css-fonts/Fonts.html

Mon, 10 Jun 2013 17:47:39 +0900

author
John Daggett <jdaggett@mozilla.com>
date
Mon, 10 Jun 2013 17:47:39 +0900
changeset 8397
8b231a13093c
parent 8391
f8ed09648c85
child 8430
330ae631cc35
permissions
-rw-r--r--

[css3-fonts] editorial fixes in cluster matching section

     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-10-june-2013>Editor's Draft 10
   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-20130610/">http://www.w3.org/TR/2013/ED-css3-fonts-20130610/</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>In situations where font fallback occurs, fallback fonts may not share
  1657    the same aspect ratio as the desired font family and will thus appear less
  1658    readable. The font-size-adjust property is a way to preserve the
  1659    readability of text when font fallback occurs. It does this by adjusting
  1660    the font-size so that the x-height is the same regardless of the font
  1661    used.
  1663   <div class=example>
  1664    <p>The style defined below defines Verdana as the desired font family, but
  1665     if Verdana is not available Futura or Times will be used.</p>
  1667    <pre>p {
  1668     font-family: Verdana, Futura, Times;
  1671 &lt;p>Lorem ipsum dolor sit amet, ...&lt;/p>
  1672 </pre>
  1674    <p>Verdana has a relatively high aspect ratio, lowercase letters are
  1675     relatively tall compared to uppercase letters, so at small sizes text
  1676     appears legible. Times has a lower aspect ratio and so if fallback
  1677     occurs, the text will be less legible at small sizes than Verdana.</p>
  1678   </div>
  1680   <p>How text rendered in each of these fonts compares is shown below, the
  1681    columns show text rendered in Verdana, Futura and Times. The same
  1682    font-size value is used across cells within each row and red lines are
  1683    included to show the differences in x-height. In the upper half each row
  1684    is rendered in the same font-size value. The same is true for the lower
  1685    half but in this half the font-size-adjust property is also set so that
  1686    the actual font size is adjusted to preserve the x-height across each row.
  1687    Note how small text remains relatively legible across each row in the
  1688    lower half.
  1690   <div class=figure><img alt="text with and without font-size-adjust"
  1691    src=fontsizeadjust.png>
  1692    <p class=caption>Text with and without the use of font-size-adjust
  1693   </div>
  1695   <p>This property allows authors to specify an aspect value for an element
  1696    that will effectively preserve the x-height of the first choice font,
  1697    whether it is substituted or not. Values have the following meanings:
  1699   <dl>
  1700    <dt><dfn id=font-size-adjust-none-value
  1701     title="none!!font-size-adjust">none</dfn>
  1703    <dd>Do not preserve the font's x-height.
  1705    <dt><dfn id=font-size-adjust-auto-value
  1706     title="auto!!font-size-adjust">auto</dfn>
  1708    <dd>Behaves just like &lt;number>, except the number used is the aspect
  1709     value calculated by user agents for the first font in the list of fonts
  1710     defined for the initial value of the <a href="#propdef-font-family"
  1711     title="font-family!!property">‘<code
  1712     class=property>font-family</code>’</a> property. Effectively this is
  1713     the default font used when <a href="#propdef-font-family"
  1714     title="font-family!!property">‘<code
  1715     class=property>font-family</code>’</a> is not otherwise specified.
  1716     <p>Authors can use this value to specify that font size should be
  1717      normalized across fonts based on the x-height without the need to
  1718      specify the aspect ratio explicitly.</p>
  1720    <dt><dfn id=aspect-ratio-value><var>&lt;number&gt;</var></dfn>
  1722    <dd>Specifies the aspect value used in the calculation below to calculate
  1723     the adjusted font size:
  1724     <pre>c  =  ( a / a' ) s
  1725 </pre>
  1727     <p>where:</p>
  1729     <pre>s  =  font-size value
  1730 a  =  aspect value as specified by the font-size-adjust property
  1731 a' =  aspect value of actual font
  1732 c  =  adjusted font-size to use
  1733 </pre>
  1735     <p>This value applies to any font that is selected but in typical usage
  1736      it should be based on the aspect value of the first font in the
  1737      font-family list. If this is specified accurately, the <tt>(a/a')</tt>
  1738      term in the formula above is effectively 1 for the first font and no
  1739      adjustment occurs. If the value is specified inaccurately, text rendered
  1740      using the first font in the family list will display differently in
  1741      older user agents that don't support font-size-adjust.</p>
  1742   </dl>
  1744   <p>Authors can calculate the aspect value for a given font by comparing
  1745    spans with the same content but different font-size-adjust properties. If
  1746    the same font-size is used, the spans will match when the font-size-adjust
  1747    value is accurate for the given font.
  1749   <div class=example>
  1750    <p>Two spans with borders are used to determine the aspect value of a
  1751     font. The font-size is the same for both spans but the font-size-adjust
  1752     property is specified only for the right span. Starting with a value of
  1753     0.5, the aspect value can be adjusted until the borders around the two
  1754     letters line up.</p>
  1756    <pre>p {
  1757     font-family: Futura;
  1758     font-size: 500px;
  1761 span {
  1762     border: solid 1px red;
  1765 .adjust {
  1766     font-size-adjust: 0.5;
  1769 &lt;p>&lt;span>b&lt;/span>&lt;span class="adjust">b&lt;/span>&lt;/p>
  1770 </pre>
  1772    <div class=figure><img alt="Futura with an aspect value of 0.5"
  1773     src=beforefontsizeadjust.png>
  1774     <p class=caption>Futura with an aspect value of 0.5
  1775    </div>
  1777    <p>The box on the right is a bit bigger than the one on the left, so the
  1778     aspect value of this font is something less than 0.5. Adjust the value
  1779     until the boxes align.</p>
  1780   </div>
  1781   <!-- prop: font -->
  1783   <h3 id=font-prop><span class=secno>3.7 </span>Shorthand font property: the
  1784    <a href="#propdef-font">font</a> property</h3>
  1786   <table class=propdef id=namefontvalue-ltlsquofont-stylersquogt-l>
  1787    <tbody>
  1788     <tr>
  1789      <td>Name:
  1791      <td><dfn id=propdef-font>font</dfn>
  1793     <tr>
  1794      <td>Value:
  1796      <td>[ [ <var>&lt;<a href="#propdef-font-style"
  1797       title="font-style!!property">‘<code
  1798       class=property>font-style</code>’</a>&gt;</var> || <a
  1799       href="#font-variant-css21-values"><var>&lt;font-variant-css21&gt;</var></a>
  1800       || <var>&lt;<a href="#propdef-font-weight"
  1801       title="font-weight!!property">‘<code
  1802       class=property>font-weight</code>’</a>&gt;</var> || <var>&lt;<a
  1803       href="#propdef-font-stretch" title="font-stretch!!property">‘<code
  1804       class=property>font-stretch</code>’</a></var> ]? <var>&lt;‘<a
  1805       href="#propdef-font-size"><code
  1806       class=property>font-size</code></a>’&gt;</var> [ / <var>&lt;‘<code
  1807       class=property>line-height</code>’&gt;</var> ]? <var>&lt;<a
  1808       href="#propdef-font-family" title="font-family!!property">‘<code
  1809       class=property>font-family</code>’</a>&gt;</var> ] | caption | icon |
  1810       menu | message-box | small-caption | status-bar
  1812     <tr>
  1813      <td>Initial:
  1815      <td>see individual properties
  1817     <tr>
  1818      <td>Applies to:
  1820      <td>all elements
  1822     <tr>
  1823      <td>Inherited:
  1825      <td>yes
  1827     <tr>
  1828      <td>Percentages:
  1830      <td>see individual properties
  1832     <tr>
  1833      <td>Media:
  1835      <td>visual
  1837     <tr>
  1838      <td>Computed value:
  1840      <td>see individual properties
  1842     <tr>
  1843      <td>Animatable:
  1845      <td>see individual properties
  1846   </table>
  1848   <p>The <span class=property>‘<a href="#propdef-font"><code
  1849    class=property>font</code></a>’</span> property is, except as described
  1850    below, a shorthand property for setting <a href="#propdef-font-style"
  1851    title="font-style!!property">‘<code
  1852    class=property>font-style</code>’</a>, <a href="#propdef-font-variant"
  1853    title="font-variant!!property">‘<code
  1854    class=property>font-variant</code>’</a>, <a href="#propdef-font-weight"
  1855    title="font-weight!!property">‘<code
  1856    class=property>font-weight</code>’</a>, <a href="#propdef-font-stretch"
  1857    title="font-stretch!!property">‘<code
  1858    class=property>font-stretch</code>’</a>, <span class=property>‘<a
  1859    href="#propdef-font-size"><code
  1860    class=property>font-size</code></a>’</span>, <a class=property
  1861    href="http://www.w3.org/TR/CSS2/visudet.html#propdef-line-height">‘<code
  1862    class=property>line-height</code>’</a>, <a href="#propdef-font-family"
  1863    title="font-family!!property">‘<code
  1864    class=property>font-family</code>’</a> at the same place in the
  1865    stylesheet. Values for the <a href="#propdef-font-variant"
  1866    title="font-variant!!property">‘<code
  1867    class=property>font-variant</code>’</a> property may also be included
  1868    but only those supported in CSS 2.1, none of the <a
  1869    href="#propdef-font-variant" title="font-variant!!property">‘<code
  1870    class=property>font-variant</code>’</a> values added in this
  1871    specification can be used in the <span class=property>‘<a
  1872    href="#propdef-font"><code class=property>font</code></a>’</span>
  1873    shorthand:
  1875   <pre
  1876    class=prod><dfn id=font-variant-css21-values><var>&lt;font-variant-css21&gt;</var></dfn> = [normal | small-caps]</pre>
  1878   <p>The syntax of this property is based on a traditional typographical
  1879    shorthand notation to set multiple properties related to fonts.
  1881   <p>All subproperties of the ‘<a href="#propdef-font"><code
  1882    class=property>font</code></a>’ property are first reset to their
  1883    initial values, including those listed above plus <span
  1884    class=property>‘<a href="#propdef-font-size-adjust"><code
  1885    class=property>font-size-adjust</code></a>’</span>, <span
  1886    class=property>‘<a href="#propdef-font-kerning"><code
  1887    class=property>font-kerning</code></a>’</span>, subproperties of <a
  1888    href="#propdef-font-variant" title="font-variant!!property">‘<code
  1889    class=property>font-variant</code>’</a> and and <span>‘<a
  1890    href="#propdef-font-language-override"><code
  1891    class=property>font-language-override</code></a>’</span>. Then, those
  1892    properties that are given explicit values in the <span
  1893    class=property>‘<a href="#propdef-font"><code
  1894    class=property>font</code></a>’</span> shorthand are set to those
  1895    values. For a definition of allowed and initial values, see the previously
  1896    defined properties. For reasons of backwards compatibility, it is not
  1897    possible to set <span class=property>‘<a
  1898    href="#propdef-font-size-adjust"><code
  1899    class=property>font-size-adjust</code></a>’</span> to anything other
  1900    than its initial value using the <span class=property>‘<a
  1901    href="#propdef-font"><code class=property>font</code></a>’</span>
  1902    shorthand property; instead, use the individual property.
  1904   <div class=example>
  1905    <p style="display:none">Example(s):
  1907    <p>
  1909    <pre>p { font: 12pt/14pt sans-serif }
  1910 p { font: 80% sans-serif }
  1911 p { font: x-large/110% &quot;new century schoolbook&quot;, serif }
  1912 p { font: bold italic large Palatino, serif }
  1913 p { font: normal small-caps 120%/120% fantasy }
  1914 p { font: condensed oblique 12pt &quot;Helvetica Neue&quot;, serif; }
  1915 </pre>
  1917    <p> In the second rule, the font size percentage value (‘<code
  1918     class=css>80%</code>’) refers to the computed ‘<a
  1919     href="#propdef-font-size"><code class=property>font-size</code></a>’ of
  1920     the parent element. In the third rule, the line height percentage
  1921     (‘<code class=css>110%</code>’) refers to the font size of the
  1922     element itself.
  1924    <p>The first three rules do not specify the <a
  1925     href="#propdef-font-variant" title="font-variant!!property">‘<code
  1926     class=property>font-variant</code>’</a> and <a
  1927     href="#propdef-font-weight" title="font-weight!!property">‘<code
  1928     class=property>font-weight</code>’</a> explicitly, so these properties
  1929     receive their initial values (<span title="normal value">‘<code
  1930     class=property>normal</code>’</span>). Notice that the font family name
  1931     "new century schoolbook", which contains spaces, is enclosed in quotes.
  1932     The fourth rule sets the <a href="#propdef-font-weight"
  1933     title="font-weight!!property">‘<code
  1934     class=property>font-weight</code>’</a> to ‘<a href="#bold"><code
  1935     class=property>bold</code></a>’, the <a href="#propdef-font-style"
  1936     title="font-style!!property">‘<code
  1937     class=property>font-style</code>’</a> to ‘<a href="#italic"><code
  1938     class=property>italic</code></a>’, and implicitly sets <a
  1939     href="#propdef-font-variant" title="font-variant!!property">‘<code
  1940     class=property>font-variant</code>’</a> to <a
  1941     href="#font-variant-normal-value" title="normal!!font-variant">‘<code
  1942     class=property>normal</code>’</a>.
  1944    <p> The fifth rule sets the <a href="#propdef-font-variant"
  1945     title="font-variant!!property">‘<code
  1946     class=property>font-variant</code>’</a> (‘<a href="#small-caps"><code
  1947     class=property>small-caps</code></a>’), the <span class=property>‘<a
  1948     href="#propdef-font-size"><code
  1949     class=property>font-size</code></a>’</span> (120% of the parent's font
  1950     size), the <a class=property
  1951     href="http://www.w3.org/TR/CSS2/visudet.html#propdef-line-height">‘<code
  1952     class=property>line-height</code>’</a> (120% of the font size) and the
  1953     <a href="#propdef-font-family" title="font-family!!property">‘<code
  1954     class=property>font-family</code>’</a> (‘<a href="#fantasy"><code
  1955     class=property>fantasy</code></a>’). It follows that the keyword <span
  1956     title="normal value">‘<code class=property>normal</code>’</span>
  1957     applies to the two remaining properties: <a href="#propdef-font-style"
  1958     title="font-style!!property">‘<code
  1959     class=property>font-style</code>’</a> and <a
  1960     href="#propdef-font-weight" title="font-weight!!property">‘<code
  1961     class=property>font-weight</code>’</a>.
  1963    <p>The sixth rule sets the <a href="#propdef-font-style"
  1964     title="font-style!!property">‘<code
  1965     class=property>font-style</code>’</a>, <a href="#propdef-font-stretch"
  1966     title="font-stretch!!property">‘<code
  1967     class=property>font-stretch</code>’</a>, <span class=property>‘<a
  1968     href="#propdef-font-size"><code
  1969     class=property>font-size</code></a>’</span>, and <a
  1970     href="#propdef-font-family" title="font-family!!property">‘<code
  1971     class=property>font-family</code>’</a>, the other font properties being
  1972     set to their initial values.
  1973   </div>
  1975   <p>Since the <a href="#propdef-font-stretch"
  1976    title="font-stretch!!property">‘<code
  1977    class=property>font-stretch</code>’</a> property was not defined in CSS
  1978    2.1, when using <a href="#propdef-font-stretch"
  1979    title="font-stretch!!property">‘<code
  1980    class=property>font-stretch</code>’</a> values within ‘<a
  1981    href="#propdef-font"><code class=property>font</code></a>’ rules,
  1982    authors should include a extra version compatible with older user agents:
  1984   <pre>p {
  1985   font: 80% sans-serif;   /* for older user agents */
  1986   font: condensed 80% sans-serif;
  1987 }</pre>
  1989   <p>The following values refer to system fonts:
  1991   <dl>
  1992    <dt><strong>caption</strong>
  1994    <dd>The font used for captioned controls (e.g., buttons, drop-downs,
  1995     etc.).
  1997    <dt><strong>icon</strong>
  1999    <dd>The font used to label icons.
  2001    <dt><strong>menu</strong>
  2003    <dd>The font used in menus (e.g., dropdown menus and menu lists).
  2005    <dt><strong>message-box</strong>
  2007    <dd>The font used in dialog boxes.
  2009    <dt><strong>small-caption</strong>
  2011    <dd>The font used for labeling small controls.
  2013    <dt><strong>status-bar</strong>
  2015    <dd>The font used in window status bars.
  2016   </dl>
  2018   <p>System fonts may only be set as a whole; that is, the font family, size,
  2019    weight, style, etc. are all set at the same time. These values may then be
  2020    altered individually if desired. If no font with the indicated
  2021    characteristics exists on a given platform, the user agent should either
  2022    intelligently substitute (e.g., a smaller version of the ‘<code
  2023    class=property>caption</code>’ font might be used for the ‘<code
  2024    class=property>small-caption</code>’ font), or substitute a user agent
  2025    default font. As for regular fonts, if, for a system font, any of the
  2026    individual properties are not part of the operating system's available
  2027    user preferences, those properties should be set to their initial values.
  2029   <p>That is why this property is "almost" a shorthand property: system fonts
  2030    can only be specified with this property, not with <a
  2031    href="#propdef-font-family" title="font-family!!property">‘<code
  2032    class=property>font-family</code>’</a> itself, so <span
  2033    class=property>‘<a href="#propdef-font"><code
  2034    class=property>font</code></a>’</span> allows authors to do more than
  2035    the sum of its subproperties. However, the individual properties such as
  2036    <a href="#propdef-font-weight" title="font-weight!!property">‘<code
  2037    class=property>font-weight</code>’</a> are still given values taken from
  2038    the system font, which can be independently varied.
  2040   <p>Note that the keywords used for the system fonts listed above are only
  2041    treated as keywords when they occur in the initial position, in other
  2042    positions the same string is treated as part of the font family name:
  2044   <pre>  font: menu;        /* use the font settings for system menus */
  2045   font: large menu;  /* use a font family named "menu" */</pre>
  2047   <div class=example>
  2048    <p style="display:none">Example(s):
  2050    <p>
  2052    <pre>button { font: 300 italic 1.3em/1.7em &quot;FB Armada&quot;, sans-serif }
  2053 button p { font: menu }
  2054 button p em { font-weight: bolder }
  2055 </pre>
  2057    <p>If the font used for dropdown menus on a particular system happened to
  2058     be, for example, 9-point Charcoal, with a weight of 600, then P elements
  2059     that were descendants of BUTTON would be displayed as if this rule were
  2060     in effect:
  2062    <pre>button p { font: 600 9pt Charcoal }
  2063 </pre>
  2065    <p>Because the <span class=property>‘<a href="#propdef-font"><code
  2066     class=property>font</code></a>’</span> shorthand resets to its initial
  2067     value any property not explicitly given a value, this has the same effect
  2068     as this declaration:
  2070    <pre>button p {
  2071   font-style: normal;
  2072   font-variant: normal;
  2073   font-weight: 600;
  2074   font-size: 9pt;
  2075   line-height: normal;
  2076   font-family: Charcoal
  2078 </pre>
  2079   </div>
  2080   <!-- prop: font-synthesis -->
  2082   <h3 id=font-synthesis-prop><span class=secno>3.8 </span>Controlling
  2083    synthetic faces: the <a href="#propdef-font-synthesis">font-synthesis</a>
  2084    property</h3>
  2086   <table class=propdef id=namefont-synthesisvaluenone-weight-style>
  2087    <tbody>
  2088     <tr>
  2089      <td>Name:
  2091      <td><dfn id=propdef-font-synthesis>font-synthesis</dfn>
  2093     <tr>
  2094      <td>Value:
  2096      <td>none | [ weight || style ]
  2098     <tr>
  2099      <td>Initial:
  2101      <td>weight style
  2103     <tr>
  2104      <td>Applies to:
  2106      <td>all elements
  2108     <tr>
  2109      <td>Inherited:
  2111      <td>yes
  2113     <tr>
  2114      <td>Percentages:
  2116      <td>N/A
  2118     <tr>
  2119      <td>Media:
  2121      <td>visual
  2123     <tr>
  2124      <td>Computed value:
  2126      <td>as specified
  2128     <tr>
  2129      <td>Animatable:
  2131      <td>no
  2132   </table>
  2134   <p>This property controls whether user agents are allowed to synthesize
  2135    bold or oblique font faces when a font family lacks bold or italic faces.
  2136    If ‘<a href="#weight"><code class=property>weight</code></a>’ is not
  2137    specified, user agents must not synthesize bold faces and if ‘<code
  2138    class=property>style</code>’ is not specified user agents must not
  2139    synthesize italic faces. A value of ‘<code class=property>none</code>’
  2140    disallows all synthetic faces.
  2142   <div class=example>
  2143    <p>The style rule below disables the use of synthetically obliqued Arabic:</p>
  2145    <pre>*:lang(ar) { font-synthesis: none; }
  2146 </pre>
  2147   </div>
  2149   <h2 id=font-resources><span class=secno>4 </span>Font Resources</h2>
  2151   <h3 id=font-face-rule><span class=secno>4.1 </span>The <dfn
  2152    id=at-font-face-rule style="font-weight: inherit; font-style:
  2153    inherit"><code>@font-face</code></dfn> rule</h3>
  2155   <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule allows
  2156    for linking to fonts that are automatically fetched and activated when
  2157    needed. This allows authors to select a font that closely matches the
  2158    design goals for a given page rather than limiting the font choice to a
  2159    set of fonts available on all platforms. A set of font descriptors define
  2160    the location of a font resource, either locally or externally, along with
  2161    the style characteristics of an individual face. Multiple <a
  2162    href="#at-font-face-rule"><code>@font-face</code></a> rules can be used to
  2163    construct font families with a variety of faces. Using CSS font matching
  2164    rules, a user agent can selectively download only those faces that are
  2165    needed for a given piece of text.
  2167   <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule
  2168    consists of the <a href="#at-font-face-rule"><code>@font-face</code></a>
  2169    at-keyword followed by a block of descriptor declarations. In terms of the
  2170    grammar, this specification defines the following productions:
  2172   <pre><dfn id=fontfacerule>font_face_rule</dfn>
  2173   : <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>*
  2176 <dfn id=descriptordeclaration>descriptor_declaration</dfn>
  2177   : <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>
  2178   ;</pre>
  2180   <p>The following new definitions are introduced:
  2182   <pre>-    -|\\0{0,4}2d(\r\n|[ \t\r\n\f])?
  2183 F    f|\\0{0,4}(46|66)(\r\n|[ \t\r\n\f])?</pre>
  2185   <p>The following new token is introduced:
  2187   <pre>@{F}{O}{N}{T}{-}{F}{A}{C}{E} {return <dfn id=fontfacesym>FONT_FACE_SYM</dfn>;}</pre>
  2189   <p>Each <a href="#at-font-face-rule"><code>@font-face</code></a> rule
  2190    specifies a value for every font descriptor, either implicitly or
  2191    explicitly. Those not given explicit values in the rule take the initial
  2192    value listed with each descriptor in this specification. These descriptors
  2193    apply solely within the context of the <a
  2194    href="#at-font-face-rule"><code>@font-face</code></a> rule in which they
  2195    are defined, and do not apply to document language elements. There is no
  2196    notion of which elements the descriptors apply to or whether the values
  2197    are inherited by child elements. When a given descriptor occurs multiple
  2198    times in a given <a href="#at-font-face-rule"><code>@font-face</code></a>
  2199    rule, only the last descriptor declaration is used and all prior
  2200    declarations for that descriptor are ignored.
  2202   <div class=example>
  2203    <p>To use a downloadable font called Gentium:</p>
  2205    <pre>
  2206 @font-face {
  2207   font-family: Gentium;
  2208   src: url(http://example.com/fonts/Gentium.ttf);
  2211 p { font-family: Gentium, serif; }
  2212 </pre>
  2214    <p>The user agent will download Gentium and use it when rendering text
  2215     within paragraph elements. If for some reason the site serving the font
  2216     is unavailable, the default serif font will be used.</p>
  2217   </div>
  2219   <p>A given set of <a href="#at-font-face-rule"><code>@font-face</code></a>
  2220    rules define a set of fonts available for use within the documents that
  2221    contain these rules. When font matching is done, fonts defined using these
  2222    rules are considered before other available fonts on a system.
  2224   <p>Downloaded fonts are only available to documents that reference them.
  2225    The process of activating these fonts must not make them available to
  2226    other applications or to documents that don't directly link to the same
  2227    font. User agent implementers might consider it convenient to use
  2228    downloaded fonts when rendering characters in other documents for which no
  2229    other available font exists as part of the <a
  2230    href="#system-font-fallback"><em>system font fallback</em></a> procedure.
  2231    However, this would cause a security leak since the contents of one page
  2232    would be able to affect other pages, something an attacker could use as an
  2233    attack vector. These restrictions do not affect caching behavior, fonts
  2234    are cached the same way other web resources are cached.
  2236   <p>This at-rule follows the forward-compatible parsing rules of CSS. Like
  2237    properties in a declaration block, declarations of any descriptors that
  2238    are not supported by the user agent must be ignored. <a
  2239    href="#at-font-face-rule"><code>@font-face</code></a> rules require a
  2240    font-family and src descriptor; if either of these are missing, the <a
  2241    href="#at-font-face-rule"><code>@font-face</code></a> rule is invalid and
  2242    must be ignored entirely.
  2244   <p>In cases where user agents have limited platform resources or implement
  2245    the ability to disable downloadable font resources, <a
  2246    href="#at-font-face-rule"><code>@font-face</code></a> rules must simply be
  2247    ignored; the behavior of individual descriptors as defined in this
  2248    specification should not be altered.
  2250   <h3 id=font-family-desc><span class=secno>4.2 </span>Font family: the <a
  2251    href="#descdef-font-family">font-family</a> descriptor</h3>
  2253   <table class=descdef>
  2254    <tbody>
  2255     <tr>
  2256      <td>Name:
  2258      <td><dfn id=descdef-font-family
  2259       title="font-family!!descriptor">font-family</dfn>
  2261     <tr>
  2262      <td>Value:
  2264      <td><a href="#family-name-value"><var>&lt;family-name&gt;</var></a>
  2266     <tr>
  2267      <td><em>Initial:</em>
  2269      <td>N/A
  2270   </table>
  2272   <p>This descriptor defines the font family name that will be used in all
  2273    CSS font family name matching. It is required for the <a
  2274    href="#at-font-face-rule"><code>@font-face</code></a> rule to be valid. It
  2275    overrides the font family names contained in the underlying font data. If
  2276    the font family name is the same as a font family available in a given
  2277    user's environment, it effectively hides the underlying font for documents
  2278    that use the stylesheet. This permits a web author to freely choose
  2279    font-family names without worrying about conflicts with font family names
  2280    present in a given user's environment. Likewise, platform substitutions
  2281    for a given font family name must not be used.
  2283   <h3 id=src-desc><span class=secno>4.3 </span>Font reference: the <a
  2284    href="#descdef-src">src</a> descriptor</h3>
  2286   <table class=descdef>
  2287    <tbody>
  2288     <tr>
  2289      <td>Name:
  2291      <td><dfn id=descdef-src>src</dfn>
  2293     <tr>
  2294      <td>Value:
  2296      <td>[ &lt;url> [format(&lt;string> #)]? | <a
  2297       href="#font-face-name-value"><var>&lt;font-face-name&gt;</var></a> ] #
  2299     <tr>
  2300      <td><em>Initial:</em>
  2302      <td>N/A
  2303   </table>
  2305   <p>This descriptor specifies the resource containing font data. It is
  2306    required for the <a href="#at-font-face-rule"><code>@font-face</code></a>
  2307    rule to be valid. Its value is a prioritized, comma-separated list of
  2308    external references or locally-installed font face names. When a font is
  2309    needed the user agent iterates over the set of references listed, using
  2310    the first one it can successfully activate. Fonts containing invalid data
  2311    or local font faces that are not found are ignored and the user agent
  2312    loads the next font in the list.
  2314   <p>As with other URLs in CSS, the URL may be relative, in which case it is
  2315    resolved relative to the location of the style sheet containing the <a
  2316    href="#at-font-face-rule"><code>@font-face</code></a> rule. In the case of
  2317    SVG fonts, the URL points to an element within a document containing SVG
  2318    font definitions. If the element reference is omitted, a reference to the
  2319    first defined font is implied. Similarly, font container formats that can
  2320    contain more than one font must load one and only one of the fonts for a
  2321    given <a href="#at-font-face-rule"><code>@font-face</code></a> rule.
  2322    Fragment identifiers are used to indicate which font to load. If a
  2323    container format lacks a defined fragment identifier scheme,
  2324    implementations should use a simple 1-based indexing scheme (e.g.
  2325    "font-collection#1" for the first font, "font-collection#2" for the second
  2326    font).
  2328   <pre>
  2329 src: url(fonts/simple.ttf);   /* load simple.ttf relative to stylesheet location */
  2330 src: url(/fonts/simple.ttf);  /* load simple.ttf from absolute location */
  2331 src: url(fonts.svg#simple);   /* load SVG font with id 'simple' */
  2332 </pre>
  2334   <p>External references consist of a URL, followed by an optional hint
  2335    describing the format of the font resource referenced by that URL. The
  2336    format hint contains a comma-separated list of format strings that denote
  2337    well-known font formats. Conformant user agents must skip downloading a
  2338    font resource if the format hints indicate only unsupported or unknown
  2339    font formats. If no format hints are supplied, the user agent should
  2340    download the font resource.
  2342   <pre>
  2343 /* load WOFF font if possible, otherwise use OpenType font */
  2344 @font-face {
  2345   font-family: bodytext;
  2346   src: url(ideal-sans-serif.woff) format("woff"),
  2347        url(basic-sans-serif.ttf) format("opentype");
  2349 </pre>
  2351   <p>Format strings defined by this specification:
  2353   <table class=data id=fontformats>
  2354    <thead>
  2355     <tr>
  2356      <th>String
  2358      <th>Font Format
  2360      <th>Common extensions
  2362    <tbody>
  2363     <tr>
  2364      <th>"woff"
  2366      <td><a href="http://www.w3.org/TR/WOFF/">WOFF (Web Open Font Format)</a>
  2368      <td>.woff
  2370     <tr>
  2371      <th>"truetype"
  2373      <td><a
  2374       href="http://www.microsoft.com/typography/otspec/default.htm">TrueType</a>
  2376      <td>.ttf
  2378     <tr>
  2379      <th>"opentype"
  2381      <td><a
  2382       href="http://www.microsoft.com/typography/otspec/default.htm">OpenType</a>
  2384      <td>.ttf, .otf
  2386     <tr>
  2387      <th>"embedded-opentype"
  2389      <td><a
  2390       href="http://www.w3.org/Submission/2008/SUBM-EOT-20080305/">Embedded
  2391       OpenType</a>
  2393      <td>.eot
  2395     <tr>
  2396      <th>"svg"
  2398      <td><a href="http://www.w3.org/TR/SVG/fonts.html">SVG Font</a>
  2400      <td>.svg, .svgz
  2401   </table>
  2403   <p>Given the overlap in common usage between TrueType and OpenType, the
  2404    format hints "truetype" and "opentype" must be considered as synonymous; a
  2405    format hint of "opentype" does not imply that the font contains Postscript
  2406    CFF style glyph data or that it contains OpenType layout information (see
  2407    <a href="#platform-props-to-css">Appendix A</a> for more background on
  2408    this).
  2410   <p>When authors would prefer to use a locally available copy of a given
  2411    font and download it if it's not, <code>local()</code> can be used. The
  2412    locally-installed <dfn
  2413    id=font-face-name-value><var>&lt;font-face-name&gt;</var></dfn> argument
  2414    to <code>local()</code> is a format-specific string that uniquely
  2415    identifies a single font face within a larger family. The syntax for a <a
  2416    href="#font-face-name-value"><var>&lt;font-face-name&gt;</var></a> is a
  2417    unique font face name enclosed by "local(" and ")". The name can
  2418    optionally be enclosed in quotes. If unquoted, the unquoted font family
  2419    name processing conventions apply; the name must be a sequence of
  2420    identifiers separated by whitespace which is converted to a string by
  2421    joining the identifiers together separated by a single space.
  2423   <pre>
  2424 /* regular face of Gentium */
  2425 @font-face {
  2426   font-family: MyGentium;
  2427   src: local(Gentium),   /* use locally available Gentium */
  2428        url(Gentium.ttf); /* otherwise, download it */
  2430 </pre>
  2432   <p>For OpenType and TrueType fonts, this string is used to match only the
  2433    Postscript name or the full font name in the name table of locally
  2434    available fonts. Which type of name is used varies by platform and font,
  2435    so authors should include both of these names to assure proper matching
  2436    across platforms. Platform substitutions for a given font name must not be
  2437    used.
  2439   <pre>
  2440 /* bold face of Gentium */
  2441 @font-face {
  2442   font-family: MyGentium;
  2443   src: local(Gentium Bold),   /* full font name */
  2444        local(Gentium-Bold),   /* Postscript name */
  2445        url(GentiumBold.ttf);  /* otherwise, download it */
  2446   font-weight: bold;
  2448 </pre>
  2450   <p>Just as a <a href="#at-font-face-rule"><code>@font-face</code></a> rule
  2451    specifies the characteristics of a single font within a family, the unique
  2452    name used with <code>local()</code> specifies a single font, not an entire
  2453    font family. Defined in terms of OpenType font data, the Postscript name
  2454    is found in the font's <a
  2455    href="http://www.microsoft.com/typography/otspec/name.htm">name table</a>,
  2456    in the name record with nameID = 6 (see <a href="#OPENTYPE"
  2457    rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a> for more details). The
  2458    Postscript name is the commonly used key for all fonts on OSX and for
  2459    Postscript CFF fonts under Windows. The full font name (nameID = 4) is
  2460    used as a unique key for fonts with TrueType glyphs on Windows.
  2462   <p>For OpenType fonts with multiple localizations of the full font name,
  2463    the US English version is used (language ID = 0x409 for Windows and
  2464    language ID = 0 for Macintosh) or the first localization when a US English
  2465    full font name is not available (the OpenType specification recommends
  2466    that <a href="http://www.microsoft.com/typography/otspec/recom.htm">all
  2467    fonts minimally include US English names</a>). User agents that also match
  2468    other full font names, e.g. matching the Dutch name when the current
  2469    system locale is set to Dutch, are considered non-conformant. This is done
  2470    not to prefer English but to avoid matching inconsistencies across font
  2471    versions and OS localizations, since font style names (e.g. "Bold") are
  2472    frequently localized into many languages and the set of localizations
  2473    available varies widely across platform and font version. User agents that
  2474    match a concatenation of family name (nameID = 1) with style name (nameID
  2475    = 2) are considered non-conformant.
  2477   <p>This also allows for referencing faces that belong to larger families
  2478    that cannot otherwise be referenced.
  2480   <div class=example>
  2481    <p>Use a local font or reference an SVG font in another document:</p>
  2483    <pre>
  2484 @font-face {
  2485   font-family: Headline;
  2486   src: local(Futura-Medium),
  2487        url(fonts.svg#MyGeometricModern) format("svg");
  2489 </pre>
  2491    <p>Create an alias for local Japanese fonts on different platforms:</p>
  2493    <pre>
  2494 @font-face {
  2495   font-family: jpgothic;
  2496   src: local(HiraKakuPro-W3), local(Meiryo), local(IPAPGothic);
  2498 </pre>
  2500    <p>Reference a font face that cannot be matched within a larger family:</p>
  2502    <pre>
  2503 @font-face {
  2504   font-family: Hoefler Text Ornaments;
  2505   /* has the same font properties as Hoefler Text Regular */
  2506   src: local(HoeflerText-Ornaments);
  2508 </pre>
  2510    <p>Since localized fullnames never match, a document with the header style
  2511     rules below would always render using the default serif font, regardless
  2512     whether a particular system locale parameter is set to Finnish or not:</p>
  2514    <pre>
  2515 @font-face {
  2516   font-family: SectionHeader;
  2517   src: local("Arial Lihavoitu");  /* Finnish fullname for Arial Bold, should fail */
  2518   font-weight: bold;
  2521 h2 { font-family: SectionHeader, serif; }
  2522 </pre>
  2524    <p>A conformant user agent would never load the font ‘<code
  2525     class=css>gentium.eot</code>’ in the example below, since it is
  2526     included in the first definition of the ‘<a href="#descdef-src"><code
  2527     class=property>src</code></a>’ descriptor which is overridden by the
  2528     second definition in the same <a
  2529     href="#at-font-face-rule"><code>@font-face</code></a> rule:</p>
  2531    <pre>
  2532 @font-face {
  2533   font-family: MainText;
  2534   src: url(gentium.eot); /* for use with older non-conformant user agents */
  2535   src: local("Gentium"), url(gentium.ttf);  /* Overrides src definition */
  2537 </pre>
  2538   </div>
  2540   <h3 id=font-prop-desc><span class=secno>4.4 </span>Font property
  2541    descriptors: the <a href="#descdef-font-style">font-style</a>, <a
  2542    href="#descdef-font-weight">font-weight</a>, <a
  2543    href="#descdef-font-stretch">font-stretch</a> descriptors</h3>
  2545   <table class=descdef>
  2546    <tbody>
  2547     <tr>
  2548      <td>Name:
  2550      <td><dfn id=descdef-font-style
  2551       title="font-style!!descriptor">font-style</dfn>
  2553     <tr>
  2554      <td>Value:
  2556      <td>normal | italic | oblique
  2558     <tr>
  2559      <td><em>Initial:</em>
  2561      <td>normal
  2562   </table>
  2564   <table class=descdef>
  2565    <tbody>
  2566     <tr>
  2567      <td>Name:
  2569      <td><dfn id=descdef-font-weight
  2570       title="font-weight!!descriptor">font-weight</dfn>
  2572     <tr>
  2573      <td>Value:
  2575      <td>normal | bold | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900
  2577     <tr>
  2578      <td><em>Initial:</em>
  2580      <td>normal
  2581   </table>
  2583   <table class=descdef>
  2584    <tbody>
  2585     <tr>
  2586      <td>Name:
  2588      <td><dfn id=descdef-font-stretch
  2589       title="font-stretch!!descriptor">font-stretch</dfn>
  2591     <tr>
  2592      <td>Value:
  2594      <td>normal | ultra-condensed | extra-condensed | condensed |
  2595       semi-condensed | semi-expanded | expanded | extra-expanded |
  2596       ultra-expanded
  2598     <tr>
  2599      <td><em>Initial:</em>
  2601      <td>normal
  2602   </table>
  2604   <p>These descriptors define the characteristics of a font face and are used
  2605    in the process of matching styles to specific faces. For a font family
  2606    defined with several <a
  2607    href="#at-font-face-rule"><code>@font-face</code></a> rules, user agents
  2608    can either download all faces in the family or use these descriptors to
  2609    selectively download font faces that match actual styles used in document.
  2610    The values for these descriptors are the same as those for the
  2611    corresponding font properties except that relative keywords are not
  2612    allowed, ‘<a href="#bolder"><code class=property>bolder</code></a>’
  2613    and ‘<a href="#lighter"><code class=property>lighter</code></a>’. If
  2614    these descriptors are omitted, initial values are assumed.
  2616   <p>The value for these font face style attributes is used in place of the
  2617    style implied by the underlying font data. This allows authors to combine
  2618    faces in flexible combinations, even in situations where the original font
  2619    data was arranged differently. User agents that implement synthetic
  2620    bolding and obliquing must only apply synthetic styling in cases where the
  2621    font descriptors imply this is needed, rather than based on the style
  2622    attributes implied by the font data.
  2624   <h3 id=unicode-range-desc><span class=secno>4.5 </span>Character range: the
  2625    <a href="#descdef-unicode-range">unicode-range</a> descriptor</h3>
  2627   <table class=descdef>
  2628    <tbody>
  2629     <tr>
  2630      <td>Name:
  2632      <td><dfn id=descdef-unicode-range>unicode-range</dfn>
  2634     <tr>
  2635      <td>Value:
  2637      <td><a href="#urange-value"><var>&lt;urange&gt;</var></a> #
  2639     <tr>
  2640      <td><em>Initial:</em>
  2642      <td>U+0-10FFFF
  2643   </table>
  2645   <p>This descriptor defines the set of Unicode codepoints that may be
  2646    supported by the font face for which it is declared. The descriptor value
  2647    is a comma-delimited list of Unicode range (<a
  2648    href="#urange-value"><var>&lt;urange&gt;</var></a>) values. The union of
  2649    these ranges defines the set of codepoints that serves as a hint for user
  2650    agents when deciding whether or not to download a font resource for a
  2651    given text run.
  2653   <p>Each <dfn id=urange-value><var>&lt;urange&gt;</var></dfn> value is a <a
  2654    href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><code
  2655    title="UNICODE-RANGE token">UNICODE-RANGE</code></a> token made up of a
  2656    "U+" or "u+" prefix followed by a codepoint range in one of the three
  2657    forms listed below. Ranges that do not fit one of the these forms are
  2658    invalid and cause the declaration to be ignored.
  2660   <dl>
  2661    <dt>single codepoint (e.g. U+416)
  2663    <dd>a valid Unicode codepoint, represented as one to six hexadecimal
  2664     digits
  2666    <dt>interval range (e.g. U+400-4ff)
  2668    <dd>represented as two hyphen-separated valid Unicode codepoints
  2669     indicating the inclusive start and end codepoints of a range
  2671    <dt>wildcard range (e.g. U+4??)
  2673    <dd>defined by the set of codepoints implied when trailing ‘<code
  2674     class=css>?</code>’ characters signify any hexadeximal digit
  2675   </dl>
  2677   <p>Individual codepoints are written using hexadecimal values that
  2678    correspond to <a href="http://www.unicode.org/charts/">Unicode character
  2679    codepoints</a>. Valid Unicode codepoint values vary between 0 and 10FFFF
  2680    inclusive. Digit values of codepoints are ASCII case-insensitive. For
  2681    interval ranges, the start and end codepoints are valid Unicode values and
  2682    the end codepoint is greater than or equal to the start codepoint.
  2684   <p>Wildcard ranges specified with ‘?’ that lack an initial digit (e.g.
  2685    "U+???") are valid and equivalent to a wildcard range with an initial zero
  2686    digit (e.g. "U+0???" = "U+0000-0FFF"). Wildcard ranges that extend beyond
  2687    the range of valid Unicode codepoints are invalid. Because of this, the
  2688    maximum number of trailing ‘<code class=css>?</code>’ wildcard
  2689    characters is five, even though the <a
  2690    href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><code
  2691    title="UNICODE-RANGE token">UNICODE-RANGE</code></a> token accepts six.
  2693   <p>Within the comma-delimited list of Unicode ranges in a ‘<a
  2694    href="#descdef-unicode-range"><code
  2695    class=property>unicode-range</code></a>’ descriptor declaration, ranges
  2696    may overlap. The union of these ranges defines the set of codepoints for
  2697    which the corresponding font may be used. User agents must not download or
  2698    use the font for codepoints outside this set. User agents may normalize
  2699    the list of ranges into a list that is different but represents the same
  2700    set of codepoints.
  2702   <p>The associated font might not contain glyphs for the entire set of
  2703    codepoints defined by the ‘<a href="#descdef-unicode-range"><code
  2704    class=property>unicode-range</code></a>’ descriptor. When the font is
  2705    used, the <dfn id=effective-character-map>effective character map</dfn> is
  2706    the intersection of the codepoints defined by ‘<a
  2707    href="#descdef-unicode-range"><code
  2708    class=property>unicode-range</code></a>’ with the font's <a
  2709    href="#character-map"><em>character map</em></a>. This allows authors to
  2710    define supported ranges in terms of broad ranges without worrying about
  2711    the precise codepoint ranges supported by the underlying font.
  2713   <h3 id=composite-fonts><span class=secno>4.6 </span>Using character ranges
  2714    to define composite fonts</h3>
  2716   <p>Multiple <a href="#at-font-face-rule"><code>@font-face</code></a> rules
  2717    with different unicode ranges for the same family and style descriptor
  2718    values can be used to create composite fonts that mix the glyphs from
  2719    different fonts for different scripts. This can be used to combine fonts
  2720    that only contain glyphs for a single script (e.g. Latin, Greek, Cyrillic)
  2721    or it can be used by authors as a way of segmenting a font into fonts for
  2722    commonly used characters and less frequently used characters. Since the
  2723    user agent will only pull down the fonts it needs this helps reduce page
  2724    bandwidth.
  2726   <p>If the unicode ranges overlap for a set of <a
  2727    href="#at-font-face-rule"><code>@font-face</code></a> rules with the same
  2728    family and style descriptor values, the rules are ordered in the reverse
  2729    order they were defined; the last rule defined is the first to be checked
  2730    for a given character.
  2732   <p>Example ranges for specific languages or characters:
  2734   <dl>
  2735    <dt>unicode-range: U+A5;
  2737    <dd>a single code point, the yen/yuan symbol
  2739    <dt>unicode-range: U+0-7F;
  2741    <dd>code range for basic ASCII characters
  2743    <dt>unicode-range: U+590-5ff;
  2745    <dd>code range for Hebrew characters
  2747    <dt>unicode-range: U+A5, U+4E00-9FFF, U+30??, U+FF00-FF9F;
  2749    <dd>code range for Japanese kanji, hiragana and katakana characters plus
  2750     yen/yuan symbol
  2751   </dl>
  2753   <div class=example>
  2754    <p>The BBC provides news services in a wide variety of languages, many
  2755     that are not well supported across all platforms. Using an <a
  2756     href="#at-font-face-rule"><code>@font-face</code></a> rule, the BBC could
  2757     provide a font for any of these languages, as it already does via a
  2758     manual font download.</p>
  2760    <pre>
  2761 @font-face {
  2762   font-family: BBCBengali;
  2763   src: url(fonts/BBCBengali.ttf) format("opentype");
  2764   unicode-range: U+00-FF, U+980-9FF;
  2766 </pre>
  2767   </div>
  2769   <div class=example>
  2770    <p>Technical documents often require a wide range of symbols. The STIX
  2771     Fonts project is one project aimed at providing fonts to support a wide
  2772     range of technical typesetting in a standardized way. The example below
  2773     shows the use of a font that provides glyphs for many of the mathematical
  2774     and technical symbol ranges within Unicode:</p>
  2776    <pre>
  2777 @font-face {
  2778   font-family: STIXGeneral;
  2779   src: local(STIXGeneral), url(/stixfonts/STIXGeneral.otf);
  2780   unicode-range: U+000-49F, U+2000-27FF, U+2900-2BFF, U+1D400-1D7FF;
  2782 </pre>
  2783   </div>
  2785   <div class=example>
  2786    <p>This example shows how an author can override the glyphs used for Latin
  2787     characters in a Japanese font with glyphs from a different font. The
  2788     first rule specifies no range so it defaults to the entire range. The
  2789     range specified in the second rule overlaps but takes precedence because
  2790     it is defined later.</p>
  2792    <pre>
  2793 @font-face {
  2794   font-family: JapaneseWithGentium;
  2795   src: local(MSMincho);
  2796   /* no range specified, defaults to entire range */
  2799 @font-face {
  2800   font-family: JapaneseWithGentium;
  2801   src: url(../fonts/Gentium.ttf);
  2802   unicode-range: U+0-2FF;
  2804 </pre>
  2805   </div>
  2807   <div class=example>
  2808    <p>Consider a family constructed to optimize bandwidth by separating out
  2809     Latin, Japanese and other characters into different font files:</p>
  2811    <pre>
  2812 /* fallback font - size: 4.5MB */
  2813 @font-face {
  2814   font-family: DroidSans;
  2815   src: url(DroidSansFallback.ttf);
  2816   /* no range specified, defaults to entire range */
  2819 /* Japanese glyphs - size: 1.2MB */
  2820 @font-face {
  2821   font-family: DroidSans;
  2822   src: url(DroidSansJapanese.ttf);
  2823   unicode-range: U+3000-9FFF, U+ff??;
  2826 /* Latin, Greek, Cyrillic along with some
  2827    punctuation and symbols - size: 190KB */
  2828 @font-face {
  2829   font-family: DroidSans;
  2830   src: url(DroidSans.ttf);
  2831   unicode-range: U+000-5FF, U+1e00-1fff, U+2000-2300;
  2833 </pre>
  2835    <p>For simple Latin text, only the font for Latin characters is
  2836     downloaded:</p>
  2838    <pre>
  2839 body { font-family: DroidSans; }
  2841 &lt;p>This is that&lt;/p>
  2842 </pre>
  2844    <p>In this case the user agent first checks the unicode-range for the font
  2845     containing Latin characters (DroidSans.ttf). Since all the characters
  2846     above are in the range U+0-5FF, the user agent downloads the font and
  2847     renders the text with that font.</p>
  2849    <p>Next, consider text that makes use of an arrow character (⇨):</p>
  2851    <pre>
  2852 &lt;p>This &amp;#x21e8; that&lt;p>
  2853 </pre>
  2855    <p>The user agent again first checks the unicode-range of the font
  2856     containing Latin characters. Since U+2000-2300 includes the arrow code
  2857     point (U+21E8), the user agent downloads the font. For this character
  2858     however the Latin font does not have a matching glyph, so the effective
  2859     unicode-range used for font matching excludes this code point. Next, the
  2860     user agent evaluates the Japanese font. The unicode-range for the
  2861     Japanese font, U+3000-9FFF and U+ff??, does not include U+21E8, so the
  2862     user agent does not download the Japanese font. Next the fallback font is
  2863     considered. The <a href="#at-font-face-rule"><code>@font-face</code></a>
  2864     rule for the fallback font does not define unicode-range so its value
  2865     defaults to the range of all Unicode code points. The fallback font is
  2866     downloaded and used to render the arrow character.</p>
  2867   </div>
  2869   <h3 id=font-rend-desc><span class=secno>4.7 </span>Font features: the <a
  2870    href="#descdef-font-variant">font-variant</a> and <a
  2871    href="#descdef-font-feature-settings">font-feature-settings</a>
  2872    descriptors</h3>
  2874   <table class=descdef>
  2875    <tbody>
  2876     <tr>
  2877      <td>Name:
  2879      <td><dfn id=descdef-font-variant
  2880       title="font-variant!!descriptor">font-variant</dfn>
  2882     <tr>
  2883      <td>Value:
  2885      <td><a href="#font-variant-normal-value"
  2886       title="normal!!font-variant">normal</a> | <a
  2887       href="#font-variant-none-value" title="none!!font-variant">none</a> | [
  2888       <a href="#common-lig-values"><var>&lt;common-lig-values&gt;</var></a>
  2889       || <a
  2890       href="#discretionary-lig-values"><var>&lt;discretionary-lig-values&gt;</var></a>
  2891       || <a
  2892       href="#historical-lig-values"><var>&lt;historical-lig-values&gt;</var></a>
  2893       || <a
  2894       href="#contextual-alt-values"><var>&lt;contextual-alt-values&gt;</var></a>
  2895       || <a href="#stylistic"><var
  2896       title=stylistic>stylistic(&lt;feature-value-name&gt;)</var></a> || <a
  2897       href="#historical-forms"><var>historical-forms</var></a> || <a
  2898       href="#styleset"><var
  2899       title=styleset>styleset(&lt;feature-value-name&gt; #)</var></a> || <a
  2900       href="#character-variant"><var
  2901       title=character-variant>character-variant(&lt;feature-value-name&gt;
  2902       #)</var></a> || <a href="#swash"><var
  2903       title=swash>swash(&lt;feature-value-name&gt;)</var></a> || <a
  2904       href="#ornaments"><var
  2905       title=ornaments>ornaments(&lt;feature-value-name&gt;)</var></a> || <a
  2906       href="#annotation"><var
  2907       title=annotation>annotation(&lt;feature-value-name&gt;)</var></a> || [
  2908       <a href="#small-caps"><i>small-caps</i></a> | <a
  2909       href="#all-small-caps"><i>all-small-caps</i></a> | <a
  2910       href="#petite-caps"><i>petite-caps</i></a> | <a
  2911       href="#all-petite-caps"><i>all-petite-caps</i></a> | <a
  2912       href="#unicase"><i>unicase</i></a> | <a
  2913       href="#titling-caps"><i>titling-caps</i></a> ] || <a
  2914       href="#numeric-figure-values"><var>&lt;numeric-figure-values&gt;</var></a>
  2915       || <a
  2916       href="#numeric-spacing-values"><var>&lt;numeric-spacing-values&gt;</var></a>
  2917       || <a
  2918       href="#numeric-fraction-values"><var>&lt;numeric-fraction-values&gt;</var></a>
  2919       || <a href="#ordinal"><i>ordinal</i></a> || <a
  2920       href="#slashed-zero"><i>slashed-zero</i></a> || <a
  2921       href="#east-asian-variant-values"><var>&lt;east-asian-variant-values&gt;</var></a>
  2922       || <a
  2923       href="#east-asian-width-values"><var>&lt;east-asian-width-values&gt;</var></a>
  2924       || <a href="#ruby"><i>ruby</i></a> ]
  2926     <tr>
  2927      <td><em>Initial:</em>
  2929      <td>normal
  2930   </table>
  2932   <table class=descdef>
  2933    <tbody>
  2934     <tr>
  2935      <td>Name:
  2937      <td><dfn id=descdef-font-feature-settings
  2938       title="font-feature-settings!!descriptor">font-feature-settings</dfn>
  2940     <tr>
  2941      <td>Value:
  2943      <td><a href="#font-feature-settings-normal-value"
  2944       title="normal!!font-feature-settings">normal</a> | <a
  2945       href="#feature-tag-value"><var>&lt;feature-tag-value&gt;</var></a> #
  2947     <tr>
  2948      <td><em>Initial:</em>
  2950      <td>normal
  2951   </table>
  2953   <p>These descriptors define initial settings that apply when the font
  2954    defined by an <a href="#at-font-face-rule"><code>@font-face</code></a>
  2955    rule is rendered. They do not affect font selection. Values are identical
  2956    to those defined for the corresponding <a href="#propdef-font-variant"
  2957    title="font-variant!!property">‘<code
  2958    class=property>font-variant</code>’</a> and <a
  2959    href="#propdef-font-feature-settings"
  2960    title="font-feature-settings!!property">‘<code
  2961    class=property>font-feature-settings</code>’</a> properties defined
  2962    below except that the value ‘<code class=property>inherit</code>’ is
  2963    omitted. When multiple font feature descriptors or properties are used,
  2964    the cumulative effect on text rendering is detailed in the section <a
  2965    href="#font-feature-resolution">Font Feature Resolution</a> below. In
  2966    cases where specific values define synthesized fallback for certain <a
  2967    href="#propdef-font-variant" title="font-variant!!property">‘<code
  2968    class=property>font-variant</code>’</a> subproperties, the same
  2969    synthesized fallback applies when used within those values are used with
  2970    the <a href="#descdef-font-style" title="font-style!!descriptor">‘<code
  2971    class=property>font-variant</code>’</a> descriptor.
  2973   <h3 id=font-face-loading><span class=secno>4.8 </span>Font loading
  2974    guidelines</h3>
  2976   <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule is
  2977    designed to allow lazy loading of font resources that are only downloaded
  2978    when used within a document. A stylesheet can include <a
  2979    href="#at-font-face-rule"><code>@font-face</code></a> rules for a library
  2980    of fonts of which only a select set are used; user agents must only
  2981    download those fonts that are referred to within the style rules
  2982    applicable to a given page. User agents that download all fonts defined in
  2983    <a href="#at-font-face-rule"><code>@font-face</code></a> rules without
  2984    considering whether those fonts are in fact used within a page are
  2985    considered non-conformant. In cases where a font might be downloaded in
  2986    character fallback cases, user agents may download a font if it's
  2987    contained within the computed value of <a href="#propdef-font-family"
  2988    title="font-family!!property">‘<code
  2989    class=property>font-family</code>’</a> for a given text run.
  2991   <pre>
  2992 @font-face {
  2993   font-family: GeometricModern;
  2994   src: url(font.ttf);
  2997 p {
  2998   /* font will be downloaded for pages with p elements */
  2999   font-family: GeometricModern, sans-serif;
  3002 h2 {
  3003   /* font may be downloaded for pages with h2 elements, even if Futura is available locally */
  3004   font-family: Futura, GeometricModern, sans-serif;
  3006 </pre>
  3008   <p>In cases where textual content is loaded before downloadable fonts are
  3009    available, user agents may render text as it would be rendered if
  3010    downloadable font resources are not available or they may render text
  3011    transparently with fallback fonts to avoid a flash of text using a
  3012    fallback font. In cases where the font download fails user agents must
  3013    display text, simply leaving transparent text is considered non-conformant
  3014    behavior. Authors are advised to use fallback fonts in their font lists
  3015    that closely match the vertical metrics of the downloadable fonts to avoid
  3016    large page reflows where possible.
  3018   <h3 id=same-origin-restriction><span class=secno>4.9 </span>Same-origin
  3019    restriction for fonts</h3>
  3021   <h4 id=default-same-origin-restriction><span class=secno>4.9.1
  3022    </span>Default same-origin restriction</h4>
  3023   <!-- TPAC 2011 Resolution to require same-origin restriction for loading fonts:
  3024   http://lists.w3.org/Archives/Public/www-style/2011Nov/0711.html
  3025   http://www.w3.org/2011/10/31-webapps-minutes.html#item02
  3026 -->
  3028   <p>User agents must implement a same-origin restriction when loading fonts
  3029    via the <a href="#at-font-face-rule"><code>@font-face</code></a>
  3030    mechanism. This restriction limits the loading of fonts for a given
  3031    document to fonts loaded from the same origin. Fonts can only be loaded
  3032    via the same host, port, and method combination as the containing
  3033    document, using the <a
  3034    href="http://www.w3.org/TR/html5/browsers.html#origin">origin matching
  3035    algorithm</a> described in the <a href="#HTML5"
  3036    rel=biblioentry>[HTML5]<!--{{!HTML5}}--></a> specification. The origin of
  3037    the stylesheet containing <a
  3038    href="#at-font-face-rule"><code>@font-face</code></a> rules is not used
  3039    when deciding whether a font is same origin or not, only the origin of the
  3040    containing document is used. The restriction applies to all font types.
  3042   <p>Given a document located at http://example.com/page.html, fonts defined
  3043    with ‘<a href="#descdef-src"><code class=property>src</code></a>’
  3044    definitions considered cross origin must not be loaded:
  3046   <pre>
  3047 /* same origin (i.e. domain, protocol, port match document) */
  3048 src: url(fonts/simple.ttf);
  3049 src: url(//fonts/simple.ttf);
  3051 /* cross origin, different protocol */
  3052 src: url(https://example.com/fonts/simple.ttf);
  3054 /* cross origin, different domain */
  3055 src: url(http://another.example.com/fonts/simple.ttf);
  3056 </pre>
  3058   <h4 id=allowing-cross-origin-font-loading><span class=secno>4.9.2
  3059    </span>Allowing cross-origin font loading</h4>
  3061   <p>User agents must also implement the ability to relax this restriction
  3062    using cross-site origin controls <a href="#CORS"
  3063    rel=biblioentry>[CORS]<!--{{!CORS}}--></a> for fonts loaded via HTTP.
  3064    Sites can explicitly allow cross-site downloading of font data using the
  3065    <code>Access-Control-Allow-Origin</code> HTTP header. For other protocols,
  3066    no explicit relaxation mechanism is defined or required.
  3068   <p>For font loads over HTTP, cross-origin requests must be made with the
  3069    following parameter settings which are used in conjunction with the <a
  3070    href="http://www.w3.org/TR/cors/#cross-origin-request-0"> <em>cross-origin
  3071    request algorithm</em></a> <a href="#CORS"
  3072    rel=biblioentry>[CORS]<!--{{!CORS}}--></a>:
  3074   <ul>
  3075    <li><em>request URL</em> — the URL of the font resource in the <a
  3076     href="#descdef-src"><code>src</code></a> descriptor
  3078    <li><em>request method</em> — GET
  3080    <li><em>author request headers</em> — none
  3082    <li><em>request entity body</em> — empty
  3084    <li><em>source origin</em> — the origin of the page which linked to the
  3085     stylesheet
  3087    <li><em>manual redirect flag</em> — false
  3089    <li><em>omit credentials flag</em> — true
  3091    <li><em>force preflight flag</em> — false
  3092   </ul>
  3094   <h2 id=font-matching-algorithm><span class=secno>5 </span>Font Matching
  3095    Algorithm</h2>
  3097   <p>The algorithm below describes how fonts are associated with individual
  3098    runs of text. For each character in the run a font family is chosen and a
  3099    particular font face is selected containing a glyph for that character.
  3101   <h3 id=font-family-casing><span class=secno>5.1 </span>Case sensitivity of
  3102    font family names</h3>
  3104   <p>As part of the font matching algorithm outlined below, user agents must
  3105    match font family names used in style rules with actual font family names
  3106    contained in fonts available in a given environment or with font family
  3107    names defined in <a href="#at-font-face-rule"><code>@font-face</code></a>
  3108    rules. User agents must match these names case insensitively, using the
  3109    "Default Caseless Matching" algorithm outlined in the Unicode
  3110    specification <a href="#UNICODE6"
  3111    rel=biblioentry>[UNICODE6]<!--{{!UNICODE6}}--></a>. This algorithm is
  3112    detailed in section 3.13 entitled "Default Case Algorithms". Specifically,
  3113    the algorithm must be applied without normalizing the strings involved and
  3114    without applying any language-specific tailorings. The case folding method
  3115    specified by this algorithm uses the case mappings with status field
  3116    ‘<code class=property>C</code>’ or ‘<code class=property>F</code>’
  3117    in the CaseFolding.txt file of the Unicode Character Database.
  3119   <p class=note> For authors this means that font family names are matched
  3120    case insensitively, whether those names exist in a platform font or in the
  3121    <a href="#at-font-face-rule"><code>@font-face</code></a> rules contained
  3122    in a stylesheet. Authors should take care to ensure that names use a
  3123    character sequence consistent with the actual font family name,
  3124    particularly when using combining characters such as diacritical marks.
  3125    For example, a family name that contains an uppercase A (U+0041) followed
  3126    by a combining ring (U+030A) will <strong>not</strong> match a name that
  3127    looks identical but which uses the precomposed lowercase a-ring character
  3128    (U+00E5) instead of the combining sequence.
  3130   <p class=note> Implementors should take care to verify that a given
  3131    caseless string comparison implementation uses this precise algorithm and
  3132    not assume that a given platform string matching routine follows it, as
  3133    many of these have locale-specific behavior or use some level of string
  3134    normalization.
  3136   <h3 id=font-style-matching><span class=secno>5.2 </span>Matching font
  3137    styles</h3>
  3139   <p>The procedure for choosing a font for a given character in a run of text
  3140    consists of iterating over the font families named by the <a
  3141    href="#propdef-font-family" title="font-family!!property">‘<code
  3142    class=property>font-family</code>’</a> property, selecting a font face
  3143    with the appropriate style based on other font properties and then
  3144    determining whether a glyph exists for the given character. This is done
  3145    using the <dfn id=character-map>character map</dfn> of the font, data
  3146    which maps characters to the default glyph for that character. A font is
  3147    considered to <dfn id=support>support</dfn> a given character if (1) the
  3148    character is contained in the font's <a
  3149    href="#character-map"><em>character map</em></a> and (2) if required by
  3150    the containing script, shaping information is available for that
  3151    character.
  3153   <p>Some legacy fonts may include a given character in the <a
  3154    href="#character-map"><em>character map</em></a> but lack the shaping
  3155    information (e.g. <a
  3156    href="http://www.microsoft.com/typography/otspec/ttochap1.htm">OpenType
  3157    layout tables</a> or <a
  3158    href="http://scripts.sil.org/cms/scripts/page.php?site_id=projects&amp;item_id=graphite_techAbout">Graphite
  3159    tables</a>) necessary for correctly rendering text runs containing that
  3160    character.
  3162   <p>Codepoint sequences consisting of a base character followed by a
  3163    sequence of combining characters are treated slightly differently, see the
  3164    section on <a href="#cluster-matching">cluster matching</a> below.
  3166   <p>For this procedure, the <dfn id=default-face>default face</dfn> for a
  3167    given font family is defined to be the face that would be selected if all
  3168    font style properties were set to their initial value.
  3170   <ol id=fontmatchingalg>
  3171    <li>Using the computed font property values for a given element, the user
  3172     agent starts with the first family name specified by the <a
  3173     href="#propdef-font-family" title="font-family!!property">‘<code
  3174     class=property>font-family</code>’</a> property.
  3176    <li>If the family name is a generic family keyword, the user agent looks
  3177     up the appropriate font family name to be used. User agents may choose
  3178     the generic font family to use based on the language of the containing
  3179     element or the Unicode range of the character.
  3181    <li>For other family names, the user agent attempts to find the family
  3182     name among fonts defined via <a
  3183     href="#at-font-face-rule"><code>@font-face</code></a> rules and then
  3184     among available system fonts, matching names with a <a
  3185     href="#font-family-casing">case-insensitive comparison</a> as outlined in
  3186     the section above. On systems containing fonts with multiple localized
  3187     font family names, user agents must match any of these names independent
  3188     of the underlying system locale or platform API used. If the font
  3189     resources defined for a given face in an <a
  3190     href="#at-font-face-rule"><code>@font-face</code></a> rule are either not
  3191     available or contain invalid font data, then the face should be treated
  3192     as not present in the family. If no faces are present for a family
  3193     defined via <a href="#at-font-face-rule"><code>@font-face</code></a>
  3194     rules, the family should be treated as missing; matching a platform font
  3195     with the same name must not occur in this case.
  3197    <li>If a font family match occurs, the user agent assembles the set of
  3198     font faces in that family and then narrows the set to a single face using
  3199     other font properties in the order given below. A group of faces defined
  3200     via <a href="#at-font-face-rule"><code>@font-face</code></a> rules with
  3201     identical font descriptor values but differing ‘<a
  3202     href="#descdef-unicode-range"><code
  3203     class=property>unicode-range</code></a>’ values are considered to be a
  3204     single <dfn id=composite-face>composite face</dfn> for this step:
  3205     <ol id=fontstylematchingalg>
  3206      <li><a href="#propdef-font-stretch"
  3207       title="font-stretch!!property">‘<code
  3208       class=property>font-stretch</code>’</a> is tried first. If the
  3209       matching set contains faces with width values matching the <a
  3210       href="#propdef-font-stretch" title="font-stretch!!property">‘<code
  3211       class=property>font-stretch</code>’</a> value, faces with other width
  3212       values are removed from the matching set. If there is no face that
  3213       exactly matches the width value the nearest width is used instead. If
  3214       the value of <a href="#propdef-font-stretch"
  3215       title="font-stretch!!property">‘<code
  3216       class=property>font-stretch</code>’</a> is <a
  3217       href="#font-stretch-normal-value" title="normal!!font-stretch">‘<code
  3218       class=property>normal</code>’</a> or one of the condensed values,
  3219       narrower width values are checked first, then wider values. If the
  3220       value of <a href="#propdef-font-stretch"
  3221       title="font-stretch!!property">‘<code
  3222       class=property>font-stretch</code>’</a> is one of the expanded
  3223       values, wider values are checked first, followed by narrower values.
  3224       Once the closest matching width has been determined by this process,
  3225       faces with other widths are removed from the matching set.
  3227      <li><a href="#propdef-font-style" title="font-style!!property">‘<code
  3228       class=property>font-style</code>’</a> is tried next. If the value of
  3229       <a href="#propdef-font-style" title="font-style!!property">‘<code
  3230       class=property>font-style</code>’</a> is ‘<a href="#italic"><code
  3231       class=property>italic</code></a>’, italic faces are checked first,
  3232       then oblique, then normal faces. If the value is ‘<a
  3233       href="#oblique"><code class=property>oblique</code></a>’, oblique
  3234       faces are checked first, then italic faces and then normal faces. If
  3235       the value is <a href="#font-style-normal-value"
  3236       title="normal!!font-style">‘<code
  3237       class=property>normal</code>’</a>, normal faces are checked first,
  3238       then oblique faces, then italic faces. Faces with other style values
  3239       are excluded from the matching set. User agents are permitted to
  3240       distinguish between italic and oblique faces within platform font
  3241       families but this is not required, so all italic or oblique faces may
  3242       be treated as italic faces. However, within font families defined via
  3243       <a href="#at-font-face-rule"><code>@font-face</code></a> rules, italic
  3244       and oblique faces must be distinguished using the value of the <a
  3245       href="#descdef-font-style" title="font-style!!descriptor">‘<code
  3246       class=property>font-style</code>’</a> descriptor. For families that
  3247       lack any italic or oblique faces, users agents may create artificial
  3248       oblique faces, if this is permitted by the value of the ‘<a
  3249       href="#propdef-font-synthesis"><code
  3250       class=property>font-synthesis</code></a>’ property.
  3252      <li><a href="#propdef-font-weight"
  3253       title="font-weight!!property">‘<code
  3254       class=property>font-weight</code>’</a> is matched next, so it will
  3255       always reduce the matching set to a single font face. If bolder/lighter
  3256       relative weights are used, the effective weight is calculated based on
  3257       the inherited weight value, as described in the definition of the <a
  3258       href="#propdef-font-weight" title="font-weight!!property">‘<code
  3259       class=property>font-weight</code>’</a> property. Given the desired
  3260       weight and the weights of faces in the matching set after the steps
  3261       above, if the desired weight is available that face matches. Otherwise,
  3262       a weight is chosen using the rules below:
  3263       <ul>
  3264        <li>If the desired weight is less than 400, weights below the desired
  3265         weight are checked in descending order followed by weights above the
  3266         desired weight in ascending order until a match is found.
  3268        <li>If the desired weight is greater than 500, weights above the
  3269         desired weight are checked in ascending order followed by weights
  3270         below the desired weight in descending order until a match is found.
  3272        <li>If the desired weight is 400, 500 is checked first and then the
  3273         rule for desired weights less than 400 is used.
  3275        <li>If the desired weight is 500, 400 is checked first and then the
  3276         rule for desired weights less than 400 is used.
  3277       </ul>
  3279      <li><span class=property>‘<a href="#propdef-font-size"><code
  3280       class=property>font-size</code></a>’</span> must be matched within a
  3281       UA-dependent margin of tolerance. (Typically, sizes for scalable fonts
  3282       are rounded to the nearest whole pixel, while the tolerance for
  3283       bitmapped fonts could be as large as 20%.) Further computations, e.g.,
  3284       by ‘<code class=property>em</code>’ values in other properties, are
  3285       based on the <span class=property>‘<a href="#propdef-font-size"><code
  3286       class=property>font-size</code></a>’</span> value that is used, not
  3287       the one that is specified.
  3288     </ol>
  3290    <li>
  3291     <p>If the matched face is defined via <a
  3292      href="#at-font-face-rule"><code>@font-face</code></a> rules, user agents
  3293      must use the procedure below to select a single font:
  3295     <ol>
  3296      <li>If the font resource has not been loaded and the range of characters
  3297       defined by the ‘<a href="#descdef-unicode-range"><code
  3298       class=property>unicode-range</code></a>’ descriptor value includes
  3299       the character in question, load the font.
  3301      <li>After downloading, if the <a
  3302       href="#effective-character-map"><em>effective character map</em></a>
  3303       supports the character in question, select that font.
  3304     </ol>
  3306     <p>When the matched face is a <a href="#composite-face"><em>composite
  3307      face</em></a>, user agents must use the procedure above on each of the
  3308      faces in the <a href="#composite-face"><em>composite face</em></a> in
  3309      reverse order of <a
  3310      href="#at-font-face-rule"><code>@font-face</code></a> rule definition.</p>
  3312     <p>While the download occurs, user agents may either wait until the font
  3313      is downloaded or render once with substituted font metrics and render
  3314      again once the font is downloaded.</p>
  3316    <li>
  3317     <p>If no matching face exists or the matched face does not contain a
  3318      glyph for the character to be rendered, the next family name is selected
  3319      and the previous three steps repeated. Glyphs from other faces in the
  3320      family are not considered. The only exception is that user agents may
  3321      optionally substitute a synthetically obliqued version of the <a
  3322      href="#default-face"><em>default face</em></a> if that face supports a
  3323      given glyph and synthesis of these faces is permitted by the value of
  3324      the ‘<a href="#propdef-font-synthesis"><code
  3325      class=property>font-synthesis</code></a>’ property. For example, a
  3326      synthetic italic version of the regular face may be used if the italic
  3327      face doesn't support glyphs for Arabic.</p>
  3328     <!-- resolution on the above: http://lists.w3.org/Archives/Public/www-style/2012Nov/0292.html -->
  3331    <li>If there are no more font families to be evaluated and no matching
  3332     face has been found, then the user agent performs a <dfn
  3333     id=system-font-fallback>system font fallback</dfn> procedure to find the
  3334     best match for the character to be rendered. The result of this procedure
  3335     may vary across user agents.
  3337    <li>If a particular character cannot be displayed using any font, the user
  3338     agent should indicate by some means that a character is not being
  3339     displayed, displaying either a symbolic representation of the missing
  3340     glyph (e.g. using a <a
  3341     href="http://en.wikipedia.org/wiki/Last_resort_font">Last Resort
  3342     Font</a>) or using the missing character glyph from a default font.
  3343   </ol>
  3345   <h3 id=cluster-matching><span class=secno>5.3 </span>Cluster matching</h3>
  3347   <p>When text contains characters such as combining marks, ideally the base
  3348    character should be rendered using the same font as the mark, this assures
  3349    proper placement of the mark. For this reason, the font matching algorithm
  3350    for clusters is more specialized than the general case of matching a
  3351    single character by itself. For sequences containing variation selectors,
  3352    which indicate the precise glyph to be used for a given character, user
  3353    agents always attempt <a href="#system-font-fallback"><em>system font
  3354    fallback</em></a> to find the appropriate glyph before using the default
  3355    glyph of the base character.
  3357   <p>A sequence of codepoints containing combining mark or other modifiers is
  3358    termed a grapheme cluster (see <a href="#CSS3TEXT"
  3359    rel=biblioentry>[CSS3TEXT]<!--{{CSS3TEXT}}--></a> for a more complete
  3360    description). For a given cluster containing a base character, <em>b</em>
  3361    and a sequence of combining characters <em>c1, c2…</em>, the entire
  3362    cluster is matched using these steps:
  3364   <ol>
  3365    <li>For each family in the font list, a face is chosen using the style
  3366     selection rules defined in the previous section.
  3367     <ol>
  3368      <li>If all characters in the sequence <em>b + c1 + c2 …</em> are
  3369       completely supported by the font, select this font for the sequence.
  3371      <li>If a sequence of multiple codepoints is canonically equivalent to a
  3372       single character and the font <a href="#support"><em
  3373       title=support>supports</em></a> that character, select this font for
  3374       the sequence.
  3375     </ol>
  3377    <li>If no font was found in the font list in step 1:
  3378     <ol>
  3379      <li>If <em>c1</em> is a variation selector, system fallback must be used
  3380       to find a font that <a href="#support"><em
  3381       title=support>supports</em></a> the full sequence of <em>b + c1</em>.
  3382       If no font on the system <a href="#support"><em
  3383       title=support>supports</em></a> the full sequence, match the single
  3384       character <em>b</em> using the normal procedure for matching single
  3385       characters and ignore the variation selector. Note: a sequence with
  3386       more than one variation selector must be treated as an encoding error
  3387       and the trailing selectors must be ignored. <a href="#UNICODE6"
  3388       rel=biblioentry>[UNICODE6]<!--{{!UNICODE6}}--></a>
  3390      <li>Otherwise, the user agent may optionally use system font fallback to
  3391       match a font that <a href="#support"><em
  3392       title=support>supports</em></a> the entire cluster.
  3393     </ol>
  3395    <li>If no font is found in step 2, use the matching sequence from step 1
  3396     to determine the longest sequence that is completely <a
  3397     href="#support"><em title=support>supported</em></a> by a font in the
  3398     font list and attempt to match the remaining combining characters
  3399     separately using the rules for single characters.
  3400   </ol>
  3402   <h3 id=char-handling-issues><span class=secno>5.4 </span>Character handling
  3403    issues</h3>
  3405   <p>The procedure above is always performed on text runs containing Unicode
  3406    characters, documents using legacy encodings are assumed to have been
  3407    transcoded before matching fonts. For fonts containing <a
  3408    href="#character-map"><em title="character map">character maps</em></a>
  3409    for both legacy encodings and Unicode, the contents of the legacy encoding
  3410    <a href="#character-map"><em>character map</em></a> must have no effect on
  3411    the results of the font matching process.
  3413   <p>The font matching process does not assume that text runs are in either
  3414    normalized or denormalized form (see <a href="#CHARMOD-NORM"
  3415    rel=biblioentry>[CHARMOD-NORM]<!--{{CHARMOD-NORM}}--></a> for more
  3416    details). Layout engines often convert base character plus combining
  3417    character sequences into precomposed characters if they exist. The font
  3418    matching algorithm outlined here supports both ways and fonts can
  3419    generally support either but variations can occur. Authors should always
  3420    tailor their choice of fonts to their content, including whether that
  3421    content contains normalized or denormalized character streams.
  3423   <p>If a given character is a Private-Use Area Unicode codepoint and none of
  3424    the fonts in the fontlist contain a glyph for that codepoint, user agents
  3425    must display some form of missing glyph symbol for that character rather
  3426    than attempting <a href="#system-font-fallback"><em>system font
  3427    fallback</em></a> for that codepoint. When matching the replacement
  3428    character U+FFFD, user agents may skip the font matching process and
  3429    immediately display some form of missing glyph symbol, they are not
  3430    required to display the glyph from the font that would be selected by the
  3431    font matching process.
  3433   <p>In general, the fonts for a given family will all have the same or
  3434    similar <a href="#character-map"><em title="character map">character
  3435    maps</em></a>. The process outlined here is designed to handle even font
  3436    families containing faces with widely variant <a href="#character-map"><em
  3437    title="character map">character maps</em></a>. However, authors are
  3438    cautioned that the use of such families can lead to unexpected results.
  3440   <p>Optimizations of this process are allowed provided that an
  3441    implementation behaves as if the algorithm had been followed exactly.
  3442    Matching occurs in a well-defined order to insure that the results are as
  3443    consistent as possible across user agents, given an identical set of
  3444    available fonts and rendering technology.
  3446   <h3 id=font-matching-changes><span class=secno>5.5 </span>Font matching
  3447    changes since CSS 2.1</h3>
  3449   <p>The algorithm above is different from CSS 2.1 in a number of key places.
  3450    These changes were made to better reflect actual font matching behavior
  3451    across user agent implementations.
  3453   <p>Differences compared to the font matching algorithm in CSS 2.1:
  3455   <ul>
  3456    <li>The algorithm includes font-stretch matching.
  3458    <li>All possible font-style matching scenarios are delineated.
  3460    <li>Small-caps fonts are not matched as part of the font matching process,
  3461     they are now handled via font features.
  3463    <li>Unicode variation selector matching is required.
  3465    <li>Cluster sequences are matched as a unit.
  3466   </ul>
  3468   <h3 id=font-matching-examples><span class=secno>5.6 </span>Font matching
  3469    examples</h3>
  3471   <div class=example>
  3472    <p>It's useful to note that the CSS selector syntax may be used to create
  3473     language-sensitive typography. For example, some Chinese and Japanese
  3474     characters are unified to have the same Unicode code point, although the
  3475     abstract glyphs are not the same in the two languages.
  3477    <pre>*:lang(ja-jp) { font: 900 14pt/16pt &quot;Heisei Mincho W9&quot;, serif; }
  3478 *:lang(zh-tw) { font: 800 14pt/16.5pt &quot;Li Sung&quot;, serif; }
  3479 </pre>
  3481    <p>This selects any element that has the given language - Japanese or
  3482     Traditional Chinese - and uses the appropriate font.
  3483   </div>
  3485   <h2 id=font-rend-props><span class=secno>6 </span>Font Feature Properties</h2>
  3487   <p>Modern font technologies support a variety of advanced typographic and
  3488    language-specific font features. Using these features, a single font can
  3489    provide glyphs for a wide range of ligatures, contextual and stylistic
  3490    alternates, tabular and old-style figures, small capitals, automatic
  3491    fractions, swashes, and alternates specific to a given language. To allow
  3492    authors control over these font capabilities, the ‘<code
  3493    class=property>font-variant</code>’ property has been expanded for CSS3.
  3494    It now functions as a shorthand for a set of properties that provide
  3495    control over stylistic font features.
  3497   <h3 id=glyph-selection-positioning><span class=secno>6.1 </span>Glyph
  3498    selection and positioning</h3>
  3500   <p>Simple fonts used for displaying Latin text use a very basic processing
  3501    model. Fonts contain a <a href="#character-map"><em>character map</em></a>
  3502    which maps each character to a glyph for that character. Glyphs for
  3503    subsequent characters are simply placed one after the other along a run of
  3504    text. Modern font formats such as OpenType and AAT (Apple Advanced
  3505    Typography) use a richer processing model. The glyph for a given character
  3506    can be chosen and positioned not just based on the codepoint of the
  3507    character itself, but also on adjacent characters as well as the language,
  3508    script, and features enabled for the text. Font features may be required
  3509    for specific scripts, or recommended as enabled by default or they might
  3510    be stylistic features meant to be used under author control.
  3512   <p>For a good visual overview of these features, see the <a
  3513    href="#OPENTYPE-FONT-GUIDE"
  3514    rel=biblioentry>[OPENTYPE-FONT-GUIDE]<!--{{OPENTYPE-FONT-GUIDE}}--></a>.
  3515    For a detailed description of glyph processing for OpenType fonts, see <a
  3516    href="#WINDOWS-GLYPH-PROC"
  3517    rel=biblioentry>[WINDOWS-GLYPH-PROC]<!--{{WINDOWS-GLYPH-PROC}}--></a>.
  3519   <p>Stylistic font features can be classified into two broad categories:
  3520    ones that affect the harmonization of glyph shapes with the surrounding
  3521    context, such as kerning and ligature features, and ones such as the
  3522    small-caps, subscript/superscript and alternate features that affect shape
  3523    selection.
  3525   <p>The subproperties of <a href="#propdef-font-variant"
  3526    title="font-variant!!property">‘<code
  3527    class=property>font-variant</code>’</a> listed below are used to control
  3528    these stylistic font features. They do not control features that are
  3529    required for displaying certain scripts, such as the OpenType features
  3530    used when displaying Arabic or Indic language text. They affect glyph
  3531    selection and positioning, but do not affect font selection as described
  3532    in the font matching section (except in cases required for compatibility
  3533    with CSS 2.1).
  3535   <p>To assure consistent behavior across user agents, the equivalent
  3536    OpenType property settings are listed for individual properties and are
  3537    normative. When using other font formats these should be used as a
  3538    guideline to map CSS font feature property values to specific font
  3539    features.
  3541   <h3 id=language-specific-support><span class=secno>6.2
  3542    </span>Language-specific display</h3>
  3544   <p>OpenType also supports language-specific glyph selection and
  3545    positioning, so that text can be displayed correctly in cases where the
  3546    language dictates a specific display behavior. Many languages share a
  3547    common script, but the shape of certain letters can vary across those
  3548    languages. For example, certain Cyrillic letters have different shapes in
  3549    Russian text than in Bulgarian. In Latin text, it's common to render "fi"
  3550    with an explicit fi-ligature that lacks a dot on the "i". However, in
  3551    languages such as Turkish which uses both a dotted-i and a dotless-i, it's
  3552    important to not use this ligature or use a specialized version that
  3553    contains a dot over the "i". The example below shows language-specific
  3554    variations based on stylistic traditions found in Spanish, Italian and
  3555    French orthography:
  3557   <div class=featex><img alt="language specific forms, spanish"
  3558    src=locl-1.png></div>
  3560   <div class=featex><img alt="language specific forms, italian"
  3561    src=locl-2.png></div>
  3563   <div class=featex><img alt="language specific forms, french"
  3564    src=locl-3.png></div>
  3566   <p>If the content language of the element is known according to the rules
  3567    of the <a
  3568    href="http://www.w3.org/TR/CSS21/conform.html#doclanguage">document
  3569    language</a>, user agents are required to infer the OpenType language
  3570    system from the content language and use that when selecting and
  3571    positioning glyphs using an OpenType font.
  3573   <p>For OpenType fonts, in some cases it may be necessary to explicitly
  3574    declare the OpenType language to be used, for example when displaying text
  3575    in a given language that uses the typographic conventions of another
  3576    language or when the font does not explicitly support a given language but
  3577    supports a language that shares common typographic conventions. The ‘<a
  3578    href="#propdef-font-language-override"><code
  3579    class=property>font-language-override</code></a>’ property is used for
  3580    this purpose.</p>
  3581   <!-- prop: font-kerning -->
  3583   <h3 id=font-kerning-prop><span class=secno>6.3 </span>Kerning: the <a
  3584    href="#propdef-font-kerning">font-kerning</a> property</h3>
  3586   <table class=propdef id=namefont-kerningvalueauto-normal-noneini>
  3587    <tbody>
  3588     <tr>
  3589      <td>Name:
  3591      <td><dfn id=propdef-font-kerning>font-kerning</dfn>
  3593     <tr>
  3594      <td>Value:
  3596      <td><a href="#font-kerning-auto-value"
  3597       title="auto!!font-kerning">auto</a> | <a
  3598       href="#font-kerning-normal-value"
  3599       title="normal!!font-kerning">normal</a> | <a
  3600       href="#font-kerning-none-value" title="none!!font-kerning">none</a>
  3602     <tr>
  3603      <td>Initial:
  3605      <td>auto
  3607     <tr>
  3608      <td>Applies to:
  3610      <td>all elements
  3612     <tr>
  3613      <td>Inherited:
  3615      <td>yes
  3617     <tr>
  3618      <td>Percentages:
  3620      <td>N/A
  3622     <tr>
  3623      <td>Media:
  3625      <td>visual
  3627     <tr>
  3628      <td>Computed value:
  3630      <td>as specified
  3632     <tr>
  3633      <td>Animatable:
  3635      <td>no
  3636   </table>
  3638   <p>Kerning is the contextual adjustment of inter-glyph spacing. This
  3639    property controls metric kerning, kerning that utilizes adjustment data
  3640    contained in the font.
  3642   <dl>
  3643    <dt><dfn id=font-kerning-auto-value title="auto!!font-kerning">auto</dfn>
  3645    <dd>Specifies that kerning is applied at the discretion of the user agent
  3647    <dt><dfn id=font-kerning-normal-value
  3648     title="normal!!font-kerning">normal</dfn>
  3650    <dd>Specifies that kerning is applied
  3652    <dt><dfn id=font-kerning-none-value title="none!!font-kerning">none</dfn>
  3654    <dd>Specifies that kerning is not applied
  3655   </dl>
  3657   <p>For fonts that do not include kerning data this property will have no
  3658    visible effect. When rendering with OpenType fonts, the <a
  3659    href="#OPENTYPE" rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a>
  3660    specification suggests that kerning be enabled by default. When kerning is
  3661    enabled, the OpenType <span class=tag>kern</span> feature is enabled (for
  3662    vertical text runs the <span class=tag>vkrn</span> feature is enabled
  3663    instead). User agents must also support fonts that only support kerning
  3664    via data contained in a <span class=tag>kern</span> font table, as
  3665    detailed in the OpenType specification. If the ‘<code
  3666    class=property>letter-spacing</code>’ property is defined, kerning
  3667    adjustments are considered part of the default spacing and letter spacing
  3668    adjustments are made after kerning has been applied.
  3670   <p>When set to ‘<code class=property>auto</code>’, user agents can
  3671    determine whether to apply kerning or not based on a number of factors:
  3672    text size, script, or other factors that influence text processing speed.
  3673    Authors who want proper kerning should use <a
  3674    href="#font-kerning-normal-value" title="normal!!font-kerning">‘<code
  3675    class=property>normal</code>’</a> to explicitly enable kerning.
  3676    Likewise, some authors may prefer to disable kerning in situations where
  3677    performance is more important than precise appearance. However, in
  3678    well-designed modern implementations the use of kerning generally does not
  3679    have a large impact on text rendering speed.</p>
  3680   <!-- prop: font-variant-ligatures -->
  3682   <h3 id=font-variant-ligatures-prop><span class=secno>6.4 </span>Ligatures:
  3683    the <a href="#propdef-font-variant-ligatures">font-variant-ligatures</a>
  3684    property</h3>
  3686   <table class=propdef id=namefont-variant-ligaturesvaluenormal-no>
  3687    <tbody>
  3688     <tr>
  3689      <td>Name:
  3691      <td><dfn id=propdef-font-variant-ligatures>font-variant-ligatures</dfn>
  3693     <tr>
  3694      <td>Value:
  3696      <td><a href="#font-variant-ligatures-normal-value"
  3697       title="normal!!font-variant-ligatures">normal</a> | <a
  3698       href="#font-variant-ligatures-none-value"
  3699       title="none!!font-variant-ligatures">none</a> | [ <a
  3700       href="#common-lig-values"><var>&lt;common-lig-values&gt;</var></a> ||
  3701       <a
  3702       href="#discretionary-lig-values"><var>&lt;discretionary-lig-values&gt;</var></a>
  3703       || <a
  3704       href="#historical-lig-values"><var>&lt;historical-lig-values&gt;</var></a>
  3705       || <a
  3706       href="#contextual-alt-values"><var>&lt;contextual-alt-values&gt;</var></a>
  3709     <tr>
  3710      <td>Initial:
  3712      <td>normal
  3714     <tr>
  3715      <td>Applies to:
  3717      <td>all elements
  3719     <tr>
  3720      <td>Inherited:
  3722      <td>yes
  3724     <tr>
  3725      <td>Percentages:
  3727      <td>N/A
  3729     <tr>
  3730      <td>Media:
  3732      <td>visual
  3734     <tr>
  3735      <td>Computed value:
  3737      <td>as specified
  3739     <tr>
  3740      <td>Animatable:
  3742      <td>no
  3743   </table>
  3745   <p>Ligatures and contextual forms are ways of combining glyphs to produce
  3746    more harmonized forms.
  3748   <pre
  3749    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>
  3751   <pre
  3752    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>
  3754   <pre
  3755    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>
  3757   <pre
  3758    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>
  3760   <p>Individual values have the following meanings:
  3762   <dl>
  3763    <dt><dfn id=font-variant-ligatures-normal-value
  3764     title="normal!!font-variant-ligatures">normal</dfn>
  3766    <dd>A value of <a href="#font-variant-ligatures-normal-value"
  3767     title="normal!!font-variant-ligatures">‘<code
  3768     class=property>normal</code>’</a> specifies that common default
  3769     features are enabled, <a href="#font-feature-resolution">as described in
  3770     detail in the next section</a>. For OpenType fonts, common ligatures and
  3771     contextual forms are on by default, discretionary and historical
  3772     ligatures are not.
  3774    <dt><dfn id=font-variant-ligatures-none-value
  3775     title="none!!font-variant-ligatures">none</dfn>
  3777    <dd>Specifies that all types of ligatures and contextual forms covered by
  3778     this property are explicitly disabled. In situations where ligatures are
  3779     not considered necessary, this may improve the speed of text rendering.
  3781    <dt><dfn id=common-ligatures>common-ligatures</dfn>
  3783    <dd>Enables display of common ligatures (OpenType features: <span
  3784     class=tag>liga, clig</span>). For OpenType fonts, common ligatures are
  3785     enabled by default.
  3786   </dl>
  3788   <div class=featex><img alt="common ligature example" src=liga.png></div>
  3790   <dl>
  3791    <dt><dfn id=no-common-ligatures>no-common-ligatures</dfn>
  3793    <dd>Disables display of common ligatures (OpenType features: <span
  3794     class=tag>liga, clig</span>).
  3796    <dt><dfn id=discretionary-ligatures>discretionary-ligatures</dfn>
  3798    <dd>Enables display of discretionary ligatures (OpenType feature: <span
  3799     class=tag>dlig</span>). Which ligatures are discretionary or optional is
  3800     decided by the type designer, so authors will need to refer to the
  3801     documentation of a given font to understand which ligatures are
  3802     considered discretionary.
  3803   </dl>
  3805   <div class=featex><img alt="discretionary ligature example" src=dlig.png></div>
  3807   <dl>
  3808    <dt><dfn id=no-discretionary-ligatures>no-discretionary-ligatures</dfn>
  3810    <dd>Disables display of discretionary ligatures (OpenType feature: <span
  3811     class=tag>dlig</span>).
  3813    <dt><dfn id=historical-ligatures>historical-ligatures</dfn>
  3815    <dd>Enables display of historical ligatures (OpenType feature: <span
  3816     class=tag>hlig</span>).
  3817   </dl>
  3819   <div class=featex><img alt="historical ligature example" src=hlig.png></div>
  3821   <dl>
  3822    <dt><dfn id=no-historical-ligatures>no-historical-ligatures</dfn>
  3824    <dd>Disables display of historical ligatures (OpenType feature: <span
  3825     class=tag>hlig</span>).
  3827    <dt><dfn id=contextual>contextual</dfn>
  3829    <dd>Enables display of contextual alternates (OpenType feature: <span
  3830     class=tag>calt</span>). Although not strictly a ligature feature, like
  3831     ligatures this feature is commonly used to harmonize the shapes of glyphs
  3832     with the surrounding context. For OpenType fonts, this feature is on by
  3833     default.
  3834   </dl>
  3836   <div class=featex><img alt="contextual alternate example" src=calt.png></div>
  3838   <dl>
  3839    <dt><dfn id=no-contextual>no-contextual</dfn>
  3841    <dd>Disables display of contextual alternates (OpenType feature: <span
  3842     class=tag>calt</span>).
  3843   </dl>
  3845   <p>Required ligatures, needed for correctly rendering complex scripts, are
  3846    not affected by the settings above, including ‘<code
  3847    class=property>none</code>’ (OpenType feature: <span
  3848    class=tag>rlig</span>).</p>
  3849   <!-- prop: font-variant-position -->
  3851   <h3 id=font-variant-position-prop><span class=secno>6.5 </span>Subscript
  3852    and superscript forms: the <a
  3853    href="#propdef-font-variant-position">font-variant-position</a> property</h3>
  3855   <table class=propdef id=namefont-variant-positionvaluenormal-sub>
  3856    <tbody>
  3857     <tr>
  3858      <td>Name:
  3860      <td><dfn id=propdef-font-variant-position>font-variant-position</dfn>
  3862     <tr>
  3863      <td>Value:
  3865      <td><a href="#font-variant-position-normal-value"
  3866       title="normal!!font-variant-position">normal</a> | <a
  3867       href="#sub">sub</a> | <a href="#super">super</a>
  3869     <tr>
  3870      <td>Initial:
  3872      <td>normal
  3874     <tr>
  3875      <td>Applies to:
  3877      <td>all elements
  3879     <tr>
  3880      <td>Inherited:
  3882      <td>yes
  3884     <tr>
  3885      <td>Percentages:
  3887      <td>N/A
  3889     <tr>
  3890      <td>Media:
  3892      <td>visual
  3894     <tr>
  3895      <td>Computed value:
  3897      <td>as specified
  3899     <tr>
  3900      <td>Animatable:
  3902      <td>no
  3903   </table>
  3905   <p>This property is used to enable typographic subscript and superscript
  3906    glyphs. These are alternate glyphs designed within the same em-box as
  3907    default glyphs and are intended to be laid out on the same baseline as the
  3908    default glyphs, with no resizing or repositioning of the baseline. They
  3909    are explicitly designed to match the surrounding text and to be more
  3910    readable without affecting the line height.
  3912   <div class=figure><img alt="comparison between real subscript glyphs and
  3913    synthesized ones" src=realsubscripts.png>
  3914    <p class=caption>Subscript glyphs (top) vs. typical synthesized subscripts
  3915     (bottom)
  3916   </div>
  3918   <p>Individual values have the following meanings:
  3920   <dl>
  3921    <dt><dfn id=font-variant-position-normal-value
  3922     title="normal!!font-variant-position">normal</dfn>
  3924    <dd>None of the features listed below are enabled.
  3926    <dt><dfn id=sub>sub</dfn>
  3928    <dd>Enables display of subscript variants (OpenType feature: <span
  3929     class=tag>subs</span>).
  3931    <dt><dfn id=super>super</dfn>
  3933    <dd>Enables display of superscript variants (OpenType feature: <span
  3934     class=tag>sups</span>).
  3935   </dl>
  3937   <p>Because of the semantic nature of subscripts and superscripts, when the
  3938    value is either ‘<a href="#sub"><code class=property>sub</code></a>’
  3939    or ‘<a href="#super"><code class=property>super</code></a>’ for a
  3940    given contiguous run of text, if a variant glyph is not available for all
  3941    the characters in the run, simulated glyphs must be synthesized for all
  3942    characters using reduced forms of the glyphs that would be used without
  3943    this feature applied. This is done per run to avoid a mixture of variant
  3944    glyphs and synthesized ones that would not align correctly. In the case of
  3945    OpenType fonts that lack subscript or superscript glyphs for a given
  3946    character, user agents must use the appropriate subscript and superscript
  3947    metrics specified in the selected font's <a
  3948    href="http://www.microsoft.com/typography/otspec/os2.htm#subxs">OS/2
  3949    table</a> <a href="#OPENTYPE"
  3950    rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a> to calculate the size
  3951    and offset of the synthesized substitutes.
  3953   <div class=figure><img alt="alternate superscripts vs. glyphs synthesized
  3954    using superscript metrics" src=superscript-alt-synth.png>
  3955    <p class=caption>Superscript alternate glyph (left), synthesized
  3956     superscript glyphs (middle), and incorrect mixture of the two (right)
  3957   </div>
  3959   <p>In situations where text decorations are only applied to runs of text
  3960    containing superscript or subscript glyphs, the synthesized glyphs must be
  3961    used to avoid problems with the placement of decorations.
  3963   <p>In the past, user agents have used font-size and vertical-align to
  3964    simulate subscripts and superscripts for the <code title="HTML sub
  3965    element">sub</code> and <code title="HTML sup element">sup</code>
  3966    elements. To allow a backwards compatible way of defining subscripts and
  3967    superscripts, it is recommended that authors use conditional rules <a
  3968    href="#CSS3-CONDITIONAL"
  3969    rel=biblioentry>[CSS3-CONDITIONAL]<!--{{CSS3-CONDITIONAL}}--></a> so that
  3970    older user agents will still render subscripts and superscripts via the
  3971    older mechanism.
  3973   <p>Authors should note that fonts typically only provide subscript and
  3974    superscript glyphs for a subset of all characters supported by the font.
  3975    For example, while subscript and superscript glyphs are often available
  3976    for Latin numbers, glyphs for punctuation and letter characters are less
  3977    frequently provided. The synthetic fallback rules defined for this
  3978    property assure that subscripts and superscripts will always appear but
  3979    the appearance may not match author expectations if the font used does not
  3980    provide the appropriate alternate glyph for all characters contained in a
  3981    subscript or superscript.
  3983   <p>This property is not cumulative. Applying it to elements within a
  3984    subscript or superscript won't nest the placement of a subscript or
  3985    superscript glyph. Images contained within text runs where the value of
  3986    this property is ‘<a href="#sub"><code class=property>sub</code></a>’
  3987    or ‘<a href="#super"><code class=property>super</code></a>’ will be
  3988    drawn just as they would if the value was <a
  3989    href="#font-variant-position-normal-value"
  3990    title="normal!!font-variant-position">‘<code
  3991    class=property>normal</code>’</a>.</p>
  3992   <!-- due to lack of consensus, couldn't resolve on exact positioning of text decorations:
  3993 http://www.w3.org/2013/06/06-css-minutes.html#item03 -->
  3995   <p>Because of these limitations, ‘<a
  3996    href="#propdef-font-variant-position"><code
  3997    class=property>font-variant-position</code></a>’ is not recommended for
  3998    use in user agent stylesheets. Authors should use it in cases where
  3999    subscripts or superscripts will only contain the narrow range of
  4000    characters supported by the fonts specified.
  4002   <p class=note>The variant glyphs use the same baseline as the default
  4003    glyphs would use. There is no shift in the placement along the baseline,
  4004    so the use of variant glyphs doesn't affect the height of the inline box
  4005    or alter the height of the linebox. This makes superscript and subscript
  4006    variants ideal for situations where it's important that leading remain
  4007    constant, such as in multi-column layout.
  4009   <div class=example>
  4010    <p>A typical user agent default style for the <a class=tag
  4011     href="#sub">sub</a> element:</p>
  4013    <pre>sub {
  4014   vertical-align: sub;
  4015   font-size: smaller;
  4016   line-height: normal;
  4018 </pre>
  4020    <p>Using font-variant-position to specify typographic subscripts in a way
  4021     that will still show subscripts in older user agents:</p>
  4023    <pre>@supports ( font-variant-position: sub ) {
  4025   sub {
  4026     vertical-align: baseline;
  4027     font-size: 100%;
  4028     line-height: inherit;
  4029     font-variant-position: sub;
  4033 </pre>
  4035    <p>User agents that support the ‘<a
  4036     href="#propdef-font-variant-position"><code
  4037     class=property>font-variant-position</code></a>’ property will select a
  4038     subscript variant glyph and render this without adjusting the baseline or
  4039     font-size. Older user agents will ignore the ‘<a
  4040     href="#propdef-font-variant-position"><code
  4041     class=property>font-variant-position</code></a>’ property definition
  4042     and use the standard defaults for subscripts.</p>
  4043   </div>
  4044   <!-- prop: font-variant-caps -->
  4046   <h3 id=font-variant-caps-prop><span class=secno>6.6 </span>Capitalization:
  4047    the <a href="#propdef-font-variant-caps">font-variant-caps</a> property</h3>
  4049   <table class=propdef id=namefont-variant-capsvaluenormal-small-c>
  4050    <tbody>
  4051     <tr>
  4052      <td>Name:
  4054      <td><dfn id=propdef-font-variant-caps>font-variant-caps</dfn>
  4056     <tr>
  4057      <td>Value:
  4059      <td><a href="#font-variant-caps-normal-value"
  4060       title="normal!!font-variant-caps">normal</a> | <a
  4061       href="#small-caps">small-caps</a> | <a
  4062       href="#all-small-caps">all-small-caps</a> | <a
  4063       href="#petite-caps">petite-caps</a> | <a
  4064       href="#all-petite-caps">all-petite-caps</a> | <a
  4065       href="#unicase">unicase</a> | <a href="#titling-caps">titling-caps</a>
  4067     <tr>
  4068      <td>Initial:
  4070      <td>normal
  4072     <tr>
  4073      <td>Applies to:
  4075      <td>all elements
  4077     <tr>
  4078      <td>Inherited:
  4080      <td>yes
  4082     <tr>
  4083      <td>Percentages:
  4085      <td>N/A
  4087     <tr>
  4088      <td>Media:
  4090      <td>visual
  4092     <tr>
  4093      <td>Computed value:
  4095      <td>as specified
  4097     <tr>
  4098      <td>Animatable:
  4100      <td>no
  4101   </table>
  4103   <p>This property allows the selection of alternate glyphs used for small or
  4104    petite capitals or for titling. These glyphs are specifically designed to
  4105    blend well with the surrounding normal glyphs, to maintain the weight and
  4106    readability which suffers when text is simply resized to fit this purpose.
  4108   <p>Individual values have the following meanings:
  4110   <dl>
  4111    <dt><dfn id=font-variant-caps-normal-value
  4112     title="normal!!font-variant-caps">normal</dfn>
  4114    <dd>None of the features listed below are enabled.
  4116    <dt><dfn id=small-caps>small-caps</dfn>
  4118    <dd>Enables display of small capitals (OpenType feature: <span
  4119     class=tag>smcp</span>). Small-caps glyphs typically use the form of
  4120     uppercase letters but are reduced to the size of lowercase letters.
  4121   </dl>
  4123   <div class=featex><img alt="small-caps example" src=smcp.png></div>
  4125   <dl>
  4126    <dt><dfn id=all-small-caps>all-small-caps</dfn>
  4128    <dd>Enables display of small capitals for both upper and lowercase letters
  4129     (OpenType features: <span class=tag>c2sc, smcp</span>).
  4131    <dt><dfn id=petite-caps>petite-caps</dfn>
  4133    <dd>Enables display of petite capitals (OpenType feature: <span
  4134     class=tag>pcap</span>).
  4136    <dt><dfn id=all-petite-caps>all-petite-caps</dfn>
  4138    <dd>Enables display of petite capitals for both upper and lowercase
  4139     letters (OpenType features: <span class=tag>c2pc, pcap</span>).
  4141    <dt><dfn id=unicase>unicase</dfn>
  4143    <dd>Enables display of mixture of small capitals for uppercase letters
  4144     with normal lowercase letters (OpenType feature: <span
  4145     class=tag>unic</span>).
  4147    <dt><dfn id=titling-caps>titling-caps</dfn>
  4149    <dd>Enables display of titling capitals (OpenType feature: <span
  4150     class=tag>titl</span>). Uppercase letter glyphs are often designed for
  4151     use with lowercase letters. When used in all uppercase titling sequences
  4152     they can appear too strong. Titling capitals are designed specifically
  4153     for this situation.
  4154   </dl>
  4156   <p>The availability of these glyphs is based on whether a given feature is
  4157    defined or not in the feature list of the font. User agents can optionally
  4158    decide this on a per-script basis but should explicitly not decide this on
  4159    a per-character basis.
  4161   <p>Some fonts may only support a subset or none of the features described
  4162    for this property. For backwards compatibility with CSS 2.1, if ‘<a
  4163    href="#small-caps"><code class=property>small-caps</code></a>’ or ‘<a
  4164    href="#all-small-caps"><code class=property>all-small-caps</code></a>’
  4165    is specified but small-caps glyphs are not available for a given font,
  4166    user agents should simulate a small-caps font, for example by taking a
  4167    normal font and replacing the glyphs for lowercase letters with scaled
  4168    versions of the glyphs for uppercase characters (replacing the glyphs for
  4169    both upper and lowercase letters in the case of ‘<a
  4170    href="#all-small-caps"><code class=property>all-small-caps</code></a>’).
  4172   <div class=figure style="padding: 0; margin: auto;"><img alt="synthetic vs.
  4173    real small-caps" class=hires src=synthetic-vs-real-small-caps.png
  4174    width=512px>
  4175    <p class=caption>Synthetic vs. real small-caps
  4176   </div>
  4178   <p>To match the surrounding text, a font may provide alternate glyphs for
  4179    caseless characters when these features are enabled but when a user agent
  4180    simulates small capitals, it must not attempt to simulate alternates for
  4181    codepoints which are considered caseless.
  4183   <div class=figure style="padding: 0; margin: auto;"><img alt="caseless
  4184    characters with small-caps, all-small-caps enabled" class=hires
  4185    src=small-capitals-variations.png width=418px>
  4186    <p class=caption>Caseless characters with small-caps, all-small-caps
  4187     enabled
  4188   </div>
  4190   <p>If either ‘<a href="#petite-caps"><code
  4191    class=property>petite-caps</code></a>’ or ‘<a
  4192    href="#all-petite-caps"><code class=property>all-petite-caps</code></a>’
  4193    is specified for a font that doesn't support these features, the property
  4194    behaves as if ‘<a href="#small-caps"><code
  4195    class=property>small-caps</code></a>’ or ‘<a
  4196    href="#all-small-caps"><code class=property>all-small-caps</code></a>’,
  4197    respectively, had been specified. If ‘<a href="#unicase"><code
  4198    class=property>unicase</code></a>’ is specified for a font that doesn't
  4199    support that feature, the property behaves as if ‘<a
  4200    href="#small-caps"><code class=property>small-caps</code></a>’ was
  4201    applied only to lowercased uppercase letters. If ‘<a
  4202    href="#titling-caps"><code class=property>titling-caps</code></a>’ is
  4203    specified with a font that does not support this feature, this property
  4204    has no visible effect. When simulated small capital glyphs are used, for
  4205    scripts that lack uppercase and lowercase letters, ‘<a
  4206    href="#small-caps"><code class=property>small-caps</code></a>’, ‘<a
  4207    href="#all-small-caps"><code class=property>all-small-caps</code></a>’,
  4208    ‘<a href="#petite-caps"><code class=property>petite-caps</code></a>’,
  4209    ‘<a href="#all-petite-caps"><code
  4210    class=property>all-petite-caps</code></a>’ and ‘<a
  4211    href="#unicase"><code class=property>unicase</code></a>’ have no visible
  4212    effect.
  4214   <p>When casing transforms are used to simulate small capitals, the casing
  4215    transformations must match those used for the <span
  4216    class=property>‘<code class=property>text-transform</code>’</span>
  4217    property.
  4219   <p>As a last resort, unscaled uppercase letter glyphs in a normal font may
  4220    replace glyphs in a small-caps font so that the text appears in all
  4221    uppercase letters.
  4223   <div class=figure style="padding: 0; margin: auto;"><img alt="using
  4224    all-small-caps in acronym-laden text" class=hires
  4225    src=acronym-laden-text.png width=596px>
  4226    <p class=caption>Using small capitals to improve readability in
  4227     acronym-laden text
  4228   </div>
  4230   <div class=example>
  4231    <p>Quotes rendered italicised, with small-caps on the first line:</p>
  4233    <pre>blockquote            { font-style: italic; }
  4234 blockquote:first-line { font-variant: small-caps; }
  4236 &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>
  4237 </pre>
  4238   </div>
  4239   <!-- prop: font-variant-numeric -->
  4241   <h3 id=font-variant-numeric-prop><span class=secno>6.7 </span>Numerical
  4242    formatting: the <a
  4243    href="#propdef-font-variant-numeric">font-variant-numeric</a> property</h3>
  4245   <table class=propdef id=namefont-variant-numericvaluenormal-ltnu>
  4246    <tbody>
  4247     <tr>
  4248      <td>Name:
  4250      <td><dfn id=propdef-font-variant-numeric>font-variant-numeric</dfn>
  4252     <tr>
  4253      <td>Value:
  4255      <td><a href="#font-variant-numeric-normal-value"
  4256       title="normal!!font-variant-numeric">normal</a> | [ <a
  4257       href="#numeric-figure-values"><var>&lt;numeric-figure-values&gt;</var></a>
  4258       || <a
  4259       href="#numeric-spacing-values"><var>&lt;numeric-spacing-values&gt;</var></a>
  4260       || <a
  4261       href="#numeric-fraction-values"><var>&lt;numeric-fraction-values&gt;</var></a>
  4262       || <a href="#ordinal">ordinal</a> || <a
  4263       href="#slashed-zero">slashed-zero</a> ]
  4265     <tr>
  4266      <td>Initial:
  4268      <td>normal
  4270     <tr>
  4271      <td>Applies to:
  4273      <td>all elements
  4275     <tr>
  4276      <td>Inherited:
  4278      <td>yes
  4280     <tr>
  4281      <td>Percentages:
  4283      <td>N/A
  4285     <tr>
  4286      <td>Media:
  4288      <td>visual
  4290     <tr>
  4291      <td>Computed value:
  4293      <td>as specified
  4295     <tr>
  4296      <td>Animatable:
  4298      <td>no
  4299   </table>
  4301   <p>Specifies control over numerical forms. The example below shows how some
  4302    of these values can be combined to influence the rendering of tabular data
  4303    with fonts that support these features. Within normal paragraph text,
  4304    proportional numbers are used while tabular numbers are used so that
  4305    columns of numbers line up properly:
  4307   <div class=figure style="padding: 0; margin: auto;"><img alt="combining
  4308    number styles" src=numberstyles.png>
  4309    <p class=caption>Using number styles
  4310   </div>
  4312   <p>Possible combinations:
  4314   <pre
  4315    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>
  4317   <pre
  4318    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>
  4320   <pre
  4321    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>
  4323   <p>Individual values have the following meanings:
  4325   <dl>
  4326    <dt><dfn id=font-variant-numeric-normal-value
  4327     title="normal!!font-variant-numeric">normal</dfn>
  4329    <dd>None of the features listed below are enabled.
  4331    <dt><dfn id=lining-nums>lining-nums</dfn>
  4333    <dd>Enables display of lining numerals (OpenType feature: <span
  4334     class=tag>lnum</span>).
  4336    <dt><dfn id=oldstyle-nums>oldstyle-nums</dfn>
  4338    <dd>Enables display of old-style numerals (OpenType feature: <span
  4339     class=tag>onum</span>).
  4341    <dt><dfn id=proportional-nums>proportional-nums</dfn>
  4343    <dd>Enables display of proportional numerals (OpenType feature: <span
  4344     class=tag>pnum</span>).
  4346    <dt><dfn id=tabular-nums>tabular-nums</dfn>
  4348    <dd>Enables display of tabular numerals (OpenType feature: <span
  4349     class=tag>tnum</span>).
  4351    <dt><dfn id=diagonal-fractions>diagonal-fractions</dfn>
  4353    <dd>Enables display of lining diagonal fractions (OpenType feature: <span
  4354     class=tag>frac</span>).
  4355   </dl>
  4357   <div class=featex><img alt="diagonal fraction example" src=frac.png></div>
  4359   <dl>
  4360    <dt><dfn id=stacked-fractions>stacked-fractions</dfn>
  4362    <dd>Enables display of lining stacked fractions (OpenType feature: <span
  4363     class=tag>afrc</span>).
  4364   </dl>
  4366   <div class=featex><img alt="stacked fraction example" src=afrc.png></div>
  4368   <dl>
  4369    <dt><dfn id=ordinal>ordinal</dfn>
  4371    <dd>Enables display of forms used with ordinal numbers (OpenType feature:
  4372     <span class=tag>ordn</span>).
  4374    <dt><dfn id=slashed-zero>slashed-zero</dfn>
  4376    <dd>Enables display of slashed zeros (OpenType feature: <span
  4377     class=tag>zero</span>).
  4378   </dl>
  4380   <div class=featex><img alt="slashed zero example" src=zero.png></div>
  4382   <div class=example id=steak-marinade>
  4383    <p>A simple flank steak marinade recipe, rendered with automatic fractions
  4384     and old-style numerals:</p>
  4386    <pre>.amount { font-variant-numeric: oldstyle-nums diagonal-fractions; }
  4388 &lt;h4>Steak marinade:&lt;/h4>
  4389 &lt;ul>
  4390   &lt;li>&lt;span class="amount">2&lt;/span> tbsp olive oil&lt;/li>
  4391   &lt;li>&lt;span class="amount">1&lt;/span> tbsp lemon juice&lt;/li>
  4392   &lt;li>&lt;span class="amount">1&lt;/span> tbsp soy sauce&lt;/li>
  4393   &lt;li>&lt;span class="amount">1 1/2&lt;/span> tbsp dry minced onion&lt;/li>
  4394   &lt;li>&lt;span class="amount">2 1/2&lt;/span> tsp italian seasoning&lt;/li>
  4395   &lt;li>Salt &amp;amp; pepper&lt;/li>
  4396 &lt;/ul>
  4398 &lt;p>Mix the meat with the marinade and let it sit covered in the refrigerator
  4399 for a few hours or overnight.&lt;/p>
  4400 </pre>
  4402    <p>Note that the fraction feature is only applied to values not the entire
  4403     paragraph. Fonts often implement this feature using contextual rules
  4404     based on the use of the slash (‘<code class=css>/</code>’) character.
  4405     As such, it's not suitable for use as a paragraph-level style.</p>
  4406   </div>
  4407   <!-- prop: font-variant-alternates -->
  4409   <h3 id=font-variant-alternates-prop><span class=secno>6.8 </span>Alternates
  4410    and swashes: the <a
  4411    href="#propdef-font-variant-alternates">font-variant-alternates</a>
  4412    property</h3>
  4414   <table class=propdef id=namefont-variant-alternatesvaluenormal-s>
  4415    <tbody>
  4416     <tr>
  4417      <td>Name:
  4419      <td><dfn
  4420       id=propdef-font-variant-alternates>font-variant-alternates</dfn>
  4422     <tr>
  4423      <td>Value:
  4425      <td>normal | [ <a href="#stylistic"
  4426       title=stylistic>stylistic(&lt;feature-value-name&gt;)</a> || <a
  4427       href="#historical-forms">historical-forms</a> || <a href="#styleset"
  4428       title=styleset>styleset(&lt;feature-value-name&gt; #)</a> || <a
  4429       href="#character-variant"
  4430       title=character-variant>character-variant(&lt;feature-value-name&gt;
  4431       #)</a> || <a href="#swash"
  4432       title=swash>swash(&lt;feature-value-name&gt;)</a> || <a
  4433       href="#ornaments"
  4434       title=ornaments>ornaments(&lt;feature-value-name&gt;)</a> || <a
  4435       href="#annotation"
  4436       title=annotation>annotation(&lt;feature-value-name&gt;)</a> ]
  4438     <tr>
  4439      <td>Initial:
  4441      <td>normal
  4443     <tr>
  4444      <td>Applies to:
  4446      <td>all elements
  4448     <tr>
  4449      <td>Inherited:
  4451      <td>yes
  4453     <tr>
  4454      <td>Percentages:
  4456      <td>N/A
  4458     <tr>
  4459      <td>Media:
  4461      <td>visual
  4463     <tr>
  4464      <td>Computed value:
  4466      <td>as specified
  4468     <tr>
  4469      <td>Animatable:
  4471      <td>no
  4472   </table>
  4474   <p>For any given character, fonts can provide a variety of alternate glyphs
  4475    in addition to the default glyph for that character. This property
  4476    provides control over the selection of these alternate glyphs.
  4478   <p>For many of the property values listed below, several different
  4479    alternate glyphs are available. How many alternates are available and what
  4480    they represent is font-specific, so these are each marked <dfn
  4481    id=font-specific>font specific</dfn> in the value definitions below.
  4482    Because the nature of these alternates is font-specific, the <a
  4483    href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
  4484    rule is used to define values for a specific font family or set of
  4485    families that associate a font-specific numeric
  4486    <code>&lt;feature-index&gt;</code> with a custom
  4487    <code>&lt;feature-value-name&gt;</code>, which is then used in this
  4488    property to select specific alternates:
  4490   <pre>@font-feature-values Noble Script { @swash { swishy: 1; flowing: 2; } }
  4492 p {
  4493   font-family: Noble Script;
  4494   font-variant-alternates: swash(flowing); /* use swash alternate #2 */
  4495 }</pre>
  4497   <p>When a particular <code>&lt;feature-value-name&gt;</code> has not been
  4498    defined for a given family or for a particular feature type, the computed
  4499    value must be the same as if it had been defined. However, property values
  4500    that contain these undefined <code>&lt;feature-value-name&gt;</code>
  4501    identifiers must be ignored when choosing glyphs.
  4503   <pre>/* these two style rules are effectively the same */
  4504 p { font-variant-alternates: swash(unknown-value); } /* not a defined value, ignored */
  4505 p { font-variant-alternates: normal; }
  4506 </pre>
  4508   <p>This allows values to be defined and used for a given set of font
  4509    families but ignored if fallback occurs, since the font family name would
  4510    be different. If a given value is outside the range supported by a given
  4511    font, the value is ignored. These values never apply to generic font
  4512    families.
  4514   <p>Individual values have the following meanings:
  4516   <dl>
  4517    <dt><dfn id=font-variant-alternates-normal-value
  4518     title="normal!!font-variant-alternates">normal</dfn>
  4520    <dd>None of the features listed below are enabled.
  4522    <dt><dfn id=historical-forms>historical-forms</dfn>
  4524    <dd>Enables display of historical forms (OpenType feature: <span
  4525     class=tag>hist</span>).
  4526   </dl>
  4528   <div class=featex><img alt="historical form example" src=hist.png></div>
  4530   <dl>
  4531    <dt><dfn id=stylistic
  4532     title=stylistic>stylistic(&lt;feature-value-name&gt;)</dfn>
  4534    <dd>Enables display of stylistic alternates (<a
  4535     href="#font-specific"><em>font specific</em></a>, OpenType feature: <span
  4536     class=tag>salt &lt;feature-index&gt;</span>).
  4537   </dl>
  4539   <div class=featex><img alt="stylistic alternate example" src=salt.png></div>
  4541   <dl>
  4542    <dt><dfn id=styleset title=styleset>styleset(&lt;feature-value-name&gt;
  4543     #)</dfn>
  4545    <dd>Enables display with stylistic sets (<a href="#font-specific"><em>font
  4546     specific</em></a>, OpenType feature: <span
  4547     class=tag>ss&lt;feature-index&gt;</span> OpenType currently defines <span
  4548     class=tag>ss01</span> through <span class=tag>ss20</span>).
  4549   </dl>
  4551   <div class=featex><img alt="styleset example" src=ssnn.png></div>
  4553   <dl>
  4554    <dt><dfn id=character-variant
  4555     title=character-variant>character-variant(&lt;feature-value-name&gt;
  4556     #)</dfn>
  4558    <dd>Enables display of specific character variants (<a
  4559     href="#font-specific"><em>font specific</em></a>, OpenType feature: <span
  4560     class=tag>cv&lt;feature-index&gt;</span> OpenType currently defines <span
  4561     class=tag>cv01</span> through <span class=tag>cv99</span>).
  4563    <dt><dfn id=swash title=swash>swash(&lt;feature-value-name&gt;)</dfn>
  4565    <dd>Enables display of swash glyphs (<a href="#font-specific"><em>font
  4566     specific</em></a>, OpenType feature: <span class=tag>swsh
  4567     &lt;feature-index&gt;, cswh &lt;feature-index&gt;</span>).
  4568   </dl>
  4570   <div class=featex><img alt="swash example" src=swsh.png></div>
  4572   <dl>
  4573    <dt><dfn id=ornaments
  4574     title=ornaments>ornaments(&lt;feature-value-name&gt;)</dfn>
  4576    <dd>Enables replacement of default glyphs with ornaments, if provided in
  4577     the font (<a href="#font-specific"><em>font specific</em></a>, OpenType
  4578     feature: <span class=tag>ornm &lt;feature-index&gt;</span>). Some fonts
  4579     may offer ornament glyphs as alternates for a wide collection of
  4580     characters; however, displaying arbitrary characters (e.g.,
  4581     alphanumerics) as ornaments is poor practice as it distorts the semantics
  4582     of the data. Font designers are encouraged to encode all ornaments
  4583     (except those explicitly encoded in the Unicode Dingbats blocks, etc.) as
  4584     alternates for the bullet character (U+2022) to allow authors to select
  4585     the desired glyph using ‘<a href="#ornaments"><code
  4586     class=property>ornaments</code></a>’.
  4587   </dl>
  4589   <div class=featex><img alt="ornaments example" src=ornm.png></div>
  4591   <dl>
  4592    <dt><dfn id=annotation
  4593     title=annotation>annotation(&lt;feature-value-name&gt;)</dfn>
  4595    <dd>Enables display of alternate annotation forms (<a
  4596     href="#font-specific"><em>font specific</em></a>, OpenType feature: <span
  4597     class=tag>nalt &lt;feature-index&gt;</span>).
  4598   </dl>
  4600   <div class=featex><img alt="alternate annotation form example"
  4601    src=nalt.png></div>
  4603   <h3 id=font-feature-values><span class=secno>6.9 </span>Defining font
  4604    specific alternates: the <dfn id=at-font-feature-values-rule
  4605    style="font-weight: inherit; font-style:
  4606    inherit"><code>@font-feature-values</code></dfn> rule</h3>
  4608   <p>Several of the possible values of ‘<a
  4609    href="#propdef-font-variant-alternates"><code
  4610    class=property>font-variant-alternates</code></a>’ listed above are
  4611    labeled as <a href="#font-specific"><em>font specific</em></a>. For these
  4612    features fonts may define not just a single glyph but a set of alternate
  4613    glyphs with an index to select a given alternate. Since these are font
  4614    family specific, the <a
  4615    href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
  4616    rule is used to define named values for these indices for a given family.
  4618   <p class=note>See the <a href="#om-fontfeaturevalues">object model
  4619    reference section</a> for a description of the interfaces used to modify
  4620    these rules via the CSS Object Model.
  4622   <div class=example>
  4623    <p>In the case of the swash Q in the example shown above, the swash could
  4624     be specified using these style rules:</p>
  4626    <pre>
  4628 @font-feature-values Jupiter Sans {
  4629   @swash {
  4630     delicate: 1;
  4631     flowing: 2;
  4635 h2 { font-family: Jupiter Sans, sans-serif; }
  4637 /* show the second swash variant in h2 headings */
  4638 h2:first-letter { font-variant-alternates: swash(flowing); }
  4640 &lt;h2>Quick&lt;/h2></pre>
  4642    <p>When Jupiter Sans is present, the second alternate swash alternate will
  4643     be displayed. When not present, no swash character will be shown, since
  4644     the specific named value "flowing" is only defined for the Jupiter Sans
  4645     family. The @-mark indicates the name of the property value for which a
  4646     named value can be used. The name "flowing" is chosen by the author. The
  4647     index that represents each alternate is defined within a given font's
  4648     data.</p>
  4649   </div>
  4651   <h4 id=basic-syntax><span class=secno>6.9.1 </span>Basic syntax</h4>
  4653   <p>An <a
  4654    href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
  4655    rule is composed of a list of font families followed by a block containing
  4656    individual <a href="#featurevalueblock"><i
  4657    title="feature_value_block">feature value blocks</i></a> that take the
  4658    form of @-rules. Each block defines a set of named values for a specific
  4659    font feature when a given set of font families is used. Effectively, they
  4660    define a mapping of ⟨family, feature, ident⟩ → ⟨values⟩ where
  4661    ⟨values⟩ are the numeric indices used for specific features defined
  4662    for a given font.
  4664   <p>In terms of the grammar, this specification defines the following
  4665    productions:
  4667   <pre><dfn id=fontfeaturevaluesrule>font_feature_values_rule</dfn>
  4668   : <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>*
  4669     '{' <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>*
  4672 <dfn id=fontfamilynamelist>font_family_name_list</dfn>
  4673   : <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> ]*
  4676 <dfn id=fontfamilyname>font_family_name</dfn>
  4677   : <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> ]* ]
  4680 <dfn id=featurevalueblock>feature_value_block</dfn>
  4681   : <a href="#featuretype"><i>feature_type</i></a> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>*
  4682     '{' <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>*
  4685 <dfn id=featuretype>feature_type</dfn>:
  4686   <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>ATKEYWORD</i></a>
  4689 <dfn id=featurevaluedefinition>feature_value_definition</dfn>
  4690   : <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> ]*
  4692 </pre>
  4694   <p>The following new token is introduced:
  4696   <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>;}
  4697 </pre>
  4699   <p><a href="#featurevalueblock"><i title="feature_value_block">Feature
  4700    value blocks</i></a> are handled as <a
  4701    href="http://www.w3.org/TR/CSS2/syndata.html#at-rules">at-rules</a>, they
  4702    consist of everything up to the next block or semi-colon, whichever comes
  4703    first.
  4705   <p>The <a href="#fontfamilynamelist"><i title="font_family_name_list">font
  4706    family list</i></a> is a comma-delimited list of <a
  4707    href="#fontfamilyname"><i title="font_family_name">font family
  4708    names</i></a> that match the definition of <a
  4709    href="#family-name-value"><var>&lt;family-name&gt;</var></a> for the <a
  4710    href="#propdef-font-family" title="font-family!!property">‘<code
  4711    class=property>font-family</code>’</a> property. This means that only
  4712    named font families are allowed, rules that include generic or system
  4713    fonts in the list of font families are syntax errors. However, if a user
  4714    agent defines a generic font to be a specific named font (e.g. Helvetica),
  4715    the settings associated with that family name will be used. If syntax
  4716    errors occur within the font family list, the entire rule must be ignored.
  4718   <p>Within <a href="#featurevalueblock"><i
  4719    title="feature_value_block">feature value blocks</i></a>, the <a
  4720    href="#featuretype"><i title="feature_type">feature type</i></a> is
  4721    ‘<code class=css>@</code>’ followed by the name of one of the <a
  4722    href="#font-specific"><em>font specific</em></a> property values of ‘<a
  4723    href="#propdef-font-variant-alternates"><code
  4724    class=property>font-variant-alternates</code></a>’ (e.g. <a
  4725    href="#swash"><code>@swash</code></a>). The identifiers used within
  4726    feature value definitions follow the rules of CSS user identifiers and are
  4727    case-sensitive. They are unique only for a given set of font families and
  4728    <a href="#featuretype"><i title="feature_type">feature type</i></a>. The
  4729    same identifier used with a different <a href="#featuretype"><i
  4730    title="feature_type">feature type</i></a> is treated as a separate and
  4731    distinct value. If the same identifier is defined mulitple times for a
  4732    given <a href="#featuretype"><i title="feature_type">feature type</i></a>
  4733    and font family, the last defined value is used. Values associated with a
  4734    given identifier are limited to integer values 0 or greater.
  4736   <p>When syntax errors occur within a <a href="#featurevaluedefinition"><i
  4737    title="feature_value_definition">feature value definition</i></a>, such as
  4738    invalid identifiers or values, the entire <a
  4739    href="#featurevaluedefinition"><i title="feature_value_definition">feature
  4740    value definition</i></a> must be omitted, just as syntax errors in style
  4741    declarations are handled. When the <a href="#featuretype"><i
  4742    title="feature_type">feature type</i></a> is invalid, the entire
  4743    associated <a href="#featurevalueblock"><i
  4744    title="feature_value_block">feature value block</i></a> must be ignored.
  4746   <div class=example>
  4747    <p>Rules that are equivalent given syntax error handling:</p>
  4749    <pre>@font-feature-values Bongo {
  4750   @swash { ornate: 1; }
  4751   annotation { boxed: 4; } /* should be @annotation! */
  4752   @swash { double-loops: 1; flowing: -1; } /* negative value */
  4753   @ornaments ; /* incomplete definition */
  4754   @styleset { double-W: 14; sharp-terminals: 16 1 } /* missing ; */
  4755   <a href="http://www.angryalien.com/0504/shiningbunnies.html" style="text-decoration: none; border: none;">redrum</a>  /* random editing mistake */
  4756 }</pre>
  4758    <p>The example above is equivalent to:</p>
  4760    <pre>@font-feature-values Bongo {
  4761   @swash { ornate: 1; }
  4762   @swash { double-loops: 1; }
  4763   @styleset { double-W: 14; sharp-terminals: 16 1; }
  4764 }</pre>
  4765   </div>
  4767   <p>If multiple <a
  4768    href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
  4769    rules are defined for a given family, the resulting values definitions are
  4770    the union of the definitions contained within these rules. This allows a
  4771    set of named values to be defined for a given font family globally for a
  4772    site and specific additions made per-page.
  4774   <div class=example>
  4775    <p>Using both site-wide and per-page feature values:</p>
  4777    <pre>
  4778 site.css:
  4780   @font-feature-values Mercury Serif {
  4781     @styleset {
  4782       stacked-g: 3; /* "two-storey" versions of g, a */
  4783       stacked-a: 4;
  4787 page.css:
  4789   @font-feature-values Mercury Serif {
  4790     @styleset {
  4791       geometric-m: 7; /* alternate version of m */
  4795   body {
  4796     font-family: Mercury Serif, serif;
  4798     /* enable both the use of stacked g and alternate m */
  4799     font-variant-alternates: styleset(stacked-g, geometric-m);
  4800   }</pre>
  4801   </div>
  4803   <div class=example>
  4804    <p>Using a commonly named value allows authors to use a single style rule
  4805     to cover a set of fonts for which the underlying selector is different
  4806     for each font. If either font in the example below is found, a circled
  4807     number glyph will be used:</p>
  4809    <pre>@font-feature-values Taisho Gothic {
  4810   @annotation { boxed: 1; circled: 4; }
  4813 @font-feature-values Otaru Kisa {
  4814   @annotation { circled: 1; black-boxed: 3; }
  4817 h3.title {
  4818   /* circled form defined for both fonts */
  4819   font-family: Taisho Gothic, Otaru Kisa;
  4820   font-variant: annotation(circled);
  4821 }</pre>
  4822   </div>
  4824   <h4 id=multi-valued-feature-value-definitions><span class=secno>6.9.2
  4825    </span>Multi-valued feature value definitions</h4>
  4827   <p>Most <a href="#font-specific"><em>font specific</em></a> ‘<a
  4828    href="#propdef-font-variant-alternates"><code
  4829    class=property>font-variant-alternates</code></a>’ property values take
  4830    a single value (e.g. ‘<a href="#swash"><code
  4831    class=property>swash</code></a>’). The ‘<a
  4832    href="#character-variant"><code
  4833    class=property>character-variant</code></a>’ property value allows two
  4834    values and ‘<a href="#styleset"><code
  4835    class=property>styleset</code></a>’ allows an unlimited number.
  4837   <p>For the styleset property value, multiple values indicate the style sets
  4838    to be enabled. Values between 1 and 99 enable OpenType features <span
  4839    class=tag>ss01</span> through <span class=tag>ss99</span>. However, the
  4840    OpenType standard only officially defines <span class=tag>ss01</span>
  4841    through <span class=tag>ss20</span>. For OpenType fonts, values greater
  4842    than 99 or equal to 0 do not generate a syntax error when parsed but
  4843    enable no OpenType features.
  4845   <pre>@font-feature-values Mars Serif {
  4846   @styleset {
  4847     alt-g: 1;        /* implies ss01 = 1 */
  4848     curly-quotes: 3; /* implies ss03 = 1 */
  4849     code: 4 5;       /* implies ss04 = 1, ss05 = 1 */
  4852   @styleset {
  4853     dumb: 125;        /* &gt;99, ignored */
  4856   @swash {
  4857     swishy: 3 5;     /* more than 1 value for swash, syntax error */
  4861 p.codeblock {
  4862   /* implies ss03 = 1, ss04 = 1, ss05 = 1 */
  4863   font-variant-alternates: styleset(curly-quotes, code);
  4864 }</pre>
  4866   <p>For character-variant, a single value between 1 and 99 indicates the
  4867    enabling of OpenType feature <span class=tag>cv01</span> through <span
  4868    class=tag>cv99</span>. For OpenType fonts, values greater than 99 or equal
  4869    to 0 are ignored but do not generate a syntax error when parsed but enable
  4870    no OpenType features. When two values are listed, the first value
  4871    indicates the feature used and the second the value passed for that
  4872    feature. If more than two values are assigned to a given name, a syntax
  4873    error occurs and the entire <a href="#featurevaluedefinition"><i
  4874    title="feature_value_definition">feature value definition</i></a> is
  4875    ignored.
  4877   <pre>@font-feature-values MM Greek {
  4878   @character-variant { alpha-2: 1 2; }   /* implies cv01 = 2 */
  4879   @character-variant { beta-3: 2 3; }    /* implies cv02 = 3 */
  4880   @character-variant { epsilon: 5 3 6; } /* more than 2 values, syntax error, definition ignored */
  4881   @character-variant { gamma: 12; }      /* implies cv12 = 1 */
  4882   @character-variant { zeta:   20 3; }   /* implies cv20 = 3 */
  4883   @character-variant { zeta-2: 20 2; }   /* implies cv20 = 2 */
  4884   @character-variant { silly: 105; }     /* &gt;99, ignored */
  4885   @character-variant { dumb: 323 3; }    /* &gt;99, ignored */
  4888 #title {
  4889   /* use the third alternate beta, first alternate gamma */
  4890   font-variant-alternates: character-variant(beta-3, gamma);
  4893 p {
  4894   /* zeta-2 follows zeta, implies cv20 = 2  */
  4895   font-variant-alternates: character-variant(zeta, zeta-2);
  4898 .special {
  4899   /* zeta follows zeta-2, implies cv20 = 3  */
  4900   font-variant-alternates: character-variant(zeta-2, zeta);
  4901 }</pre>
  4903   <div class=figure><img alt="Matching text on Byzantine seals using
  4904    character variants" src=byzantineseal.png>
  4905    <p class=caption>Byzantine seal text displayed with character variants
  4906   </div>
  4908   <div class=example>
  4909    <p>In the figure above, the text in red is rendered using a font
  4910     containing character variants that mimic the character forms found on a
  4911     Byzantine seal from the 8th century A.D. Two lines below is the same text
  4912     displayed in a font without variants. Note the two variants for U and N
  4913     used on the seal.</p>
  4915    <pre>@font-feature-values Athena Ruby {
  4916   @character-variant {
  4917     leo-B: 2 1;
  4918     leo-M: 13 3;
  4919     leo-alt-N: 14 1;
  4920     leo-N: 14 2;
  4921     leo-T: 20 1;
  4922     leo-U: 21 2;
  4923     leo-alt-U: 21 4;
  4927 p {
  4928   font-variant: discretionary-ligatures,
  4929                 character-variant(leo-B, leo-M, leo-N, leo-T, leo-U);
  4932 span.alt-N {
  4933   font-variant-alternates: character-variant(leo-alt-N);
  4936 span.alt-U {
  4937   font-variant-alternates: character-variant(leo-alt-U);
  4940 &lt;p>ENO....UP͞RSTU&lt;span class="alt-U">U&lt;/span>͞&lt;span class="alt-U">U&lt;/span>ΚΑΙTỤẠG̣IUPNS&lt;/p>
  4942 &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>
  4943 </pre>
  4944   </div>
  4946   <h3 id=font-variant-east-asian-prop><span class=secno>6.10 </span>East
  4947    Asian text rendering: the <a
  4948    href="#propdef-font-variant-east-asian">font-variant-east-asian</a>
  4949    property</h3>
  4951   <table class=propdef id=namefont-variant-east-asianvaluenormal-l>
  4952    <tbody>
  4953     <tr>
  4954      <td>Name:
  4956      <td><dfn
  4957       id=propdef-font-variant-east-asian>font-variant-east-asian</dfn>
  4959     <tr>
  4960      <td>Value:
  4962      <td><a href="#font-variant-east-asian-normal-value"
  4963       title="normal!!font-variant-east-asian">normal</a> | [ <a
  4964       href="#east-asian-variant-values"><var>&lt;east-asian-variant-values&gt;</var></a>
  4965       || <a
  4966       href="#east-asian-width-values"><var>&lt;east-asian-width-values&gt;</var></a>
  4967       || <a href="#ruby">ruby</a> ]
  4969     <tr>
  4970      <td>Initial:
  4972      <td>normal
  4974     <tr>
  4975      <td>Applies to:
  4977      <td>all elements
  4979     <tr>
  4980      <td>Inherited:
  4982      <td>yes
  4984     <tr>
  4985      <td>Percentages:
  4987      <td>N/A
  4989     <tr>
  4990      <td>Media:
  4992      <td>visual
  4994     <tr>
  4995      <td>Computed value:
  4997      <td>as specified
  4999     <tr>
  5000      <td>Animatable:
  5002      <td>no
  5003   </table>
  5005   <p>Allows control of glyph substitution and sizing in East Asian text.
  5007   <pre
  5008    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>
  5010   <pre
  5011    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>
  5013   <p>Individual values have the following meanings:
  5015   <dl>
  5016    <dt><dfn id=font-variant-east-asian-normal-value
  5017     title="normal!!font-variant-east-asian">normal</dfn>
  5019    <dd>None of the features listed below are enabled.
  5021    <dt><dfn id=jis78>jis78</dfn>
  5023    <dd>Enables rendering of JIS78 forms (OpenType feature: <span
  5024     class=tag>jp78</span>).
  5025   </dl>
  5027   <div class=featex><img alt="JIS78 form example" src=jp78.png></div>
  5029   <dl>
  5030    <dt><dfn id=jis83>jis83</dfn>
  5032    <dd>Enables rendering of JIS83 forms (OpenType feature: <span
  5033     class=tag>jp83</span>).
  5035    <dt><dfn id=jis90>jis90</dfn>
  5037    <dd>Enables rendering of JIS90 forms (OpenType feature: <span
  5038     class=tag>jp90</span>).
  5040    <dt><dfn id=jis04>jis04</dfn>
  5042    <dd>Enables rendering of JIS2004 forms (OpenType feature: <span
  5043     class=tag>jp04</span>).
  5044     <p>The various JIS variants reflect the glyph forms defined in different
  5045      Japanese national standards. Fonts generally include glyphs defined by
  5046      the most recent national standard but it's sometimes necessary to use
  5047      older variants, to match signage for example.</p>
  5049    <dt><dfn id=simplified>simplified</dfn>
  5051    <dd>Enables rendering of simplified forms (OpenType feature: <span
  5052     class=tag>smpl</span>).
  5054    <dt><dfn id=traditional>traditional</dfn>
  5056    <dd>Enables rendering of traditional forms (OpenType feature: <span
  5057     class=tag>trad</span>).
  5058   </dl>
  5060   <p>The ‘<a href="#simplified"><code
  5061    class=property>simplified</code></a>’ and ‘<a
  5062    href="#traditional"><code class=property>traditional</code></a>’ values
  5063    allow control over the glyph forms for characters which have been
  5064    simplified over time but for which the older, traditional form is still
  5065    used in some contexts. The exact set of characters and glyph forms will
  5066    vary to some degree by context for which a given font was designed.
  5068   <div class=featex><img alt="tradtional form example" src=trad.png></div>
  5070   <dl>
  5071    <dt><dfn id=full-width>full-width</dfn>
  5073    <dd>Enables rendering of full-width variants (OpenType feature: <span
  5074     class=tag>fwid</span>).
  5076    <dt><dfn id=proportional-width>proportional-width</dfn>
  5078    <dd>Enables rendering of proportionally-spaced variants (OpenType feature:
  5079     <span class=tag>pwid</span>).
  5080   </dl>
  5082   <div class=featex><img alt="proportionally spaced Japanese example"
  5083    src=pwid.png></div>
  5085   <dl>
  5086    <dt><dfn id=ruby>ruby</dfn>
  5088    <dd>Enables display of ruby variant glyphs (OpenType feature: <span
  5089     class=tag>ruby</span>). Since ruby text is generally smaller than the
  5090     associated body text, font designers can design special glyphs for use
  5091     with ruby that are more readable than scaled down versions of the default
  5092     glyphs. Only glyph selection is affected, there is no associated font
  5093     scaling or other change that affects line layout. The red ruby text below
  5094     is shown with default glyphs (top) and with ruby variant glyphs (bottom).
  5095     Note the slight difference in stroke thickness.
  5096   </dl>
  5098   <div class=featex><img alt="ruby variant example" src=rubyshinkansen.png></div>
  5100   <h3 id=font-variant-prop><span class=secno>6.11 </span>Overall shorthand
  5101    for font rendering: the <a href="#propdef-font-variant">font-variant</a>
  5102    property</h3>
  5104   <table class=propdef id=namefont-variantvaluenormal-none-ltcommo>
  5105    <tbody>
  5106     <tr>
  5107      <td>Name:
  5109      <td><dfn id=propdef-font-variant
  5110       title="font-variant!!property">font-variant</dfn>
  5112     <tr>
  5113      <td>Value:
  5115      <td><a href="#font-variant-normal-value"
  5116       title="normal!!font-variant">normal</a> | <a
  5117       href="#font-variant-none-value" title="none!!font-variant">none</a> | [
  5118       <a href="#common-lig-values"><var>&lt;common-lig-values&gt;</var></a>
  5119       || <a
  5120       href="#discretionary-lig-values"><var>&lt;discretionary-lig-values&gt;</var></a>
  5121       || <a
  5122       href="#historical-lig-values"><var>&lt;historical-lig-values&gt;</var></a>
  5123       || <a
  5124       href="#contextual-alt-values"><var>&lt;contextual-alt-values&gt;</var></a>
  5125       || <a href="#stylistic"><var
  5126       title=stylistic>stylistic(&lt;feature-value-name&gt;)</var></a> || <a
  5127       href="#historical-forms"><var>historical-forms</var></a> || <a
  5128       href="#styleset"><var
  5129       title=styleset>styleset(&lt;feature-value-name&gt; #)</var></a> || <a
  5130       href="#character-variant"><var
  5131       title=character-variant>character-variant(&lt;feature-value-name&gt;
  5132       #)</var></a> || <a href="#swash"><var
  5133       title=swash>swash(&lt;feature-value-name&gt;)</var></a> || <a
  5134       href="#ornaments"><var
  5135       title=ornaments>ornaments(&lt;feature-value-name&gt;)</var></a> || <a
  5136       href="#annotation"><var
  5137       title=annotation>annotation(&lt;feature-value-name&gt;)</var></a> || [
  5138       <a href="#small-caps"><i>small-caps</i></a> | <a
  5139       href="#all-small-caps"><i>all-small-caps</i></a> | <a
  5140       href="#petite-caps"><i>petite-caps</i></a> | <a
  5141       href="#all-petite-caps"><i>all-petite-caps</i></a> | <a
  5142       href="#unicase"><i>unicase</i></a> | <a
  5143       href="#titling-caps"><i>titling-caps</i></a> ] || <a
  5144       href="#numeric-figure-values"><var>&lt;numeric-figure-values&gt;</var></a>
  5145       || <a
  5146       href="#numeric-spacing-values"><var>&lt;numeric-spacing-values&gt;</var></a>
  5147       || <a
  5148       href="#numeric-fraction-values"><var>&lt;numeric-fraction-values&gt;</var></a>
  5149       || <a href="#ordinal"><i>ordinal</i></a> || <a
  5150       href="#slashed-zero"><i>slashed-zero</i></a> || <a
  5151       href="#east-asian-variant-values"><var>&lt;east-asian-variant-values&gt;</var></a>
  5152       || <a
  5153       href="#east-asian-width-values"><var>&lt;east-asian-width-values&gt;</var></a>
  5154       || <a href="#ruby"><i>ruby</i></a> ]
  5156     <tr>
  5157      <td>Initial:
  5159      <td>normal
  5161     <tr>
  5162      <td>Applies to:
  5164      <td>all elements
  5166     <tr>
  5167      <td>Inherited:
  5169      <td>yes
  5171     <tr>
  5172      <td>Percentages:
  5174      <td>see individual properties
  5176     <tr>
  5177      <td>Media:
  5179      <td>visual
  5181     <tr>
  5182      <td>Computed value:
  5184      <td>see individual properties
  5186     <tr>
  5187      <td>Animatable:
  5189      <td>see individual properties
  5190   </table>
  5192   <p>The <a href="#propdef-font-variant"
  5193    title="font-variant!!property">‘<code
  5194    class=property>font-variant</code>’</a> property is a shorthand for all
  5195    font-variant subproperties. The value <dfn id=font-variant-normal-value
  5196    title="normal!!font-variant">‘<code
  5197    class=property>normal</code>’</dfn> resets all subproperties of <a
  5198    href="#propdef-font-variant" title="font-variant!!property">‘<code
  5199    class=property>font-variant</code>’</a> to their inital value. The <dfn
  5200    id=font-variant-none-value title="none!!font-variant">‘<code
  5201    class=property>none</code>’</dfn> value sets ‘<a
  5202    href="#propdef-font-variant-ligatures"><code
  5203    class=property>font-variant-ligatures</code></a>’ to ‘<code
  5204    class=property>none</code>’ and resets all other font feature properties
  5205    to their initial value. Like other shorthands, using <a
  5206    href="#propdef-font-variant" title="font-variant!!property">‘<code
  5207    class=property>font-variant</code>’</a> resets unspecified <a
  5208    href="#propdef-font-variant" title="font-variant!!property">‘<code
  5209    class=property>font-variant</code>’</a> subproperties to their initial
  5210    values. It does not reset the values of either ‘<a
  5211    href="#propdef-font-language-override"><code
  5212    class=property>font-language-override</code></a>’ or <a
  5213    href="#propdef-font-feature-settings"
  5214    title="font-feature-settings!!property">‘<code
  5215    class=property>font-feature-settings</code>’</a>.
  5217   <h3 id=font-feature-settings-prop><span class=secno>6.12 </span>Low-level
  5218    font feature settings control: the <a
  5219    href="#propdef-font-feature-settings">font-feature-settings</a> property</h3>
  5221   <table class=propdef id=namefont-feature-settingsvaluenormal-ltf>
  5222    <tbody>
  5223     <tr>
  5224      <td>Name:
  5226      <td><dfn id=propdef-font-feature-settings
  5227       title="font-feature-settings!!property">font-feature-settings</dfn>
  5229     <tr>
  5230      <td>Value:
  5232      <td><a href="#font-feature-settings-normal-value"
  5233       title="normal!!font-feature-settings">normal</a> | <a
  5234       href="#feature-tag-value"><var>&lt;feature-tag-value&gt;</var></a> #
  5236     <tr>
  5237      <td>Initial:
  5239      <td>normal
  5241     <tr>
  5242      <td>Applies to:
  5244      <td>all elements
  5246     <tr>
  5247      <td>Inherited:
  5249      <td>yes
  5251     <tr>
  5252      <td>Percentages:
  5254      <td>N/A
  5256     <tr>
  5257      <td>Media:
  5259      <td>visual
  5261     <tr>
  5262      <td>Computed value:
  5264      <td>as specified
  5266     <tr>
  5267      <td>Animatable:
  5269      <td>no
  5270   </table>
  5272   <p>This property provides low-level control over OpenType font features. It
  5273    is intended as a way of providing access to font features that are not
  5274    widely used but are needed for a particular use case.
  5276   <p>Authors should generally use <a href="#propdef-font-variant"
  5277    title="font-variant!!property">‘<code
  5278    class=property>font-variant</code>’</a> and its related subproperties
  5279    whenever possible and only use this property for special cases where its
  5280    use is the only way of accessing a particular infrequently used font
  5281    feature.
  5283   <pre>/* enable small caps and use second swash alternate */
  5284 font-feature-settings: "smcp", "swsh" 2;</pre>
  5286   <p>A value of <dfn id=font-feature-settings-normal-value
  5287    title="normal!!font-feature-settings">‘<code
  5288    class=property>normal</code>’</dfn> means that no change in glyph
  5289    selection or positioning occurs due to this property.
  5291   <p>Feature tag values have the following syntax:
  5293   <pre
  5294    class=prod><dfn id=feature-tag-value><var>&lt;feature-tag-value&gt;</var></dfn> = &lt;string&gt; [ &lt;integer&gt; | on | off ]?</pre>
  5296   <p>The &lt;string&gt; is a case-sensitive OpenType feature tag. As
  5297    specified in the OpenType specification, feature tags contain four ASCII
  5298    characters. Tag strings longer or shorter than four characters, or
  5299    containing characters outside the U+20–7E codepoint range are invalid.
  5300    Feature tags need only match a feature tag defined in the font, so they
  5301    are not limited to explicitly registered OpenType features. Fonts defining
  5302    custom feature tags should follow the <a
  5303    href="http://www.microsoft.com/typography/otspec/featuretags.htm">tag name
  5304    rules</a> defined in the OpenType specification <a
  5305    href="#OPENTYPE-FEATURES"
  5306    rel=biblioentry>[OPENTYPE-FEATURES]<!--{{!OPENTYPE-FEATURES}}--></a>.
  5307    Feature tags not present in the font are ignored; a user agent must not
  5308    attempt to synthesize fallback behavior based on these feature tags.
  5310   <p>This means that explicitly disabling the <span class=tag>kern</span>
  5311    feature will not affect the application of kerning data found in the
  5312    ‘<code class=property>kern</code>’ table (as opposed to kerning data
  5313    associated with the <span class=tag>kern</span> feature in the ‘<code
  5314    class=property>GPOS</code>’ table). Authors should use the ‘<a
  5315    href="#propdef-font-kerning"><code
  5316    class=property>font-kerning</code></a>’ property to explictly enable or
  5317    disable kerning since this property affects both types of kerning.
  5319   <p>If present, a value indicates an index used for glyph selection. An
  5320    &lt;integer&gt; value must be 0 or greater. A value of 0 indicates that
  5321    the feature is disabled. For boolean features, a value of 1 enables the
  5322    feature. For non-boolean features, a value of 1 or greater enables the
  5323    feature and indicates the feature selection index. A value of ‘<code
  5324    class=property>on</code>’ is synonymous with 1 and ‘<code
  5325    class=property>off</code>’ is synonymous with 0. If the value is
  5326    omitted, a value of 1 is assumed.
  5328   <pre>
  5329 font-feature-settings: "dlig" 1;       /* dlig=1 enable discretionary ligatures */
  5330 font-feature-settings: "smcp" on;      /* smcp=1 enable small caps */
  5331 font-feature-settings: 'c2sc';         /* c2sc=1 enable caps to small caps */
  5332 font-feature-settings: "liga" off;     /* liga=0 no common ligatures */
  5333 font-feature-settings: "tnum", 'hist'; /* tnum=1, hist=1 enable tabular numbers and historical forms */
  5334 font-feature-settings: "tnum" "hist";  /* invalid, need a comma-delimited list */
  5335 font-feature-settings: "palin" off;    /* good idea but invalid tagname */
  5336 font-feature-settings: "PKRN";         /* PKRN=1 enable custom feature */
  5337 font-feature-settings: dlig;           /* invalid, tag must be a string */
  5338 </pre>
  5340   <p>When values greater than the range supported by the font are specified,
  5341    the behavior is explicitly undefined. For boolean features, in general
  5342    these will enable the feature. For non-boolean features, out of range
  5343    values will in general be equivalent to a 0 value. However, in both cases
  5344    the exact behavior will depend upon the way the font is designed
  5345    (specifically, which type of lookup is used to define the feature).
  5347   <p>Although specifically defined for OpenType feature tags, feature tags
  5348    for other modern font formats that support font features may be added in
  5349    the future. Where possible, features defined for other font formats should
  5350    attempt to follow the pattern of registered OpenType tags.
  5352   <div class=example>
  5353    <p>The Japanese text below will be rendered with half-width kana
  5354     characters:</p>
  5356    <pre lang=ja>
  5357 body { font-feature-settings: "hwid"; /* Half-width OpenType feature */ }
  5359 &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>
  5360 </pre>
  5361   </div>
  5363   <h3 id=font-language-override-prop><span class=secno>6.13 </span>Font
  5364    language override: the <a
  5365    href="#propdef-font-language-override">font-language-override</a> property</h3>
  5367   <table class=propdef id=namefont-language-overridevaluenormal-lt>
  5368    <tbody>
  5369     <tr>
  5370      <td>Name:
  5372      <td><dfn id=propdef-font-language-override>font-language-override</dfn>
  5374     <tr>
  5375      <td>Value:
  5377      <td><a href="#font-language-override-normal-value"
  5378       title="normal!!font-language-override">normal</a> | <a
  5379       href="#font-language-override-string-value"><var>&lt;string&gt;</var></a>
  5381     <tr>
  5382      <td>Initial:
  5384      <td><a href="#font-language-override-normal-value"
  5385       title="normal!!font-language-override">normal</a>
  5387     <tr>
  5388      <td>Applies to:
  5390      <td>all elements
  5392     <tr>
  5393      <td>Inherited:
  5395      <td>yes
  5397     <tr>
  5398      <td>Percentages:
  5400      <td>N/A
  5402     <tr>
  5403      <td>Media:
  5405      <td>visual
  5407     <tr>
  5408      <td>Computed value:
  5410      <td>as specified
  5412     <tr>
  5413      <td>Animatable:
  5415      <td>no
  5416   </table>
  5418   <p>Normally, authors can control the use of language-specific glyph
  5419    substitutions and positioning by setting the content language of an
  5420    element, as <a href="#language-specific-support">described above</a>:
  5422   <pre>&lt;!-- Display text using S'gaw Karen specific features -->
  5423 &lt;p lang="ksw">...&lt;/p></pre>
  5425   <p>In some cases, authors may need to specify a language system that
  5426    differs from the content language, for example due to the need to mimic
  5427    another language's typographic traditions. The ‘<a
  5428    href="#propdef-font-language-override"><code
  5429    class=property>font-language-override</code></a>’ property allows
  5430    authors to explicitly specify the language system of the font, overriding
  5431    the language system implied by the content language.
  5433   <p>Values have the following meanings:
  5435   <dl>
  5436    <dt><dfn id=font-language-override-normal-value
  5437     title="normal!!font-language-override">normal</dfn>
  5439    <dd>specifies that when rendering with OpenType fonts, the content
  5440     language of the element is used to infer the OpenType language system
  5442    <dt><dfn
  5443     id=font-language-override-string-value><var>&lt;string&gt;</var></dfn>
  5445    <dd>single three-letter case-sensitive OpenType <a
  5446     href="http://www.microsoft.com/typography/otspec/languagetags.htm">language
  5447     system tag</a>, specifies the OpenType language system to be used instead
  5448     of the language system implied by the language of the element
  5449   </dl>
  5450   <!-- For this level, string represents a single language code, there's no concept of "fallback" 
  5451 http://www.w3.org/2013/06/07-css-minutes.html#item04 -->
  5453   <p>Use of invalid OpenType language system tags must not generate a parse
  5454    error but must be ignored when doing glyph selection and placement.
  5456   <div class=example>
  5457    <p>The <a href="http://www.un.org/en/documents/udhr/index.shtml">Universal
  5458     Declaration of Human Rights</a> has been translated into a wide variety
  5459     of languages. In Turkish, Article 9 of this document might be marked up
  5460     as below:</p>
  5462    <pre lang=tr>&lt;body lang="tr">
  5464 &lt;h4>Madde 9&lt;/h4>
  5465 &lt;p>Hiç kimse keyfi olarak tutuklanamaz, alıkonulanamaz veya sürülemez.&lt;/p>
  5466 </pre>
  5468    <p>Here the user agent uses the value of the ‘<code
  5469     class=property>lang</code>’ attribute when rendering text and
  5470     appropriately renders this text without ‘<code
  5471     class=property>fi</code>’ ligatures. There is no need to use the ‘<a
  5472     href="#propdef-font-language-override"><code
  5473     class=property>font-language-override</code></a>’ property.</p>
  5475    <p>However, a given font may lack support for a specific language. In this
  5476     situation authors may need to use the typographic conventions of a
  5477     related language that are supported by that font:</p>
  5479    <pre lang=mk>&lt;body lang="mk">     &lt;!-- Macedonian lang code --&gt;
  5481 body { font-language-override: "SRB"; /* Serbian OpenType language tag */ }
  5483 &lt;h4>Члeн 9&lt;/h4>
  5484 &lt;p>Никoj чoвeк нeмa дa бидe пoдлoжeн нa прoизвoлнo aпсeњe, притвoр или прoгoнувaњe.&lt;/p>
  5486 </pre>
  5488    <p>The Macedonian text here will be rendered using Serbian typographic
  5489     conventions, with the assumption that the font specified supports
  5490     Serbian.</p>
  5491   </div>
  5493   <p><a id=rendering-considerations></a>
  5495   <h2 id=font-feature-resolution><span class=secno>7 </span>Font Feature
  5496    Resolution</h2>
  5498   <p>As described in the previous section, font features can be enabled in a
  5499    variety of ways, either via the use of <a href="#propdef-font-variant"
  5500    title="font-variant!!property">‘<code
  5501    class=property>font-variant</code>’</a> or <a
  5502    href="#propdef-font-feature-settings"
  5503    title="font-feature-settings!!property">‘<code
  5504    class=property>font-feature-settings</code>’</a> in a style rule or
  5505    within an <a href="#at-font-face-rule"><code>@font-face</code></a> rule.
  5506    The resolution order for the union of these settings is defined below.
  5507    Features defined via CSS properties are applied on top of layout engine
  5508    default features.
  5510   <h3 id=default-features><span class=secno>7.1 </span>Default features</h3>
  5512   <p>For OpenType fonts, user agents must enable the default features defined
  5513    in the OpenType documentation for a given script and writing mode.
  5514    Required ligatures, common ligatures and contextual forms must be enabled
  5515    by default (OpenType features: <span class=tag>rlig, liga, clig,
  5516    calt</span>), along with localized forms (OpenType feature: <span
  5517    class=tag>locl</span>), and features required for proper display of
  5518    composed characters and marks (OpenType features: <span class=tag>ccmp,
  5519    mark, mkmk</span>). These features must always be enabled, even when the
  5520    value of the <a href="#propdef-font-variant"
  5521    title="font-variant!!property">‘<code
  5522    class=property>font-variant</code>’</a> and <a
  5523    href="#propdef-font-feature-settings"
  5524    title="font-feature-settings!!property">‘<code
  5525    class=property>font-feature-settings</code>’</a> properties is <span
  5526    title="normal value">‘<code class=property>normal</code>’</span>.
  5527    Individual features are only disabled when explicitly overridden by the
  5528    author, as when ‘<a href="#propdef-font-variant-ligatures"><code
  5529    class=property>font-variant-ligatures</code></a>’ is set to ‘<a
  5530    href="#no-common-ligatures"><code
  5531    class=property>no-common-ligatures</code></a>’. For handling complex
  5532    scripts such as <a
  5533    href="http://www.microsoft.com/typography/otfntdev/arabicot/features.aspx">Arabic</a>,
  5534    <a
  5535    href="http://www.microsoft.com/typography/otfntdev/mongolot/features.htm">Mongolian</a>
  5536    or <a
  5537    href="http://www.microsoft.com/typography/otfntdev/devanot/features.aspx">Devanagari</a>
  5538    additional features are required. For upright text within vertical text
  5539    runs, vertical alternates (OpenType feature: <span class=tag>vert</span>)
  5540    must be enabled.
  5542   <h3 id=feature-precedence><span class=secno>7.2 </span>Feature precedence</h3>
  5544   <p>General and <a href="#font-specific"><em>font specific</em></a> font
  5545    feature property settings are resolved in the order below, in ascending
  5546    order of precedence. This ordering is used to construct a combined list of
  5547    font features that affect a given text run.
  5549   <ol>
  5550    <li>Font features enabled by default, including features required for a
  5551     given script.
  5553    <li>If the font is defined via an <a
  5554     href="#at-font-face-rule"><code>@font-face</code></a> rule, the font
  5555     features implied by the font-variant descriptor in the <a
  5556     href="#at-font-face-rule"><code>@font-face</code></a> rule.
  5558    <li>If the font is defined via an <a
  5559     href="#at-font-face-rule"><code>@font-face</code></a> rule, the font
  5560     features implied by the font-feature-settings descriptor in the <a
  5561     href="#at-font-face-rule"><code>@font-face</code></a> rule.
  5563    <li>Feature settings determined by properties other than <a
  5564     href="#propdef-font-variant" title="font-variant!!property">‘<code
  5565     class=property>font-variant</code>’</a> or <a
  5566     href="#propdef-font-feature-settings"
  5567     title="font-feature-settings!!property">‘<code
  5568     class=property>font-feature-settings</code>’</a>. For example, setting
  5569     a non-default value for the ‘<code
  5570     class=property>letter-spacing</code>’ property disables common
  5571     ligatures.
  5573    <li>Font features implied by the value of the <a
  5574     href="#propdef-font-variant" title="font-variant!!property">‘<code
  5575     class=property>font-variant</code>’</a> property, the related <a
  5576     href="#propdef-font-variant" title="font-variant!!property">‘<code
  5577     class=property>font-variant</code>’</a> subproperties and any other CSS
  5578     property that uses OpenType features (e.g. the ‘<a
  5579     href="#propdef-font-kerning"><code
  5580     class=property>font-kerning</code></a>’ property).
  5582    <li>Font features implied by the value of <a
  5583     href="#propdef-font-feature-settings"
  5584     title="font-feature-settings!!property">‘<code
  5585     class=property>font-feature-settings</code>’</a> property.
  5586   </ol>
  5588   <p>This ordering allows authors to set up a general set of defaults for
  5589    fonts within their <a
  5590    href="#at-font-face-rule"><code>@font-face</code></a> rules, then override
  5591    them with property settings for specific elements. General property
  5592    settings override the settings in <a
  5593    href="#at-font-face-rule"><code>@font-face</code></a> rules and low-level
  5594    font feature settings override <a href="#propdef-font-variant"
  5595    title="font-variant!!property">‘<code
  5596    class=property>font-variant</code>’</a> property settings.
  5598   <p>For situations where the combined list of font feature settings contains
  5599    more than one value for the same feature, the last value is used. When a
  5600    font lacks support for a given underlying font feature, text is simply
  5601    rendered as if that font feature was not enabled; font fallback does not
  5602    occur and no attempt is made to synthesize the feature except where
  5603    explicitly defined for specific properties.
  5605   <h3 id=feature-precedence-examples><span class=secno>7.3 </span>Feature
  5606    precedence examples</h3>
  5608   <div class=example>
  5609    <p>With the styles below, numbers are rendered proportionally when used
  5610     within a paragraph but are shown in tabular form within tables of prices:</p>
  5612    <pre>body {
  5613   font-variant-numeric: proportional-nums;
  5616 table.prices td {
  5617   font-variant-numeric: tabular-nums;
  5619 </pre>
  5620   </div>
  5622   <div class=example>
  5623    <p>When the <a href="#descdef-font-variant"
  5624     title="font-variant!!descriptor">font-variant</a> descriptor is used
  5625     within an <a href="#at-font-face-rule"><code>@font-face</code></a> rule,
  5626     it only applies to the font defined by that rule.</p>
  5628    <pre>@font-face {
  5629   font-family: MainText;
  5630   src: url(http://example.com/font.ttf);
  5631   font-variant: oldstyle-nums proportional-nums styleset(1,3);
  5634 body {
  5635   font-family: MainText, Helvetica;
  5638 table.prices td {
  5639   font-variant-numeric: tabular-nums;
  5641 </pre>
  5643    <p>In this case, old-style numerals will be used throughout but only where
  5644     the font "MainText" is used. Just as in the previous example, tabular
  5645     values will be used in price tables since ‘<a
  5646     href="#tabular-nums"><code class=property>tabular-nums</code></a>’
  5647     appears in a general style rule and its use is mutually exclusive with
  5648     ‘<a href="#proportional-nums"><code
  5649     class=property>proportional-nums</code></a>’. Stylistic alternate sets
  5650     will only be used where MainText is used.</p>
  5651   </div>
  5653   <div class=example>
  5654    <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule can
  5655     also be used to access font features in locally available fonts via the
  5656     use of <code>local()</code> in the ‘<a href="#descdef-src"><code
  5657     class=property>src</code></a>’ descriptor of the <a
  5658     href="#at-font-face-rule"><code>@font-face</code></a> definition:</p>
  5660    <pre>@font-face {
  5661   font-family: BodyText;
  5662   src: local("HiraMaruPro-W4");
  5663   font-variant: proportional-width;
  5664   font-feature-settings: "ital"; /* Latin italics within CJK text feature */
  5667 body { font-family: BodyText, serif; }
  5668 </pre>
  5670    <p>If available, a Japanese font "Hiragino Maru Gothic" will be used. When
  5671     text rendering occurs, Japanese kana will be proportionally spaced and
  5672     Latin text will be italicised. Text rendered with the fallback serif font
  5673     will use default rendering properties.</p>
  5674   </div>
  5676   <div class=example>
  5677    <p>In the example below, discretionary ligatures are enabled only for a
  5678     downloadable font but are disabled within spans of class "special":</p>
  5680    <pre>@font-face {
  5681   font-family: main;
  5682   src: url(fonts/ffmeta.woff) format("woff");
  5683   font-variant: discretionary-ligatures;
  5686 body         { font-family: main, Helvetica; }
  5687 span.special { font-variant-ligatures: no-discretionary-ligatures; }
  5688 </pre>
  5690    <p>Suppose one adds a rule using ‘<code
  5691     class=property>font-feature-settings</code>’ to enable discretionary
  5692     ligatures:</p>
  5694    <pre>body         { font-family: main, Helvetica; }
  5695 span         { font-feature-settings: "dlig"; }
  5696 span.special { font-variant-ligatures: no-discretionary-ligatures; }
  5697 </pre>
  5699    <p>In this case, discretionary ligatures <em>will</em> be rendered within
  5700     spans of class "special". This is because both the <a
  5701     href="#propdef-font-feature-settings"
  5702     title="font-feature-settings!!property">‘<code
  5703     class=property>font-feature-settings</code>’</a> and ‘<a
  5704     href="#propdef-font-variant-ligatures"><code
  5705     class=property>font-variant-ligatures</code></a>’ properties apply to
  5706     these spans. Although the ‘<code class=css>no-discretionary
  5707     ligatures</code>’ setting of ‘<a
  5708     href="#propdef-font-variant-ligatures"><code
  5709     class=property>font-variant-ligatures</code></a>’ effectively disables
  5710     the OpenType <span class=tag>dlig</span> feature, because the <a
  5711     href="#propdef-font-feature-settings"
  5712     title="font-feature-settings!!property">‘<code
  5713     class=property>font-feature-settings</code>’</a> is resolved after
  5714     that, the ‘<code class=property>dlig</code>’ value reenables
  5715     discretionary ligatures.</p>
  5716   </div>
  5718   <h2 id=object-model><span class=secno>8 </span>Object Model</h2>
  5720   <p>The contents of <a href="#at-font-face-rule"><code>@font-face</code></a>
  5721    and <a
  5722    href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
  5723    rules can be accessed via the following extensions to the CSS Object
  5724    Model.
  5726   <h3 id=om-fontface><span class=secno>8.1 </span>The <a
  5727    href="#cssfontfacerule"><code>CSSFontFaceRule</code></a> interface</h3>
  5729   <p>The <dfn id=cssfontfacerule>CSSFontFaceRule</dfn> interface represents a
  5730    <a href="#at-font-face-rule"><code>@font-face</code></a> rule.
  5732   <pre class=idl>
  5733 interface CSSFontFaceRule : CSSRule {
  5734   attribute DOMString family;
  5735   attribute DOMString src;
  5736   attribute DOMString style;
  5737   attribute DOMString weight;
  5738   attribute DOMString stretch;
  5739   attribute DOMString unicodeRange;
  5740   attribute DOMString variant;
  5741   attribute DOMString featureSettings;
  5742 }</pre>
  5744   <p>The DOM Level 2 Style specification <a href="#DOM-LEVEL-2-STYLE"
  5745    rel=biblioentry>[DOM-LEVEL-2-STYLE]<!--{{DOM-LEVEL-2-STYLE}}--></a>
  5746    defined a different variant of this rule. This definition supercedes that
  5747    one.
  5749   <h3 id=om-fontfeaturevalues><span class=secno>8.2 </span>The <a
  5750    href="#cssfontfeaturevaluesrule"><code>CSSFontFeatureValuesRule</code></a>
  5751    interface</h3>
  5753   <p>The <code>CSSRule</code> interface is extended as follows:
  5755   <pre class=idl>partial interface CSSRule {
  5756   const unsigned short FONT_FEATURE_VALUES_RULE = 14;
  5757 }</pre>
  5759   <p>The <dfn id=cssfontfeaturevaluesrule>CSSFontFeatureValuesRule</dfn>
  5760    interface represents a <a
  5761    href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
  5762    rule.
  5764   <pre class=idl>interface CSSFontFeatureValuesRule : CSSRule {
  5765   readonly attribute DOMString familyList;
  5766   readonly attribute DOMString valueText;
  5767 };</pre>
  5769   <dl class=idl-attributes>
  5770    <dt><var>familyList</var> of type <code>DOMString</code>, readonly
  5772    <dd>The list of one or more font families for which a given set of feature
  5773     values is defined.
  5775    <dt><var>valueText</var> of type <code>DOMString</code>, readonly
  5777    <dd>Serialized set of feature values.
  5778   </dl>
  5780   <p class=issue>This needs to be reworked along the lines of <a
  5781    href="http://lists.w3.org/Archives/Public/www-style/2013May/0781.html">Tab's
  5782    proposal</a> for a rule containing a family list and map objects for each
  5783    of the feature types.
  5785   <h2 class=no-num id=platform-props-to-css>Appendix A: Mapping platform font
  5786    properties to CSS properties</h2>
  5788   <p><em>This appendix is included as background for some of the problems and
  5789    situations that are described in other sections. It should be viewed as
  5790    informative only.</em>
  5792   <p>Font properties in CSS are designed to be independent of the underlying
  5793    font formats used; they can be used to specify bitmap fonts, Type1 fonts,
  5794    SVG fonts in addition to the common TrueType and OpenType fonts. But there
  5795    are facets of the TrueType and OpenType formats that often cause confusion
  5796    for authors and present challenges to implementers on different platforms.
  5798   <p>Originally developed at Apple, TrueType was designed as an outline font
  5799    format for both screen and print. Microsoft joined Apple in developing the
  5800    TrueType format and both platforms have supported TrueType fonts since
  5801    then. Font data in the TrueType format consists of a set of tables
  5802    distinguished with common four-letter tag names, each containing a
  5803    specific type of data. For example, naming information, including
  5804    copyright and license information, is stored in the ‘<code
  5805    class=property>name</code>’ table. The <a
  5806    href="#character-map"><em>character map</em></a> (‘<code
  5807    class=property>cmap</code>’) table contains a mapping of character
  5808    encodings to glyphs. Apple later added additional tables for supporting
  5809    enhanced typographic functionality; these are now called Apple Advanced
  5810    Typography, or AAT, fonts. Microsoft and Adobe developed a separate set of
  5811    tables for advanced typography and called their format OpenType <a
  5812    href="#OPENTYPE" rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a>.
  5814   <p>In many cases the font data used under Microsoft Windows or Linux is
  5815    slightly different from the data used under Apple's Mac OS X because the
  5816    TrueType format allowed for explicit variation across platforms. This
  5817    includes font metrics, names and <a href="#character-map"><em>character
  5818    map</em></a> data.
  5820   <p>Specifically, font family name data is handled differently across
  5821    platforms. For TrueType and OpenType fonts these names are contained in
  5822    the ‘<code class=property>name</code>’ table, in name records with
  5823    name ID 1. Mulitple names can be stored for different locales, but
  5824    Microsoft recommends fonts always include at least a US English version of
  5825    the name. On Windows, Microsoft made the decision for backwards
  5826    compatibility to limit this family name to a maximum of four faces; for
  5827    larger groupings the "preferred family" (name ID 16) or "WWS family" (name
  5828    ID 21) can be used. Other platforms such as OSX don't have this
  5829    limitation, so the family name is used to define all possible groupings.
  5831   <p>Other name table data provides names used to uniquely identify a
  5832    specific face within a family. The full font name (name ID 4) and the
  5833    Postscript name (name ID 6) describe a single face uniquely. For example,
  5834    the bold face of the Gill Sans family has a fullname of "Gill Sans Bold"
  5835    and a Postscript name of "GillSans-Bold". There can be multiple localized
  5836    versions of the fullname for a given face, but the Postscript name is
  5837    always a unique name made from a limited set of ASCII characters.
  5839   <p>On various platforms, different names are used to search for a font. For
  5840    example, with the Windows GDI CreateIndirectFont API, either a family or
  5841    fullname can be used to lookup a face, while on Mac OS X the
  5842    CTFontCreateWithName API call is used to lookup a given face using the
  5843    fullname and Postscript name. Under Linux, the fontconfig API allows fonts
  5844    to be searched using any of these names. In situations where platform
  5845    API's automatically substitute other font choices, it may be necessary to
  5846    verify a returned font matches a given name.
  5848   <p>The weight of a given face can be determined via the usWeightClass field
  5849    of the OS/2 table or inferred from the style name (name ID 2). Likewise,
  5850    the width can be determined via the usWidthClass of the OS/2 table or
  5851    inferred from the style name. For historical reasons related to synthetic
  5852    bolding at weights 200 or lower with the Windows GDI API, font designers
  5853    have sometimes skewed values in the OS/2 table to avoid these weights.
  5855   <p>Rendering complex scripts that use contextual shaping such as Thai,
  5856    Arabic and Devanagari requires features present only in OpenType or AAT
  5857    fonts. Currently, complex script rendering is supported on Windows and
  5858    Linux using OpenType font features while both OpenType and AAT font
  5859    features are used under Mac OS X.
  5861   <h2 class=no-num id=ch-ch-ch-changes>Changes</h2>
  5863   <h3 class=no-num id=recent-changes> Changes from the <a
  5864    href="http://www.w3.org/TR/2013/WD-css3-fonts-20130212/">February 2013
  5865    CSS3 Fonts Working Draft</a></h3>
  5867   <p>Major changes include:
  5869   <ul>
  5870    <li>Moved font load events into a separate <a
  5871     href="http://dev.w3.org/csswg/css3-font-load-events/">spec</a>
  5873    <li>Tightened syntax rules for <a
  5874     href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
  5875     rules
  5877    <li>Added grammar productions for <a
  5878     href="#at-font-face-rule"><code>@font-face</code></a> and <a
  5879     href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
  5880     rules
  5882    <li>Tightened definition of synthetic oblique
  5884    <li>Revised definition of ‘<a href="#descdef-unicode-range"><code
  5885     class=property>unicode-range</code></a>’ descriptor
  5887    <li>Detailed font matching of composite faces
  5888   </ul>
  5890   <h2 class=no-num id=acknowledgments>Acknowledgments</h2>
  5892   <p>I'd like to thank Tal Leming, Jonathan Kew and Christopher Slye for all
  5893    their help and feedback. John Hudson was kind enough to take the time to
  5894    explain the subtleties of OpenType language tags and provided the example
  5895    of character variant usage for displaying text on Byzantine seals. Ken
  5896    Lunde and Eric Muller provided valuable feedback on CJK OpenType features
  5897    and Unicode variation selectors. The idea for supporting font features by
  5898    using <a href="#propdef-font-variant"
  5899    title="font-variant!!property">‘<code
  5900    class=property>font-variant</code>’</a> subproperties originated with
  5901    Håkon Wium Lie, Adam Twardoch and Tal Leming. Elika Etemad supplied some
  5902    of the initial design ideas for the <a
  5903    href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
  5904    rule. Thanks also to House Industries for allowing the use of Ed Interlock
  5905    in the discretionary ligatures example.
  5907   <p>A special thanks to Robert Bringhurst for the sublime mind expansion
  5908    that is <em>The Elements of Typographic Style</em>.
  5910   <h2 class=no-num id=conformance> Conformance</h2>
  5912   <h3 class=no-num id=conventions> Document Conventions</h3>
  5914   <p>Conformance requirements are expressed with a combination of descriptive
  5915    assertions and RFC 2119 terminology. The key words “MUST”, “MUST
  5916    NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”,
  5917    “SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL” in the
  5918    normative parts of this document are to be interpreted as described in RFC
  5919    2119. However, for readability, these words do not appear in all uppercase
  5920    letters in this specification.
  5922   <p>All of the text of this specification is normative except sections
  5923    explicitly marked as non-normative, examples, and notes. <a
  5924    href="#RFC2119" rel=biblioentry>[RFC2119]<!--{{!RFC2119}}--></a>
  5926   <p>Examples in this specification are introduced with the words “for
  5927    example” or are set apart from the normative text with
  5928    <code>class="example"</code>, like this:
  5930   <div class=example>
  5931    <p>This is an example of an informative example.
  5932   </div>
  5934   <p>Informative notes begin with the word “Note” and are set apart from
  5935    the normative text with <code>class="note"</code>, like this:
  5937   <p class=note>Note, this is an informative note.
  5939   <h3 class=no-num id=conformance-classes> Conformance Classes</h3>
  5941   <p>Conformance to CSS Fonts Level 3 Module is defined for three conformance
  5942    classes:
  5944   <dl>
  5945    <dt><dfn id=style-sheet title="style sheet!!as conformance class">style
  5946     sheet</dfn>
  5948    <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#style-sheet">CSS
  5949     style sheet</a>.
  5951    <dt><dfn id=renderer>renderer</dfn>
  5953    <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
  5954     that interprets the semantics of a style sheet and renders documents that
  5955     use them.
  5957    <dt><dfn id=authoring-tool>authoring tool</dfn>
  5959    <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
  5960     that writes a style sheet.
  5961   </dl>
  5963   <p>A style sheet is conformant to CSS Fonts Level 3 Module if all of its
  5964    declarations that use properties defined in this module have values that
  5965    are valid according to the generic CSS grammar and the individual grammars
  5966    of each property as given in this module.
  5968   <p>A renderer is conformant to CSS Fonts Level 3 Module if, in addition to
  5969    interpreting the style sheet as defined by the appropriate specifications,
  5970    it supports all the features defined by CSS Fonts Level 3 Module by
  5971    parsing them correctly and rendering the document accordingly. However,
  5972    the inability of a UA to correctly render a document due to limitations of
  5973    the device does not make the UA non-conformant. (For example, a UA is not
  5974    required to render color on a monochrome monitor.)
  5976   <p>An authoring tool is conformant to CSS Fonts Level 3 Module if it writes
  5977    style sheets that are syntactically correct according to the generic CSS
  5978    grammar and the individual grammars of each feature in this module, and
  5979    meet all other conformance requirements of style sheets as described in
  5980    this module.
  5982   <h3 class=no-num id=partial> Partial Implementations</h3>
  5984   <p>So that authors can exploit the forward-compatible parsing rules to
  5985    assign fallback values, CSS renderers <strong>must</strong> treat as
  5986    invalid (and <a
  5987    href="http://www.w3.org/TR/CSS21/conform.html#ignore">ignore as
  5988    appropriate</a>) any at-rules, properties, property values, keywords, and
  5989    other syntactic constructs for which they have no usable level of support.
  5990    In particular, user agents <strong>must not</strong> selectively ignore
  5991    unsupported component values and honor supported values in a single
  5992    multi-value property declaration: if any value is considered invalid (as
  5993    unsupported values must be), CSS requires that the entire declaration be
  5994    ignored.
  5996   <h3 class=no-num id=experimental> Experimental Implementations</h3>
  5998   <p>To avoid clashes with future CSS features, the CSS2.1 specification
  5999    reserves a <a
  6000    href="http://www.w3.org/TR/CSS21/syndata.html#vendor-keywords">prefixed
  6001    syntax</a> for proprietary and experimental extensions to CSS.
  6003   <p>Prior to a specification reaching the Candidate Recommendation stage in
  6004    the W3C process, all implementations of a CSS feature are considered
  6005    experimental. The CSS Working Group recommends that implementations use a
  6006    vendor-prefixed syntax for such features, including those in W3C Working
  6007    Drafts. This avoids incompatibilities with future changes in the draft.
  6009   <h3 class=no-num id=testing> Non-Experimental Implementations</h3>
  6011   <p>Once a specification reaches the Candidate Recommendation stage,
  6012    non-experimental implementations are possible, and implementors should
  6013    release an unprefixed implementation of any CR-level feature they can
  6014    demonstrate to be correctly implemented according to spec.
  6016   <p>To establish and maintain the interoperability of CSS across
  6017    implementations, the CSS Working Group requests that non-experimental CSS
  6018    renderers submit an implementation report (and, if necessary, the
  6019    testcases used for that implementation report) to the W3C before releasing
  6020    an unprefixed implementation of any CSS features. Testcases submitted to
  6021    W3C are subject to review and correction by the CSS Working Group.
  6023   <p>Further information on submitting testcases and implementation reports
  6024    can be found from on the CSS Working Group's website at <a
  6025    href="http://www.w3.org/Style/CSS/Test/">http://www.w3.org/Style/CSS/Test/</a>.
  6026    Questions should be directed to the <a
  6027    href="http://lists.w3.org/Archives/Public/public-css-testsuite">public-css-testsuite@w3.org</a>
  6028    mailing list.
  6030   <h2 class=no-num id=references>References</h2>
  6032   <h3 class=no-num id=normative-references>Normative References</h3>
  6033   <!--begin-normative-->
  6034   <!-- Sorted by label -->
  6036   <dl class=bibliography>
  6037    <dd style="display: none"><!-- keeps the doc valid if the DL is empty -->
  6038     <!---->
  6040    <dt id=CHARMOD>[CHARMOD]
  6042    <dd>Martin J. Dürst; et al. <a
  6043     href="http://www.w3.org/TR/2005/REC-charmod-20050215/"><cite>Character
  6044     Model for the World Wide Web 1.0: Fundamentals.</cite></a> 15 February
  6045     2005. W3C Recommendation. URL: <a
  6046     href="http://www.w3.org/TR/2005/REC-charmod-20050215/">http://www.w3.org/TR/2005/REC-charmod-20050215/</a>
  6047     </dd>
  6048    <!---->
  6050    <dt id=CORS>[CORS]
  6052    <dd>Anne van Kesteren. <a
  6053     href="http://www.w3.org/TR/2013/CR-cors-20130129/"><cite>Cross-Origin
  6054     Resource Sharing.</cite></a> 29 January 2013. W3C Candidate
  6055     Recommendation. (Work in progress.) URL: <a
  6056     href="http://www.w3.org/TR/2013/CR-cors-20130129/">http://www.w3.org/TR/2013/CR-cors-20130129/</a>
  6057     </dd>
  6058    <!---->
  6060    <dt id=CSS21>[CSS21]
  6062    <dd>Bert Bos; et al. <a
  6063     href="http://www.w3.org/TR/2011/REC-CSS2-20110607"><cite>Cascading Style
  6064     Sheets Level 2 Revision 1 (CSS 2.1) Specification.</cite></a> 7 June
  6065     2011. W3C Recommendation. URL: <a
  6066     href="http://www.w3.org/TR/2011/REC-CSS2-20110607">http://www.w3.org/TR/2011/REC-CSS2-20110607</a>
  6067     </dd>
  6068    <!---->
  6070    <dt id=CSS3VAL>[CSS3VAL]
  6072    <dd>Håkon Wium Lie; Tab Atkins; Elika J. Etemad. <a
  6073     href="http://www.w3.org/TR/2013/CR-css3-values-20130404/"><cite>CSS
  6074     Values and Units Module Level 3.</cite></a> 4 April 2013. W3C Candidate
  6075     Recommendation. (Work in progress.) URL: <a
  6076     href="http://www.w3.org/TR/2013/CR-css3-values-20130404/">http://www.w3.org/TR/2013/CR-css3-values-20130404/</a>
  6077     </dd>
  6078    <!---->
  6080    <dt id=HTML5>[HTML5]
  6082    <dd>Ian Hickson. <a
  6083     href="http://www.w3.org/TR/2012/CR-html5-20121217/"><cite>HTML5.</cite></a>
  6084     17 December 2012. W3C Candidate Recommendation. (Work in progress.) URL:
  6085     <a
  6086     href="http://www.w3.org/TR/2012/CR-html5-20121217/">http://www.w3.org/TR/2012/CR-html5-20121217/</a>
  6087     </dd>
  6088    <!---->
  6090    <dt id=OPEN-FONT-FORMAT>[OPEN-FONT-FORMAT]
  6092    <dd><a
  6093     href="http://standards.iso.org/ittf/PubliclyAvailableStandards/c052136_ISO_IEC_14496-22_2009(E).zip"><cite>Information
  6094     technology — Coding of audio-visual objects — Part 22: Open Font
  6095     Format.</cite></a> International Organization for Standardization.
  6096     ISO/IEC 14496-22:2009. URL: <a
  6097     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>
  6098     </dd>
  6099    <!---->
  6101    <dt id=OPENTYPE>[OPENTYPE]
  6103    <dd><a
  6104     href="http://www.microsoft.com/typography/otspec/default.htm"><cite>OpenType
  6105     specification.</cite></a> Microsoft. URL: <a
  6106     href="http://www.microsoft.com/typography/otspec/default.htm">http://www.microsoft.com/typography/otspec/default.htm</a>
  6107     </dd>
  6108    <!---->
  6110    <dt id=OPENTYPE-FEATURES>[OPENTYPE-FEATURES]
  6112    <dd><a
  6113     href="http://www.microsoft.com/typography/otspec/featurelist.htm"><cite>OpenType
  6114     feature registry.</cite></a> Microsoft. URL: <a
  6115     href="http://www.microsoft.com/typography/otspec/featurelist.htm">http://www.microsoft.com/typography/otspec/featurelist.htm</a>
  6116     </dd>
  6117    <!---->
  6119    <dt id=RFC2119>[RFC2119]
  6121    <dd>S. Bradner. <a href="http://www.ietf.org/rfc/rfc2119.txt"><cite>Key
  6122     words for use in RFCs to Indicate Requirement Levels.</cite></a> Internet
  6123     RFC 2119. URL: <a
  6124     href="http://www.ietf.org/rfc/rfc2119.txt">http://www.ietf.org/rfc/rfc2119.txt</a>
  6125     </dd>
  6126    <!---->
  6128    <dt id=UAX15>[UAX15]
  6130    <dd>Mark Davis; Ken Whistler. <a
  6131     href="http://www.unicode.org/reports/tr15/"><cite>Unicode Normalization
  6132     Forms.</cite></a> 31 August 2012. Unicode Standard Annex #15. URL: <a
  6133     href="http://www.unicode.org/reports/tr15/">http://www.unicode.org/reports/tr15/</a>
  6134     </dd>
  6135    <!---->
  6137    <dt id=UAX29>[UAX29]
  6139    <dd>Mark Davis. <a
  6140     href="http://www.unicode.org/reports/tr29/"><cite>Unicode Text
  6141     Segmentation.</cite></a> 12 September 2012. Unicode Standard Annex #29.
  6142     URL: <a
  6143     href="http://www.unicode.org/reports/tr29/">http://www.unicode.org/reports/tr29/</a>
  6144     </dd>
  6145    <!---->
  6147    <dt id=UNICODE6>[UNICODE6]
  6149    <dd>The Unicode Consortium. <a
  6150     href="http://www.unicode.org/versions/Unicode6.2.0/"><cite>The Unicode
  6151     Standard, Version 6.2.0.</cite></a> Defined by: The Unicode Standard,
  6152     Version 6.2.0 URL: <a
  6153     href="http://www.unicode.org/versions/Unicode6.2.0/">http://www.unicode.org/versions/Unicode6.2.0/</a>
  6154     </dd>
  6155    <!---->
  6156   </dl>
  6157   <!--end-normative-->
  6158   <!--{{!CSS21}}-->
  6159   <!--{{!CSS3VAL}}-->
  6160   <!--{{!OPENTYPE}}-->
  6161   <!--{{!OPENTYPE-FEATURES}}-->
  6162   <!--{{!OPEN-FONT-FORMAT}}-->
  6163   <!--{{!UNICODE6}}-->
  6164   <!--{{!UAX15}}-->
  6165   <!--{{!UAX29}}-->
  6166   <!--{{!CORS}}-->
  6167   <!--{{!HTML5}}-->
  6168   <!--{{!CHARMOD}}-->
  6170   <h3 class=no-num id=other-references>Other References</h3>
  6171   <!--begin-informative-->
  6172   <!-- Sorted by label -->
  6174   <dl class=bibliography>
  6175    <dd style="display: none"><!-- keeps the doc valid if the DL is empty -->
  6176     <!---->
  6178    <dt id=AAT-FEATURES>[AAT-FEATURES]
  6180    <dd><a href="http://developer.apple.com/fonts/registry/"><cite>Apple
  6181     Advanced Typography font feature registry.</cite></a> Apple. URL: <a
  6182     href="http://developer.apple.com/fonts/registry/">http://developer.apple.com/fonts/registry/</a>
  6183     </dd>
  6184    <!---->
  6186    <dt id=ARABIC-TYPO>[ARABIC-TYPO]
  6188    <dd>Huda Smitshuijzen AbiFares. <cite>Arabic Typography: A Comprehensive
  6189     Sourcebook.</cite> Saqi Books. 2001. ISBN 0-86356-347-3.</dd>
  6190    <!---->
  6192    <dt id=CHARMOD-NORM>[CHARMOD-NORM]
  6194    <dd>François Yergeau; et al. <a
  6195     href="http://www.w3.org/TR/2012/WD-charmod-norm-20120501/"><cite>Character
  6196     Model for the World Wide Web 1.0: Normalization.</cite></a> 1 May 2012.
  6197     W3C Working Draft. (Work in progress.) URL: <a
  6198     href="http://www.w3.org/TR/2012/WD-charmod-norm-20120501/">http://www.w3.org/TR/2012/WD-charmod-norm-20120501/</a>
  6199     </dd>
  6200    <!---->
  6202    <dt id=CJKV-INFO-PROCESSING>[CJKV-INFO-PROCESSING]
  6204    <dd>Ken Lunde. <cite>CJKV Information Processing, Second Edition.</cite>
  6205     O'Reilly Media, Inc. 2009. ISBN 0-596-51447-1.</dd>
  6206    <!---->
  6208    <dt id=CSS3-CONDITIONAL>[CSS3-CONDITIONAL]
  6210    <dd>L. David Baron. <a
  6211     href="http://www.w3.org/TR/2013/CR-css3-conditional-20130404/"><cite>CSS
  6212     Conditional Rules Module Level 3.</cite></a> 4 April 2013. W3C Candidate
  6213     Recommendation. (Work in progress.) URL: <a
  6214     href="http://www.w3.org/TR/2013/CR-css3-conditional-20130404/">http://www.w3.org/TR/2013/CR-css3-conditional-20130404/</a>
  6215     </dd>
  6216    <!---->
  6218    <dt id=CSS3TEXT>[CSS3TEXT]
  6220    <dd>Elika J. Etemad; Koji Ishii. <a
  6221     href="http://www.w3.org/TR/2012/WD-css3-text-20121113/"><cite>CSS Text
  6222     Module Level 3.</cite></a> 13 November 2012. W3C Working Draft. (Work in
  6223     progress.) URL: <a
  6224     href="http://www.w3.org/TR/2012/WD-css3-text-20121113/">http://www.w3.org/TR/2012/WD-css3-text-20121113/</a>
  6225     </dd>
  6226    <!---->
  6228    <dt id=DIGITAL-TYPOGRAPHY>[DIGITAL-TYPOGRAPHY]
  6230    <dd>Richard Rubinstein. <cite>Digital Typography, An Introduction to Type
  6231     and Composition for Computer System Design.</cite> Addison-Wesley. 1988.
  6232     ISBN 0-201-17633-5.</dd>
  6233    <!---->
  6235    <dt id=DOM-LEVEL-2-STYLE>[DOM-LEVEL-2-STYLE]
  6237    <dd>Chris Wilson; Philippe Le Hégaret; Vidur Apparao. <a
  6238     href="http://www.w3.org/TR/2000/REC-DOM-Level-2-Style-20001113/"><cite>Document
  6239     Object Model (DOM) Level 2 Style Specification.</cite></a> 13 November
  6240     2000. W3C Recommendation. URL: <a
  6241     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>
  6242     </dd>
  6243    <!---->
  6245    <dt id=ELEMTYPO>[ELEMTYPO]
  6247    <dd>Robert Bringhurst. <cite>The Elements of Typographic Style, Version
  6248     4.</cite> Hartley &amp; Marks. 2013. ISBN 0-88179-212-8.</dd>
  6249    <!---->
  6251    <dt id=LANGCULTTYPE>[LANGCULTTYPE]
  6253    <dd>John D. Berry, Ed. <cite>Language Culture Type.</cite> Graphis. 2001.
  6254     ISBN 1-932026-01-0.</dd>
  6255    <!---->
  6257    <dt id=OPENTYPE-FONT-GUIDE>[OPENTYPE-FONT-GUIDE]
  6259    <dd><a
  6260     href="https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf"><cite>OpenType
  6261     User Guide.</cite></a> FontShop International. URL: <a
  6262     href="https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf">https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf</a>
  6263     </dd>
  6264    <!---->
  6266    <dt id=RASTER-TRAGEDY>[RASTER-TRAGEDY]
  6268    <dd>Beat Stamm. <a href="http://www.rastertragedy.com/"><cite>The Raster
  6269     Tragedy at Low-Resolution Revisited.</cite></a> 7 December 2011. URL: <a
  6270     href="http://www.rastertragedy.com/">http://www.rastertragedy.com/</a></dd>
  6271    <!---->
  6273    <dt id=WINDOWS-GLYPH-PROC>[WINDOWS-GLYPH-PROC]
  6275    <dd>John Hudson. <a
  6276     href="http://www.microsoft.com/typography/developers/opentype/default.htm"><cite>Windows
  6277     Glyph Processing.</cite></a> Microsoft Typogrraphy. URL: <a
  6278     href="http://www.microsoft.com/typography/developers/opentype/default.htm">http://www.microsoft.com/typography/developers/opentype/default.htm</a>
  6279     </dd>
  6280    <!---->
  6281   </dl>
  6282   <!--end-informative-->
  6283   <!--{{ARABIC-TYPO}}-->
  6284   <!--{{CJKV-INFO-PROCESSING}}-->
  6285   <!--{{DIGITAL-TYPOGRAPHY}}-->
  6286   <!--{{DOM-LEVEL-2-STYLE}}-->
  6287   <!--{{ELEMTYPO}}-->
  6288   <!--{{LANGCULTTYPE}}-->
  6289   <!--{{OPENTYPE-FONT-GUIDE}}-->
  6290   <!--{{RASTER-TRAGEDY}}-->
  6291   <!--{{WINDOWS-GLYPH-PROC}}-->
  6292   <!--{{CHARMOD-NORM}}-->
  6293   <!--{{AAT-FEATURES}}-->
  6294   <!--{{CSS3-CONDITIONAL}}-->
  6295   <!--{{CSS3TEXT}}-->
  6297   <h2 class=no-num id=index>Index</h2>
  6298   <!--begin-index-->
  6300   <ul class=indexlist>
  6301    <li>100...900 weight values, <a href="#font-weight-numeric-values"
  6302     title="100...900 weight values"><strong>3.2</strong></a>
  6304    <li><var>&lt;absolute-size&gt;</var>, <a href="#absolute-size-value"
  6305     title="&lt;absolute-size&gt;"><strong>3.5</strong></a>
  6307    <li><var>&lt;common-lig-values&gt;</var>, <a href="#common-lig-values"
  6308     title="&lt;common-lig-values&gt;"><strong>6.4</strong></a>
  6310    <li><var>&lt;contextual-alt-values&gt;</var>, <a
  6311     href="#contextual-alt-values"
  6312     title="&lt;contextual-alt-values&gt;"><strong>6.4</strong></a>
  6314    <li><var>&lt;discretionary-lig-values&gt;</var>, <a
  6315     href="#discretionary-lig-values"
  6316     title="&lt;discretionary-lig-values&gt;"><strong>6.4</strong></a>
  6318    <li><var>&lt;east-asian-variant-values&gt;</var>, <a
  6319     href="#east-asian-variant-values"
  6320     title="&lt;east-asian-variant-values&gt;"><strong>6.10</strong></a>
  6322    <li><var>&lt;east-asian-width-values&gt;</var>, <a
  6323     href="#east-asian-width-values"
  6324     title="&lt;east-asian-width-values&gt;"><strong>6.10</strong></a>
  6326    <li><var>&lt;family-name&gt;</var>, <a href="#family-name-value"
  6327     title="&lt;family-name&gt;"><strong>3.1</strong></a>
  6329    <li><var>&lt;feature-tag-value&gt;</var>, <a href="#feature-tag-value"
  6330     title="&lt;feature-tag-value&gt;"><strong>6.12</strong></a>
  6332    <li><var>&lt;font-face-name&gt;</var>, <a href="#font-face-name-value"
  6333     title="&lt;font-face-name&gt;"><strong>4.3</strong></a>
  6335    <li><var>&lt;font-variant-css21&gt;</var>, <a
  6336     href="#font-variant-css21-values"
  6337     title="&lt;font-variant-css21&gt;"><strong>3.7</strong></a>
  6339    <li><var>&lt;generic-family&gt;</var>, <a href="#generic-family-value"
  6340     title="&lt;generic-family&gt;"><strong>3.1</strong></a>
  6342    <li><var>&lt;historical-lig-values&gt;</var>, <a
  6343     href="#historical-lig-values"
  6344     title="&lt;historical-lig-values&gt;"><strong>6.4</strong></a>
  6346    <li><var>&lt;length&gt;</var>, <a href="#length-size-value"
  6347     title="&lt;length&gt;"><strong>3.5</strong></a>
  6349    <li><var>&lt;number&gt;</var>, <a href="#aspect-ratio-value"
  6350     title="&lt;number&gt;"><strong>3.6</strong></a>
  6352    <li><var>&lt;numeric-figure-values&gt;</var>, <a
  6353     href="#numeric-figure-values"
  6354     title="&lt;numeric-figure-values&gt;"><strong>6.7</strong></a>
  6356    <li><var>&lt;numeric-fraction-values&gt;</var>, <a
  6357     href="#numeric-fraction-values"
  6358     title="&lt;numeric-fraction-values&gt;"><strong>6.7</strong></a>
  6360    <li><var>&lt;numeric-spacing-values&gt;</var>, <a
  6361     href="#numeric-spacing-values"
  6362     title="&lt;numeric-spacing-values&gt;"><strong>6.7</strong></a>
  6364    <li><var>&lt;percentage&gt;</var>, <a href="#percentage-size-value"
  6365     title="&lt;percentage&gt;"><strong>3.5</strong></a>
  6367    <li><var>&lt;relative-size&gt;</var>, <a href="#relative-size-value"
  6368     title="&lt;relative-size&gt;"><strong>3.5</strong></a>
  6370    <li><var>&lt;string&gt;</var>, <a
  6371     href="#font-language-override-string-value"
  6372     title="&lt;string&gt;"><strong>6.13</strong></a>
  6374    <li><var>&lt;urange&gt;</var>, <a href="#urange-value"
  6375     title="&lt;urange&gt;"><strong>4.5</strong></a>
  6377    <li><code>@font-face</code>, <a href="#at-font-face-rule"
  6378     title="@font-face"><strong>4.1</strong></a>
  6380    <li><code>@font-feature-values</code>, <a
  6381     href="#at-font-feature-values-rule"
  6382     title="@font-feature-values"><strong>6.9</strong></a>
  6384    <li>all-petite-caps, <a href="#all-petite-caps"
  6385     title=all-petite-caps><strong>6.6</strong></a>
  6387    <li>all-small-caps, <a href="#all-small-caps"
  6388     title=all-small-caps><strong>6.6</strong></a>
  6390    <li>annotation, <a href="#annotation"
  6391     title=annotation><strong>6.8</strong></a>
  6393    <li>aspect value, <a href="#aspect-value0" title="aspect
  6394     value"><strong>3.6</strong></a>
  6396    <li>authoring tool, <a href="#authoring-tool" title="authoring
  6397     tool"><strong>#</strong></a>
  6399    <li>auto
  6400     <ul>
  6401      <li>font-kerning, <a href="#font-kerning-auto-value" title="auto,
  6402       font-kerning"><strong>6.3</strong></a>
  6404      <li>font-size-adjust, <a href="#font-size-adjust-auto-value"
  6405       title="auto, font-size-adjust"><strong>3.6</strong></a>
  6406     </ul>
  6408    <li>bold, <a href="#bold" title=bold><strong>3.2</strong></a>
  6410    <li>bolder, <a href="#bolder" title=bolder><strong>3.2</strong></a>
  6412    <li>character map, <a href="#character-map" title="character
  6413     map"><strong>5.2</strong></a>
  6415    <li>character-variant, <a href="#character-variant"
  6416     title=character-variant><strong>6.8</strong></a>
  6418    <li>common-ligatures, <a href="#common-ligatures"
  6419     title=common-ligatures><strong>6.4</strong></a>
  6421    <li>composite face, <a href="#composite-face" title="composite
  6422     face"><strong>5.2</strong></a>
  6424    <li>condensed, <a href="#condensed"
  6425     title=condensed><strong>3.3</strong></a>
  6427    <li>contextual, <a href="#contextual"
  6428     title=contextual><strong>6.4</strong></a>
  6430    <li>CSSFontFaceRule, <a href="#cssfontfacerule"
  6431     title=CSSFontFaceRule><strong>8.1</strong></a>
  6433    <li>CSSFontFeatureValuesRule, <a href="#cssfontfeaturevaluesrule"
  6434     title=CSSFontFeatureValuesRule><strong>8.2</strong></a>
  6436    <li>cursive, definition of, <a href="#cursive0" title="cursive, definition
  6437     of"><strong>#</strong></a>
  6439    <li>default face, <a href="#default-face" title="default
  6440     face"><strong>5.2</strong></a>
  6442    <li>descriptor_declaration, <a href="#descriptordeclaration"
  6443     title="descriptor_declaration"><strong>4.1</strong></a>
  6445    <li>diagonal-fractions, <a href="#diagonal-fractions"
  6446     title=diagonal-fractions><strong>6.7</strong></a>
  6448    <li>discretionary-ligatures, <a href="#discretionary-ligatures"
  6449     title=discretionary-ligatures><strong>6.4</strong></a>
  6451    <li>effective character map, <a href="#effective-character-map"
  6452     title="effective character map"><strong>4.5</strong></a>
  6454    <li>expanded, <a href="#expanded" title=expanded><strong>3.3</strong></a>
  6456    <li>extra-condensed, <a href="#extra-condensed"
  6457     title=extra-condensed><strong>3.3</strong></a>
  6459    <li>extra-expanded, <a href="#extra-expanded"
  6460     title=extra-expanded><strong>3.3</strong></a>
  6462    <li>fantasy, definition of, <a href="#fantasy0" title="fantasy, definition
  6463     of"><strong>#</strong></a>
  6465    <li>feature_type, <a href="#featuretype"
  6466     title="feature_type"><strong>6.9.1</strong></a>
  6468    <li>feature_value_block, <a href="#featurevalueblock"
  6469     title="feature_value_block"><strong>6.9.1</strong></a>
  6471    <li>feature_value_definition, <a href="#featurevaluedefinition"
  6472     title="feature_value_definition"><strong>6.9.1</strong></a>
  6474    <li>font, <a href="#propdef-font" title=font><strong>3.7</strong></a>
  6476    <li>font specific, <a href="#font-specific" title="font
  6477     specific"><strong>6.8</strong></a>
  6479    <li>font-family
  6480     <ul>
  6481      <li>descriptor, <a href="#descdef-font-family" title="font-family,
  6482       descriptor"><strong>4.2</strong></a>
  6484      <li>property, <a href="#propdef-font-family" title="font-family,
  6485       property"><strong>3.1</strong></a>
  6486     </ul>
  6488    <li>font-feature-settings
  6489     <ul>
  6490      <li>descriptor, <a href="#descdef-font-feature-settings"
  6491       title="font-feature-settings, descriptor"><strong>4.7</strong></a>
  6493      <li>property, <a href="#propdef-font-feature-settings"
  6494       title="font-feature-settings, property"><strong>6.12</strong></a>
  6495     </ul>
  6497    <li>font-kerning, <a href="#propdef-font-kerning"
  6498     title=font-kerning><strong>6.3</strong></a>
  6500    <li>font-language-override, <a href="#propdef-font-language-override"
  6501     title=font-language-override><strong>6.13</strong></a>
  6503    <li>font-size, <a href="#propdef-font-size"
  6504     title=font-size><strong>3.5</strong></a>
  6506    <li>font-size-adjust, <a href="#propdef-font-size-adjust"
  6507     title=font-size-adjust><strong>3.6</strong></a>
  6509    <li>font-stretch
  6510     <ul>
  6511      <li>descriptor, <a href="#descdef-font-stretch" title="font-stretch,
  6512       descriptor"><strong>4.4</strong></a>
  6514      <li>property, <a href="#propdef-font-stretch" title="font-stretch,
  6515       property"><strong>3.3</strong></a>
  6516     </ul>
  6518    <li>font-style
  6519     <ul>
  6520      <li>descriptor, <a href="#descdef-font-style" title="font-style,
  6521       descriptor"><strong>4.4</strong></a>
  6523      <li>property, <a href="#propdef-font-style" title="font-style,
  6524       property"><strong>3.4</strong></a>
  6525     </ul>
  6527    <li>font-synthesis, <a href="#propdef-font-synthesis"
  6528     title=font-synthesis><strong>3.8</strong></a>
  6530    <li>font-variant
  6531     <ul>
  6532      <li>descriptor, <a href="#descdef-font-variant" title="font-variant,
  6533       descriptor"><strong>4.7</strong></a>
  6535      <li>property, <a href="#propdef-font-variant" title="font-variant,
  6536       property"><strong>6.11</strong></a>
  6537     </ul>
  6539    <li>font-variant-alternates, <a href="#propdef-font-variant-alternates"
  6540     title=font-variant-alternates><strong>6.8</strong></a>
  6542    <li>font-variant-caps, <a href="#propdef-font-variant-caps"
  6543     title=font-variant-caps><strong>6.6</strong></a>
  6545    <li>font-variant-east-asian, <a href="#propdef-font-variant-east-asian"
  6546     title=font-variant-east-asian><strong>6.10</strong></a>
  6548    <li>font-variant-ligatures, <a href="#propdef-font-variant-ligatures"
  6549     title=font-variant-ligatures><strong>6.4</strong></a>
  6551    <li>font-variant-numeric, <a href="#propdef-font-variant-numeric"
  6552     title=font-variant-numeric><strong>6.7</strong></a>
  6554    <li>font-variant-position, <a href="#propdef-font-variant-position"
  6555     title=font-variant-position><strong>6.5</strong></a>
  6557    <li>font-weight
  6558     <ul>
  6559      <li>descriptor, <a href="#descdef-font-weight" title="font-weight,
  6560       descriptor"><strong>4.4</strong></a>
  6562      <li>property, <a href="#propdef-font-weight" title="font-weight,
  6563       property"><strong>3.2</strong></a>
  6564     </ul>
  6566    <li>font_face_rule, <a href="#fontfacerule"
  6567     title="font_face_rule"><strong>4.1</strong></a>
  6569    <li>FONT_FACE_SYM, <a href="#fontfacesym"
  6570     title="FONT_FACE_SYM"><strong>4.1</strong></a>
  6572    <li>font_family_name, <a href="#fontfamilyname"
  6573     title="font_family_name"><strong>6.9.1</strong></a>
  6575    <li>font_family_name_list, <a href="#fontfamilynamelist"
  6576     title="font_family_name_list"><strong>6.9.1</strong></a>
  6578    <li>font_feature_values_rule, <a href="#fontfeaturevaluesrule"
  6579     title="font_feature_values_rule"><strong>6.9.1</strong></a>
  6581    <li>FONT_FEATURE_VALUES_SYM, <a href="#fontfeaturevaluessym"
  6582     title="FONT_FEATURE_VALUES_SYM"><strong>6.9.1</strong></a>
  6584    <li>full-width, <a href="#full-width"
  6585     title=full-width><strong>6.10</strong></a>
  6587    <li>historical-forms, <a href="#historical-forms"
  6588     title=historical-forms><strong>6.8</strong></a>
  6590    <li>historical-ligatures, <a href="#historical-ligatures"
  6591     title=historical-ligatures><strong>6.4</strong></a>
  6593    <li>italic, <a href="#italic" title=italic><strong>3.4</strong></a>
  6595    <li>jis04, <a href="#jis04" title=jis04><strong>6.10</strong></a>
  6597    <li>jis78, <a href="#jis78" title=jis78><strong>6.10</strong></a>
  6599    <li>jis83, <a href="#jis83" title=jis83><strong>6.10</strong></a>
  6601    <li>jis90, <a href="#jis90" title=jis90><strong>6.10</strong></a>
  6603    <li>lighter, <a href="#lighter" title=lighter><strong>3.2</strong></a>
  6605    <li>lining-nums, <a href="#lining-nums"
  6606     title=lining-nums><strong>6.7</strong></a>
  6608    <li>monospace, definition of, <a href="#monospace0" title="monospace,
  6609     definition of"><strong>#</strong></a>
  6611    <li>no-common-ligatures, <a href="#no-common-ligatures"
  6612     title=no-common-ligatures><strong>6.4</strong></a>
  6614    <li>no-contextual, <a href="#no-contextual"
  6615     title=no-contextual><strong>6.4</strong></a>
  6617    <li>no-discretionary-ligatures, <a href="#no-discretionary-ligatures"
  6618     title=no-discretionary-ligatures><strong>6.4</strong></a>
  6620    <li>no-historical-ligatures, <a href="#no-historical-ligatures"
  6621     title=no-historical-ligatures><strong>6.4</strong></a>
  6623    <li>none
  6624     <ul>
  6625      <li>font-kerning, <a href="#font-kerning-none-value" title="none,
  6626       font-kerning"><strong>6.3</strong></a>
  6628      <li>font-size-adjust, <a href="#font-size-adjust-none-value"
  6629       title="none, font-size-adjust"><strong>3.6</strong></a>
  6631      <li>font-variant, <a href="#font-variant-none-value" title="none,
  6632       font-variant"><strong>6.11</strong></a>
  6634      <li>font-variant-ligatures, <a href="#font-variant-ligatures-none-value"
  6635       title="none, font-variant-ligatures"><strong>6.4</strong></a>
  6636     </ul>
  6638    <li>normal
  6639     <ul>
  6640      <li>font-feature-settings, <a href="#font-feature-settings-normal-value"
  6641       title="normal, font-feature-settings"><strong>6.12</strong></a>
  6643      <li>font-kerning, <a href="#font-kerning-normal-value" title="normal,
  6644       font-kerning"><strong>6.3</strong></a>
  6646      <li>font-language-override, <a
  6647       href="#font-language-override-normal-value" title="normal,
  6648       font-language-override"><strong>6.13</strong></a>
  6650      <li>font-stretch, <a href="#font-stretch-normal-value" title="normal,
  6651       font-stretch"><strong>3.3</strong></a>
  6653      <li>font-style, <a href="#font-style-normal-value" title="normal,
  6654       font-style"><strong>3.4</strong></a>
  6656      <li>font-variant, <a href="#font-variant-normal-value" title="normal,
  6657       font-variant"><strong>6.11</strong></a>
  6659      <li>font-variant-alternates, <a
  6660       href="#font-variant-alternates-normal-value" title="normal,
  6661       font-variant-alternates"><strong>6.8</strong></a>
  6663      <li>font-variant-caps, <a href="#font-variant-caps-normal-value"
  6664       title="normal, font-variant-caps"><strong>6.6</strong></a>
  6666      <li>font-variant-east-asian, <a
  6667       href="#font-variant-east-asian-normal-value" title="normal,
  6668       font-variant-east-asian"><strong>6.10</strong></a>
  6670      <li>font-variant-ligatures, <a
  6671       href="#font-variant-ligatures-normal-value" title="normal,
  6672       font-variant-ligatures"><strong>6.4</strong></a>
  6674      <li>font-variant-numeric, <a href="#font-variant-numeric-normal-value"
  6675       title="normal, font-variant-numeric"><strong>6.7</strong></a>
  6677      <li>font-variant-position, <a href="#font-variant-position-normal-value"
  6678       title="normal, font-variant-position"><strong>6.5</strong></a>
  6680      <li>font-weight, <a href="#font-weight-normal-value" title="normal,
  6681       font-weight"><strong>3.2</strong></a>
  6682     </ul>
  6684    <li>oblique, <a href="#oblique" title=oblique><strong>3.4</strong></a>
  6686    <li>oldstyle-nums, <a href="#oldstyle-nums"
  6687     title=oldstyle-nums><strong>6.7</strong></a>
  6689    <li>ordinal, <a href="#ordinal" title=ordinal><strong>6.7</strong></a>
  6691    <li>ornaments, <a href="#ornaments"
  6692     title=ornaments><strong>6.8</strong></a>
  6694    <li>petite-caps, <a href="#petite-caps"
  6695     title=petite-caps><strong>6.6</strong></a>
  6697    <li>proportional-nums, <a href="#proportional-nums"
  6698     title=proportional-nums><strong>6.7</strong></a>
  6700    <li>proportional-width, <a href="#proportional-width"
  6701     title=proportional-width><strong>6.10</strong></a>
  6703    <li>renderer, <a href="#renderer" title=renderer><strong>#</strong></a>
  6705    <li>ruby, <a href="#ruby" title=ruby><strong>6.10</strong></a>
  6707    <li>sans-serif, definition of, <a href="#sans-serif0" title="sans-serif,
  6708     definition of"><strong>#</strong></a>
  6710    <li>semi-condensed, <a href="#semi-condensed-"
  6711     title=semi-condensed><strong>3.3</strong></a>
  6713    <li>semi-expanded, <a href="#semi-expanded"
  6714     title=semi-expanded><strong>3.3</strong></a>
  6716    <li>serif, definition of, <a href="#serif0" title="serif, definition
  6717     of"><strong>#</strong></a>
  6719    <li>simplified, <a href="#simplified"
  6720     title=simplified><strong>6.10</strong></a>
  6722    <li>slashed-zero, <a href="#slashed-zero"
  6723     title=slashed-zero><strong>6.7</strong></a>
  6725    <li>small-caps, <a href="#small-caps"
  6726     title=small-caps><strong>6.6</strong></a>
  6728    <li>src, <a href="#descdef-src" title=src><strong>4.3</strong></a>
  6730    <li>stacked-fractions, <a href="#stacked-fractions"
  6731     title=stacked-fractions><strong>6.7</strong></a>
  6733    <li>style sheet
  6734     <ul>
  6735      <li>as conformance class, <a href="#style-sheet" title="style sheet, as
  6736       conformance class"><strong>#</strong></a>
  6737     </ul>
  6739    <li>styleset, <a href="#styleset" title=styleset><strong>6.8</strong></a>
  6741    <li>stylistic, <a href="#stylistic"
  6742     title=stylistic><strong>6.8</strong></a>
  6744    <li>sub, <a href="#sub" title=sub><strong>6.5</strong></a>
  6746    <li>super, <a href="#super" title=super><strong>6.5</strong></a>
  6748    <li>support, <a href="#support" title=support><strong>5.2</strong></a>
  6750    <li>swash, <a href="#swash" title=swash><strong>6.8</strong></a>
  6752    <li>system font fallback, <a href="#system-font-fallback" title="system
  6753     font fallback"><strong>5.2</strong></a>
  6755    <li>tabular-nums, <a href="#tabular-nums"
  6756     title=tabular-nums><strong>6.7</strong></a>
  6758    <li>titling-caps, <a href="#titling-caps"
  6759     title=titling-caps><strong>6.6</strong></a>
  6761    <li>traditional, <a href="#traditional"
  6762     title=traditional><strong>6.10</strong></a>
  6764    <li>ultra-condensed, <a href="#ultra-condensed"
  6765     title=ultra-condensed><strong>3.3</strong></a>
  6767    <li>ultra-expanded, <a href="#ultra-expanded"
  6768     title=ultra-expanded><strong>3.3</strong></a>
  6770    <li>unicase, <a href="#unicase" title=unicase><strong>6.6</strong></a>
  6772    <li>unicode-range, <a href="#descdef-unicode-range"
  6773     title=unicode-range><strong>4.5</strong></a>
  6775    <li>weight, <a href="#weight" title=weight><strong>2</strong></a>
  6777    <li>width, <a href="#width" title=width><strong>2</strong></a>
  6778   </ul>
  6779   <!--end-index-->
  6781   <h2 class=no-num id=property-index>Property index</h2>
  6782   <!--begin-properties-->
  6784   <table class=proptable>
  6785    <thead>
  6786     <tr>
  6787      <th>Property
  6789      <th>Values
  6791      <th>Initial
  6793      <th>Applies to
  6795      <th>Inh.
  6797      <th>Percentages
  6799      <th>Media
  6801    <tbody>
  6802     <tr>
  6803      <th><a class=property href="#propdef-font">font</a>
  6805      <td>[ [ &lt;‘font-style’&gt; || &lt;font-variant-css21&gt; ||
  6806       &lt;‘font-weight’&gt; || &lt;‘font-stretch’ ]?
  6807       &lt;‘font-size’&gt; [ / &lt;‘line-height’&gt; ]?
  6808       &lt;‘font-family’&gt; ] | caption | icon | menu | message-box |
  6809       small-caption | status-bar
  6811      <td>see individual properties
  6813      <td>all elements
  6815      <td>yes
  6817      <td>see individual properties
  6819      <td>visual
  6821     <tr>
  6822      <th><span class=property>font-family</span>
  6824      <td>[ &lt;family-name&gt; | &lt;generic-family&gt; ] #
  6826      <td>depends on user agent
  6828      <td>all elements
  6830      <td>yes
  6832      <td>N/A
  6834      <td>visual
  6836     <tr>
  6837      <th><span class=property>font-feature-settings</span>
  6839      <td>normal | &lt;feature-tag-value&gt; #
  6841      <td>normal
  6843      <td>all elements
  6845      <td>yes
  6847      <td>N/A
  6849      <td>visual
  6851     <tr>
  6852      <th><a class=property href="#propdef-font-kerning">font-kerning</a>
  6854      <td>auto | normal | none
  6856      <td>auto
  6858      <td>all elements
  6860      <td>yes
  6862      <td>N/A
  6864      <td>visual
  6866     <tr>
  6867      <th><a class=property
  6868       href="#propdef-font-language-override">font-language-override</a>
  6870      <td>normal | &lt;string&gt;
  6872      <td>normal
  6874      <td>all elements
  6876      <td>yes
  6878      <td>N/A
  6880      <td>visual
  6882     <tr>
  6883      <th><a class=property href="#propdef-font-size">font-size</a>
  6885      <td>&lt;absolute-size&gt; | &lt;relative-size&gt; | &lt;length&gt; |
  6886       &lt;percentage&gt;
  6888      <td>medium
  6890      <td>all elements
  6892      <td>yes
  6894      <td>refer to parent element's font size
  6896      <td>visual
  6898     <tr>
  6899      <th><a class=property
  6900       href="#propdef-font-size-adjust">font-size-adjust</a>
  6902      <td>none | auto | &lt;number&gt;
  6904      <td>none
  6906      <td>all elements
  6908      <td>yes
  6910      <td>N/A
  6912      <td>visual
  6914     <tr>
  6915      <th><span class=property>font-stretch</span>
  6917      <td>normal | ultra-condensed | extra-condensed | condensed |
  6918       semi-condensed | semi-expanded | expanded | extra-expanded |
  6919       ultra-expanded
  6921      <td>normal
  6923      <td>all elements
  6925      <td>yes
  6927      <td>N/A
  6929      <td>visual
  6931     <tr>
  6932      <th><span class=property>font-style</span>
  6934      <td>normal | italic | oblique
  6936      <td>normal
  6938      <td>all elements
  6940      <td>yes
  6942      <td>N/A
  6944      <td>visual
  6946     <tr>
  6947      <th><a class=property href="#propdef-font-synthesis">font-synthesis</a>
  6949      <td>none | [ weight || style ]
  6951      <td>weight style
  6953      <td>all elements
  6955      <td>yes
  6957      <td>N/A
  6959      <td>visual
  6961     <tr>
  6962      <th><span class=property>font-variant</span>
  6964      <td>normal | none | [ &lt;common-lig-values&gt; ||
  6965       &lt;discretionary-lig-values&gt; || &lt;historical-lig-values&gt; ||
  6966       &lt;contextual-alt-values&gt; || stylistic(&lt;feature-value-name&gt;)
  6967       || historical-forms || styleset(&lt;feature-value-name&gt; #) ||
  6968       character-variant(&lt;feature-value-name&gt; #) ||
  6969       swash(&lt;feature-value-name&gt;) ||
  6970       ornaments(&lt;feature-value-name&gt;) ||
  6971       annotation(&lt;feature-value-name&gt;) || [ small-caps | all-small-caps
  6972       | petite-caps | all-petite-caps | unicase | titling-caps ] ||
  6973       &lt;numeric-figure-values&gt; || &lt;numeric-spacing-values&gt; ||
  6974       &lt;numeric-fraction-values&gt; || ordinal || slashed-zero ||
  6975       &lt;east-asian-variant-values&gt; || &lt;east-asian-width-values&gt; ||
  6976       ruby ]
  6978      <td>normal
  6980      <td>all elements
  6982      <td>yes
  6984      <td>see individual properties
  6986      <td>visual
  6988     <tr>
  6989      <th><a class=property
  6990       href="#propdef-font-variant-alternates">font-variant-alternates</a>
  6992      <td>normal | [ stylistic(&lt;feature-value-name&gt;) || historical-forms
  6993       || styleset(&lt;feature-value-name&gt; #) ||
  6994       character-variant(&lt;feature-value-name&gt; #) ||
  6995       swash(&lt;feature-value-name&gt;) ||
  6996       ornaments(&lt;feature-value-name&gt;) ||
  6997       annotation(&lt;feature-value-name&gt;) ]
  6999      <td>normal
  7001      <td>all elements
  7003      <td>yes
  7005      <td>N/A
  7007      <td>visual
  7009     <tr>
  7010      <th><a class=property
  7011       href="#propdef-font-variant-caps">font-variant-caps</a>
  7013      <td>normal | small-caps | all-small-caps | petite-caps | all-petite-caps
  7014       | unicase | titling-caps
  7016      <td>normal
  7018      <td>all elements
  7020      <td>yes
  7022      <td>N/A
  7024      <td>visual
  7026     <tr>
  7027      <th><a class=property
  7028       href="#propdef-font-variant-east-asian">font-variant-east-asian</a>
  7030      <td>normal | [ &lt;east-asian-variant-values&gt; ||
  7031       &lt;east-asian-width-values&gt; || ruby ]
  7033      <td>normal
  7035      <td>all elements
  7037      <td>yes
  7039      <td>N/A
  7041      <td>visual
  7043     <tr>
  7044      <th><a class=property
  7045       href="#propdef-font-variant-ligatures">font-variant-ligatures</a>
  7047      <td>normal | none | [ &lt;common-lig-values&gt; ||
  7048       &lt;discretionary-lig-values&gt; || &lt;historical-lig-values&gt; ||
  7049       &lt;contextual-alt-values&gt; ]
  7051      <td>normal
  7053      <td>all elements
  7055      <td>yes
  7057      <td>N/A
  7059      <td>visual
  7061     <tr>
  7062      <th><a class=property
  7063       href="#propdef-font-variant-numeric">font-variant-numeric</a>
  7065      <td>normal | [ &lt;numeric-figure-values&gt; ||
  7066       &lt;numeric-spacing-values&gt; || &lt;numeric-fraction-values&gt; ||
  7067       ordinal || slashed-zero ]
  7069      <td>normal
  7071      <td>all elements
  7073      <td>yes
  7075      <td>N/A
  7077      <td>visual
  7079     <tr>
  7080      <th><a class=property
  7081       href="#propdef-font-variant-position">font-variant-position</a>
  7083      <td>normal | sub | super
  7085      <td>normal
  7087      <td>all elements
  7089      <td>yes
  7091      <td>N/A
  7093      <td>visual
  7095     <tr>
  7096      <th><span class=property>font-weight</span>
  7098      <td>normal | bold | bolder | lighter | 100 | 200 | 300 | 400 | 500 | 600
  7099       | 700 | 800 | 900
  7101      <td>normal
  7103      <td>all elements
  7105      <td>yes
  7107      <td>N/A
  7109      <td>visual
  7110   </table>
  7111   <!--end-properties-->
  7112   <!--begin-descriptors-->
  7114   <table class=proptable>
  7115    <thead>
  7116     <tr>
  7117      <th>Descriptor
  7119      <th>Value
  7121      <th>Initial
  7123      <th>Percentages
  7125      <th>Media
  7127    <tbody>
  7128     <tr>
  7129      <th><span class=property>font-family</span>
  7131      <td>&lt;family-name&gt;
  7133      <td>N/A
  7135     <tr>
  7136      <th><span class=property>font-feature-settings</span>
  7138      <td>normal | &lt;feature-tag-value&gt; #
  7140      <td>normal
  7142     <tr>
  7143      <th><span class=property>font-stretch</span>
  7145      <td>normal | ultra-condensed | extra-condensed | condensed |
  7146       semi-condensed | semi-expanded | expanded | extra-expanded |
  7147       ultra-expanded
  7149      <td>normal
  7151     <tr>
  7152      <th><span class=property>font-style</span>
  7154      <td>normal | italic | oblique
  7156      <td>normal
  7158     <tr>
  7159      <th><span class=property>font-variant</span>
  7161      <td>normal | none | [ &lt;common-lig-values&gt; ||
  7162       &lt;discretionary-lig-values&gt; || &lt;historical-lig-values&gt; ||
  7163       &lt;contextual-alt-values&gt; || stylistic(&lt;feature-value-name&gt;)
  7164       || historical-forms || styleset(&lt;feature-value-name&gt; #) ||
  7165       character-variant(&lt;feature-value-name&gt; #) ||
  7166       swash(&lt;feature-value-name&gt;) ||
  7167       ornaments(&lt;feature-value-name&gt;) ||
  7168       annotation(&lt;feature-value-name&gt;) || [ small-caps | all-small-caps
  7169       | petite-caps | all-petite-caps | unicase | titling-caps ] ||
  7170       &lt;numeric-figure-values&gt; || &lt;numeric-spacing-values&gt; ||
  7171       &lt;numeric-fraction-values&gt; || ordinal || slashed-zero ||
  7172       &lt;east-asian-variant-values&gt; || &lt;east-asian-width-values&gt; ||
  7173       ruby ]
  7175      <td>normal
  7177     <tr>
  7178      <th><span class=property>font-weight</span>
  7180      <td>normal | bold | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900
  7182      <td>normal
  7184     <tr>
  7185      <th><a class=property href="#descdef-src">src</a>
  7187      <td>[ &lt;url> [format(&lt;string> #)]? | &lt;font-face-name&gt; ] #
  7189      <td>N/A
  7191     <tr>
  7192      <th><a class=property href="#descdef-unicode-range">unicode-range</a>
  7194      <td>&lt;urange&gt; #
  7196      <td>U+0-10FFFF
  7197   </table>
  7198   <!--end-descriptors-->
  7199   <script type="text/javascript">
  7200 window.onload = function () {
  7201   if (!("devicePixelRatio" in window && window.devicePixelRatio > 1)) return;
  7202   var i, hiresElements = document.getElementsByClassName("hires");
  7203   for (i = 0; i < hiresElements.length; i++) {
  7204     var h = hiresElements[i];
  7205     if (h.tagName != "IMG") continue;
  7206     var src = h.getAttribute("src");
  7207     var src2x = src.replace(/\.\w+$/, function(m) { return "@2x" + m; });
  7208     h.src = src2x;
  7211 </script>
  7212 </html>
  7213 <!-- Keep this comment at the end of the file
  7214 Local variables:
  7215 mode: sgml
  7216 sgml-declaration:"~/SGML/HTML4.decl"
  7217 sgml-default-doctype-name:"html"
  7218 sgml-minimize-attributes:t
  7219 sgml-nofill-elements:("pre" "style" "br")
  7220 sgml-live-element-indicator:t
  7221 sgml-omittag:nil
  7222 sgml-shorttag:nil
  7223 sgml-namecase-general:t
  7224 sgml-general-insert-case:lower
  7225 sgml-always-quote-attributes:t
  7226 sgml-indent-step:nil
  7227 sgml-indent-data:t
  7228 sgml-parent-document:nil
  7229 sgml-exposed-tags:nil
  7230 sgml-local-catalogs:nil
  7231 sgml-local-ecat-files:nil
  7232 End:
  7233 -->
  7234 <!--
  7236 to do:
  7238 - wording of OpenType family name handling
  7239 - handling combining sequences in the font matching algorithm
  7240 - fix-up fi ligature example
  7242 -->

mercurial