-feature-settings"
  5584     title="font-feature-settings!!property">‘<code
  5585     class=property>font-feature-settings</code>’</a>. For example, setting
  5586     a non-default value for the ‘<code
  5587     class=property>letter-spacing</code>’ property disables common
  5588     ligatures.
  5590    <li>Font features implied by the value of the <a
  5591     href="#propdef-font-variant" title="font-variant!!property">‘<code
  5592     class=property>font-variant</code>’</a> property, the related <a
  5593     href="#propdef-font-variant" title="font-variant!!property">‘<code
  5594     class=property>font-variant</code>’</a> subproperties and any other CSS
  5595     property that uses OpenType features (e.g. the ‘<a
  5596     href="#propdef-font-kerning"><code
  5597     class=property>font-kerning</code></a>’ property).
  5599    <li>Font features implied by the value of <a
  5600     href="#propdef-font-feature-settings"
  5601     title="font-feature-settings!!property">‘<code
  5602     class=property>font-feature-settings</code>’</a> property.
  5603   </ol>
  5605   <p>This ordering allows authors to set up a general set of defaults for
  5606    fonts within their <a
  5607    href="#at-font-face-rule"><code>@font-face</code></a> rules, then override
  5608    them with property settings for specific elements. General property
  5609    settings override the settings in <a
  5610    href="#at-font-face-rule"><code>@font-face</code></a> rules and low-level
  5611    font feature settings override <a href="#propdef-font-variant"
  5612    title="font-variant!!property">‘<code
  5613    class=property>font-variant</code>’</a> property settings.
  5615   <p>For situations where the combined list of font feature settings contains
  5616    more than one value for the same feature, the last value is used. When a
  5617    font lacks support for a given underlying font feature, text is simply
  5618    rendered as if that font feature was not enabled; font fallback does not
  5619    occur and no attempt is made to synthesize the feature except where
  5620    explicitly defined for specific properties.
  5622   <h3 id=feature-precedence-examples><span class=secno>7.3 </span>Feature
  5623    precedence examples</h3>
  5625   <div class=example>
  5626    <p>With the styles below, numbers are rendered proportionally when used
  5627     within a paragraph but are shown in tabular form within tables of prices:</p>
  5629    <pre>body {
  5630   font-variant-numeric: proportional-nums;
  5633 table.prices td {
  5634   font-variant-numeric: tabular-nums;
  5636 </pre>
  5637   </div>
  5639   <div class=example>
  5640    <p>When the <a href="#descdef-font-variant"
  5641     title="font-variant!!descriptor">font-variant</a> descriptor is used
  5642     within an <a href="#at-font-face-rule"><code>@font-face</code></a> rule,
  5643     it only applies to the font defined by that rule.</p>
  5645    <pre>@font-face {
  5646   font-family: MainText;
  5647   src: url(http://example.com/font.ttf);
  5648   font-variant: oldstyle-nums proportional-nums styleset(1,3);
  5651 body {
  5652   font-family: MainText, Helvetica;
  5655 table.prices td {
  5656   font-variant-numeric: tabular-nums;
  5658 </pre>
  5660    <p>In this case, old-style numerals will be used throughout but only where
  5661     the font "MainText" is used. Just as in the previous example, tabular
  5662     values will be used in price tables since ‘<a
  5663     href="#tabular-nums"><code class=property>tabular-nums</code></a>’
  5664     appears in a general style rule and its use is mutually exclusive with
  5665     ‘<a href="#proportional-nums"><code
  5666     class=property>proportional-nums</code></a>’. Stylistic alternate sets
  5667     will only be used where MainText is used.</p>
  5668   </div>
  5670   <div class=example>
  5671    <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule can
  5672     also be used to access font features in locally available fonts via the
  5673     use of <code>local()</code> in the ‘<a href="#descdef-src"><code
  5674     class=property>src</code></a>’ descriptor of the <a
  5675     href="#at-font-face-rule"><code>@font-face</code></a> definition:</p>
  5677    <pre>@font-face {
  5678   font-family: BodyText;
  5679   src: local("HiraMaruPro-W4");
  5680   font-variant: proportional-width;
  5681   font-feature-settings: "ital"; /* Latin italics within CJK text feature */
  5684 body { font-family: BodyText, serif; }
  5685 </pre>
  5687    <p>If available, a Japanese font "Hiragino Maru Gothic" will be used. When
  5688     text rendering occurs, Japanese kana will be proportionally spaced and
  5689     Latin text will be italicised. Text rendered with the fallback serif font
  5690     will use default rendering properties.</p>
  5691   </div>
  5693   <div class=example>
  5694    <p>In the example below, discretionary ligatures are enabled only for a
  5695     downloadable font but are disabled within spans of class "special":</p>
  5697    <pre>@font-face {
  5698   font-family: main;
  5699   src: url(fonts/ffmeta.woff) format("woff");
  5700   font-variant: discretionary-ligatures;
  5703 body         { font-family: main, Helvetica; }
  5704 span.special { font-variant-ligatures: no-discretionary-ligatures; }
  5705 </pre>
  5707    <p>Suppose one adds a rule using ‘<code
  5708     class=property>font-feature-settings</code>’ to enable discretionary
  5709     ligatures:</p>
  5711    <pre>body         { font-family: main, Helvetica; }
  5712 span         { font-feature-settings: "dlig"; }
  5713 span.special { font-variant-ligatures: no-discretionary-ligatures; }
  5714 </pre>
  5716    <p>In this case, discretionary ligatures <em>will</em> be rendered within
  5717     spans of class "special". This is because both the <a
  5718     href="#propdef-font-feature-settings"
  5719     title="font-feature-settings!!property">‘<code
  5720     class=property>font-feature-settings</code>’</a> and ‘<a
  5721     href="#propdef-font-variant-ligatures"><code
  5722     class=property>font-variant-ligatures</code></a>’ properties apply to
  5723     these spans. Although the ‘<code class=css>no-discretionary
  5724     ligatures</code>’ setting of ‘<a
  5725     href="#propdef-font-variant-ligatures"><code
  5726     class=property>font-variant-ligatures</code></a>’ effectively disables
  5727     the OpenType <span class=tag>dlig</span> feature, because the <a
  5728     href="#propdef-font-feature-settings"
  5729     title="font-feature-settings!!property">‘<code
  5730     class=property>font-feature-settings</code>’</a> is resolved after
  5731     that, the ‘<code class=property>dlig</code>’ value reenables
  5732     discretionary ligatures.</p>
  5733   </div>
  5735   <h2 id=object-model><span class=secno>8 </span>Object Model</h2>
  5737   <p>The contents of <a href="#at-font-face-rule"><code>@font-face</code></a>
  5738    and <a
  5739    href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
  5740    rules can be accessed via the following extensions to the CSS Object
  5741    Model.
  5743   <h3 id=om-fontface><span class=secno>8.1 </span>The <a
  5744    href="#cssfontfacerule"><code>CSSFontFaceRule</code></a> interface</h3>
  5746   <p>The <dfn id=cssfontfacerule>CSSFontFaceRule</dfn> interface represents a
  5747    <a href="#at-font-face-rule"><code>@font-face</code></a> rule.
  5749   <pre class=idl>
  5750 interface CSSFontFaceRule : CSSRule {
  5751   attribute DOMString family;
  5752   attribute DOMString src;
  5753   attribute DOMString style;
  5754   attribute DOMString weight;
  5755   attribute DOMString stretch;
  5756   attribute DOMString unicodeRange;
  5757   attribute DOMString variant;
  5758   attribute DOMString featureSettings;
  5759 }</pre>
  5761   <p>The DOM Level 2 Style specification <a href="#DOM-LEVEL-2-STYLE"
  5762    rel=biblioentry>[DOM-LEVEL-2-STYLE]<!--{{DOM-LEVEL-2-STYLE}}--></a>
  5763    defined a different variant of this rule. This definition supercedes that
  5764    one.
  5766   <h3 id=om-fontfeaturevalues><span class=secno>8.2 </span>The <a
  5767    href="#cssfontfeaturevaluesrule"><code>CSSFontFeatureValuesRule</code></a>
  5768    interface</h3>
  5770   <p>The <code>CSSRule</code> interface is extended as follows:
  5772   <pre class=idl>partial interface CSSRule {
  5773   const unsigned short FONT_FEATURE_VALUES_RULE = 14;
  5774 }</pre>
  5776   <p>The <dfn id=cssfontfeaturevaluesrule>CSSFontFeatureValuesRule</dfn>
  5777    interface represents a <a
  5778    href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
  5779    rule.
  5781   <pre class=idl>interface CSSFontFeatureValuesRule : CSSRule {
  5782   readonly attribute DOMString familyList;
  5783   readonly attribute DOMString valueText;
  5784 };</pre>
  5786   <dl class=idl-attributes>
  5787    <dt><var>familyList</var> of type <code>DOMString</code>, readonly
  5789    <dd>The list of one or more font families for which a given set of feature
  5790     values is defined.
  5792    <dt><var>valueText</var> of type <code>DOMString</code>, readonly
  5794    <dd>Serialized set of feature values.
  5795   </dl>
  5797   <p class=issue>This needs to be reworked along the lines of <a
  5798    href="http://lists.w3.org/Archives/Public/www-style/2013May/0781.html">Tab's
  5799    proposal</a> for a rule containing a family list and map objects for each
  5800    of the feature types.
  5802   <h2 class=no-num id=platform-props-to-css>Appendix A: Mapping platform font
  5803    properties to CSS properties</h2>
  5805   <p><em>This appendix is included as background for some of the problems and
  5806    situations that are described in other sections. It should be viewed as
  5807    informative only.</em>
  5809   <p>Font properties in CSS are designed to be independent of the underlying
  5810    font formats used; they can be used to specify bitmap fonts, Type1 fonts,
  5811    SVG fonts in addition to the common TrueType and OpenType fonts. But there
  5812    are facets of the TrueType and OpenType formats that often cause confusion
  5813    for authors and present challenges to implementers on different platforms.
  5815   <p>Originally developed at Apple, TrueType was designed as an outline font
  5816    format for both screen and print. Microsoft joined Apple in developing the
  5817    TrueType format and both platforms have supported TrueType fonts since
  5818    then. Font data in the TrueType format consists of a set of tables
  5819    distinguished with common four-letter tag names, each containing a
  5820    specific type of data. For example, naming information, including
  5821    copyright and license information, is stored in the ‘<code
  5822    class=property>name</code>’ table. The <a
  5823    href="#character-map"><em>character map</em></a> (‘<code
  5824    class=property>cmap</code>’) table contains a mapping of character
  5825    encodings to glyphs. Apple later added additional tables for supporting
  5826    enhanced typographic functionality; these are now called Apple Advanced
  5827    Typography, or AAT, fonts. Microsoft and Adobe developed a separate set of
  5828    tables for advanced typography and called their format OpenType <a
  5829    href="#OPENTYPE" rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a>.
  5831   <p>In many cases the font data used under Microsoft Windows or Linux is
  5832    slightly different from the data used under Apple's Mac OS X because the
  5833    TrueType format allowed for explicit variation across platforms. This
  5834    includes font metrics, names and <a href="#character-map"><em>character
  5835    map</em></a> data.
  5837   <p>Specifically, font family name data is handled differently across
  5838    platforms. For TrueType and OpenType fonts these names are contained in
  5839    the ‘<code class=property>name</code>’ table, in name records with
  5840    name ID 1. Mulitple names can be stored for different locales, but
  5841    Microsoft recommends fonts always include at least a US English version of
  5842    the name. On Windows, Microsoft made the decision for backwards
  5843    compatibility to limit this family name to a maximum of four faces; for
  5844    larger groupings the "preferred family" (name ID 16) or "WWS family" (name
  5845    ID 21) can be used. Other platforms such as OSX don't have this
  5846    limitation, so the family name is used to define all possible groupings.
  5848   <p>Other name table data provides names used to uniquely identify a
  5849    specific face within a family. The full font name (name ID 4) and the
  5850    Postscript name (name ID 6) describe a single face uniquely. For example,
  5851    the bold face of the Gill Sans family has a fullname of "Gill Sans Bold"
  5852    and a Postscript name of "GillSans-Bold". There can be multiple localized
  5853    versions of the fullname for a given face, but the Postscript name is
  5854    always a unique name made from a limited set of ASCII characters.
  5856   <p>On various platforms, different names are used to search for a font. For
  5857    example, with the Windows GDI CreateIndirectFont API, either a family or
  5858    fullname can be used to lookup a face, while on Mac OS X the
  5859    CTFontCreateWithName API call is used to lookup a given face using the
  5860    fullname and Postscript name. Under Linux, the fontconfig API allows fonts
  5861    to be searched using any of these names. In situations where platform
  5862    API's automatically substitute other font choices, it may be necessary to
  5863    verify a returned font matches a given name.
  5865   <p>The weight of a given face can be determined via the usWeightClass field
  5866    of the OS/2 table or inferred from the style name (name ID 2). Likewise,
  5867    the width can be determined via the usWidthClass of the OS/2 table or
  5868    inferred from the style name. For historical reasons related to synthetic
  5869    bolding at weights 200 or lower with the Windows GDI API, font designers
  5870    have sometimes skewed values in the OS/2 table to avoid these weights.
  5872   <p>Rendering complex scripts that use contextual shaping such as Thai,
  5873    Arabic and Devanagari requires features present only in OpenType or AAT
  5874    fonts. Currently, complex script rendering is supported on Windows and
  5875    Linux using OpenType font features while both OpenType and AAT font
  5876    features are used under Mac OS X.
  5878   <h2 class=no-num id=ch-ch-ch-changes>Changes</h2>
  5880   <h3 class=no-num id=recent-changes> Changes from the <a
  5881    href="http://www.w3.org/TR/2013/WD-css3-fonts-20130212/">February 2013
  5882    CSS3 Fonts Working Draft</a></h3>
  5884   <p>Major changes include:
  5886   <ul>
  5887    <li>Moved font load events into a separate <a
  5888     href="http://dev.w3.org/csswg/css3-font-load-events/">spec</a>
  5890    <li>Tightened syntax rules for <a
  5891     href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
  5892     rules
  5894    <li>Added grammar productions for <a
  5895     href="#at-font-face-rule"><code>@font-face</code></a> and <a
  5896     href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
  5897     rules
  5899    <li>Tightened definition of synthetic oblique
  5901    <li>Revised definition of ‘<a href="#descdef-unicode-range"><code
  5902     class=property>unicode-range</code></a>’ descriptor
  5904    <li>Detailed font matching of composite faces
  5905   </ul>
  5907   <h2 class=no-num id=acknowledgments>Acknowledgments</h2>
  5909   <p>I'd like to thank Tal Leming, Jonathan Kew and Christopher Slye for all
  5910    their help and feedback. John Hudson was kind enough to take the time to
  5911    explain the subtleties of OpenType language tags and provided the example
  5912    of character variant usage for displaying text on Byzantine seals. Ken
  5913    Lunde and Eric Muller provided valuable feedback on CJK OpenType features
  5914    and Unicode variation selectors. The idea for supporting font features by
  5915    using <a href="#propdef-font-variant"
  5916    title="font-variant!!property">‘<code
  5917    class=property>font-variant</code>’</a> subproperties originated with
  5918    Håkon Wium Lie, Adam Twardoch and Tal Leming. Elika Etemad supplied some
  5919    of the initial design ideas for the <a
  5920    href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
  5921    rule. Thanks also to House Industries for allowing the use of Ed Interlock
  5922    in the discretionary ligatures example.
  5924   <p>A special thanks to Robert Bringhurst for the sublime mind expansion
  5925    that is <em>The Elements of Typographic Style</em>.
  5927   <h2 class=no-num id=conformance> Conformance</h2>
  5929   <h3 class=no-num id=conventions> Document Conventions</h3>
  5931   <p>Conformance requirements are expressed with a combination of descriptive
  5932    assertions and RFC 2119 terminology. The key words “MUST”, “MUST
  5933    NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”,
  5934    “SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL” in the
  5935    normative parts of this document are to be interpreted as described in RFC
  5936    2119. However, for readability, these words do not appear in all uppercase
  5937    letters in this specification.
  5939   <p>All of the text of this specification is normative except sections
  5940    explicitly marked as non-normative, examples, and notes. <a
  5941    href="#RFC2119" rel=biblioentry>[RFC2119]<!--{{!RFC2119}}--></a>
  5943   <p>Examples in this specification are introduced with the words “for
  5944    example” or are set apart from the normative text with
  5945    <code>class="example"</code>, like this:
  5947   <div class=example>
  5948    <p>This is an example of an informative example.
  5949   </div>
  5951   <p>Informative notes begin with the word “Note” and are set apart from
  5952    the normative text with <code>class="note"</code>, like this:
  5954   <p class=note>Note, this is an informative note.
  5956   <h3 class=no-num id=conformance-classes> Conformance Classes</h3>
  5958   <p>Conformance to CSS Fonts Level 3 Module is defined for three conformance
  5959    classes:
  5961   <dl>
  5962    <dt><dfn id=style-sheet title="style sheet!!as conformance class">style
  5963     sheet</dfn>
  5965    <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#style-sheet">CSS
  5966     style sheet</a>.
  5968    <dt><dfn id=renderer>renderer</dfn>
  5970    <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
  5971     that interprets the semantics of a style sheet and renders documents that
  5972     use them.
  5974    <dt><dfn id=authoring-tool>authoring tool</dfn>
  5976    <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
  5977     that writes a style sheet.
  5978   </dl>
  5980   <p>A style sheet is conformant to CSS Fonts Level 3 Module if all of its
  5981    declarations that use properties defined in this module have values that
  5982    are valid according to the generic CSS grammar and the individual grammars
  5983    of each property as given in this module.
  5985   <p>A renderer is conformant to CSS Fonts Level 3 Module if, in addition to
  5986    interpreting the style sheet as defined by the appropriate specifications,
  5987    it supports all the features defined by CSS Fonts Level 3 Module by
  5988    parsing them correctly and rendering the document accordingly. However,
  5989    the inability of a UA to correctly render a document due to limitations of
  5990    the device does not make the UA non-conformant. (For example, a UA is not
  5991    required to render color on a monochrome monitor.)
  5993   <p>An authoring tool is conformant to CSS Fonts Level 3 Module if it writes
  5994    style sheets that are syntactically correct according to the generic CSS
  5995    grammar and the individual grammars of each feature in this module, and
  5996    meet all other conformance requirements of style sheets as described in
  5997    this module.
  5999   <h3 class=no-num id=partial> Partial Implementations</h3>
  6001   <p>So that authors can exploit the forward-compatible parsing rules to
  6002    assign fallback values, CSS renderers <strong>must</strong> treat as
  6003    invalid (and <a
  6004    href="http://www.w3.org/TR/CSS21/conform.html#ignore">ignore as
  6005    appropriate</a>) any at-rules, properties, property values, keywords, and
  6006    other syntactic constructs for which they have no usable level of support.
  6007    In particular, user agents <strong>must not</strong> selectively ignore
  6008    unsupported component values and honor supported values in a single
  6009    multi-value property declaration: if any value is considered invalid (as
  6010    unsupported values must be), CSS requires that the entire declaration be
  6011    ignored.
  6013   <h3 class=no-num id=experimental> Experimental Implementations</h3>
  6015   <p>To avoid clashes with future CSS features, the CSS2.1 specification
  6016    reserves a <a
  6017    href="http://www.w3.org/TR/CSS21/syndata.html#vendor-keywords">prefixed
  6018    syntax</a> for proprietary and experimental extensions to CSS.
  6020   <p>Prior to a specification reaching the Candidate Recommendation stage in
  6021    the W3C process, all implementations of a CSS feature are considered
  6022    experimental. The CSS Working Group recommends that implementations use a
  6023    vendor-prefixed syntax for such features, including those in W3C Working
  6024    Drafts. This avoids incompatibilities with future changes in the draft.
  6026   <h3 class=no-num id=testing> Non-Experimental Implementations</h3>
  6028   <p>Once a specification reaches the Candidate Recommendation stage,
  6029    non-experimental implementations are possible, and implementors should
  6030    release an unprefixed implementation of any CR-level feature they can
  6031    demonstrate to be correctly implemented according to spec.
  6033   <p>To establish and maintain the interoperability of CSS across
  6034    implementations, the CSS Working Group requests that non-experimental CSS
  6035    renderers submit an implementation report (and, if necessary, the
  6036    testcases used for that implementation report) to the W3C before releasing
  6037    an unprefixed implementation of any CSS features. Testcases submitted to
  6038    W3C are subject to review and correction by the CSS Working Group.
  6040   <p>Further information on submitting testcases and implementation reports
  6041    can be found from on the CSS Working Group's website at <a
  6042    href="http://www.w3.org/Style/CSS/Test/">http://www.w3.org/Style/CSS/Test/</a>.
  6043    Questions should be directed to the <a
  6044    href="http://lists.w3.org/Archives/Public/public-css-testsuite">public-css-testsuite@w3.org</a>
  6045    mailing list.
  6047   <h2 class=no-num id=references>References</h2>
  6049   <h3 class=no-num id=normative-references>Normative References</h3>
  6050   <!--begin-normative-->
  6051   <!-- Sorted by label -->
  6053   <dl class=bibliography>
  6054    <dd style="display: none"><!-- keeps the doc valid if the DL is empty -->
  6055     <!---->
  6057    <dt id=CHARMOD>[CHARMOD]
  6059    <dd>Martin J. Dürst; et al. <a
  6060     href="http://www.w3.org/TR/2005/REC-charmod-20050215/"><cite>Character
  6061     Model for the World Wide Web 1.0: Fundamentals.</cite></a> 15 February
  6062     2005. W3C Recommendation. URL: <a
  6063     href="http://www.w3.org/TR/2005/REC-charmod-20050215/">http://www.w3.org/TR/2005/REC-charmod-20050215/</a>
  6064     </dd>
  6065    <!---->
  6067    <dt id=CORS>[CORS]
  6069    <dd>Anne van Kesteren. <a
  6070     href="http://www.w3.org/TR/2013/CR-cors-20130129/"><cite>Cross-Origin
  6071     Resource Sharing.</cite></a> 29 January 2013. W3C Candidate
  6072     Recommendation. (Work in progress.) URL: <a
  6073     href="http://www.w3.org/TR/2013/CR-cors-20130129/">http://www.w3.org/TR/2013/CR-cors-20130129/</a>
  6074     </dd>
  6075    <!---->
  6077    <dt id=CSS21>[CSS21]
  6079    <dd>Bert Bos; et al. <a
  6080     href="http://www.w3.org/TR/2011/REC-CSS2-20110607"><cite>Cascading Style
  6081     Sheets Level 2 Revision 1 (CSS 2.1) Specification.</cite></a> 7 June
  6082     2011. W3C Recommendation. URL: <a
  6083     href="http://www.w3.org/TR/2011/REC-CSS2-20110607">http://www.w3.org/TR/2011/REC-CSS2-20110607</a>
  6084     </dd>
  6085    <!---->
  6087    <dt id=CSS3VAL>[CSS3VAL]
  6089    <dd>Håkon Wium Lie; Tab Atkins; Elika J. Etemad. <a
  6090     href="http://www.w3.org/TR/2013/CR-css3-values-20130404/"><cite>CSS
  6091     Values and Units Module Level 3.</cite></a> 4 April 2013. W3C Candidate
  6092     Recommendation. (Work in progress.) URL: <a
  6093     href="http://www.w3.org/TR/2013/CR-css3-values-20130404/">http://www.w3.org/TR/2013/CR-css3-values-20130404/</a>
  6094     </dd>
  6095    <!---->
  6097    <dt id=HTML5>[HTML5]
  6099    <dd>Ian Hickson. <a
  6100     href="http://www.w3.org/TR/2012/CR-html5-20121217/"><cite>HTML5.</cite></a>
  6101     17 December 2012. W3C Candidate Recommendation. (Work in progress.) URL:
  6102     <a
  6103     href="http://www.w3.org/TR/2012/CR-html5-20121217/">http://www.w3.org/TR/2012/CR-html5-20121217/</a>
  6104     </dd>
  6105    <!---->
  6107    <dt id=OPEN-FONT-FORMAT>[OPEN-FONT-FORMAT]
  6109    <dd><a
  6110     href="http://standards.iso.org/ittf/PubliclyAvailableStandards/c052136_ISO_IEC_14496-22_2009(E).zip"><cite>Information
  6111     technology — Coding of audio-visual objects — Part 22: Open Font
  6112     Format.</cite></a> International Organization for Standardization.
  6113     ISO/IEC 14496-22:2009. URL: <a
  6114     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>
  6115     </dd>
  6116    <!---->
  6118    <dt id=OPENTYPE>[OPENTYPE]
  6120    <dd><a
  6121     href="http://www.microsoft.com/typography/otspec/default.htm"><cite>OpenType
  6122     specification.</cite></a> Microsoft. URL: <a
  6123     href="http://www.microsoft.com/typography/otspec/default.htm">http://www.microsoft.com/typography/otspec/default.htm</a>
  6124     </dd>
  6125    <!---->
  6127    <dt id=OPENTYPE-FEATURES>[OPENTYPE-FEATURES]
  6129    <dd><a
  6130     href="http://www.microsoft.com/typography/otspec/featurelist.htm"><cite>OpenType
  6131     feature registry.</cite></a> Microsoft. URL: <a
  6132     href="http://www.microsoft.com/typography/otspec/featurelist.htm">http://www.microsoft.com/typography/otspec/featurelist.htm</a>
  6133     </dd>
  6134    <!---->
  6136    <dt id=RFC2119>[RFC2119]
  6138    <dd>S. Bradner. <a href="http://www.ietf.org/rfc/rfc2119.txt"><cite>Key
  6139     words for use in RFCs to Indicate Requirement Levels.</cite></a> Internet
  6140     RFC 2119. URL: <a
  6141     href="http://www.ietf.org/rfc/rfc2119.txt">http://www.ietf.org/rfc/rfc2119.txt</a>
  6142     </dd>
  6143    <!---->
  6145    <dt id=UAX15>[UAX15]
  6147    <dd>Mark Davis; Ken Whistler. <a
  6148     href="http://www.unicode.org/reports/tr15/"><cite>Unicode Normalization
  6149     Forms.</cite></a> 31 August 2012. Unicode Standard Annex #15. URL: <a
  6150     href="http://www.unicode.org/reports/tr15/">http://www.unicode.org/reports/tr15/</a>
  6151     </dd>
  6152    <!---->
  6154    <dt id=UAX29>[UAX29]
  6156    <dd>Mark Davis. <a
  6157     href="http://www.unicode.org/reports/tr29/"><cite>Unicode Text
  6158     Segmentation.</cite></a> 12 September 2012. Unicode Standard Annex #29.
  6159     URL: <a
  6160     href="http://www.unicode.org/reports/tr29/">http://www.unicode.org/reports/tr29/</a>
  6161     </dd>
  6162    <!---->
  6164    <dt id=UNICODE6>[UNICODE6]
  6166    <dd>The Unicode Consortium. <a
  6167     href="http://www.unicode.org/versions/Unicode6.2.0/"><cite>The Unicode
  6168     Standard, Version 6.2.0.</cite></a> Defined by: The Unicode Standard,
  6169     Version 6.2.0 URL: <a
  6170     href="http://www.unicode.org/versions/Unicode6.2.0/">http://www.unicode.org/versions/Unicode6.2.0/</a>
  6171     </dd>
  6172    <!---->
  6173   </dl>
  6174   <!--end-normative-->
  6175   <!--{{!CSS21}}-->
  6176   <!--{{!CSS3VAL}}-->
  6177   <!--{{!OPENTYPE}}-->
  6178   <!--{{!OPENTYPE-FEATURES}}-->
  6179   <!--{{!OPEN-FONT-FORMAT}}-->
  6180   <!--{{!UNICODE6}}-->
  6181   <!--{{!UAX15}}-->
  6182   <!--{{!UAX29}}-->
  6183   <!--{{!CORS}}-->
  6184   <!--{{!HTML5}}-->
  6185   <!--{{!CHARMOD}}-->
  6187   <h3 class=no-num id=other-references>Other References</h3>
  6188   <!--begin-informative-->
  6189   <!-- Sorted by label -->
  6191   <dl class=bibliography>
  6192    <dd style="display: none"><!-- keeps the doc valid if the DL is empty -->
  6193     <!---->
  6195    <dt id=AAT-FEATURES>[AAT-FEATURES]
  6197    <dd><a href="http://developer.apple.com/fonts/registry/"><cite>Apple
  6198     Advanced Typography font feature registry.</cite></a> Apple. URL: <a
  6199     href="http://developer.apple.com/fonts/registry/">http://developer.apple.com/fonts/registry/</a>
  6200     </dd>
  6201    <!---->
  6203    <dt id=ARABIC-TYPO>[ARABIC-TYPO]
  6205    <dd>Huda Smitshuijzen AbiFares. <cite>Arabic Typography: A Comprehensive
  6206     Sourcebook.</cite> Saqi Books. 2001. ISBN 0-86356-347-3.</dd>
  6207    <!---->
  6209    <dt id=CHARMOD-NORM>[CHARMOD-NORM]
  6211    <dd>François Yergeau; et al. <a
  6212     href="http://www.w3.org/TR/2012/WD-charmod-norm-20120501/"><cite>Character
  6213     Model for the World Wide Web 1.0: Normalization.</cite></a> 1 May 2012.
  6214     W3C Working Draft. (Work in progress.) URL: <a
  6215     href="http://www.w3.org/TR/2012/WD-charmod-norm-20120501/">http://www.w3.org/TR/2012/WD-charmod-norm-20120501/</a>
  6216     </dd>
  6217    <!---->
  6219    <dt id=CJKV-INFO-PROCESSING>[CJKV-INFO-PROCESSING]
  6221    <dd>Ken Lunde. <cite>CJKV Information Processing, Second Edition.</cite>
  6222     O'Reilly Media, Inc. 2009. ISBN 0-596-51447-1.</dd>
  6223    <!---->
  6225    <dt id=CSS3-CONDITIONAL>[CSS3-CONDITIONAL]
  6227    <dd>L. David Baron. <a
  6228     href="http://www.w3.org/TR/2013/CR-css3-conditional-20130404/"><cite>CSS
  6229     Conditional Rules Module Level 3.</cite></a> 4 April 2013. W3C Candidate
  6230     Recommendation. (Work in progress.) URL: <a
  6231     href="http://www.w3.org/TR/2013/CR-css3-conditional-20130404/">http://www.w3.org/TR/2013/CR-css3-conditional-20130404/</a>
  6232     </dd>
  6233    <!---->
  6235    <dt id=CSS3TEXT>[CSS3TEXT]
  6237    <dd>Elika J. Etemad; Koji Ishii. <a
  6238     href="http://www.w3.org/TR/2012/WD-css3-text-20121113/"><cite>CSS Text
  6239     Module Level 3.</cite></a> 13 November 2012. W3C Working Draft. (Work in
  6240     progress.) URL: <a
  6241     href="http://www.w3.org/TR/2012/WD-css3-text-20121113/">http://www.w3.org/TR/2012/WD-css3-text-20121113/</a>
  6242     </dd>
  6243    <!---->
  6245    <dt id=DIGITAL-TYPOGRAPHY>[DIGITAL-TYPOGRAPHY]
  6247    <dd>Richard Rubinstein. <cite>Digital Typography, An Introduction to Type
  6248     and Composition for Computer System Design.</cite> Addison-Wesley. 1988.
  6249     ISBN 0-201-17633-5.</dd>
  6250    <!---->
  6252    <dt id=DOM-LEVEL-2-STYLE>[DOM-LEVEL-2-STYLE]
  6254    <dd>Chris Wilson; Philippe Le Hégaret; Vidur Apparao. <a
  6255     href="http://www.w3.org/TR/2000/REC-DOM-Level-2-Style-20001113/"><cite>Document
  6256     Object Model (DOM) Level 2 Style Specification.</cite></a> 13 November
  6257     2000. W3C Recommendation. URL: <a
  6258     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>
  6259     </dd>
  6260    <!---->
  6262    <dt id=ELEMTYPO>[ELEMTYPO]
  6264    <dd>Robert Bringhurst. <cite>The Elements of Typographic Style, Version
  6265     4.</cite> Hartley &amp; Marks. 2013. ISBN 0-88179-212-8.</dd>
  6266    <!---->
  6268    <dt id=LANGCULTTYPE>[LANGCULTTYPE]
  6270    <dd>John D. Berry, Ed. <cite>Language Culture Type.</cite> Graphis. 2001.
  6271     ISBN 1-932026-01-0.</dd>
  6272    <!---->
  6274    <dt id=OPENTYPE-FONT-GUIDE>[OPENTYPE-FONT-GUIDE]
  6276    <dd><a
  6277     href="https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf"><cite>OpenType
  6278     User Guide.</cite></a> FontShop International. URL: <a
  6279     href="https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf">https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf</a>
  6280     </dd>
  6281    <!---->
  6283    <dt id=RASTER-TRAGEDY>[RASTER-TRAGEDY]
  6285    <dd>Beat Stamm. <a href="http://www.rastertragedy.com/"><cite>The Raster
  6286     Tragedy at Low-Resolution Revisited.</cite></a> 7 December 2011. URL: <a
  6287     href="http://www.rastertragedy.com/">http://www.rastertragedy.com/</a></dd>
  6288    <!---->
  6290    <dt id=WINDOWS-GLYPH-PROC>[WINDOWS-GLYPH-PROC]
  6292    <dd>John Hudson. <a
  6293     href="http://www.microsoft.com/typography/developers/opentype/default.htm"><cite>Windows
  6294     Glyph Processing.</cite></a> Microsoft Typogrraphy. URL: <a
  6295     href="http://www.microsoft.com/typography/developers/opentype/default.htm">http://www.microsoft.com/typography/developers/opentype/default.htm</a>
  6296     </dd>
  6297    <!---->
  6298   </dl>
  6299   <!--end-informative-->
  6300   <!--{{ARABIC-TYPO}}-->
  6301   <!--{{CJKV-INFO-PROCESSING}}-->
  6302   <!--{{DIGITAL-TYPOGRAPHY}}-->
  6303   <!--{{DOM-LEVEL-2-STYLE}}-->
  6304   <!--{{ELEMTYPO}}-->
  6305   <!--{{LANGCULTTYPE}}-->
  6306   <!--{{OPENTYPE-FONT-GUIDE}}-->
  6307   <!--{{RASTER-TRAGEDY}}-->
  6308   <!--{{WINDOWS-GLYPH-PROC}}-->
  6309   <!--{{CHARMOD-NORM}}-->
  6310   <!--{{AAT-FEATURES}}-->
  6311   <!--{{CSS3-CONDITIONAL}}-->
  6312   <!--{{CSS3TEXT}}-->
  6314   <h2 class=no-num id=index>Index</h2>
  6315   <!--begin-index-->
  6317   <ul class=indexlist>
  6318    <li>100...900 weight values, <a href="#font-weight-numeric-values"
  6319     title="100...900 weight values"><strong>3.2</strong></a>
  6321    <li><var>&lt;absolute-size&gt;</var>, <a href="#absolute-size-value"
  6322     title="&lt;absolute-size&gt;"><strong>3.5</strong></a>
  6324    <li><var>&lt;common-lig-values&gt;</var>, <a href="#common-lig-values"
  6325     title="&lt;common-lig-values&gt;"><strong>6.4</strong></a>
  6327    <li><var>&lt;contextual-alt-values&gt;</var>, <a
  6328     href="#contextual-alt-values"
  6329     title="&lt;contextual-alt-values&gt;"><strong>6.4</strong></a>
  6331    <li><var>&lt;discretionary-lig-values&gt;</var>, <a
  6332     href="#discretionary-lig-values"
  6333     title="&lt;discretionary-lig-values&gt;"><strong>6.4</strong></a>
  6335    <li><var>&lt;east-asian-variant-values&gt;</var>, <a
  6336     href="#east-asian-variant-values"
  6337     title="&lt;east-asian-variant-values&gt;"><strong>6.10</strong></a>
  6339    <li><var>&lt;east-asian-width-values&gt;</var>, <a
  6340     href="#east-asian-width-values"
  6341     title="&lt;east-asian-width-values&gt;"><strong>6.10</strong></a>
  6343    <li><var>&lt;family-name&gt;</var>, <a href="#family-name-value"
  6344     title="&lt;family-name&gt;"><strong>3.1</strong></a>
  6346    <li><var>&lt;feature-tag-value&gt;</var>, <a href="#feature-tag-value"
  6347     title="&lt;feature-tag-value&gt;"><strong>6.12</strong></a>
  6349    <li><var>&lt;font-face-name&gt;</var>, <a href="#font-face-name-value"
  6350     title="&lt;font-face-name&gt;"><strong>4.3</strong></a>
  6352    <li><var>&lt;font-variant-css21&gt;</var>, <a
  6353     href="#font-variant-css21-values"
  6354     title="&lt;font-variant-css21&gt;"><strong>3.7</strong></a>
  6356    <li><var>&lt;generic-family&gt;</var>, <a href="#generic-family-value"
  6357     title="&lt;generic-family&gt;"><strong>3.1</strong></a>
  6359    <li><var>&lt;historical-lig-values&gt;</var>, <a
  6360     href="#historical-lig-values"
  6361     title="&lt;historical-lig-values&gt;"><strong>6.4</strong></a>
  6363    <li><var>&lt;length&gt;</var>, <a href="#length-size-value"
  6364     title="&lt;length&gt;"><strong>3.5</strong></a>
  6366    <li><var>&lt;number&gt;</var>, <a href="#aspect-ratio-value"
  6367     title="&lt;number&gt;"><strong>3.6</strong></a>
  6369    <li><var>&lt;numeric-figure-values&gt;</var>, <a
  6370     href="#numeric-figure-values"
  6371     title="&lt;numeric-figure-values&gt;"><strong>6.7</strong></a>
  6373    <li><var>&lt;numeric-fraction-values&gt;</var>, <a
  6374     href="#numeric-fraction-values"
  6375     title="&lt;numeric-fraction-values&gt;"><strong>6.7</strong></a>
  6377    <li><var>&lt;numeric-spacing-values&gt;</var>, <a
  6378     href="#numeric-spacing-values"
  6379     title="&lt;numeric-spacing-values&gt;"><strong>6.7</strong></a>
  6381    <li><var>&lt;percentage&gt;</var>, <a href="#percentage-size-value"
  6382     title="&lt;percentage&gt;"><strong>3.5</strong></a>
  6384    <li><var>&lt;relative-size&gt;</var>, <a href="#relative-size-value"
  6385     title="&lt;relative-size&gt;"><strong>3.5</strong></a>
  6387    <li><var>&lt;string&gt;</var>, <a
  6388     href="#font-language-override-string-value"
  6389     title="&lt;string&gt;"><strong>6.13</strong></a>
  6391    <li><var>&lt;urange&gt;</var>, <a href="#urange-value"
  6392     title="&lt;urange&gt;"><strong>4.5</strong></a>
  6394    <li><code>@font-face</code>, <a href="#at-font-face-rule"
  6395     title="@font-face"><strong>4.1</strong></a>
  6397    <li><code>@font-feature-values</code>, <a
  6398     href="#at-font-feature-values-rule"
  6399     title="@font-feature-values"><strong>6.9</strong></a>
  6401    <li>all-petite-caps, <a href="#all-petite-caps"
  6402     title=all-petite-caps><strong>6.6</strong></a>
  6404    <li>all-small-caps, <a href="#all-small-caps"
  6405     title=all-small-caps><strong>6.6</strong></a>
  6407    <li>annotation, <a href="#annotation"
  6408     title=annotation><strong>6.8</strong></a>
  6410    <li>aspect value, <a href="#aspect-value0" title="aspect
  6411     value"><strong>3.6</strong></a>
  6413    <li>authoring tool, <a href="#authoring-tool" title="authoring
  6414     tool"><strong>#</strong></a>
  6416    <li>auto
  6417     <ul>
  6418      <li>font-kerning, <a href="#font-kerning-auto-value" title="auto,
  6419       font-kerning"><strong>6.3</strong></a>
  6421      <li>font-size-adjust, <a href="#font-size-adjust-auto-value"
  6422       title="auto, font-size-adjust"><strong>3.6</strong></a>
  6423     </ul>
  6425    <li>bold, <a href="#bold" title=bold><strong>3.2</strong></a>
  6427    <li>bolder, <a href="#bolder" title=bolder><strong>3.2</strong></a>
  6429    <li>character map, <a href="#character-map" title="character
  6430     map"><strong>5.2</strong></a>
  6432    <li>character-variant, <a href="#character-variant"
  6433     title=character-variant><strong>6.8</strong></a>
  6435    <li>common-ligatures, <a href="#common-ligatures"
  6436     title=common-ligatures><strong>6.4</strong></a>
  6438    <li>composite face, <a href="#composite-face" title="composite
  6439     face"><strong>5.2</strong></a>
  6441    <li>condensed, <a href="#condensed"
  6442     title=condensed><strong>3.3</strong></a>
  6444    <li>contextual, <a href="#contextual"
  6445     title=contextual><strong>6.4</strong></a>
  6447    <li>CSSFontFaceRule, <a href="#cssfontfacerule"
  6448     title=CSSFontFaceRule><strong>8.1</strong></a>
  6450    <li>CSSFontFeatureValuesRule, <a href="#cssfontfeaturevaluesrule"
  6451     title=CSSFontFeatureValuesRule><strong>8.2</strong></a>
  6453    <li>cursive, definition of, <a href="#cursive0" title="cursive, definition
  6454     of"><strong>#</strong></a>
  6456    <li>default face, <a href="#default-face" title="default
  6457     face"><strong>5.2</strong></a>
  6459    <li>descriptor_declaration, <a href="#descriptordeclaration"
  6460     title="descriptor_declaration"><strong>4.1</strong></a>
  6462    <li>diagonal-fractions, <a href="#diagonal-fractions"
  6463     title=diagonal-fractions><strong>6.7</strong></a>
  6465    <li>discretionary-ligatures, <a href="#discretionary-ligatures"
  6466     title=discretionary-ligatures><strong>6.4</strong></a>
  6468    <li>effective character map, <a href="#effective-character-map"
  6469     title="effective character map"><strong>4.5</strong></a>
  6471    <li>expanded, <a href="#expanded" title=expanded><strong>3.3</strong></a>
  6473    <li>extra-condensed, <a href="#extra-condensed"
  6474     title=extra-condensed><strong>3.3</strong></a>
  6476    <li>extra-expanded, <a href="#extra-expanded"
  6477     title=extra-expanded><strong>3.3</strong></a>
  6479    <li>fantasy, definition of, <a href="#fantasy0" title="fantasy, definition
  6480     of"><strong>#</strong></a>
  6482    <li>feature_type, <a href="#featuretype"
  6483     title="feature_type"><strong>6.9.1</strong></a>
  6485    <li>feature_value_block, <a href="#featurevalueblock"
  6486     title="feature_value_block"><strong>6.9.1</strong></a>
  6488    <li>feature_value_definition, <a href="#featurevaluedefinition"
  6489     title="feature_value_definition"><strong>6.9.1</strong></a>
  6491    <li>first available font, <a href="#first-available-font" title="first
  6492     available font"><strong>5.2</strong></a>
  6494    <li>font, <a href="#propdef-font" title=font><strong>3.7</strong></a>
  6496    <li>font specific, <a href="#font-specific" title="font
  6497     specific"><strong>6.8</strong></a>
  6499    <li>font-family
  6500     <ul>
  6501      <li>descriptor, <a href="#descdef-font-family" title="font-family,
  6502       descriptor"><strong>4.2</strong></a>
  6504      <li>property, <a href="#propdef-font-family" title="font-family,
  6505       property"><strong>3.1</strong></a>
  6506     </ul>
  6508    <li>font-feature-settings
  6509     <ul>
  6510      <li>descriptor, <a href="#descdef-font-feature-settings"
  6511       title="font-feature-settings, descriptor"><strong>4.7</strong></a>
  6513      <li>property, <a href="#propdef-font-feature-settings"
  6514       title="font-feature-settings, property"><strong>6.12</strong></a>
  6515     </ul>
  6517    <li>font-kerning, <a href="#propdef-font-kerning"
  6518     title=font-kerning><strong>6.3</strong></a>
  6520    <li>font-language-override, <a href="#propdef-font-language-override"
  6521     title=font-language-override><strong>6.13</strong></a>
  6523    <li>font-size, <a href="#propdef-font-size"
  6524     title=font-size><strong>3.5</strong></a>
  6526    <li>font-size-adjust, <a href="#propdef-font-size-adjust"
  6527     title=font-size-adjust><strong>3.6</strong></a>
  6529    <li>font-stretch
  6530     <ul>
  6531      <li>descriptor, <a href="#descdef-font-stretch" title="font-stretch,
  6532       descriptor"><strong>4.4</strong></a>
  6534      <li>property, <a href="#propdef-font-stretch" title="font-stretch,
  6535       property"><strong>3.3</strong></a>
  6536     </ul>
  6538    <li>font-style
  6539     <ul>
  6540      <li>descriptor, <a href="#descdef-font-style" title="font-style,
  6541       descriptor"><strong>4.4</strong></a>
  6543      <li>property, <a href="#propdef-font-style" title="font-style,
  6544       property"><strong>3.4</strong></a>
  6545     </ul>
  6547    <li>font-synthesis, <a href="#propdef-font-synthesis"
  6548     title=font-synthesis><strong>3.8</strong></a>
  6550    <li>font-variant
  6551     <ul>
  6552      <li>descriptor, <a href="#descdef-font-variant" title="font-variant,
  6553       descriptor"><strong>4.7</strong></a>
  6555      <li>property, <a href="#propdef-font-variant" title="font-variant,
  6556       property"><strong>6.11</strong></a>
  6557     </ul>
  6559    <li>font-variant-alternates, <a href="#propdef-font-variant-alternates"
  6560     title=font-variant-alternates><strong>6.8</strong></a>
  6562    <li>font-variant-caps, <a href="#propdef-font-variant-caps"
  6563     title=font-variant-caps><strong>6.6</strong></a>
  6565    <li>font-variant-east-asian, <a href="#propdef-font-variant-east-asian"
  6566     title=font-variant-east-asian><strong>6.10</strong></a>
  6568    <li>font-variant-ligatures, <a href="#propdef-font-variant-ligatures"
  6569     title=font-variant-ligatures><strong>6.4</strong></a>
  6571    <li>font-variant-numeric, <a href="#propdef-font-variant-numeric"
  6572     title=font-variant-numeric><strong>6.7</strong></a>
  6574    <li>font-variant-position, <a href="#propdef-font-variant-position"
  6575     title=font-variant-position><strong>6.5</strong></a>
  6577    <li>font-weight
  6578     <ul>
  6579      <li>descriptor, <a href="#descdef-font-weight" title="font-weight,
  6580       descriptor"><strong>4.4</strong></a>
  6582      <li>property, <a href="#propdef-font-weight" title="font-weight,
  6583       property"><strong>3.2</strong></a>
  6584     </ul>
  6586    <li>font_face_rule, <a href="#fontfacerule"
  6587     title="font_face_rule"><strong>4.1</strong></a>
  6589    <li>FONT_FACE_SYM, <a href="#fontfacesym"
  6590     title="FONT_FACE_SYM"><strong>4.1</strong></a>
  6592    <li>font_family_name, <a href="#fontfamilyname"
  6593     title="font_family_name"><strong>6.9.1</strong></a>
  6595    <li>font_family_name_list, <a href="#fontfamilynamelist"
  6596     title="font_family_name_list"><strong>6.9.1</strong></a>
  6598    <li>font_feature_values_rule, <a href="#fontfeaturevaluesrule"
  6599     title="font_feature_values_rule"><strong>6.9.1</strong></a>
  6601    <li>FONT_FEATURE_VALUES_SYM, <a href="#fontfeaturevaluessym"
  6602     title="FONT_FEATURE_VALUES_SYM"><strong>6.9.1</strong></a>
  6604    <li>full-width, <a href="#full-width"
  6605     title=full-width><strong>6.10</strong></a>
  6607    <li>historical-forms, <a href="#historical-forms"
  6608     title=historical-forms><strong>6.8</strong></a>
  6610    <li>historical-ligatures, <a href="#historical-ligatures"
  6611     title=historical-ligatures><strong>6.4</strong></a>
  6613    <li>italic, <a href="#italic" title=italic><strong>3.4</strong></a>
  6615    <li>jis04, <a href="#jis04" title=jis04><strong>6.10</strong></a>
  6617    <li>jis78, <a href="#jis78" title=jis78><strong>6.10</strong></a>
  6619    <li>jis83, <a href="#jis83" title=jis83><strong>6.10</strong></a>
  6621    <li>jis90, <a href="#jis90" title=jis90><strong>6.10</strong></a>
  6623    <li>lighter, <a href="#lighter" title=lighter><strong>3.2</strong></a>
  6625    <li>lining-nums, <a href="#lining-nums"
  6626     title=lining-nums><strong>6.7</strong></a>
  6628    <li>monospace, definition of, <a href="#monospace0" title="monospace,
  6629     definition of"><strong>#</strong></a>
  6631    <li>no-common-ligatures, <a href="#no-common-ligatures"
  6632     title=no-common-ligatures><strong>6.4</strong></a>
  6634    <li>no-contextual, <a href="#no-contextual"
  6635     title=no-contextual><strong>6.4</strong></a>
  6637    <li>no-discretionary-ligatures, <a href="#no-discretionary-ligatures"
  6638     title=no-discretionary-ligatures><strong>6.4</strong></a>
  6640    <li>no-historical-ligatures, <a href="#no-historical-ligatures"
  6641     title=no-historical-ligatures><strong>6.4</strong></a>
  6643    <li>none
  6644     <ul>
  6645      <li>font-kerning, <a href="#font-kerning-none-value" title="none,
  6646       font-kerning"><strong>6.3</strong></a>
  6648      <li>font-size-adjust, <a href="#font-size-adjust-none-value"
  6649       title="none, font-size-adjust"><strong>3.6</strong></a>
  6651      <li>font-variant, <a href="#font-variant-none-value" title="none,
  6652       font-variant"><strong>6.11</strong></a>
  6654      <li>font-variant-ligatures, <a href="#font-variant-ligatures-none-value"
  6655       title="none, font-variant-ligatures"><strong>6.4</strong></a>
  6656     </ul>
  6658    <li>normal
  6659     <ul>
  6660      <li>font-feature-settings, <a href="#font-feature-settings-normal-value"
  6661       title="normal, font-feature-settings"><strong>6.12</strong></a>
  6663      <li>font-kerning, <a href="#font-kerning-normal-value" title="normal,
  6664       font-kerning"><strong>6.3</strong></a>
  6666      <li>font-language-override, <a
  6667       href="#font-language-override-normal-value" title="normal,
  6668       font-language-override"><strong>6.13</strong></a>
  6670      <li>font-stretch, <a href="#font-stretch-normal-value" title="normal,
  6671       font-stretch"><strong>3.3</strong></a>
  6673      <li>font-style, <a href="#font-style-normal-value" title="normal,
  6674       font-style"><strong>3.4</strong></a>
  6676      <li>font-variant, <a href="#font-variant-normal-value" title="normal,
  6677       font-variant"><strong>6.11</strong></a>
  6679      <li>font-variant-alternates, <a
  6680       href="#font-variant-alternates-normal-value" title="normal,
  6681       font-variant-alternates"><strong>6.8</strong></a>
  6683      <li>font-variant-caps, <a href="#font-variant-caps-normal-value"
  6684       title="normal, font-variant-caps"><strong>6.6</strong></a>
  6686      <li>font-variant-east-asian, <a
  6687       href="#font-variant-east-asian-normal-value" title="normal,
  6688       font-variant-east-asian"><strong>6.10</strong></a>
  6690      <li>font-variant-ligatures, <a
  6691       href="#font-variant-ligatures-normal-value" title="normal,
  6692       font-variant-ligatures"><strong>6.4</strong></a>
  6694      <li>font-variant-numeric, <a href="#font-variant-numeric-normal-value"
  6695       title="normal, font-variant-numeric"><strong>6.7</strong></a>
  6697      <li>font-variant-position, <a href="#font-variant-position-normal-value"
  6698       title="normal, font-variant-position"><strong>6.5</strong></a>
  6700      <li>font-weight, <a href="#font-weight-normal-value" title="normal,
  6701       font-weight"><strong>3.2</strong></a>
  6702     </ul>
  6704    <li>oblique, <a href="#oblique" title=oblique><strong>3.4</strong></a>
  6706    <li>oldstyle-nums, <a href="#oldstyle-nums"
  6707     title=oldstyle-nums><strong>6.7</strong></a>
  6709    <li>ordinal, <a href="#ordinal" title=ordinal><strong>6.7</strong></a>
  6711    <li>ornaments, <a href="#ornaments"
  6712     title=ornaments><strong>6.8</strong></a>
  6714    <li>petite-caps, <a href="#petite-caps"
  6715     title=petite-caps><strong>6.6</strong></a>
  6717    <li>proportional-nums, <a href="#proportional-nums"
  6718     title=proportional-nums><strong>6.7</strong></a>
  6720    <li>proportional-width, <a href="#proportional-width"
  6721     title=proportional-width><strong>6.10</strong></a>
  6723    <li>renderer, <a href="#renderer" title=renderer><strong>#</strong></a>
  6725    <li>ruby, <a href="#ruby" title=ruby><strong>6.10</strong></a>
  6727    <li>sans-serif, definition of, <a href="#sans-serif0" title="sans-serif,
  6728     definition of"><strong>#</strong></a>
  6730    <li>semi-condensed, <a href="#semi-condensed-"
  6731     title=semi-condensed><strong>3.3</strong></a>
  6733    <li>semi-expanded, <a href="#semi-expanded"
  6734     title=semi-expanded><strong>3.3</strong></a>
  6736    <li>serif, definition of, <a href="#serif0" title="serif, definition
  6737     of"><strong>#</strong></a>
  6739    <li>simplified, <a href="#simplified"
  6740     title=simplified><strong>6.10</strong></a>
  6742    <li>slashed-zero, <a href="#slashed-zero"
  6743     title=slashed-zero><strong>6.7</strong></a>
  6745    <li>small-caps, <a href="#small-caps"
  6746     title=small-caps><strong>6.6</strong></a>
  6748    <li>src, <a href="#descdef-src" title=src><strong>4.3</strong></a>
  6750    <li>stacked-fractions, <a href="#stacked-fractions"
  6751     title=stacked-fractions><strong>6.7</strong></a>
  6753    <li>style sheet
  6754     <ul>
  6755      <li>as conformance class, <a href="#style-sheet" title="style sheet, as
  6756       conformance class"><strong>#</strong></a>
  6757     </ul>
  6759    <li>styleset, <a href="#styleset" title=styleset><strong>6.8</strong></a>
  6761    <li>stylistic, <a href="#stylistic"
  6762     title=stylistic><strong>6.8</strong></a>
  6764    <li>sub, <a href="#sub" title=sub><strong>6.5</strong></a>
  6766    <li>super, <a href="#super" title=super><strong>6.5</strong></a>
  6768    <li>support, <a href="#support" title=support><strong>5.2</strong></a>
  6770    <li>swash, <a href="#swash" title=swash><strong>6.8</strong></a>
  6772    <li>system font fallback, <a href="#system-font-fallback" title="system
  6773     font fallback"><strong>5.2</strong></a>
  6775    <li>tabular-nums, <a href="#tabular-nums"
  6776     title=tabular-nums><strong>6.7</strong></a>
  6778    <li>titling-caps, <a href="#titling-caps"
  6779     title=titling-caps><strong>6.6</strong></a>
  6781    <li>traditional, <a href="#traditional"
  6782     title=traditional><strong>6.10</strong></a>
  6784    <li>ultra-condensed, <a href="#ultra-condensed"
  6785     title=ultra-condensed><strong>3.3</strong></a>
  6787    <li>ultra-expanded, <a href="#ultra-expanded"
  6788     title=ultra-expanded><strong>3.3</strong></a>
  6790    <li>unicase, <a href="#unicase" title=unicase><strong>6.6</strong></a>
  6792    <li>unicode-range, <a href="#descdef-unicode-range"
  6793     title=unicode-range><strong>4.5</strong></a>
  6795    <li>weight, <a href="#weight" title=weight><strong>2</strong></a>
  6797    <li>width, <a href="#width" title=width><strong>2</strong></a>
  6798   </ul>
  6799   <!--end-index-->
  6801   <h2 class=no-num id=property-index>Property index</h2>
  6802   <!--begin-properties-->
  6804   <table class=proptable>
  6805    <thead>
  6806     <tr>
  6807      <th>Property
  6809      <th>Values
  6811      <th>Initial
  6813      <th>Applies to
  6815      <th>Inh.
  6817      <th>Percentages
  6819      <th>Media
  6821    <tbody>
  6822     <tr>
  6823      <th><a class=property href="#propdef-font">font</a>
  6825      <td>[ [ &lt;‘font-style’&gt; || &lt;font-variant-css21&gt; ||
  6826       &lt;‘font-weight’&gt; || &lt;‘font-stretch’ ]?
  6827       &lt;‘font-size’&gt; [ / &lt;‘line-height’&gt; ]?
  6828       &lt;‘font-family’&gt; ] | caption | icon | menu | message-box |
  6829       small-caption | status-bar
  6831      <td>see individual properties
  6833      <td>all elements
  6835      <td>yes
  6837      <td>see individual properties
  6839      <td>visual
  6841     <tr>
  6842      <th><span class=property>font-family</span>
  6844      <td>[ &lt;family-name&gt; | &lt;generic-family&gt; ] #
  6846      <td>depends on user agent
  6848      <td>all elements
  6850      <td>yes
  6852      <td>N/A
  6854      <td>visual
  6856     <tr>
  6857      <th><span class=property>font-feature-settings</span>
  6859      <td>normal | &lt;feature-tag-value&gt; #
  6861      <td>normal
  6863      <td>all elements
  6865      <td>yes
  6867      <td>N/A
  6869      <td>visual
  6871     <tr>
  6872      <th><a class=property href="#propdef-font-kerning">font-kerning</a>
  6874      <td>auto | normal | none
  6876      <td>auto
  6878      <td>all elements
  6880      <td>yes
  6882      <td>N/A
  6884      <td>visual
  6886     <tr>
  6887      <th><a class=property
  6888       href="#propdef-font-language-override">font-language-override</a>
  6890      <td>normal | &lt;string&gt;
  6892      <td>normal
  6894      <td>all elements
  6896      <td>yes
  6898      <td>N/A
  6900      <td>visual
  6902     <tr>
  6903      <th><a class=property href="#propdef-font-size">font-size</a>
  6905      <td>&lt;absolute-size&gt; | &lt;relative-size&gt; | &lt;length&gt; |
  6906       &lt;percentage&gt;
  6908      <td>medium
  6910      <td>all elements
  6912      <td>yes
  6914      <td>refer to parent element's font size
  6916      <td>visual
  6918     <tr>
  6919      <th><a class=property
  6920       href="#propdef-font-size-adjust">font-size-adjust</a>
  6922      <td>none | auto | &lt;number&gt;
  6924      <td>none
  6926      <td>all elements
  6928      <td>yes
  6930      <td>N/A
  6932      <td>visual
  6934     <tr>
  6935      <th><span class=property>font-stretch</span>
  6937      <td>normal | ultra-condensed | extra-condensed | condensed |
  6938       semi-condensed | semi-expanded | expanded | extra-expanded |
  6939       ultra-expanded
  6941      <td>normal
  6943      <td>all elements
  6945      <td>yes
  6947      <td>N/A
  6949      <td>visual
  6951     <tr>
  6952      <th><span class=property>font-style</span>
  6954      <td>normal | italic | oblique
  6956      <td>normal
  6958      <td>all elements
  6960      <td>yes
  6962      <td>N/A
  6964      <td>visual
  6966     <tr>
  6967      <th><a class=property href="#propdef-font-synthesis">font-synthesis</a>
  6969      <td>none | [ weight || style ]
  6971      <td>weight style
  6973      <td>all elements
  6975      <td>yes
  6977      <td>N/A
  6979      <td>visual
  6981     <tr>
  6982      <th><span class=property>font-variant</span>
  6984      <td>normal | none | [ &lt;common-lig-values&gt; ||
  6985       &lt;discretionary-lig-values&gt; || &lt;historical-lig-values&gt; ||
  6986       &lt;contextual-alt-values&gt; || stylistic(&lt;feature-value-name&gt;)
  6987       || historical-forms || styleset(&lt;feature-value-name&gt; #) ||
  6988       character-variant(&lt;feature-value-name&gt; #) ||
  6989       swash(&lt;feature-value-name&gt;) ||
  6990       ornaments(&lt;feature-value-name&gt;) ||
  6991       annotation(&lt;feature-value-name&gt;) || [ small-caps | all-small-caps
  6992       | petite-caps | all-petite-caps | unicase | titling-caps ] ||
  6993       &lt;numeric-figure-values&gt; || &lt;numeric-spacing-values&gt; ||
  6994       &lt;numeric-fraction-values&gt; || ordinal || slashed-zero ||
  6995       &lt;east-asian-variant-values&gt; || &lt;east-asian-width-values&gt; ||
  6996       ruby ]
  6998      <td>normal
  7000      <td>all elements
  7002      <td>yes
  7004      <td>see individual properties
  7006      <td>visual
  7008     <tr>
  7009      <th><a class=property
  7010       href="#propdef-font-variant-alternates">font-variant-alternates</a>
  7012      <td>normal | [ stylistic(&lt;feature-value-name&gt;) || historical-forms
  7013       || styleset(&lt;feature-value-name&gt; #) ||
  7014       character-variant(&lt;feature-value-name&gt; #) ||
  7015       swash(&lt;feature-value-name&gt;) ||
  7016       ornaments(&lt;feature-value-name&gt;) ||
  7017       annotation(&lt;feature-value-name&gt;) ]
  7019      <td>normal
  7021      <td>all elements
  7023      <td>yes
  7025      <td>N/A
  7027      <td>visual
  7029     <tr>
  7030      <th><a class=property
  7031       href="#propdef-font-variant-caps">font-variant-caps</a>
  7033      <td>normal | small-caps | all-small-caps | petite-caps | all-petite-caps
  7034       | unicase | titling-caps
  7036      <td>normal
  7038      <td>all elements
  7040      <td>yes
  7042      <td>N/A
  7044      <td>visual
  7046     <tr>
  7047      <th><a class=property
  7048       href="#propdef-font-variant-east-asian">font-variant-east-asian</a>
  7050      <td>normal | [ &lt;east-asian-variant-values&gt; ||
  7051       &lt;east-asian-width-values&gt; || ruby ]
  7053      <td>normal
  7055      <td>all elements
  7057      <td>yes
  7059      <td>N/A
  7061      <td>visual
  7063     <tr>
  7064      <th><a class=property
  7065       href="#propdef-font-variant-ligatures">font-variant-ligatures</a>
  7067      <td>normal | none | [ &lt;common-lig-values&gt; ||
  7068       &lt;discretionary-lig-values&gt; || &lt;historical-lig-values&gt; ||
  7069       &lt;contextual-alt-values&gt; ]
  7071      <td>normal
  7073      <td>all elements
  7075      <td>yes
  7077      <td>N/A
  7079      <td>visual
  7081     <tr>
  7082      <th><a class=property
  7083       href="#propdef-font-variant-numeric">font-variant-numeric</a>
  7085      <td>normal | [ &lt;numeric-figure-values&gt; ||
  7086       &lt;numeric-spacing-values&gt; || &lt;numeric-fraction-values&gt; ||
  7087       ordinal || slashed-zero ]
  7089      <td>normal
  7091      <td>all elements
  7093      <td>yes
  7095      <td>N/A
  7097      <td>visual
  7099     <tr>
  7100      <th><a class=property
  7101       href="#propdef-font-variant-position">font-variant-position</a>
  7103      <td>normal | sub | super
  7105      <td>normal
  7107      <td>all elements
  7109      <td>yes
  7111      <td>N/A
  7113      <td>visual
  7115     <tr>
  7116      <th><span class=property>font-weight</span>
  7118      <td>normal | bold | bolder | lighter | 100 | 200 | 300 | 400 | 500 | 600
  7119       | 700 | 800 | 900
  7121      <td>normal
  7123      <td>all elements
  7125      <td>yes
  7127      <td>N/A
  7129      <td>visual
  7130   </table>
  7131   <!--end-properties-->
  7132   <!--begin-descriptors-->
  7134   <table class=proptable>
  7135    <thead>
  7136     <tr>
  7137      <th>Descriptor
  7139      <th>Value
  7141      <th>Initial
  7143      <th>Percentages
  7145      <th>Media
  7147    <tbody>
  7148     <tr>
  7149      <th><span class=property>font-family</span>
  7151      <td>&lt;family-name&gt;
  7153      <td>N/A
  7155     <tr>
  7156      <th><span class=property>font-feature-settings</span>
  7158      <td>normal | &lt;feature-tag-value&gt; #
  7160      <td>normal
  7162     <tr>
  7163      <th><span class=property>font-stretch</span>
  7165      <td>normal | ultra-condensed | extra-condensed | condensed |
  7166       semi-condensed | semi-expanded | expanded | extra-expanded |
  7167       ultra-expanded
  7169      <td>normal
  7171     <tr>
  7172      <th><span class=property>font-style</span>
  7174      <td>normal | italic | oblique
  7176      <td>normal
  7178     <tr>
  7179      <th><span class=property>font-variant</span>
  7181      <td>normal | none | [ &lt;common-lig-values&gt; ||
  7182       &lt;discretionary-lig-values&gt; || &lt;historical-lig-values&gt; ||
  7183       &lt;contextual-alt-values&gt; || stylistic(&lt;feature-value-name&gt;)
  7184       || historical-forms || styleset(&lt;feature-value-name&gt; #) ||
  7185       character-variant(&lt;feature-value-name&gt; #) ||
  7186       swash(&lt;feature-value-name&gt;) ||
  7187       ornaments(&lt;feature-value-name&gt;) ||
  7188       annotation(&lt;feature-value-name&gt;) || [ small-caps | all-small-caps
  7189       | petite-caps | all-petite-caps | unicase | titling-caps ] ||
  7190       &lt;numeric-figure-values&gt; || &lt;numeric-spacing-values&gt; ||
  7191       &lt;numeric-fraction-values&gt; || ordinal || slashed-zero ||
  7192       &lt;east-asian-variant-values&gt; || &lt;east-asian-width-values&gt; ||
  7193       ruby ]
  7195      <td>normal
  7197     <tr>
  7198      <th><span class=property>font-weight</span>
  7200      <td>normal | bold | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900
  7202      <td>normal
  7204     <tr>
  7205      <th><a class=property href="#descdef-src">src</a>
  7207      <td>[ &lt;url> [format(&lt;string> #)]? | &lt;font-face-name&gt; ] #
  7209      <td>N/A
  7211     <tr>
  7212      <th><a class=property href="#descdef-unicode-range">unicode-range</a>
  7214      <td>&lt;urange&gt; #
  7216      <td>U+0-10FFFF
  7217   </table>
  7218   <!--end-descriptors-->
  7219   <script type="text/javascript">
  7220 window.onload = function () {
  7221   if (!("devicePixelRatio" in window && window.devicePixelRatio > 1)) return;
  7222   var i, hiresElements = document.getElementsByClassName("hires");
  7223   for (i = 0; i < hiresElements.length; i++) {
  7224     var h = hiresElements[i];
  7225     if (h.tagName != "IMG") continue;
  7226     var src = h.getAttribute("src");
  7227     var src2x = src.replace(/\.\w+$/, function(m) { return "@2x" + m; });
  7228     h.src = src2x;
  7231 </script>
  7232 </html>
  7233 <!-- Keep this comment at the end of the file
  7234 Local variables:
  7235 mode: sgml
  7236 sgml-declaration:"~/SGML/HTML4.decl"
  7237 sgml-default-doctype-name:"html"
  7238 sgml-minimize-attributes:t
  7239 sgml-nofill-elements:("pre" "style" "br")
  7240 sgml-live-element-indicator:t
  7241 sgml-omittag:nil
  7242 sgml-shorttag:nil
  7243 sgml-namecase-general:t
  7244 sgml-general-insert-case:lower
  7245 sgml-always-quote-attributes:t
  7246 sgml-indent-step:nil
  7247 sgml-indent-data:t
  7248 sgml-parent-document:nil
  7249 sgml-exposed-tags:nil
  7250 sgml-local-catalogs:nil
  7251 sgml-local-ecat-files:nil
  7252 End:
  7253 -->
  7254 <!--
  7256 to do:
  7258 - wording of OpenType family name handling
  7259 - handling combining sequences in the font matching algorithm
  7260 - fix-up fi ligature example
  7262 -->

mercurial