css-fonts/Fonts.html

Mon, 26 Aug 2013 15:28:36 +0900

author
John Daggett <jdaggett@mozilla.com>
date
Mon, 26 Aug 2013 15:28:36 +0900
changeset 8927
9c4ae1da9e9a
parent 8872
9905e92b4df5
child 8930
77d3edf17f8c
permissions
-rw-r--r--

[css3-fonts] allow user agents to synthesize kern feature from kern table data

     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-26-august-2013>Editor's Draft
   119     26 August 2013</h2>
   121    <dl id=authors>
   122     <dt>This version:
   124     <dd><a
   125      href="http://dev.w3.org/csswg/css-fonts/">http://dev.w3.org/csswg/css-fonts/</a>
   126      <!-- <dd><a href="http://www.w3.org/TR/2013/ED-css-fonts-3-20130826/">http://www.w3.org/TR/2013/ED-css-fonts-3-20130826/</a>  -->
   129     <dt>Latest version:
   131     <dd><a
   132      href="http://www.w3.org/TR/css-fonts-3/">http://www.w3.org/TR/css-fonts-3/</a>
   134     <dt>Latest editor's draft:
   136     <dd><a
   137      href="http://dev.w3.org/csswg/css-fonts/">http://dev.w3.org/csswg/css-fonts/</a>
   138      (<a
   139      href="https://dvcs.w3.org/hg/csswg/log/tip/css-fonts/Fonts.html">change
   140      log</a>)
   142     <dt>Previous version:
   144     <dd><a
   145      href="http://www.w3.org/TR/2013/WD-css-fonts-3-20130711/">http://www.w3.org/TR/2013/WD-css-fonts-3-20130711/</a>
   147     <dt>Issues List:
   149     <dd><a href="http://www.w3.org/Style/CSS/Tracker/products/18">CSS3 Fonts
   150      issues in Tracker</a>
   152     <dd><a
   153      href="https://www.w3.org/Bugs/Public/buglist.cgi?query_format=advanced&amp;product=CSS&amp;component=Fonts&amp;bug_status=NEW&amp;bug_status=ASSIGNED&amp;bug_status=REOPENED">CSS3
   154      Fonts issues in Bugzilla</a>
   156     <dt>Discussion:
   158     <dd><a
   159      href="mailto:www-style@w3.org?subject=%5Bcss-fonts%5D%20feedback">www-style@w3.org</a>
   160      with subject line “<kbd>[css-fonts] <var>… message topic
   161      …</var></kbd>” (<a
   162      href="http://lists.w3.org/Archives/Public/www-style/"
   163      rel=discussion>archives</a>)
   165     <dt>Editor:
   167     <dd><a href="mailto:jdaggett@mozilla.com">John Daggett (Mozilla)</a>
   168    </dl>
   169    <!--begin-copyright-->
   170    <p class=copyright><a
   171     href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright"
   172     rel=license>Copyright</a> © 2013 <a href="http://www.w3.org/"><abbr
   173     title="World Wide Web Consortium">W3C</abbr></a><sup>®</sup> (<a
   174     href="http://www.csail.mit.edu/"><abbr title="Massachusetts Institute of
   175     Technology">MIT</abbr></a>, <a href="http://www.ercim.eu/"><abbr
   176     title="European Research Consortium for Informatics and
   177     Mathematics">ERCIM</abbr></a>, <a href="http://www.keio.ac.jp/">Keio</a>,
   178     <a href="http://ev.buaa.edu.cn/">Beihang</a>), All Rights Reserved. W3C
   179     <a
   180     href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>,
   181     <a
   182     href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a>
   183     and <a
   184     href="http://www.w3.org/Consortium/Legal/copyright-documents">document
   185     use</a> rules apply.</p>
   186    <!--end-copyright-->
   187    <hr title="Separator for header">
   188   </div>
   190   <h2 class="no-num no-toc" id=abstract>Abstract</h2>
   192   <p>This CSS3 module describes how font properties are specified and how
   193    font resources are loaded dynamically. The contents of this specification
   194    are a consolidation of content previously divided into <a
   195    href="http://www.w3.org/TR/2002/WD-css3-fonts-20020802/">CSS3 Fonts</a>
   196    and <a href="http://www.w3.org/TR/2002/WD-css3-webfonts-20020802/">CSS3
   197    Web Fonts</a> modules. The description of font load events was moved into
   198    the <a href="http://dev.w3.org/csswg/css-font-load-events/">CSS3 Font Load
   199    Events</a> module.
   201   <h2 class="no-num no-toc" id=status>Status of this document</h2>
   202   <!--begin-status-->
   204   <p>This is a public copy of the editors' draft. It is provided for
   205    discussion only and may change at any moment. Its publication here does
   206    not imply endorsement of its contents by W3C. Don't cite this document
   207    other than as work in progress.
   209   <p>The (<a
   210    href="http://lists.w3.org/Archives/Public/www-style/">archived</a>) public
   211    mailing list <a
   212    href="mailto:www-style@w3.org?Subject=%5Bcss3-fonts%5D%20PUT%20SUBJECT%20HERE">
   213    www-style@w3.org</a> (see <a
   214    href="http://www.w3.org/Mail/Request">instructions</a>) is preferred for
   215    discussion of this specification. When sending e-mail, please put the text
   216    “css3-fonts” in the subject, preferably like this:
   217    “[<!---->css3-fonts<!---->] <em>…summary of comment…</em>”
   219   <p>This document was produced by the <a
   220    href="http://www.w3.org/Style/CSS/members">CSS Working Group</a> (part of
   221    the <a href="http://www.w3.org/Style/">Style Activity</a>).
   223   <p>This document was produced by a group operating under the <a
   224    href="http://www.w3.org/Consortium/Patent-Policy-20040205/">5 February
   225    2004 W3C Patent Policy</a>. W3C maintains a <a
   226    href="http://www.w3.org/2004/01/pp-impl/32061/status"
   227    rel=disclosure>public list of any patent disclosures</a> made in
   228    connection with the deliverables of the group; that page also includes
   229    instructions for disclosing a patent. An individual who has actual
   230    knowledge of a patent which the individual believes contains <a
   231    href="http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">Essential
   232    Claim(s)</a> must disclose the information in accordance with <a
   233    href="http://www.w3.org/Consortium/Patent-Policy-20040205/#sec-Disclosure">section
   234    6 of the W3C Patent Policy</a>.</p>
   235   <!--end-status-->
   237   <h3 class="no-num no-toc" id=atrisk>Features at risk</h3>
   239   <p>The following features are at risk and may be removed when exiting CR:
   241   <ul>
   242    <li>fallback handling for text decoration in superscript/subscript variant
   243     glyphs (‘<a href="#propdef-font-variant-position"><code
   244     class=property>font-variant-position</code></a>’)
   246    <li>‘<a href="#propdef-font-language-override"><code
   247     class=property>font-language-override</code></a>’ property
   248   </ul>
   249   <!--
   250 <p>This draft is a <strong>Last Call Working Draft</strong>.
   251 Please send comments to the 
   252 <a href="http://lists.w3.org/Archives/Public/www-style/">www-style mailing list</a>
   253 as described above.  The <strong>deadline for comments</strong> 
   254 is six weeks after the date of publication in the header, 22 August 2013.</p>
   255 -->
   257   <h2 class="no-num no-toc" id=contents>Table of contents</h2>
   258   <!--begin-toc-->
   260   <ul class=toc>
   261    <li><a href="#introduction"><span class=secno>1 </span>Introduction</a>
   263    <li><a href="#typography-background"><span class=secno>2 </span>Typography
   264     Background</a>
   266    <li><a href="#basic-font-props"><span class=secno>3 </span>Basic Font
   267     Properties</a>
   268     <ul class=toc>
   269      <li><a href="#font-family-prop"><span class=secno>3.1 </span>Font
   270       family: the font-family property</a>
   271       <ul class=toc>
   272        <li><a href="#generic-font-families"><span class=secno>3.1.1
   273         </span>Generic font families</a>
   274       </ul>
   276      <li><a href="#font-weight-prop"><span class=secno>3.2 </span>Font
   277       weight: the font-weight property</a>
   279      <li><a href="#font-stretch-prop"><span class=secno>3.3 </span>Font
   280       width: the font-stretch property</a>
   282      <li><a href="#font-style-prop"><span class=secno>3.4 </span>Font style:
   283       the font-style property</a>
   285      <li><a href="#font-size-prop"><span class=secno>3.5 </span>Font size:
   286       the font-size property</a>
   288      <li><a href="#font-size-adjust-prop"><span class=secno>3.6
   289       </span>Relative sizing: the font-size-adjust property</a>
   291      <li><a href="#font-prop"><span class=secno>3.7 </span>Shorthand font
   292       property: the font property</a>
   294      <li><a href="#font-synthesis-prop"><span class=secno>3.8
   295       </span>Controlling synthetic faces: the font-synthesis property</a>
   296     </ul>
   298    <li><a href="#font-resources"><span class=secno>4 </span>Font
   299     Resources</a>
   300     <ul class=toc>
   301      <li><a href="#font-face-rule"><span class=secno>4.1 </span>The
   302       <code>@font-face</code> rule</a>
   304      <li><a href="#font-family-desc"><span class=secno>4.2 </span>Font
   305       family: the font-family descriptor</a>
   307      <li><a href="#src-desc"><span class=secno>4.3 </span>Font reference: the
   308       src descriptor</a>
   310      <li><a href="#font-prop-desc"><span class=secno>4.4 </span>Font property
   311       descriptors: the font-style, font-weight, font-stretch descriptors</a>
   313      <li><a href="#unicode-range-desc"><span class=secno>4.5 </span>Character
   314       range: the unicode-range descriptor</a>
   316      <li><a href="#composite-fonts"><span class=secno>4.6 </span>Using
   317       character ranges to define composite fonts</a>
   319      <li><a href="#font-rend-desc"><span class=secno>4.7 </span>Font
   320       features: the font-variant and font-feature-settings descriptors</a>
   322      <li><a href="#font-face-loading"><span class=secno>4.8 </span>Font
   323       loading guidelines</a>
   325      <li><a href="#font-fetching-requirements"><span class=secno>4.9
   326       </span>Font fetching requirements</a>
   327     </ul>
   329    <li><a href="#font-matching-algorithm"><span class=secno>5 </span>Font
   330     Matching Algorithm</a>
   331     <ul class=toc>
   332      <li><a href="#font-family-casing"><span class=secno>5.1 </span>Case
   333       sensitivity of font family names</a>
   335      <li><a href="#font-style-matching"><span class=secno>5.2 </span>Matching
   336       font styles</a>
   338      <li><a href="#cluster-matching"><span class=secno>5.3 </span>Cluster
   339       matching</a>
   341      <li><a href="#char-handling-issues"><span class=secno>5.4
   342       </span>Character handling issues</a>
   344      <li><a href="#font-matching-changes"><span class=secno>5.5 </span>Font
   345       matching changes since CSS 2.1</a>
   347      <li><a href="#font-matching-examples"><span class=secno>5.6 </span>Font
   348       matching examples</a>
   349     </ul>
   351    <li><a href="#font-rend-props"><span class=secno>6 </span>Font Feature
   352     Properties</a>
   353     <ul class=toc>
   354      <li><a href="#glyph-selection-positioning"><span class=secno>6.1
   355       </span>Glyph selection and positioning</a>
   357      <li><a href="#language-specific-support"><span class=secno>6.2
   358       </span>Language-specific display</a>
   360      <li><a href="#font-kerning-prop"><span class=secno>6.3 </span>Kerning:
   361       the font-kerning property</a>
   363      <li><a href="#font-variant-ligatures-prop"><span class=secno>6.4
   364       </span>Ligatures: the font-variant-ligatures property</a>
   366      <li><a href="#font-variant-position-prop"><span class=secno>6.5
   367       </span>Subscript and superscript forms: the font-variant-position
   368       property</a>
   370      <li><a href="#font-variant-caps-prop"><span class=secno>6.6
   371       </span>Capitalization: the font-variant-caps property</a>
   373      <li><a href="#font-variant-numeric-prop"><span class=secno>6.7
   374       </span>Numerical formatting: the font-variant-numeric property</a>
   376      <li><a href="#font-variant-alternates-prop"><span class=secno>6.8
   377       </span>Alternates and swashes: the font-variant-alternates property</a>
   380      <li><a href="#font-feature-values"><span class=secno>6.9 </span>Defining
   381       font specific alternates: the <code>@font-feature-values</code>
   382       rule</a>
   383       <ul class=toc>
   384        <li><a href="#basic-syntax"><span class=secno>6.9.1 </span>Basic
   385         syntax</a>
   387        <li><a href="#multi-valued-feature-value-definitions"><span
   388         class=secno>6.9.2 </span>Multi-valued feature value definitions</a>
   389       </ul>
   391      <li><a href="#font-variant-east-asian-prop"><span class=secno>6.10
   392       </span>East Asian text rendering: the font-variant-east-asian
   393       property</a>
   395      <li><a href="#font-variant-prop"><span class=secno>6.11 </span>Overall
   396       shorthand for font rendering: the font-variant property</a>
   398      <li><a href="#font-feature-settings-prop"><span class=secno>6.12
   399       </span>Low-level font feature settings control: the
   400       font-feature-settings property</a>
   402      <li><a href="#font-language-override-prop"><span class=secno>6.13
   403       </span>Font language override: the font-language-override property</a>
   404     </ul>
   406    <li><a href="#font-feature-resolution"><span class=secno>7 </span>Font
   407     Feature Resolution </a>
   408     <ul class=toc>
   409      <li><a href="#default-features"><span class=secno>7.1 </span>Default
   410       features</a>
   412      <li><a href="#feature-precedence"><span class=secno>7.2 </span>Feature
   413       precedence</a>
   415      <li><a href="#feature-precedence-examples"><span class=secno>7.3
   416       </span>Feature precedence examples</a>
   417     </ul>
   419    <li><a href="#object-model"><span class=secno>8 </span>Object Model</a>
   420     <ul class=toc>
   421      <li><a href="#om-fontface"><span class=secno>8.1 </span>The
   422       <code>CSSFontFaceRule</code> interface</a>
   424      <li><a href="#om-fontfeaturevalues"><span class=secno>8.2 </span>The
   425       <code>CSSFontFeatureValuesRule</code> interface</a>
   426     </ul>
   428    <li class=no-num><a href="#platform-props-to-css">Appendix A: Mapping
   429     platform font properties to CSS properties</a>
   431    <li class=no-num><a href="#ch-ch-ch-changes">Changes</a>
   432     <ul class=toc>
   433      <li class=no-num><a href="#recent-changes"> Changes from the July 2013
   434       CSS3 Fonts Last Call Working Draft</a>
   435     </ul>
   437    <li class=no-num><a href="#acknowledgments">Acknowledgments</a>
   439    <li class=no-num><a href="#conformance"> Conformance</a>
   440     <ul class=toc>
   441      <li class=no-num><a href="#conventions"> Document Conventions</a>
   443      <li class=no-num><a href="#conformance-classes"> Conformance Classes</a>
   446      <li class=no-num><a href="#partial"> Partial Implementations</a>
   448      <li class=no-num><a href="#experimental"> Experimental
   449       Implementations</a>
   451      <li class=no-num><a href="#testing"> Non-Experimental
   452       Implementations</a>
   453     </ul>
   455    <li class=no-num><a href="#references">References</a>
   456     <ul class=toc>
   457      <li class=no-num><a href="#normative-references">Normative
   458       References</a>
   460      <li class=no-num><a href="#other-references">Other References</a>
   461     </ul>
   463    <li class=no-num><a href="#index">Index</a>
   465    <li class=no-num><a href="#property-index">Property index</a>
   466   </ul>
   467   <!--end-toc-->
   469   <h2 id=introduction><span class=secno>1 </span>Introduction</h2>
   471   <p>A font provides a resource containing the visual representation of
   472    characters. At the simplest level it contains information that maps
   473    character codes to shapes (called glyphs) that represent these characters.
   474    Fonts sharing a common design style are commonly grouped into font
   475    families classified by a set of standard font properties. Within a family,
   476    the shape displayed for a given character can vary by stroke weight, slant
   477    or relative width, among others. An individual font face is described by a
   478    unique combination of these properties. For a given range of text, CSS
   479    font properties are used to select a font family and a specific font face
   480    within that family to be used when rendering that text. As a simple
   481    example, to use the bold form of Helvetica one could use:
   483   <pre>body {
   484     font-family: Helvetica;
   485     font-weight: bold;
   486 }</pre>
   488   <p>Font resources may be installed locally on the system on which a user
   489    agent is running or downloadable. For local font resources descriptive
   490    information can be obtained directly from the font resource. For
   491    downloadable font resources (sometimes referred to as web fonts), the
   492    descriptive information is included with the reference to the font
   493    resource.
   495   <p>Families of fonts typically don't contain a single face for each
   496    possible variation of font properties. The CSS font selection mechanism
   497    describes how to match a given set of CSS font properties to a single font
   498    face.
   500   <h2 id=typography-background><span class=secno>2 </span>Typography
   501    Background</h2>
   503   <p><em>This section is non-normative.</em>
   505   <p> Typographic traditions vary across the globe, so there is no unique way
   506    to classify all fonts across languages and cultures. For even common Latin
   507    letters, wide variations are possible:
   509   <div class=figure><img alt="variations in glyphs for a single character"
   510    src=aaaaaa.png>
   511    <p class=caption>One character, many glyph variations
   512   </div>
   514   <p>Differences in the anatomy of letterforms is one way to distinguish
   515    fonts. For Latin fonts, flourishes at the ends of a character's main
   516    strokes, or serifs, can distinguish a font from those without. Similar
   517    comparisons exist in non-Latin fonts between fonts with tapered strokes
   518    and those using primarily uniform strokes:
   520   <div class=figure><img alt="serif vs. non-serifs" src=serifvssansserif.png>
   521    <p class=caption>Letterforms with and without serifs
   522   </div>
   524   <div class=figure><img alt="serif vs. non-serifs for japanese"
   525    src=minchovsgothic.png>
   526    <p class=caption>Similar groupings for Japanese typefaces
   527   </div>
   529   <p>Fonts contain letterforms and the data needed to map characters to these
   530    letterforms. Often this may be a simple one-to-one mapping, but more
   531    complex mappings are also possible. The use of combining diacritic marks
   532    creates many variations for an underlying letterform:
   534   <div class=figure><img alt="diacritic marks" src=aaaaaa-diacritics.png>
   535    <p class=caption>Variations with diacritic marks
   536   </div>
   538   <p>A sequence of characters can be represented by a single glyph known as a
   539    ligature:
   541   <div class=figure><img alt="example of a fi ligature"
   542    src=final-ligature.png>
   543    <p class=caption>Ligature example
   544   </div>
   546   <p>Visual transformations based on textual context are often stylistic
   547    option in European languages. They are required to correctly render
   548    languages like Arabic, the lam and alef characters below <em>must</em> be
   549    combined when they exist in sequence:
   551   <div class=figure><img alt="lam alef ligature" src=lamaleflig.png>
   552    <p class=caption>Required Arabic ligature
   553   </div>
   555   <p>The relative complexity of these shaping transformations requires
   556    additional data within the font.
   558   <p>Sets of font faces with various stylistic variations are often grouped
   559    together into font families. In the simplest case a regular face is
   560    supplemented with bold and italic faces, but much more extensive groupings
   561    are possible. Variations in the thickness of letterform strokes, the <dfn
   562    id=weight>weight</dfn>, and the overall proportions of the letterform, the
   563    <dfn id=width>width</dfn>, are most common. In the example below, each
   564    letter uses a different font face within the Univers font family. The
   565    width used increases from top to bottom and the weight increases from left
   566    to right:
   568   <div class=figure><img alt="various width and weight variations within a
   569    single family" src=weightwidthvariations.png>
   570    <p class=caption>Weight and width variations within a single font family
   571   </div>
   573   <p>Creating fonts that support multiple scripts is a difficult task;
   574    designers need to understand the cultural traditions surrounding the use
   575    of type in different scripts and come up with letterforms that somehow
   576    share a common theme. Many languages often share a common script and each
   577    of these languages may have noticeable stylistic differences. For example,
   578    the Arabic script is shared by Persian and Urdu and Cyrillic is used with
   579    many languages, not just Russian.
   581   <p>The <a href="#character-map"><em>character map</em></a> of a font
   582    defines the mapping of characters to glyphs for that font. If a document
   583    contains characters not supported by the <a href="#character-map"><em
   584    title="character map">character maps</em></a> of the fonts contained in a
   585    font family list, a user agent may use a <a
   586    href="#system-font-fallback"><em>system font fallback</em></a> procedure
   587    to locate an appropriate font that does. If no appropriate font can be
   588    found, some form of "missing glyph" character will be rendered by the user
   589    agent. System fallback can occur when the specified list of font families
   590    does not include a font that supports a given character.
   592   <p>Although the <a href="#character-map"><em>character map</em></a> of a
   593    font maps a given character to a glyph for that character, modern font
   594    technologies such as OpenType and AAT (Apple Advanced Typography) provide
   595    ways of mapping a character to different glyphs based upon feature
   596    settings. Fonts in these formats allow these features to be embedded in
   597    the font itself and controlled by applications. Common typographic
   598    features which can be specified this way include ligatures, swashes,
   599    contextual alternates, proportional and tabular figures, and automatic
   600    fractions, to list just a few. For a visual overview of OpenType features,
   601    see the <a href="#OPENTYPE-FONT-GUIDE"
   602    rel=biblioentry>[OPENTYPE-FONT-GUIDE]<!--{{OPENTYPE-FONT-GUIDE}}--></a>.
   604   <h2 id=basic-font-props><span class=secno>3 </span>Basic Font Properties</h2>
   606   <p>The particular font face used to render a character is determined by the
   607    font family and other font properties that apply to a given element. This
   608    structure allows settings to be varied independent of each other.</p>
   609   <!-- prop: font-family -->
   611   <h3 id=font-family-prop><span class=secno>3.1 </span>Font family: the <a
   612    href="#propdef-font-family">font-family</a> property</h3>
   614   <table class=propdef id=namefont-familyvalue-ltfamily-namegt-ltg>
   615    <tbody>
   616     <tr>
   617      <td>Name:
   619      <td><dfn id=propdef-font-family
   620       title="font-family!!property">font-family</dfn>
   622     <tr>
   623      <td>Value:
   625      <td>[ <a href="#family-name-value"><var>&lt;family-name&gt;</var></a> |
   626       <a href="#generic-family-value"><var>&lt;generic-family&gt;</var></a> ]
   627       #
   629     <tr>
   630      <td>Initial:
   632      <td>depends on user agent
   634     <tr>
   635      <td>Applies to:
   637      <td>all elements
   639     <tr>
   640      <td>Inherited:
   642      <td>yes
   644     <tr>
   645      <td>Percentages:
   647      <td>N/A
   649     <tr>
   650      <td>Media:
   652      <td>visual
   654     <tr>
   655      <td>Computed value:
   657      <td>as specified
   659     <tr>
   660      <td>Animatable:
   662      <td>no
   663   </table>
   665   <p>This property specifies a prioritized list of font family names or
   666    generic family names. A font family defines a set of faces that vary in
   667    weight, width or slope. CSS uses the combination of a family name with
   668    other style attributes to select an individual face. Using this selection
   669    mechanism, rather than selecting a face via the style name as is often
   670    done in design applications, allows some degree of regularity in textual
   671    display when fallback occurs.
   673   <p class=note>Designers should note that the CSS definition of font
   674    attributes used for selection are explicitly not intended to define a font
   675    taxonomy. A type designer's idea of a family may often extend to a set of
   676    faces that vary along axes other than just the standard axes of weight,
   677    width and slope. A family may extend to include both a set of serif faces
   678    and a set of sans-serif faces or vary along axes that are unique to that
   679    family. The CSS font selection mechanism merely provides a way to
   680    determine the “closest” substitute when substitution is necessary.
   682   <p>Unlike other CSS properties, component values are a comma-separated list
   683    indicating alternatives. A user agent iterates through the list of family
   684    names until it matches an available font that contains a glyph for the
   685    character to be rendered. This allows for differences in available fonts
   686    across platforms and for differences in the range of characters supported
   687    by individual fonts.
   689   <p>A font family name only specifies a name given to a set of font faces,
   690    it does not specify an individual face. For example, given the
   691    availability of the fonts below, Futura would match but Futura Medium
   692    would not:
   694   <div class=figure><img alt="family and face names"
   695    src=familyvsfacename.png>
   696    <p class=caption>Family and individual face names
   697   </div>
   699   <p>Consider the example below:
   701   <div class=example>
   702    <pre>body {
   703     font-family: Helvetica, Verdana, sans-serif;
   704 }</pre>
   706    <p>If Helvetica is available it will be used when rendering. If neither
   707     Helvetica nor Verdana is present, then the user-agent-defined sans serif
   708     font will be used.</p>
   709   </div>
   711   <p>There are two types of font family names:
   713   <dl>
   714    <dt><dfn id=family-name-value><var>&lt;family-name&gt;</var></dfn>
   716    <dd>The name of a font family of choice such as Helvetica or Verdana in
   717     the previous example.
   719    <dt><dfn id=generic-family-value><var>&lt;generic-family&gt;</var></dfn>
   721    <dd> The following generic family keywords are defined: ‘<a
   722     href="#serif"><code class=property>serif</code></a>’, ‘<a
   723     href="#sans-serif"><code class=property>sans-serif</code></a>’, ‘<a
   724     href="#cursive"><code class=property>cursive</code></a>’, ‘<a
   725     href="#fantasy"><code class=property>fantasy</code></a>’, and ‘<a
   726     href="#monospace"><code class=property>monospace</code></a>’. These
   727     keywords can be used as a general fallback mechanism when an author's
   728     desired font choices are not available. As keywords, they must not be
   729     quoted. Authors are encouraged to append a generic font family as a last
   730     alternative for improved robustness.
   731   </dl>
   733   <p>Font family names other than generic families must either be given
   734    quoted as <a
   735    href="http://www.w3.org/TR/CSS21/syndata.html#strings">strings,</a> or
   736    unquoted as a sequence of one or more <a
   737    href="http://www.w3.org/TR/CSS21/syndata.html#value-def-identifier">identifiers.</a>
   738    This means most punctuation characters and digits at the start of each
   739    token must be escaped in unquoted font family names.
   741   <p>To illustrate this, the following declarations are invalid:
   743   <pre>
   744 font-family: Red/Black, sans-serif;
   745 font-family: "Lucida" Grande, sans-serif;
   746 font-family: Ahem!, sans-serif;
   747 font-family: test@foo, sans-serif;
   748 font-family: #POUND, sans-serif;
   749 font-family: Hawaii 5-0, sans-serif;
   750 </pre>
   752   <p>If a sequence of identifiers is given as a font family name, the
   753    computed value is the name converted to a string by joining all the
   754    identifiers in the sequence by single spaces.
   756   <p>To avoid mistakes in escaping, it is recommended to quote font family
   757    names that contain white space, digits, or punctuation characters other
   758    than hyphens:
   760   <pre>
   761 body { font-family: "New Century Schoolbook", serif }
   763 &lt;BODY STYLE="font-family: '21st Century', fantasy">
   764 </pre>
   766   <p>Font family <em>names</em> that happen to be the same as a keyword value
   767    (‘<code class=property>inherit</code>’, ‘<a href="#serif"><code
   768    class=property>serif</code></a>’, ‘<a href="#sans-serif"><code
   769    class=property>sans-serif</code></a>’, ‘<a href="#monospace"><code
   770    class=property>monospace</code></a>’, ‘<a href="#fantasy"><code
   771    class=property>fantasy</code></a>’, and ‘<a href="#cursive"><code
   772    class=property>cursive</code></a>’) must be quoted to prevent confusion
   773    with the keywords with the same names. The keywords ‘<code
   774    class=property>initial</code>’ and ‘<code
   775    class=property>default</code>’ are reserved for future use and must also
   776    be quoted when used as font names. UAs must not consider these keywords as
   777    matching the <a
   778    href="#family-name-value"><var>&lt;family-name&gt;</var></a> type.
   780   <p>The precise way a set of fonts are grouped into font families varies
   781    depending upon the platform font management API's. The Windows GDI API
   782    only allows four faces to be grouped into a family while the DirectWrite
   783    API and API's on OSX and other platforms support font families with a
   784    variety of weights, widths and slopes (see <a
   785    href="#platform-props-to-css">Appendix A</a> for more details).
   787   <p>Some font formats allow fonts to carry multiple localizations of the
   788    family name. User agents must recognize and correctly match all of these
   789    names independent of the underlying platform localization, system API used
   790    or document encoding:
   792   <div class=figure><img alt="examples of localized family names"
   793    src=localizedfamilynames.png>
   794    <p class=caption>Localized family names
   795   </div>
   797   <h4 id=generic-font-families><span class=secno>3.1.1 </span>Generic font
   798    families</h4>
   800   <p>All five generic font families are defined to exist in all CSS
   801    implementations (they need not necessarily map to five distinct actual
   802    fonts). User agents should provide reasonable default choices for the
   803    generic font families, which express the characteristics of each family as
   804    well as possible within the limits allowed by the underlying technology.
   805    User agents are encouraged to allow users to select alternative choices
   806    for the generic fonts.
   808   <h5 class="no-num no-toc"> <span class=index-def id=serif0 title="serif,
   809    definition of"><a name=serif-def><dfn id=serif>serif</dfn></a></span></h5>
   811   <p>Serif fonts represent the formal text style for a script. This often
   812    means but is not limited to glyphs that have finishing strokes, flared or
   813    tapering ends, or have actual serifed endings (including slab serifs).
   814    Serif fonts are typically proportionately-spaced. They often display a
   815    greater variation between thick and thin strokes than fonts from the ‘<a
   816    href="#sans-serif"><code class=property>sans-serif</code></a>’ generic
   817    font family. CSS uses the term ‘<a href="#serif"><code
   818    class=property>serif</code></a>’ to apply to a font for any script,
   819    although other names may be more familiar for particular scripts, such as
   820    Mincho (Japanese), Sung, Song or Kai (Chinese), Batang (Korean). For
   821    Arabic, the Naskh style would correspond to ‘<a href="#serif"><code
   822    class=property>serif</code></a>’ more due to its typographic role rather
   823    than its actual design style. Any font that is so described may be used to
   824    represent the generic ‘<a href="#serif"><code
   825    class=property>serif</code></a>’ family.
   827   <div class=figure><img alt="sample serif fonts" src=serifexamples.png>
   828    <p class=caption>Sample serif fonts
   829   </div>
   831   <h5 class="no-num no-toc"> <span class=index-def id=sans-serif0
   832    title="sans-serif, definition of"> <a name=sans-serif-def><dfn
   833    id=sans-serif>sans-serif</dfn></a></span></h5>
   835   <p>Glyphs in sans-serif fonts, as the term is used in CSS, are generally
   836    low contrast (vertical and horizontal stems have the close to the same
   837    thickness) and have stroke endings that are plain -- without any flaring,
   838    cross stroke, or other ornamentation. Sans-serif fonts are typically
   839    proportionately-spaced. They often have little variation between thick and
   840    thin strokes, compared to fonts from the ‘<a href="#serif"><code
   841    class=property>serif</code></a>’ family. CSS uses the term ‘<a
   842    href="#sans-serif"><code class=property>sans-serif</code></a>’ to apply
   843    to a font for any script, although other names may be more familiar for
   844    particular scripts, such as Gothic (Japanese), Hei (Chinese), or Gulim
   845    (Korean). Any font that is so described may be used to represent the
   846    generic ‘<a href="#sans-serif"><code
   847    class=property>sans-serif</code></a>’ family.
   849   <div class=figure><img alt="sample sans-serif fonts"
   850    src=sansserifexamples.png>
   851    <p class=caption>Sample sans-serif fonts
   852   </div>
   854   <h5 class="no-num no-toc"> <span class=index-def id=cursive0
   855    title="cursive, definition of"> <a name=cursive-def><dfn
   856    id=cursive>cursive</dfn></a></span></h5>
   858   <p>Glyphs in cursive fonts generally use a more informal script style, and
   859    the result looks more like handwritten pen or brush writing than printed
   860    letterwork. CSS uses the term ‘<a href="#cursive"><code
   861    class=property>cursive</code></a>’ to apply to a font for any script,
   862    although other names such as Chancery, Brush, Swing and Script are also
   863    used in font names.
   865   <div class=figure><img alt="sample cursive fonts" src=cursiveexamples.png>
   866    <p class=caption>Sample cursive fonts
   867   </div>
   869   <h5 class="no-num no-toc"> <span class=index-def id=fantasy0
   870    title="fantasy, definition of"> <a name=fantasy-def><dfn
   871    id=fantasy>fantasy</dfn></a></span></h5>
   873   <p>Fantasy fonts are primarily decorative or expressive fonts that contain
   874    playful representations of characters. These do not include Pi or Picture
   875    fonts which do not represent actual characters.
   877   <div class=figure><img alt="sample fantasy fonts" src=fantasyexamples.png>
   878    <p class=caption>Sample fantasy fonts
   879   </div>
   881   <h5 class="no-num no-toc"> <span class=index-def id=monospace0
   882    title="monospace, definition of"> <a name=monospace-def><dfn
   883    id=monospace>monospace</dfn></a></span></h5>
   885   <p>The sole criterion of a monospace font is that all glyphs have the same
   886    fixed width. This is often used to render samples of computer code.
   888   <div class=figure><img alt="sample monospace fonts"
   889    src=monospaceexamples.png>
   890    <p class=caption>Sample monospace fonts
   891   </div>
   892   <!-- prop: font-weight -->
   894   <h3 id=font-weight-prop><span class=secno>3.2 </span>Font weight: the <a
   895    href="#propdef-font-weight">font-weight</a> property</h3>
   897   <table class=propdef id=namefont-weightvaluenormal-bold-bolder-l>
   898    <tbody>
   899     <tr>
   900      <td>Name:
   902      <td><dfn id=propdef-font-weight
   903       title="font-weight!!property">font-weight</dfn>
   905     <tr>
   906      <td>Value:
   908      <td><a href="#font-weight-normal-value"
   909       title="normal!!font-weight">normal</a> | <a href="#bold">bold</a> | <a
   910       href="#bolder">bolder</a> | <a href="#lighter">lighter</a> | <a
   911       href="#font-weight-numeric-values" title="100...900 weight
   912       values">100</a> | <a href="#font-weight-numeric-values"
   913       title="100...900 weight values">200</a> | <a
   914       href="#font-weight-numeric-values" title="100...900 weight
   915       values">300</a> | <a href="#font-weight-numeric-values"
   916       title="100...900 weight values">400</a> | <a
   917       href="#font-weight-numeric-values" title="100...900 weight
   918       values">500</a> | <a href="#font-weight-numeric-values"
   919       title="100...900 weight values">600</a> | <a
   920       href="#font-weight-numeric-values" title="100...900 weight
   921       values">700</a> | <a href="#font-weight-numeric-values"
   922       title="100...900 weight values">800</a> | <a
   923       href="#font-weight-numeric-values" title="100...900 weight
   924       values">900</a>
   926     <tr>
   927      <td>Initial:
   929      <td>normal
   931     <tr>
   932      <td>Applies to:
   934      <td>all elements
   936     <tr>
   937      <td>Inherited:
   939      <td>yes
   941     <tr>
   942      <td>Percentages:
   944      <td>N/A
   946     <tr>
   947      <td>Media:
   949      <td>visual
   951     <tr>
   952      <td>Computed value:
   954      <td>numeric weight value (see description)
   956     <tr>
   957      <td>Animatable:
   959      <td>as <a
   960       href="http://dev.w3.org/csswg/css3-transitions/#animtype-font-weight">font
   961       weight</a>
   962   </table>
   964   <p>The <a href="#propdef-font-weight"
   965    title="font-weight!!property">‘<code
   966    class=property>font-weight</code>’</a> property specifies the weight of
   967    glyphs in the font, their degree of blackness or stroke thickness.
   969   <p>Values have the following meanings:
   971   <dl>
   972    <dt><dfn id=font-weight-numeric-values title="100...900 weight values">100
   973     to 900</dfn>
   975    <dd>These values form an ordered sequence, where each number indicates a
   976     weight that is at least as dark as its predecessor. These roughly
   977     correspond to the commonly used weight names below:
   978   </dl>
   980   <ul>
   981    <li>100 - Thin
   983    <li>200 - Extra Light (Ultra Light)
   985    <li>300 - Light
   987    <li>400 - Normal
   989    <li>500 - Medium
   991    <li>600 - Semi Bold (Demi Bold)
   993    <li>700 - Bold
   995    <li>800 - Extra Bold (Ultra Bold)
   997    <li>900 - Black (Heavy)
   998   </ul>
  1000   <dl>
  1001    <dt><dfn id=font-weight-normal-value
  1002     title="normal!!font-weight">normal</dfn>
  1004    <dd>Same as ‘<code class=css>400</code>’.
  1006    <dt><dfn id=bold>bold</dfn>
  1008    <dd>Same as ‘<code class=css>700</code>’.
  1010    <dt><dfn id=bolder>bolder</dfn>
  1012    <dd>Specifies a bolder weight than the inherited value.
  1014    <dt><dfn id=lighter>lighter</dfn>
  1016    <dd>Specifies a lighter weight than the inherited value.
  1017   </dl>
  1019   <p>Font formats that use a scale other than a nine-step scale should map
  1020    their scale onto the CSS scale so that 400 roughly corresponds with a face
  1021    that would be labeled as Regular, Book, Roman and 700 roughly matches a
  1022    face that would be labeled as Bold. Or weights may be inferred from the
  1023    style names, ones that correspond roughly with the scale above. The scale
  1024    is relative, so a face with a larger weight value must never appear
  1025    lighter. If style names are used to infer weights, care should be taken to
  1026    handle variations in style names across locales.
  1028   <p>Quite often there are only a few weights available for a particular font
  1029    family. When a weight is specified for which no face exists, a face with a
  1030    nearby weight is used. In general, bold weights map to faces with heavier
  1031    weights and light weights map to faces with lighter weights (see the <a
  1032    href="#font-matching-algorithm">font matching section below</a> for a
  1033    precise definition). The examples here illustrate which face is used for
  1034    different weights, grey indicates a face for that weight does not exist so
  1035    a face with a nearby weight is used:
  1037   <div class=figure><img alt="weight mappings for a family with 400, 700 and
  1038    900 weights" src=optimaweights.png>
  1039    <p class=caption>Weight mappings for a font family with 400, 700 and 900
  1040     weight faces
  1041   </div>
  1043   <div class=figure><img alt="weight mappings for a family with 300, 600
  1044    weights" src=hiraginoweights.png>
  1045    <p class=caption>Weight mappings for a font family with 300 and 600 weight
  1046     faces
  1047   </div>
  1049   <p>Although the practice is not well-loved by typographers, bold faces are
  1050    often synthesized by user agents for faces that lack actual bold faces.
  1051    For the purposes of style matching, these faces must be treated as if they
  1052    exist within the family. Authors can explicitly avoid this behavior by
  1053    using the ‘<a href="#propdef-font-synthesis"><code
  1054    class=property>font-synthesis</code></a>’ property.
  1056   <p>Specified values of ‘<a href="#bolder"><code
  1057    class=property>bolder</code></a>’ and ‘<a href="#lighter"><code
  1058    class=property>lighter</code></a>’ indicate weights relative to the
  1059    weight of the parent element. The computed weight is calculated based on
  1060    the inherited <a href="#propdef-font-weight"
  1061    title="font-weight!!property">‘<code
  1062    class=property>font-weight</code>’</a> value using the chart below.
  1064   <table class=data id=bolderlighter summary="Bolder/lighter mappings">
  1065    <thead>
  1066     <tr>
  1067      <th>Inherited value
  1069      <th>bolder
  1071      <th>lighter
  1073    <tbody>
  1074     <tr>
  1075      <th>100
  1077      <td>400
  1079      <td>100
  1081     <tr>
  1082      <th>200
  1084      <td>400
  1086      <td>100
  1088     <tr>
  1089      <th>300
  1091      <td>400
  1093      <td>100
  1095     <tr>
  1096      <th>400
  1098      <td>700
  1100      <td>100
  1102     <tr>
  1103      <th>500
  1105      <td>700
  1107      <td>100
  1109     <tr>
  1110      <th>600
  1112      <td>900
  1114      <td>400
  1116     <tr>
  1117      <th>700
  1119      <td>900
  1121      <td>400
  1123     <tr>
  1124      <th>800
  1126      <td>900
  1128      <td>700
  1130     <tr>
  1131      <th>900
  1133      <td>900
  1135      <td>700
  1136   </table>
  1138   <p>The table above is equivalent to selecting the next relative bolder or
  1139    lighter face, given a font family containing normal and bold faces along
  1140    with a thin and a heavy face. Authors who desire finer control over the
  1141    exact weight values used for a given element may use numerical values
  1142    instead of relative weights.</p>
  1143   <!-- prop: font-stretch -->
  1145   <h3 id=font-stretch-prop><span class=secno>3.3 </span>Font width: the <a
  1146    href="#propdef-font-stretch">font-stretch</a> property</h3>
  1148   <table class=propdef id=namefont-stretchvalue-normal-ultra-conde>
  1149    <tbody>
  1150     <tr>
  1151      <td>Name:
  1153      <td><dfn id=propdef-font-stretch
  1154       title="font-stretch!!property">font-stretch</dfn>
  1156     <tr>
  1157      <td>Value:
  1159      <td> <a href="#font-stretch-normal-value"
  1160       title="normal!!font-stretch">normal</a> | <a
  1161       href="#ultra-condensed">ultra-condensed</a> | <a
  1162       href="#extra-condensed">extra-condensed</a> | <a
  1163       href="#condensed">condensed</a> | <a
  1164       href="#semi-condensed-">semi-condensed</a> | <a
  1165       href="#semi-expanded">semi-expanded</a> | <a
  1166       href="#expanded">expanded</a> | <a
  1167       href="#extra-expanded">extra-expanded</a> | <a
  1168       href="#ultra-expanded">ultra-expanded</a>
  1170     <tr>
  1171      <td>Initial:
  1173      <td>normal
  1175     <tr>
  1176      <td>Applies to:
  1178      <td>all elements
  1180     <tr>
  1181      <td>Inherited:
  1183      <td>yes
  1185     <tr>
  1186      <td>Percentages:
  1188      <td>N/A
  1190     <tr>
  1191      <td>Media:
  1193      <td>visual
  1195     <tr>
  1196      <td>Computed value:
  1198      <td>as specified
  1200     <tr>
  1201      <td>Animatable:
  1203      <td>as <a href="#font-stretch-animation">font stretch</a>
  1204   </table>
  1206   <p>The <a href="#propdef-font-stretch"
  1207    title="font-stretch!!property">‘<code
  1208    class=property>font-stretch</code>’</a> property selects a normal,
  1209    condensed, or expanded face from a font family. Absolute keyword values
  1210    have the following ordering, from narrowest to widest:
  1212   <ul>
  1213    <li><dfn id=ultra-condensed>ultra-condensed</dfn>
  1215    <li><dfn id=extra-condensed>extra-condensed</dfn>
  1217    <li><dfn id=condensed>condensed</dfn>
  1219    <li><dfn id=semi-condensed->semi-condensed </dfn>
  1221    <li><dfn id=font-stretch-normal-value
  1222     title="normal!!font-stretch">normal</dfn>
  1224    <li><dfn id=semi-expanded>semi-expanded</dfn>
  1226    <li><dfn id=expanded>expanded</dfn>
  1228    <li><dfn id=extra-expanded>extra-expanded</dfn>
  1230    <li><dfn id=ultra-expanded>ultra-expanded</dfn>
  1231   </ul>
  1233   <p>When a face does not exist for a given width, normal or condensed values
  1234    map to a narrower face, otherwise a wider face. Conversely, expanded
  1235    values map to a wider face, otherwise a narrower face. The figure below
  1236    shows how the nine font-stretch property settings affect font selection
  1237    for font family containing a variety of widths, grey indicates a width for
  1238    which no face exists and a different width is substituted:
  1240   <div class=figure><img alt="width mappings for a family with condensed,
  1241    normal and expanded faces" src=universwidths.png>
  1242    <p class=caption>Width mappings for a font family with condensed, normal
  1243     and expanded width faces
  1244   </div>
  1246   <p id=font-stretch-animation>Animation of font stretch: Font stretch is
  1247    interpolated in discrete steps. The interpolation happens as though the
  1248    ordered values are equally spaced real numbers. The interpolation result
  1249    is rounded to the nearest value, with values exactly halfway between two
  1250    values rounded towards the later value in the list above.</p>
  1251   <!-- prop: font-style -->
  1253   <h3 id=font-style-prop><span class=secno>3.4 </span>Font style: the <a
  1254    href="#propdef-font-style">font-style</a> property</h3>
  1256   <table class=propdef id=namefont-stylevaluenormal-italic-oblique>
  1257    <tbody>
  1258     <tr>
  1259      <td>Name:
  1261      <td><dfn id=propdef-font-style
  1262       title="font-style!!property">font-style</dfn>
  1264     <tr>
  1265      <td>Value:
  1267      <td><a href="#font-style-normal-value"
  1268       title="normal!!font-style">normal</a> | <a href="#italic">italic</a> |
  1269       <a href="#oblique">oblique</a>
  1271     <tr>
  1272      <td>Initial:
  1274      <td>normal
  1276     <tr>
  1277      <td>Applies to:
  1279      <td>all elements
  1281     <tr>
  1282      <td>Inherited:
  1284      <td>yes
  1286     <tr>
  1287      <td>Percentages:
  1289      <td>N/A
  1291     <tr>
  1292      <td>Media:
  1294      <td>visual
  1296     <tr>
  1297      <td>Computed value:
  1299      <td>as specified
  1301     <tr>
  1302      <td>Animatable:
  1304      <td>no
  1305   </table>
  1307   <p>The <a href="#propdef-font-style" title="font-style!!property">‘<code
  1308    class=property>font-style</code>’</a> property allows italic or oblique
  1309    faces to be selected. Italic forms are generally cursive in nature while
  1310    oblique faces are typically sloped versions of the regular face. Oblique
  1311    faces can be simulated by artificially sloping the glyphs of the regular
  1312    face. Compare the artificially sloped renderings of Palatino ‘<code
  1313    class=property>a</code>’ and Baskerville ‘<code
  1314    class=property>N</code>’ in grey with the actual italic versions:
  1316   <div class=figure><img alt="artificial sloping vs. real italics"
  1317    src=realvsfakeitalics.png>
  1318    <p class=caption>Artificial sloping versus real italics
  1319   </div>
  1321   <p>Values have the following meanings:
  1323   <dl>
  1324    <dt><dfn id=font-style-normal-value
  1325     title="normal!!font-style">normal</dfn>
  1327    <dd>selects a face that is classified as a normal face, one that is
  1328     neither italic or obliqued
  1330    <dt><dfn id=italic>italic</dfn>
  1332    <dd>selects a font that is labeled as an italic face, or an oblique face
  1333     if one is not
  1335    <dt><dfn id=oblique>oblique</dfn>
  1337    <dd>selects a font that is labeled as an oblique face, or an italic face
  1338     if one is not
  1339   </dl>
  1341   <p>If no italic or oblique face is available, oblique faces can be
  1342    synthesized by rendering non-obliqued faces with an artificial obliquing
  1343    operation. The use of these artificially obliqued faces can be disabled
  1344    using the ‘<a href="#propdef-font-synthesis"><code
  1345    class=property>font-synthesis</code></a>’ property. The details of the
  1346    obliquing operation are not explicitly defined.</p>
  1347   <!-- resolution on the "undefined" nature of synthetics: http://www.w3.org/2013/06/06-css-minutes.html#item03 -->
  1349   <p>Many scripts lack the tradition of mixing a cursive form within text
  1350    rendered with a normal face. Chinese, Japanese and Korean fonts almost
  1351    always lack italic or oblique faces. Fonts that support a mixture of
  1352    scripts will sometimes omit specific scripts such as Arabic from the set
  1353    of glyphs supported in the italic face. User agents should be careful
  1354    about making <a href="#character-map"><em>character map</em></a>
  1355    assumptions across faces when implementing support for <a
  1356    href="#system-font-fallback"><em>system font fallback</em></a>.</p>
  1357   <!-- prop: font-size -->
  1359   <h3 id=font-size-prop><span class=secno>3.5 </span>Font size: the <a
  1360    href="#propdef-font-size">font-size</a> property</h3>
  1362   <table class=propdef id=namefont-sizevalueltabsolute-sizegt-ltre>
  1363    <tbody>
  1364     <tr>
  1365      <td>Name:
  1367      <td><dfn id=propdef-font-size>font-size</dfn>
  1369     <tr>
  1370      <td>Value:
  1372      <td><a href="#absolute-size-value"><var>&lt;absolute-size&gt;</var></a>
  1373       | <a href="#relative-size-value"><var>&lt;relative-size&gt;</var></a> |
  1374       <a href="#length-size-value"><var>&lt;length&gt;</var></a> | <a
  1375       href="#percentage-size-value"><var>&lt;percentage&gt;</var></a>
  1377     <tr>
  1378      <td>Initial:
  1380      <td>medium
  1382     <tr>
  1383      <td>Applies to:
  1385      <td>all elements
  1387     <tr>
  1388      <td>Inherited:
  1390      <td>yes
  1392     <tr>
  1393      <td>Percentages:
  1395      <td>refer to parent element's font size
  1397     <tr>
  1398      <td>Media:
  1400      <td>visual
  1402     <tr>
  1403      <td>Computed value:
  1405      <td>absolute length
  1407     <tr>
  1408      <td>Animatable:
  1410      <td>as <a
  1411       href="http://dev.w3.org/csswg/css3-transitions/#animtype-length">length</a>
  1412   </table>
  1414   <p>This property indicates the desired height of glyphs from the font. For
  1415    scalable fonts, the font-size is a scale factor applied to the EM unit of
  1416    the font. (Note that certain glyphs may bleed outside their EM box.) For
  1417    non-scalable fonts, the font-size is converted into absolute units and
  1418    matched against the declared font-size of the font, using the same
  1419    absolute coordinate space for both of the matched values. Values have the
  1420    following meanings:
  1422   <dl>
  1423    <dt><dfn id=absolute-size-value><var>&lt;absolute-size&gt;</var></dfn>
  1425    <dd> An <a
  1426     href="#absolute-size-value"><var>&lt;absolute-size&gt;</var></a> keyword
  1427     refers to an entry in a table of font sizes computed and kept by the user
  1428     agent. Possible values are:
  1429     <p> [ xx-small | x-small | small | medium | large | x-large | xx-large ]</p>
  1431    <dt><dfn id=relative-size-value><var>&lt;relative-size&gt;</var></dfn>
  1433    <dd> A <a href="#relative-size-value"><var>&lt;relative-size&gt;</var></a>
  1434     keyword is interpreted relative to the table of font sizes and the
  1435     computed ‘<a href="#propdef-font-size"><code
  1436     class=property>font-size</code></a>’ of the parent element. Possible
  1437     values are:
  1438     <p> [ larger | smaller ]
  1440     <p> For example, if the parent element has a font size of ‘<code
  1441      class=property>medium</code>’, a value of ‘<code
  1442      class=property>larger</code>’ will make the font size of the current
  1443      element be ‘<code class=property>large</code>’. If the parent
  1444      element's size is not close to a table entry, the user agent is free to
  1445      interpolate between table entries or round off to the closest one. The
  1446      user agent may have to extrapolate table values if the numerical value
  1447      goes beyond the keywords.
  1449    <dt><dfn id=length-size-value><var>&lt;length&gt;</var></dfn>
  1451    <dd>A length value specifies an absolute font size (independent of the
  1452     user agent's font table). Negative lengths are illegal.
  1454    <dt><dfn id=percentage-size-value><var>&lt;percentage&gt;</var></dfn>
  1456    <dd>A percentage value specifies an absolute font size relative to the
  1457     parent element's font size. Use of percentage values, or values in
  1458     ‘<code class=property>em</code>’s, leads to more robust and
  1459     cascadable style sheets.
  1460   </dl>
  1462   <p>The following table provides user agent guidelines for the absolute-size
  1463    scaling factor and their mapping to HTML heading and absolute font-sizes.
  1464    The ‘<code class=property>medium</code>’ value is used as the
  1465    reference middle value. The user agent may fine-tune these values for
  1466    different fonts or different types of display devices.
  1468   <table class=data>
  1469    <thead>
  1470     <tr>
  1471      <th>CSS absolute-size values
  1473      <th>xx-small
  1475      <th>x-small
  1477      <th>small
  1479      <th>medium
  1481      <th>large
  1483      <th>x-large
  1485      <th>xx-large
  1487      <th> 
  1489    <tbody>
  1490     <tr>
  1491      <th>scaling factor
  1493      <td>3/5
  1495      <td>3/4
  1497      <td>8/9
  1499      <td>1
  1501      <td>6/5
  1503      <td>3/2
  1505      <td>2/1
  1507      <td>3/1
  1509     <tr>
  1510      <th>HTML headings
  1512      <td>h6
  1514      <td> 
  1516      <td>h5
  1518      <td>h4
  1520      <td>h3
  1522      <td>h2
  1524      <td>h1
  1526      <td> 
  1528     <tr>
  1529      <th>HTML font sizes
  1531      <td>1
  1533      <td> 
  1535      <td>2
  1537      <td>3
  1539      <td>4
  1541      <td>5
  1543      <td>6
  1545      <td>7
  1546   </table>
  1548   <p class=note><em><strong>Note 1.</strong> To preserve readability, an UA
  1549    applying these guidelines should nevertheless avoid creating font-size
  1550    resulting in less than 9 device pixels per EM unit on a computer
  1551    display.</em>
  1553   <p class=note><em><strong>Note 2.</strong> In CSS1, the suggested scaling
  1554    factor between adjacent indexes was 1.5 which user experience proved to be
  1555    too large. In CSS2, the suggested scaling factor for computer screen
  1556    between adjacent indexes was 1.2 which still created issues for the small
  1557    sizes. The new scaling factor varies between each index to provide a
  1558    better readability.</em>
  1560   <p>The actual value of this property may differ from the computed value due
  1561    a numerical value on ‘<a href="#propdef-font-size-adjust"><code
  1562    class=property>font-size-adjust</code></a>’ and the unavailability of
  1563    certain font sizes.
  1565   <p>Child elements inherit the computed <a class=noxref
  1566    href="#font-size-prop"> <span class=property>‘<code
  1567    class=property>font-size</code>’</span></a> value (otherwise, the effect
  1568    of <a class=noxref href="#font-size-adjust-prop"><span
  1569    class=property>‘<code
  1570    class=property>font-size-adjust</code>’</span></a> would compound).
  1572   <div class=example>
  1573    <p style="display:none">Example(s):</p>
  1575    <pre>p { font-size: 12pt; }
  1576 blockquote { font-size: larger }
  1577 em { font-size: 150% }
  1578 em { font-size: 1.5em }
  1579 </pre>
  1580   </div>
  1581   <!-- prop: font-size-adjust -->
  1583   <h3 id=font-size-adjust-prop><span class=secno>3.6 </span>Relative sizing:
  1584    the <a href="#propdef-font-size-adjust">font-size-adjust</a> property</h3>
  1586   <table class=propdef id=namefont-size-adjustvaluenone-auto-ltnum>
  1587    <tbody>
  1588     <tr>
  1589      <td>Name:
  1591      <td><dfn id=propdef-font-size-adjust>font-size-adjust</dfn>
  1593     <tr>
  1594      <td>Value:
  1596      <td><a href="#font-size-adjust-none-value"
  1597       title="none!!font-size-adjust">none</a> | <a
  1598       href="#font-size-adjust-auto-value"
  1599       title="auto!!font-size-adjust">auto</a> | <a
  1600       href="#aspect-ratio-value"><var>&lt;number&gt;</var></a>
  1602     <tr>
  1603      <td>Initial:
  1605      <td>none
  1607     <tr>
  1608      <td>Applies to:
  1610      <td>all elements
  1612     <tr>
  1613      <td>Inherited:
  1615      <td>yes
  1617     <tr>
  1618      <td>Percentages:
  1620      <td>N/A
  1622     <tr>
  1623      <td>Media:
  1625      <td>visual
  1627     <tr>
  1628      <td>Computed value:
  1630      <td>as specified
  1632     <tr>
  1633      <td>Animatable:
  1635      <td>as <a
  1636       href="http://dev.w3.org/csswg/css3-transitions/#animtype-number">number</a>
  1637   </table>
  1639   <p>For any given font size, the apparent size and legibility of text varies
  1640    across fonts. For scripts such as Latin or Cyrillic that distinguish
  1641    between upper and lowercase letters, the relative height of lowercase
  1642    letters compared to their uppercase counterparts is a determining factor
  1643    of legibility. This is commonly referred to as the <a class=index-def
  1644    href="#aspect-value" id=aspect-value0 title="aspect value"><dfn
  1645    id=aspect-value>aspect value</dfn></a>. Precisely defined, it is equal to
  1646    the x-height of a font divided by the font size.
  1648   <p>In situations where font fallback occurs, fallback fonts may not share
  1649    the same aspect ratio as the desired font family and will thus appear less
  1650    readable. The font-size-adjust property is a way to preserve the
  1651    readability of text when font fallback occurs. It does this by adjusting
  1652    the font-size so that the x-height is the same regardless of the font
  1653    used.
  1655   <div class=example>
  1656    <p>The style defined below defines Verdana as the desired font family, but
  1657     if Verdana is not available Futura or Times will be used.</p>
  1659    <pre>p {
  1660     font-family: Verdana, Futura, Times;
  1663 &lt;p>Lorem ipsum dolor sit amet, ...&lt;/p>
  1664 </pre>
  1666    <p>Verdana has a relatively high aspect ratio, lowercase letters are
  1667     relatively tall compared to uppercase letters, so at small sizes text
  1668     appears legible. Times has a lower aspect ratio and so if fallback
  1669     occurs, the text will be less legible at small sizes than Verdana.</p>
  1670   </div>
  1672   <p>How text rendered in each of these fonts compares is shown below, the
  1673    columns show text rendered in Verdana, Futura and Times. The same
  1674    font-size value is used across cells within each row and red lines are
  1675    included to show the differences in x-height. In the upper half each row
  1676    is rendered in the same font-size value. The same is true for the lower
  1677    half but in this half the font-size-adjust property is also set so that
  1678    the actual font size is adjusted to preserve the x-height across each row.
  1679    Note how small text remains relatively legible across each row in the
  1680    lower half.
  1682   <div class=figure><img alt="text with and without font-size-adjust"
  1683    src=fontsizeadjust.png>
  1684    <p class=caption>Text with and without the use of font-size-adjust
  1685   </div>
  1687   <p>This property allows authors to specify an <a
  1688    href="#aspect-value"><i>aspect value</i></a> for an element that will
  1689    effectively preserve the x-height of the first choice font, whether it is
  1690    substituted or not. Values have the following meanings:
  1692   <dl>
  1693    <dt><dfn id=font-size-adjust-none-value
  1694     title="none!!font-size-adjust">none</dfn>
  1696    <dd>Do not preserve the font's x-height.
  1698    <dt><dfn id=font-size-adjust-auto-value
  1699     title="auto!!font-size-adjust">auto</dfn>
  1701    <dd>Behaves just like &lt;number>, except the number used is the <a
  1702     href="#aspect-value"><i>aspect value</i></a> calculated by user agents
  1703     for the first font in the list of fonts defined for the initial value of
  1704     the <a href="#propdef-font-family" title="font-family!!property">‘<code
  1705     class=property>font-family</code>’</a> property. Effectively this is
  1706     the default font used when <a href="#propdef-font-family"
  1707     title="font-family!!property">‘<code
  1708     class=property>font-family</code>’</a> is not otherwise specified.
  1709     <p>Authors can use this value to specify that font size should be
  1710      normalized across fonts based on the x-height without the need to
  1711      specify the aspect ratio explicitly.</p>
  1713    <dt><dfn id=aspect-ratio-value><var>&lt;number&gt;</var></dfn>
  1715    <dd>Specifies the <a href="#aspect-value"><i>aspect value</i></a> used in
  1716     the calculation below to calculate the adjusted font size:
  1717     <pre>c  =  ( a / a' ) s
  1718 </pre>
  1720     <p>where:</p>
  1722     <pre>s  =  font-size value
  1723 a  =  <a href="#aspect-value"><i>aspect value</i></a> as specified by the font-size-adjust property
  1724 a' =  <a href="#aspect-value"><i>aspect value</i></a> of actual font
  1725 c  =  adjusted font-size to use
  1726 </pre>
  1728     <p>This value applies to any font that is selected but in typical usage
  1729      it should be based on the <a href="#aspect-value"><i>aspect
  1730      value</i></a> of the first font in the font-family list. If this is
  1731      specified accurately, the <tt>(a/a')</tt> term in the formula above is
  1732      effectively 1 for the first font and no adjustment occurs. If the value
  1733      is specified inaccurately, text rendered using the first font in the
  1734      family list will display differently in older user agents that don't
  1735      support font-size-adjust.</p>
  1736   </dl>
  1738   <p>The value of ‘<a href="#propdef-font-size-adjust"><code
  1739    class=property>font-size-adjust</code></a>’ affects the size of relative
  1740    units that are based on font metrics of the <a
  1741    href="#first-available-font"><i>first available font</i></a> such as
  1742    <code>ex</code> and <code>ch</code> but does not affect the size of
  1743    <code>em</code> units.
  1745   <p>Authors can calculate the <a href="#aspect-value"><i>aspect
  1746    value</i></a> for a given font by comparing spans with the same content
  1747    but different font-size-adjust properties. If the same font-size is used,
  1748    the spans will match when the font-size-adjust value is accurate for the
  1749    given font.
  1751   <div class=example>
  1752    <p>Two spans with borders are used to determine the <a
  1753     href="#aspect-value"><i>aspect value</i></a> of a font. The font-size is
  1754     the same for both spans but the font-size-adjust property is specified
  1755     only for the right span. Starting with a value of 0.5, the aspect value
  1756     can be adjusted until the borders around the two letters line up.</p>
  1758    <pre>p {
  1759     font-family: Futura;
  1760     font-size: 500px;
  1763 span {
  1764     border: solid 1px red;
  1767 .adjust {
  1768     font-size-adjust: 0.5;
  1771 &lt;p>&lt;span>b&lt;/span>&lt;span class="adjust">b&lt;/span>&lt;/p>
  1772 </pre>
  1774    <div class=figure><img alt="Futura with an <i>aspect value</i> of 0.5"
  1775     src=beforefontsizeadjust.png>
  1776     <p class=caption>Futura with an <a href="#aspect-value"><i>aspect
  1777      value</i></a> of 0.5
  1778    </div>
  1780    <p>The box on the right is a bit bigger than the one on the left, so the
  1781     <a href="#aspect-value"><i>aspect value</i></a> of this font is something
  1782     less than 0.5. Adjust the value until the boxes align.</p>
  1783   </div>
  1784   <!-- prop: font -->
  1786   <h3 id=font-prop><span class=secno>3.7 </span>Shorthand font property: the
  1787    <a href="#propdef-font">font</a> property</h3>
  1789   <table class=propdef id=namefontvalue-ltlsquofont-stylersquogt-l>
  1790    <tbody>
  1791     <tr>
  1792      <td>Name:
  1794      <td><dfn id=propdef-font>font</dfn>
  1796     <tr>
  1797      <td>Value:
  1799      <td>[ [ <var>&lt;<a href="#propdef-font-style"
  1800       title="font-style!!property">‘<code
  1801       class=property>font-style</code>’</a>&gt;</var> || <a
  1802       href="#font-variant-css21-values"><var>&lt;font-variant-css21&gt;</var></a>
  1803       || <var>&lt;<a href="#propdef-font-weight"
  1804       title="font-weight!!property">‘<code
  1805       class=property>font-weight</code>’</a>&gt;</var> || <var>&lt;<a
  1806       href="#propdef-font-stretch" title="font-stretch!!property">‘<code
  1807       class=property>font-stretch</code>’</a></var> ]? <var>&lt;‘<a
  1808       href="#propdef-font-size"><code
  1809       class=property>font-size</code></a>’&gt;</var> [ / <var>&lt;‘<code
  1810       class=property>line-height</code>’&gt;</var> ]? <var>&lt;<a
  1811       href="#propdef-font-family" title="font-family!!property">‘<code
  1812       class=property>font-family</code>’</a>&gt;</var> ] | caption | icon |
  1813       menu | message-box | small-caption | status-bar
  1815     <tr>
  1816      <td>Initial:
  1818      <td>see individual properties
  1820     <tr>
  1821      <td>Applies to:
  1823      <td>all elements
  1825     <tr>
  1826      <td>Inherited:
  1828      <td>yes
  1830     <tr>
  1831      <td>Percentages:
  1833      <td>see individual properties
  1835     <tr>
  1836      <td>Media:
  1838      <td>visual
  1840     <tr>
  1841      <td>Computed value:
  1843      <td>see individual properties
  1845     <tr>
  1846      <td>Animatable:
  1848      <td>see individual properties
  1849   </table>
  1851   <p>The <span class=property>‘<a href="#propdef-font"><code
  1852    class=property>font</code></a>’</span> property is, except as described
  1853    below, a shorthand property for setting <a href="#propdef-font-style"
  1854    title="font-style!!property">‘<code
  1855    class=property>font-style</code>’</a>, <a href="#propdef-font-variant"
  1856    title="font-variant!!property">‘<code
  1857    class=property>font-variant</code>’</a>, <a href="#propdef-font-weight"
  1858    title="font-weight!!property">‘<code
  1859    class=property>font-weight</code>’</a>, <a href="#propdef-font-stretch"
  1860    title="font-stretch!!property">‘<code
  1861    class=property>font-stretch</code>’</a>, <span class=property>‘<a
  1862    href="#propdef-font-size"><code
  1863    class=property>font-size</code></a>’</span>, <a class=property
  1864    href="http://www.w3.org/TR/CSS2/visudet.html#propdef-line-height">‘<code
  1865    class=property>line-height</code>’</a>, <a href="#propdef-font-family"
  1866    title="font-family!!property">‘<code
  1867    class=property>font-family</code>’</a> at the same place in the
  1868    stylesheet. Values for the <a href="#propdef-font-variant"
  1869    title="font-variant!!property">‘<code
  1870    class=property>font-variant</code>’</a> property may also be included
  1871    but only those supported in CSS 2.1, none of the <a
  1872    href="#propdef-font-variant" title="font-variant!!property">‘<code
  1873    class=property>font-variant</code>’</a> values added in this
  1874    specification can be used in the <span class=property>‘<a
  1875    href="#propdef-font"><code class=property>font</code></a>’</span>
  1876    shorthand:
  1878   <pre
  1879    class=prod><dfn id=font-variant-css21-values><var>&lt;font-variant-css21&gt;</var></dfn> = [normal | small-caps]</pre>
  1881   <p>The syntax of this property is based on a traditional typographical
  1882    shorthand notation to set multiple properties related to fonts.
  1884   <p>All subproperties of the ‘<a href="#propdef-font"><code
  1885    class=property>font</code></a>’ property are first reset to their
  1886    initial values, including those listed above plus <span
  1887    class=property>‘<a href="#propdef-font-size-adjust"><code
  1888    class=property>font-size-adjust</code></a>’</span>, <span
  1889    class=property>‘<a href="#propdef-font-kerning"><code
  1890    class=property>font-kerning</code></a>’</span>, subproperties of <a
  1891    href="#propdef-font-variant" title="font-variant!!property">‘<code
  1892    class=property>font-variant</code>’</a> and and <span>‘<a
  1893    href="#propdef-font-language-override"><code
  1894    class=property>font-language-override</code></a>’</span>. Then, those
  1895    properties that are given explicit values in the <span
  1896    class=property>‘<a href="#propdef-font"><code
  1897    class=property>font</code></a>’</span> shorthand are set to those
  1898    values. For a definition of allowed and initial values, see the previously
  1899    defined properties. For reasons of backwards compatibility, it is not
  1900    possible to set <span class=property>‘<a
  1901    href="#propdef-font-size-adjust"><code
  1902    class=property>font-size-adjust</code></a>’</span> to anything other
  1903    than its initial value using the <span class=property>‘<a
  1904    href="#propdef-font"><code class=property>font</code></a>’</span>
  1905    shorthand property; instead, use the individual property.
  1907   <div class=example>
  1908    <p style="display:none">Example(s):</p>
  1910    <pre>p { font: 12pt/14pt sans-serif }
  1911 p { font: 80% sans-serif }
  1912 p { font: x-large/110% &quot;new century schoolbook&quot;, serif }
  1913 p { font: bold italic large Palatino, serif }
  1914 p { font: normal small-caps 120%/120% fantasy }
  1915 p { font: condensed oblique 12pt &quot;Helvetica Neue&quot;, serif; }
  1916 </pre>
  1918    <p> In the second rule, the font size percentage value (‘<code
  1919     class=css>80%</code>’) refers to the computed ‘<a
  1920     href="#propdef-font-size"><code class=property>font-size</code></a>’ of
  1921     the parent element. In the third rule, the line height percentage
  1922     (‘<code class=css>110%</code>’) refers to the font size of the
  1923     element itself.
  1925    <p>The first three rules do not specify the <a
  1926     href="#propdef-font-variant" title="font-variant!!property">‘<code
  1927     class=property>font-variant</code>’</a> and <a
  1928     href="#propdef-font-weight" title="font-weight!!property">‘<code
  1929     class=property>font-weight</code>’</a> explicitly, so these properties
  1930     receive their initial values (<span title="normal value">‘<code
  1931     class=property>normal</code>’</span>). Notice that the font family name
  1932     "new century schoolbook", which contains spaces, is enclosed in quotes.
  1933     The fourth rule sets the <a href="#propdef-font-weight"
  1934     title="font-weight!!property">‘<code
  1935     class=property>font-weight</code>’</a> to ‘<a href="#bold"><code
  1936     class=property>bold</code></a>’, the <a href="#propdef-font-style"
  1937     title="font-style!!property">‘<code
  1938     class=property>font-style</code>’</a> to ‘<a href="#italic"><code
  1939     class=property>italic</code></a>’, and implicitly sets <a
  1940     href="#propdef-font-variant" title="font-variant!!property">‘<code
  1941     class=property>font-variant</code>’</a> to <a
  1942     href="#font-variant-normal-value" title="normal!!font-variant">‘<code
  1943     class=property>normal</code>’</a>.
  1945    <p> The fifth rule sets the <a href="#propdef-font-variant"
  1946     title="font-variant!!property">‘<code
  1947     class=property>font-variant</code>’</a> (‘<a href="#small-caps"><code
  1948     class=property>small-caps</code></a>’), the <span class=property>‘<a
  1949     href="#propdef-font-size"><code
  1950     class=property>font-size</code></a>’</span> (120% of the parent's font
  1951     size), the <a class=property
  1952     href="http://www.w3.org/TR/CSS2/visudet.html#propdef-line-height">‘<code
  1953     class=property>line-height</code>’</a> (120% of the font size) and the
  1954     <a href="#propdef-font-family" title="font-family!!property">‘<code
  1955     class=property>font-family</code>’</a> (‘<a href="#fantasy"><code
  1956     class=property>fantasy</code></a>’). It follows that the keyword <span
  1957     title="normal value">‘<code class=property>normal</code>’</span>
  1958     applies to the two remaining properties: <a href="#propdef-font-style"
  1959     title="font-style!!property">‘<code
  1960     class=property>font-style</code>’</a> and <a
  1961     href="#propdef-font-weight" title="font-weight!!property">‘<code
  1962     class=property>font-weight</code>’</a>.
  1964    <p>The sixth rule sets the <a href="#propdef-font-style"
  1965     title="font-style!!property">‘<code
  1966     class=property>font-style</code>’</a>, <a href="#propdef-font-stretch"
  1967     title="font-stretch!!property">‘<code
  1968     class=property>font-stretch</code>’</a>, <span class=property>‘<a
  1969     href="#propdef-font-size"><code
  1970     class=property>font-size</code></a>’</span>, and <a
  1971     href="#propdef-font-family" title="font-family!!property">‘<code
  1972     class=property>font-family</code>’</a>, the other font properties being
  1973     set to their initial values.
  1974   </div>
  1976   <p>Since the <a href="#propdef-font-stretch"
  1977    title="font-stretch!!property">‘<code
  1978    class=property>font-stretch</code>’</a> property was not defined in CSS
  1979    2.1, when using <a href="#propdef-font-stretch"
  1980    title="font-stretch!!property">‘<code
  1981    class=property>font-stretch</code>’</a> values within ‘<a
  1982    href="#propdef-font"><code class=property>font</code></a>’ rules,
  1983    authors should include a extra version compatible with older user agents:
  1985   <pre>p {
  1986   font: 80% sans-serif;   /* for older user agents */
  1987   font: condensed 80% sans-serif;
  1988 }</pre>
  1990   <p>The following values refer to system fonts:
  1992   <dl>
  1993    <dt><strong>caption</strong>
  1995    <dd>The font used for captioned controls (e.g., buttons, drop-downs,
  1996     etc.).
  1998    <dt><strong>icon</strong>
  2000    <dd>The font used to label icons.
  2002    <dt><strong>menu</strong>
  2004    <dd>The font used in menus (e.g., dropdown menus and menu lists).
  2006    <dt><strong>message-box</strong>
  2008    <dd>The font used in dialog boxes.
  2010    <dt><strong>small-caption</strong>
  2012    <dd>The font used for labeling small controls.
  2014    <dt><strong>status-bar</strong>
  2016    <dd>The font used in window status bars.
  2017   </dl>
  2019   <p>System fonts may only be set as a whole; that is, the font family, size,
  2020    weight, style, etc. are all set at the same time. These values may then be
  2021    altered individually if desired. If no font with the indicated
  2022    characteristics exists on a given platform, the user agent should either
  2023    intelligently substitute (e.g., a smaller version of the ‘<code
  2024    class=property>caption</code>’ font might be used for the ‘<code
  2025    class=property>small-caption</code>’ font), or substitute a user agent
  2026    default font. As for regular fonts, if, for a system font, any of the
  2027    individual properties are not part of the operating system's available
  2028    user preferences, those properties should be set to their initial values.
  2030   <p>That is why this property is "almost" a shorthand property: system fonts
  2031    can only be specified with this property, not with <a
  2032    href="#propdef-font-family" title="font-family!!property">‘<code
  2033    class=property>font-family</code>’</a> itself, so <span
  2034    class=property>‘<a href="#propdef-font"><code
  2035    class=property>font</code></a>’</span> allows authors to do more than
  2036    the sum of its subproperties. However, the individual properties such as
  2037    <a href="#propdef-font-weight" title="font-weight!!property">‘<code
  2038    class=property>font-weight</code>’</a> are still given values taken from
  2039    the system font, which can be independently varied.
  2041   <p>Note that the keywords used for the system fonts listed above are only
  2042    treated as keywords when they occur in the initial position, in other
  2043    positions the same string is treated as part of the font family name:
  2045   <pre>  font: menu;        /* use the font settings for system menus */
  2046   font: large menu;  /* use a font family named "menu" */</pre>
  2048   <div class=example>
  2049    <p style="display:none">Example(s):</p>
  2051    <pre>button { font: 300 italic 1.3em/1.7em &quot;FB Armada&quot;, sans-serif }
  2052 button p { font: menu }
  2053 button p em { font-weight: bolder }
  2054 </pre>
  2056    <p>If the font used for dropdown menus on a particular system happened to
  2057     be, for example, 9-point Charcoal, with a weight of 600, then P elements
  2058     that were descendants of BUTTON would be displayed as if this rule were
  2059     in effect:
  2061    <pre>button p { font: 600 9pt Charcoal }
  2062 </pre>
  2064    <p>Because the <span class=property>‘<a href="#propdef-font"><code
  2065     class=property>font</code></a>’</span> shorthand resets to its initial
  2066     value any property not explicitly given a value, this has the same effect
  2067     as this declaration:
  2069    <pre>button p {
  2070   font-style: normal;
  2071   font-variant: normal;
  2072   font-weight: 600;
  2073   font-size: 9pt;
  2074   line-height: normal;
  2075   font-family: Charcoal
  2077 </pre>
  2078   </div>
  2079   <!-- prop: font-synthesis -->
  2081   <h3 id=font-synthesis-prop><span class=secno>3.8 </span>Controlling
  2082    synthetic faces: the <a href="#propdef-font-synthesis">font-synthesis</a>
  2083    property</h3>
  2085   <table class=propdef id=namefont-synthesisvaluenone-weight-style>
  2086    <tbody>
  2087     <tr>
  2088      <td>Name:
  2090      <td><dfn id=propdef-font-synthesis>font-synthesis</dfn>
  2092     <tr>
  2093      <td>Value:
  2095      <td>none | [ weight || style ]
  2097     <tr>
  2098      <td>Initial:
  2100      <td>weight style
  2102     <tr>
  2103      <td>Applies to:
  2105      <td>all elements
  2107     <tr>
  2108      <td>Inherited:
  2110      <td>yes
  2112     <tr>
  2113      <td>Percentages:
  2115      <td>N/A
  2117     <tr>
  2118      <td>Media:
  2120      <td>visual
  2122     <tr>
  2123      <td>Computed value:
  2125      <td>as specified
  2127     <tr>
  2128      <td>Animatable:
  2130      <td>no
  2131   </table>
  2133   <p>This property controls whether user agents are allowed to synthesize
  2134    bold or oblique font faces when a font family lacks bold or italic faces.
  2135    If ‘<a href="#weight"><code class=property>weight</code></a>’ is not
  2136    specified, user agents must not synthesize bold faces and if ‘<code
  2137    class=property>style</code>’ is not specified user agents must not
  2138    synthesize italic faces. A value of ‘<code class=property>none</code>’
  2139    disallows all synthetic faces.
  2141   <div class=example>
  2142    <p>The style rule below disables the use of synthetically obliqued Arabic:</p>
  2144    <pre>*:lang(ar) { font-synthesis: none; }
  2145 </pre>
  2146   </div>
  2148   <h2 id=font-resources><span class=secno>4 </span>Font Resources</h2>
  2150   <h3 id=font-face-rule><span class=secno>4.1 </span>The <dfn
  2151    id=at-font-face-rule style="font-weight: inherit; font-style:
  2152    inherit"><code>@font-face</code></dfn> rule</h3>
  2154   <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule allows
  2155    for linking to fonts that are automatically fetched and activated when
  2156    needed. This allows authors to select a font that closely matches the
  2157    design goals for a given page rather than limiting the font choice to a
  2158    set of fonts available on all platforms. A set of font descriptors define
  2159    the location of a font resource, either locally or externally, along with
  2160    the style characteristics of an individual face. Multiple <a
  2161    href="#at-font-face-rule"><code>@font-face</code></a> rules can be used to
  2162    construct font families with a variety of faces. Using CSS font matching
  2163    rules, a user agent can selectively download only those faces that are
  2164    needed for a given piece of text.
  2166   <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule
  2167    consists of the <a href="#at-font-face-rule"><code>@font-face</code></a>
  2168    at-keyword followed by a block of descriptor declarations. In terms of the
  2169    grammar, this specification defines the following productions:
  2171   <pre><dfn id=fontfacerule>font_face_rule</dfn>
  2172   : <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>*
  2175 <dfn id=descriptordeclaration>descriptor_declaration</dfn>
  2176   : <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>
  2177   ;</pre>
  2179   <p>The following new definitions are introduced:
  2181   <pre>-    -|\\0{0,4}2d(\r\n|[ \t\r\n\f])?
  2182 F    f|\\0{0,4}(46|66)(\r\n|[ \t\r\n\f])?</pre>
  2184   <p>The following new token is introduced:
  2186   <pre>@{F}{O}{N}{T}{-}{F}{A}{C}{E} {return <dfn id=fontfacesym>FONT_FACE_SYM</dfn>;}</pre>
  2188   <p>Each <a href="#at-font-face-rule"><code>@font-face</code></a> rule
  2189    specifies a value for every font descriptor, either implicitly or
  2190    explicitly. Those not given explicit values in the rule take the initial
  2191    value listed with each descriptor in this specification. These descriptors
  2192    apply solely within the context of the <a
  2193    href="#at-font-face-rule"><code>@font-face</code></a> rule in which they
  2194    are defined, and do not apply to document language elements. There is no
  2195    notion of which elements the descriptors apply to or whether the values
  2196    are inherited by child elements. When a given descriptor occurs multiple
  2197    times in a given <a href="#at-font-face-rule"><code>@font-face</code></a>
  2198    rule, only the last descriptor declaration is used and all prior
  2199    declarations for that descriptor are ignored.
  2201   <div class=example>
  2202    <p>To use a downloadable font called Gentium:</p>
  2204    <pre>
  2205 @font-face {
  2206   font-family: Gentium;
  2207   src: url(http://example.com/fonts/Gentium.woff);
  2210 p { font-family: Gentium, serif; }
  2211 </pre>
  2213    <p>The user agent will download Gentium and use it when rendering text
  2214     within paragraph elements. If for some reason the site serving the font
  2215     is unavailable, the default serif font will be used.</p>
  2216   </div>
  2218   <p>A given set of <a href="#at-font-face-rule"><code>@font-face</code></a>
  2219    rules define a set of fonts available for use within the documents that
  2220    contain these rules. When font matching is done, fonts defined using these
  2221    rules are considered before other available fonts on a system.
  2223   <p>Downloaded fonts are only available to documents that reference them.
  2224    The process of activating these fonts must not make them available to
  2225    other applications or to documents that don't directly link to the same
  2226    font. User agent implementers might consider it convenient to use
  2227    downloaded fonts when rendering characters in other documents for which no
  2228    other available font exists as part of the <a
  2229    href="#system-font-fallback"><em>system font fallback</em></a> procedure.
  2230    However, this would cause a security leak since the contents of one page
  2231    would be able to affect other pages, something an attacker could use as an
  2232    attack vector. These restrictions do not affect caching behavior, fonts
  2233    are cached the same way other web resources are cached.
  2235   <p>This at-rule follows the forward-compatible parsing rules of CSS. Like
  2236    properties in a declaration block, declarations of any descriptors that
  2237    are not supported by the user agent must be ignored. <a
  2238    href="#at-font-face-rule"><code>@font-face</code></a> rules require a
  2239    font-family and src descriptor; if either of these are missing, the <a
  2240    href="#at-font-face-rule"><code>@font-face</code></a> rule is invalid and
  2241    must be ignored entirely.
  2243   <p>In cases where user agents have limited platform resources or implement
  2244    the ability to disable downloadable font resources, <a
  2245    href="#at-font-face-rule"><code>@font-face</code></a> rules must simply be
  2246    ignored; the behavior of individual descriptors as defined in this
  2247    specification should not be altered.
  2249   <h3 id=font-family-desc><span class=secno>4.2 </span>Font family: the <a
  2250    href="#descdef-font-family">font-family</a> descriptor</h3>
  2252   <table class=descdef>
  2253    <tbody>
  2254     <tr>
  2255      <td>Name:
  2257      <td><dfn id=descdef-font-family
  2258       title="font-family!!descriptor">font-family</dfn>
  2260     <tr>
  2261      <td>Value:
  2263      <td><a href="#family-name-value"><var>&lt;family-name&gt;</var></a>
  2265     <tr>
  2266      <td><em>Initial:</em>
  2268      <td>N/A
  2269   </table>
  2271   <p>This descriptor defines the font family name that will be used in all
  2272    CSS font family name matching. It is required for the <a
  2273    href="#at-font-face-rule"><code>@font-face</code></a> rule to be valid. It
  2274    overrides the font family names contained in the underlying font data. If
  2275    the font family name is the same as a font family available in a given
  2276    user's environment, it effectively hides the underlying font for documents
  2277    that use the stylesheet. This permits a web author to freely choose
  2278    font-family names without worrying about conflicts with font family names
  2279    present in a given user's environment. Likewise, platform substitutions
  2280    for a given font family name must not be used.
  2282   <h3 id=src-desc><span class=secno>4.3 </span>Font reference: the <a
  2283    href="#descdef-src">src</a> descriptor</h3>
  2285   <table class=descdef>
  2286    <tbody>
  2287     <tr>
  2288      <td>Name:
  2290      <td><dfn id=descdef-src>src</dfn>
  2292     <tr>
  2293      <td>Value:
  2295      <td>[ &lt;url> [format(&lt;string> #)]? | <a
  2296       href="#font-face-name-value"><var>&lt;font-face-name&gt;</var></a> ] #
  2298     <tr>
  2299      <td><em>Initial:</em>
  2301      <td>N/A
  2302   </table>
  2304   <p>This descriptor specifies the resource containing font data. It is
  2305    required for the <a href="#at-font-face-rule"><code>@font-face</code></a>
  2306    rule to be valid. Its value is a prioritized, comma-separated list of
  2307    external references or locally-installed font face names. When a font is
  2308    needed the user agent iterates over the set of references listed, using
  2309    the first one it can successfully activate. Fonts containing invalid data
  2310    or local font faces that are not found are ignored and the user agent
  2311    loads the next font in the list.
  2313   <p>As with other URLs in CSS, the URL may be relative, in which case it is
  2314    resolved relative to the location of the style sheet containing the <a
  2315    href="#at-font-face-rule"><code>@font-face</code></a> rule. In the case of
  2316    SVG fonts, the URL points to an element within a document containing SVG
  2317    font definitions. If the element reference is omitted, a reference to the
  2318    first defined font is implied. Similarly, font container formats that can
  2319    contain more than one font must load one and only one of the fonts for a
  2320    given <a href="#at-font-face-rule"><code>@font-face</code></a> rule.
  2321    Fragment identifiers are used to indicate which font to load. If a
  2322    container format lacks a defined fragment identifier scheme,
  2323    implementations should use a simple 1-based indexing scheme (e.g.
  2324    "font-collection#1" for the first font, "font-collection#2" for the second
  2325    font).
  2327   <pre>
  2328 src: url(fonts/simple.woff);   /* load simple.woff relative to stylesheet location */
  2329 src: url(/fonts/simple.woff);  /* load simple.woff from absolute location */
  2330 src: url(fonts.svg#simple);    /* load SVG font with id 'simple' */
  2331 </pre>
  2333   <p>External references consist of a URL, followed by an optional hint
  2334    describing the format of the font resource referenced by that URL. The
  2335    format hint contains a comma-separated list of format strings that denote
  2336    well-known font formats. Conformant user agents must skip downloading a
  2337    font resource if the format hints indicate only unsupported or unknown
  2338    font formats. If no format hints are supplied, the user agent should
  2339    download the font resource.
  2341   <pre>
  2342 /* load WOFF font if possible, otherwise use OpenType font */
  2343 @font-face {
  2344   font-family: bodytext;
  2345   src: url(ideal-sans-serif.woff) format("woff"),
  2346        url(basic-sans-serif.ttf) format("opentype");
  2348 </pre>
  2350   <p>Format strings defined by this specification:
  2352   <table class=data id=fontformats>
  2353    <thead>
  2354     <tr>
  2355      <th>String
  2357      <th>Font Format
  2359      <th>Common extensions
  2361    <tbody>
  2362     <tr>
  2363      <th>"woff"
  2365      <td><a href="http://www.w3.org/TR/WOFF/">WOFF (Web Open Font Format)</a>
  2367      <td>.woff
  2369     <tr>
  2370      <th>"truetype"
  2372      <td><a
  2373       href="http://www.microsoft.com/typography/otspec/default.htm">TrueType</a>
  2375      <td>.ttf
  2377     <tr>
  2378      <th>"opentype"
  2380      <td><a
  2381       href="http://www.microsoft.com/typography/otspec/default.htm">OpenType</a>
  2383      <td>.ttf, .otf
  2385     <tr>
  2386      <th>"embedded-opentype"
  2388      <td><a
  2389       href="http://www.w3.org/Submission/2008/SUBM-EOT-20080305/">Embedded
  2390       OpenType</a>
  2392      <td>.eot
  2394     <tr>
  2395      <th>"svg"
  2397      <td><a href="http://www.w3.org/TR/SVG/fonts.html">SVG Font</a>
  2399      <td>.svg, .svgz
  2400   </table>
  2402   <p>Given the overlap in common usage between TrueType and OpenType, the
  2403    format hints "truetype" and "opentype" must be considered as synonymous; a
  2404    format hint of "opentype" does not imply that the font contains Postscript
  2405    CFF style glyph data or that it contains OpenType layout information (see
  2406    <a href="#platform-props-to-css">Appendix A</a> for more background on
  2407    this).
  2409   <p>When authors would prefer to use a locally available copy of a given
  2410    font and download it if it's not, <code>local()</code> can be used. The
  2411    locally-installed <dfn
  2412    id=font-face-name-value><var>&lt;font-face-name&gt;</var></dfn> argument
  2413    to <code>local()</code> is a format-specific string that uniquely
  2414    identifies a single font face within a larger family. The syntax for a <a
  2415    href="#font-face-name-value"><var>&lt;font-face-name&gt;</var></a> is a
  2416    unique font face name enclosed by "local(" and ")". The name can
  2417    optionally be enclosed in quotes. If unquoted, the unquoted font family
  2418    name processing conventions apply; the name must be a sequence of
  2419    identifiers separated by whitespace which is converted to a string by
  2420    joining the identifiers together separated by a single space.
  2422   <pre>
  2423 /* regular face of Gentium */
  2424 @font-face {
  2425   font-family: MyGentium;
  2426   src: local(Gentium),    /* use locally available Gentium */
  2427        url(Gentium.woff); /* otherwise, download it */
  2429 </pre>
  2431   <p>For OpenType and TrueType fonts, this string is used to match only the
  2432    Postscript name or the full font name in the name table of locally
  2433    available fonts. Which type of name is used varies by platform and font,
  2434    so authors should include both of these names to assure proper matching
  2435    across platforms. Platform substitutions for a given font name must not be
  2436    used.
  2438   <pre>
  2439 /* bold face of Gentium */
  2440 @font-face {
  2441   font-family: MyGentium;
  2442   src: local(Gentium Bold),    /* full font name */
  2443        local(Gentium-Bold),    /* Postscript name */
  2444        url(GentiumBold.woff);  /* otherwise, download it */
  2445   font-weight: bold;
  2447 </pre>
  2449   <p>Just as a <a href="#at-font-face-rule"><code>@font-face</code></a> rule
  2450    specifies the characteristics of a single font within a family, the unique
  2451    name used with <code>local()</code> specifies a single font, not an entire
  2452    font family. Defined in terms of OpenType font data, the Postscript name
  2453    is found in the font's <a
  2454    href="http://www.microsoft.com/typography/otspec/name.htm">name table</a>,
  2455    in the name record with nameID = 6 (see <a href="#OPENTYPE"
  2456    rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a> for more details). The
  2457    Postscript name is the commonly used key for all fonts on OSX and for
  2458    Postscript CFF fonts under Windows. The full font name (nameID = 4) is
  2459    used as a unique key for fonts with TrueType glyphs on Windows.
  2461   <p>For OpenType fonts with multiple localizations of the full font name,
  2462    the US English version is used (language ID = 0x409 for Windows and
  2463    language ID = 0 for Macintosh) or the first localization when a US English
  2464    full font name is not available (the OpenType specification recommends
  2465    that <a href="http://www.microsoft.com/typography/otspec/recom.htm">all
  2466    fonts minimally include US English names</a>). User agents that also match
  2467    other full font names, e.g. matching the Dutch name when the current
  2468    system locale is set to Dutch, are considered non-conformant. This is done
  2469    not to prefer English but to avoid matching inconsistencies across font
  2470    versions and OS localizations, since font style names (e.g. "Bold") are
  2471    frequently localized into many languages and the set of localizations
  2472    available varies widely across platform and font version. User agents that
  2473    match a concatenation of family name (nameID = 1) with style name (nameID
  2474    = 2) are considered non-conformant.
  2476   <p>This also allows for referencing faces that belong to larger families
  2477    that cannot otherwise be referenced.
  2479   <div class=example>
  2480    <p>Use a local font or reference an SVG font in another document:</p>
  2482    <pre>
  2483 @font-face {
  2484   font-family: Headline;
  2485   src: local(Futura-Medium),
  2486        url(fonts.svg#MyGeometricModern) format("svg");
  2488 </pre>
  2490    <p>Create an alias for local Japanese fonts on different platforms:</p>
  2492    <pre>
  2493 @font-face {
  2494   font-family: jpgothic;
  2495   src: local(HiraKakuPro-W3), local(Meiryo), local(IPAPGothic);
  2497 </pre>
  2499    <p>Reference a font face that cannot be matched within a larger family:</p>
  2501    <pre>
  2502 @font-face {
  2503   font-family: Hoefler Text Ornaments;
  2504   /* has the same font properties as Hoefler Text Regular */
  2505   src: local(HoeflerText-Ornaments);
  2507 </pre>
  2509    <p>Since localized fullnames never match, a document with the header style
  2510     rules below would always render using the default serif font, regardless
  2511     whether a particular system locale parameter is set to Finnish or not:</p>
  2513    <pre>
  2514 @font-face {
  2515   font-family: SectionHeader;
  2516   src: local("Arial Lihavoitu");  /* Finnish fullname for Arial Bold, should fail */
  2517   font-weight: bold;
  2520 h2 { font-family: SectionHeader, serif; }
  2521 </pre>
  2523    <p>A conformant user agent would never load the font ‘<code
  2524     class=css>gentium.eot</code>’ in the example below, since it is
  2525     included in the first definition of the ‘<a href="#descdef-src"><code
  2526     class=property>src</code></a>’ descriptor which is overridden by the
  2527     second definition in the same <a
  2528     href="#at-font-face-rule"><code>@font-face</code></a> rule:</p>
  2530    <pre>
  2531 @font-face {
  2532   font-family: MainText;
  2533   src: url(gentium.eot);                     /* for use with older user agents */
  2534   src: local("Gentium"), url(gentium.woff);  /* Overrides src definition */
  2536 </pre>
  2537   </div>
  2539   <h3 id=font-prop-desc><span class=secno>4.4 </span>Font property
  2540    descriptors: the <a href="#descdef-font-style">font-style</a>, <a
  2541    href="#descdef-font-weight">font-weight</a>, <a
  2542    href="#descdef-font-stretch">font-stretch</a> descriptors</h3>
  2544   <table class=descdef>
  2545    <tbody>
  2546     <tr>
  2547      <td>Name:
  2549      <td><dfn id=descdef-font-style
  2550       title="font-style!!descriptor">font-style</dfn>
  2552     <tr>
  2553      <td>Value:
  2555      <td>normal | italic | oblique
  2557     <tr>
  2558      <td><em>Initial:</em>
  2560      <td>normal
  2561   </table>
  2563   <table class=descdef>
  2564    <tbody>
  2565     <tr>
  2566      <td>Name:
  2568      <td><dfn id=descdef-font-weight
  2569       title="font-weight!!descriptor">font-weight</dfn>
  2571     <tr>
  2572      <td>Value:
  2574      <td>normal | bold | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900
  2576     <tr>
  2577      <td><em>Initial:</em>
  2579      <td>normal
  2580   </table>
  2582   <table class=descdef>
  2583    <tbody>
  2584     <tr>
  2585      <td>Name:
  2587      <td><dfn id=descdef-font-stretch
  2588       title="font-stretch!!descriptor">font-stretch</dfn>
  2590     <tr>
  2591      <td>Value:
  2593      <td>normal | ultra-condensed | extra-condensed | condensed |
  2594       semi-condensed | semi-expanded | expanded | extra-expanded |
  2595       ultra-expanded
  2597     <tr>
  2598      <td><em>Initial:</em>
  2600      <td>normal
  2601   </table>
  2603   <p>These descriptors define the characteristics of a font face and are used
  2604    in the process of matching styles to specific faces. For a font family
  2605    defined with several <a
  2606    href="#at-font-face-rule"><code>@font-face</code></a> rules, user agents
  2607    can either download all faces in the family or use these descriptors to
  2608    selectively download font faces that match actual styles used in document.
  2609    The values for these descriptors are the same as those for the
  2610    corresponding font properties except that relative keywords are not
  2611    allowed, ‘<a href="#bolder"><code class=property>bolder</code></a>’
  2612    and ‘<a href="#lighter"><code class=property>lighter</code></a>’. If
  2613    these descriptors are omitted, initial values are assumed.
  2615   <p>The value for these font face style attributes is used in place of the
  2616    style implied by the underlying font data. This allows authors to combine
  2617    faces in flexible combinations, even in situations where the original font
  2618    data was arranged differently. User agents that implement synthetic
  2619    bolding and obliquing must only apply synthetic styling in cases where the
  2620    font descriptors imply this is needed, rather than based on the style
  2621    attributes implied by the font data.
  2623   <h3 id=unicode-range-desc><span class=secno>4.5 </span>Character range: the
  2624    <a href="#descdef-unicode-range">unicode-range</a> descriptor</h3>
  2626   <table class=descdef>
  2627    <tbody>
  2628     <tr>
  2629      <td>Name:
  2631      <td><dfn id=descdef-unicode-range>unicode-range</dfn>
  2633     <tr>
  2634      <td>Value:
  2636      <td><a href="#urange-value"><var>&lt;urange&gt;</var></a> #
  2638     <tr>
  2639      <td><em>Initial:</em>
  2641      <td>U+0-10FFFF
  2642   </table>
  2644   <p>This descriptor defines the set of Unicode codepoints that may be
  2645    supported by the font face for which it is declared. The descriptor value
  2646    is a comma-delimited list of Unicode range (<a
  2647    href="#urange-value"><var>&lt;urange&gt;</var></a>) values. The union of
  2648    these ranges defines the set of codepoints that serves as a hint for user
  2649    agents when deciding whether or not to download a font resource for a
  2650    given text run.
  2652   <p>Each <dfn id=urange-value><var>&lt;urange&gt;</var></dfn> value is a <a
  2653    href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><code
  2654    title="UNICODE-RANGE token">UNICODE-RANGE</code></a> token made up of a
  2655    "U+" or "u+" prefix followed by a codepoint range in one of the three
  2656    forms listed below. Ranges that do not fit one of the these forms are
  2657    invalid and cause the declaration to be ignored.
  2659   <dl>
  2660    <dt>single codepoint (e.g. U+416)
  2662    <dd>a valid Unicode codepoint, represented as one to six hexadecimal
  2663     digits
  2665    <dt>interval range (e.g. U+400-4ff)
  2667    <dd>represented as two hyphen-separated valid Unicode codepoints
  2668     indicating the inclusive start and end codepoints of a range
  2670    <dt>wildcard range (e.g. U+4??)
  2672    <dd>defined by the set of codepoints implied when trailing ‘<code
  2673     class=css>?</code>’ characters signify any hexadeximal digit
  2674   </dl>
  2676   <p>Individual codepoints are written using hexadecimal values that
  2677    correspond to <a href="http://www.unicode.org/charts/">Unicode character
  2678    codepoints</a>. Valid Unicode codepoint values vary between 0 and 10FFFF
  2679    inclusive. Digit values of codepoints are ASCII case-insensitive. For
  2680    interval ranges, the start and end codepoints are valid Unicode values and
  2681    the end codepoint is greater than or equal to the start codepoint.
  2683   <p>Wildcard ranges specified with ‘?’ that lack an initial digit (e.g.
  2684    "U+???") are valid and equivalent to a wildcard range with an initial zero
  2685    digit (e.g. "U+0???" = "U+0000-0FFF"). Wildcard ranges that extend beyond
  2686    the range of valid Unicode codepoints are invalid. Because of this, the
  2687    maximum number of trailing ‘<code class=css>?</code>’ wildcard
  2688    characters is five, even though the <a
  2689    href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><code
  2690    title="UNICODE-RANGE token">UNICODE-RANGE</code></a> token accepts six.
  2692   <p>Within the comma-delimited list of Unicode ranges in a ‘<a
  2693    href="#descdef-unicode-range"><code
  2694    class=property>unicode-range</code></a>’ descriptor declaration, ranges
  2695    may overlap. The union of these ranges defines the set of codepoints for
  2696    which the corresponding font may be used. User agents must not download or
  2697    use the font for codepoints outside this set. User agents may normalize
  2698    the list of ranges into a list that is different but represents the same
  2699    set of codepoints.
  2701   <p>The associated font might not contain glyphs for the entire set of
  2702    codepoints defined by the ‘<a href="#descdef-unicode-range"><code
  2703    class=property>unicode-range</code></a>’ descriptor. When the font is
  2704    used, the <dfn id=effective-character-map>effective character map</dfn> is
  2705    the intersection of the codepoints defined by ‘<a
  2706    href="#descdef-unicode-range"><code
  2707    class=property>unicode-range</code></a>’ with the font's <a
  2708    href="#character-map"><em>character map</em></a>. This allows authors to
  2709    define supported ranges in terms of broad ranges without worrying about
  2710    the precise codepoint ranges supported by the underlying font.
  2712   <h3 id=composite-fonts><span class=secno>4.6 </span>Using character ranges
  2713    to define composite fonts</h3>
  2715   <p>Multiple <a href="#at-font-face-rule"><code>@font-face</code></a> rules
  2716    with different unicode ranges for the same family and style descriptor
  2717    values can be used to create composite fonts that mix the glyphs from
  2718    different fonts for different scripts. This can be used to combine fonts
  2719    that only contain glyphs for a single script (e.g. Latin, Greek, Cyrillic)
  2720    or it can be used by authors as a way of segmenting a font into fonts for
  2721    commonly used characters and less frequently used characters. Since the
  2722    user agent will only pull down the fonts it needs this helps reduce page
  2723    bandwidth.
  2725   <p>If the unicode ranges overlap for a set of <a
  2726    href="#at-font-face-rule"><code>@font-face</code></a> rules with the same
  2727    family and style descriptor values, the rules are ordered in the reverse
  2728    order they were defined; the last rule defined is the first to be checked
  2729    for a given character.
  2731   <p>Example ranges for specific languages or characters:
  2733   <dl>
  2734    <dt>unicode-range: U+A5;
  2736    <dd>a single code point, the yen/yuan symbol
  2738    <dt>unicode-range: U+0-7F;
  2740    <dd>code range for basic ASCII characters
  2742    <dt>unicode-range: U+590-5ff;
  2744    <dd>code range for Hebrew characters
  2746    <dt>unicode-range: U+A5, U+4E00-9FFF, U+30??, U+FF00-FF9F;
  2748    <dd>code range for Japanese kanji, hiragana and katakana characters plus
  2749     yen/yuan symbol
  2750   </dl>
  2752   <div class=example>
  2753    <p>The BBC provides news services in a wide variety of languages, many
  2754     that are not well supported across all platforms. Using an <a
  2755     href="#at-font-face-rule"><code>@font-face</code></a> rule, the BBC could
  2756     provide a font for any of these languages, as it already does via a
  2757     manual font download.</p>
  2759    <pre>
  2760 @font-face {
  2761   font-family: BBCBengali;
  2762   src: url(fonts/BBCBengali.woff) format("woff");
  2763   unicode-range: U+00-FF, U+980-9FF;
  2765 </pre>
  2766   </div>
  2768   <div class=example>
  2769    <p>Technical documents often require a wide range of symbols. The STIX
  2770     Fonts project is one project aimed at providing fonts to support a wide
  2771     range of technical typesetting in a standardized way. The example below
  2772     shows the use of a font that provides glyphs for many of the mathematical
  2773     and technical symbol ranges within Unicode:</p>
  2775    <pre>
  2776 @font-face {
  2777   font-family: STIXGeneral;
  2778   src: local(STIXGeneral), url(/stixfonts/STIXGeneral.otf);
  2779   unicode-range: U+000-49F, U+2000-27FF, U+2900-2BFF, U+1D400-1D7FF;
  2781 </pre>
  2782   </div>
  2784   <div class=example>
  2785    <p>This example shows how an author can override the glyphs used for Latin
  2786     characters in a Japanese font with glyphs from a different font. The
  2787     first rule specifies no range so it defaults to the entire range. The
  2788     range specified in the second rule overlaps but takes precedence because
  2789     it is defined later.</p>
  2791    <pre>
  2792 @font-face {
  2793   font-family: JapaneseWithGentium;
  2794   src: local(MSMincho);
  2795   /* no range specified, defaults to entire range */
  2798 @font-face {
  2799   font-family: JapaneseWithGentium;
  2800   src: url(../fonts/Gentium.woff);
  2801   unicode-range: U+0-2FF;
  2803 </pre>
  2804   </div>
  2806   <div class=example>
  2807    <p>Consider a family constructed to optimize bandwidth by separating out
  2808     Latin, Japanese and other characters into different font files:</p>
  2810    <pre>
  2811 /* fallback font - size: 4.5MB */
  2812 @font-face {
  2813   font-family: DroidSans;
  2814   src: url(DroidSansFallback.woff);
  2815   /* no range specified, defaults to entire range */
  2818 /* Japanese glyphs - size: 1.2MB */
  2819 @font-face {
  2820   font-family: DroidSans;
  2821   src: url(DroidSansJapanese.woff);
  2822   unicode-range: U+3000-9FFF, U+ff??;
  2825 /* Latin, Greek, Cyrillic along with some
  2826    punctuation and symbols - size: 190KB */
  2827 @font-face {
  2828   font-family: DroidSans;
  2829   src: url(DroidSans.woff);
  2830   unicode-range: U+000-5FF, U+1e00-1fff, U+2000-2300;
  2832 </pre>
  2834    <p>For simple Latin text, only the font for Latin characters is
  2835     downloaded:</p>
  2837    <pre>
  2838 body { font-family: DroidSans; }
  2840 &lt;p>This is that&lt;/p>
  2841 </pre>
  2843    <p>In this case the user agent first checks the unicode-range for the font
  2844     containing Latin characters (DroidSans.woff). Since all the characters
  2845     above are in the range U+0-5FF, the user agent downloads the font and
  2846     renders the text with that font.</p>
  2848    <p>Next, consider text that makes use of an arrow character (⇨):</p>
  2850    <pre>
  2851 &lt;p>This &amp;#x21e8; that&lt;p>
  2852 </pre>
  2854    <p>The user agent again first checks the unicode-range of the font
  2855     containing Latin characters. Since U+2000-2300 includes the arrow code
  2856     point (U+21E8), the user agent downloads the font. For this character
  2857     however the Latin font does not have a matching glyph, so the effective
  2858     unicode-range used for font matching excludes this code point. Next, the
  2859     user agent evaluates the Japanese font. The unicode-range for the
  2860     Japanese font, U+3000-9FFF and U+ff??, does not include U+21E8, so the
  2861     user agent does not download the Japanese font. Next the fallback font is
  2862     considered. The <a href="#at-font-face-rule"><code>@font-face</code></a>
  2863     rule for the fallback font does not define unicode-range so its value
  2864     defaults to the range of all Unicode code points. The fallback font is
  2865     downloaded and used to render the arrow character.</p>
  2866   </div>
  2868   <h3 id=font-rend-desc><span class=secno>4.7 </span>Font features: the <a
  2869    href="#descdef-font-variant">font-variant</a> and <a
  2870    href="#descdef-font-feature-settings">font-feature-settings</a>
  2871    descriptors</h3>
  2873   <table class=descdef>
  2874    <tbody>
  2875     <tr>
  2876      <td>Name:
  2878      <td><dfn id=descdef-font-variant
  2879       title="font-variant!!descriptor">font-variant</dfn>
  2881     <tr>
  2882      <td>Value:
  2884      <td><a href="#font-variant-normal-value"
  2885       title="normal!!font-variant">normal</a> | <a
  2886       href="#font-variant-none-value" title="none!!font-variant">none</a> | [
  2887       <a href="#common-lig-values"><var>&lt;common-lig-values&gt;</var></a>
  2888       || <a
  2889       href="#discretionary-lig-values"><var>&lt;discretionary-lig-values&gt;</var></a>
  2890       || <a
  2891       href="#historical-lig-values"><var>&lt;historical-lig-values&gt;</var></a>
  2892       || <a
  2893       href="#contextual-alt-values"><var>&lt;contextual-alt-values&gt;</var></a>
  2894       || <a href="#stylistic"><var
  2895       title=stylistic>stylistic(&lt;feature-value-name&gt;)</var></a> || <a
  2896       href="#historical-forms"><var>historical-forms</var></a> || <a
  2897       href="#styleset"><var
  2898       title=styleset>styleset(&lt;feature-value-name&gt; #)</var></a> || <a
  2899       href="#character-variant"><var
  2900       title=character-variant>character-variant(&lt;feature-value-name&gt;
  2901       #)</var></a> || <a href="#swash"><var
  2902       title=swash>swash(&lt;feature-value-name&gt;)</var></a> || <a
  2903       href="#ornaments"><var
  2904       title=ornaments>ornaments(&lt;feature-value-name&gt;)</var></a> || <a
  2905       href="#annotation"><var
  2906       title=annotation>annotation(&lt;feature-value-name&gt;)</var></a> || [
  2907       <a href="#small-caps"><i>small-caps</i></a> | <a
  2908       href="#all-small-caps"><i>all-small-caps</i></a> | <a
  2909       href="#petite-caps"><i>petite-caps</i></a> | <a
  2910       href="#all-petite-caps"><i>all-petite-caps</i></a> | <a
  2911       href="#unicase"><i>unicase</i></a> | <a
  2912       href="#titling-caps"><i>titling-caps</i></a> ] || <a
  2913       href="#numeric-figure-values"><var>&lt;numeric-figure-values&gt;</var></a>
  2914       || <a
  2915       href="#numeric-spacing-values"><var>&lt;numeric-spacing-values&gt;</var></a>
  2916       || <a
  2917       href="#numeric-fraction-values"><var>&lt;numeric-fraction-values&gt;</var></a>
  2918       || <a href="#ordinal"><i>ordinal</i></a> || <a
  2919       href="#slashed-zero"><i>slashed-zero</i></a> || <a
  2920       href="#east-asian-variant-values"><var>&lt;east-asian-variant-values&gt;</var></a>
  2921       || <a
  2922       href="#east-asian-width-values"><var>&lt;east-asian-width-values&gt;</var></a>
  2923       || <a href="#ruby"><i>ruby</i></a> ]
  2925     <tr>
  2926      <td><em>Initial:</em>
  2928      <td>normal
  2929   </table>
  2931   <table class=descdef>
  2932    <tbody>
  2933     <tr>
  2934      <td>Name:
  2936      <td><dfn id=descdef-font-feature-settings
  2937       title="font-feature-settings!!descriptor">font-feature-settings</dfn>
  2939     <tr>
  2940      <td>Value:
  2942      <td><a href="#font-feature-settings-normal-value"
  2943       title="normal!!font-feature-settings">normal</a> | <a
  2944       href="#feature-tag-value"><var>&lt;feature-tag-value&gt;</var></a> #
  2946     <tr>
  2947      <td><em>Initial:</em>
  2949      <td>normal
  2950   </table>
  2952   <p>These descriptors define initial settings that apply when the font
  2953    defined by an <a href="#at-font-face-rule"><code>@font-face</code></a>
  2954    rule is rendered. They do not affect font selection. Values are identical
  2955    to those defined for the corresponding <a href="#propdef-font-variant"
  2956    title="font-variant!!property">‘<code
  2957    class=property>font-variant</code>’</a> and <a
  2958    href="#propdef-font-feature-settings"
  2959    title="font-feature-settings!!property">‘<code
  2960    class=property>font-feature-settings</code>’</a> properties defined
  2961    below except that the value ‘<code class=property>inherit</code>’ is
  2962    omitted. When multiple font feature descriptors or properties are used,
  2963    the cumulative effect on text rendering is detailed in the section <a
  2964    href="#font-feature-resolution">Font Feature Resolution</a> below. In
  2965    cases where specific values define synthesized fallback for certain <a
  2966    href="#propdef-font-variant" title="font-variant!!property">‘<code
  2967    class=property>font-variant</code>’</a> subproperties, the same
  2968    synthesized fallback applies when used within those values are used with
  2969    the <a href="#descdef-font-style" title="font-style!!descriptor">‘<code
  2970    class=property>font-variant</code>’</a> descriptor.
  2972   <h3 id=font-face-loading><span class=secno>4.8 </span>Font loading
  2973    guidelines</h3>
  2975   <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule is
  2976    designed to allow lazy loading of font resources that are only downloaded
  2977    when used within a document. A stylesheet can include <a
  2978    href="#at-font-face-rule"><code>@font-face</code></a> rules for a library
  2979    of fonts of which only a select set are used; user agents must only
  2980    download those fonts that are referred to within the style rules
  2981    applicable to a given page. User agents that download all fonts defined in
  2982    <a href="#at-font-face-rule"><code>@font-face</code></a> rules without
  2983    considering whether those fonts are in fact used within a page are
  2984    considered non-conformant. In cases where a font might be downloaded in
  2985    character fallback cases, user agents may download a font if it's
  2986    contained within the computed value of <a href="#propdef-font-family"
  2987    title="font-family!!property">‘<code
  2988    class=property>font-family</code>’</a> for a given text run.
  2990   <pre>
  2991 @font-face {
  2992   font-family: GeometricModern;
  2993   src: url(font.woff);
  2996 p {
  2997   /* font will be downloaded for pages with p elements */
  2998   font-family: GeometricModern, sans-serif;
  3001 h2 {
  3002   /* font may be downloaded for pages with h2 elements, even if Futura is available locally */
  3003   font-family: Futura, GeometricModern, sans-serif;
  3005 </pre>
  3007   <p>In cases where textual content is loaded before downloadable fonts are
  3008    available, user agents may render text as it would be rendered if
  3009    downloadable font resources are not available or they may render text
  3010    transparently with fallback fonts to avoid a flash of text using a
  3011    fallback font. In cases where the font download fails user agents must
  3012    display text, simply leaving transparent text is considered non-conformant
  3013    behavior. Authors are advised to use fallback fonts in their font lists
  3014    that closely match the metrics of the downloadable fonts to avoid large
  3015    page reflows where possible.
  3017   <p><a id=same-origin-restriction> </a><a
  3018    id=allowing-cross-origin-font-loading> </a>
  3020   <h3 id=font-fetching-requirements><span class=secno>4.9 </span>Font
  3021    fetching requirements</h3>
  3022   <!-- TPAC 2011 Resolution to require same-origin restriction for loading fonts:
  3023   http://lists.w3.org/Archives/Public/www-style/2011Nov/0711.html
  3024   http://www.w3.org/2011/10/31-webapps-minutes.html#item02
  3025 -->
  3027   <p>For font loads, user agents must use the <a
  3028    href="http://www.w3.org/TR/html5/infrastructure.html#cors-enabled-fetch">potentially
  3029    CORS-enabled fetch</a> method defined by the <a href="#HTML5"
  3030    rel=biblioentry>[HTML5]<!--{{!HTML5}}--></a> specification for URL's
  3031    defined within @font-face rules. When fetching, user agents must use
  3032    "Anonymous" mode, set the referrer source to the stylesheet's URL and set
  3033    the origin to the URL of the containing document.
  3035   <p class=note>The implications of this for authors are that fonts will
  3036    typically not be loaded cross-origin unless authors specifically takes
  3037    steps to permit cross-origin loads. Sites can explicitly allow cross-site
  3038    loading of font data using the <code>Access-Control-Allow-Origin</code>
  3039    HTTP header. For other schemes, no explicit mechanism to allow
  3040    cross-origin loading, beyond what is permitted by the <a
  3041    href="http://www.w3.org/TR/html5/infrastructure.html#cors-enabled-fetch">potentially
  3042    CORS-enabled fetch</a> method, is defined or required.
  3044   <div class=example> For the examples given below, assume that a document is
  3045    located at <code>http://example.com/page.html</code> and all URL's link to
  3046    valid font resources supported by the user agent. Fonts defined with the
  3047    ‘<a href="#descdef-src"><code class=property>src</code></a>’
  3048    descriptor values below will be loaded:
  3049    <pre>/* same origin (i.e. domain, scheme, port match document) */
  3050 src: url(fonts/simple.woff);
  3051 src: url(//fonts/simple.woff);
  3053 /* data url's with no redirects are treated as same origin */
  3054 src: url("data:application/font-woff;base64,...");
  3056 /* cross origin, different domain */
  3057 /* Access-Control-Allow-Origin response header set to '*' */
  3058 src: url(http://another.example.com/fonts/simple.woff);
  3059 </pre>
  3060    Fonts defined with the ‘<a href="#descdef-src"><code
  3061    class=property>src</code></a>’ descriptor values below will fail to
  3062    load:
  3063    <pre>/* cross origin, different scheme */
  3064 /* no Access-Control-xxx headers in response */
  3065 src: url(https://example.com/fonts/simple.woff);
  3067 /* cross origin, different domain */
  3068 /* no Access-Control-xxx headers in response */
  3069 src: url(http://another.example.com/fonts/simple.woff);
  3070 </pre>
  3071   </div>
  3073   <h2 id=font-matching-algorithm><span class=secno>5 </span>Font Matching
  3074    Algorithm</h2>
  3076   <p>The algorithm below describes how fonts are associated with individual
  3077    runs of text. For each character in the run a font family is chosen and a
  3078    particular font face is selected containing a glyph for that character.
  3080   <h3 id=font-family-casing><span class=secno>5.1 </span>Case sensitivity of
  3081    font family names</h3>
  3083   <p>As part of the font matching algorithm outlined below, user agents must
  3084    match font family names used in style rules with actual font family names
  3085    contained in fonts available in a given environment or with font family
  3086    names defined in <a href="#at-font-face-rule"><code>@font-face</code></a>
  3087    rules. User agents must match these names case insensitively, using the
  3088    "Default Caseless Matching" algorithm outlined in the Unicode
  3089    specification <a href="#UNICODE6"
  3090    rel=biblioentry>[UNICODE6]<!--{{!UNICODE6}}--></a>. This algorithm is
  3091    detailed in section 3.13 entitled "Default Case Algorithms". Specifically,
  3092    the algorithm must be applied without normalizing the strings involved and
  3093    without applying any language-specific tailorings. The case folding method
  3094    specified by this algorithm uses the case mappings with status field
  3095    ‘<code class=property>C</code>’ or ‘<code class=property>F</code>’
  3096    in the CaseFolding.txt file of the Unicode Character Database.
  3098   <p class=note> For authors this means that font family names are matched
  3099    case insensitively, whether those names exist in a platform font or in the
  3100    <a href="#at-font-face-rule"><code>@font-face</code></a> rules contained
  3101    in a stylesheet. Authors should take care to ensure that names use a
  3102    character sequence consistent with the actual font family name,
  3103    particularly when using combining characters such as diacritical marks.
  3104    For example, a family name that contains an uppercase A (U+0041) followed
  3105    by a combining ring (U+030A) will <strong>not</strong> match a name that
  3106    looks identical but which uses the precomposed lowercase a-ring character
  3107    (U+00E5) instead of the combining sequence.
  3109   <p class=note> Implementors should take care to verify that a given
  3110    caseless string comparison implementation uses this precise algorithm and
  3111    not assume that a given platform string matching routine follows it, as
  3112    many of these have locale-specific behavior or use some level of string
  3113    normalization.
  3115   <h3 id=font-style-matching><span class=secno>5.2 </span>Matching font
  3116    styles</h3>
  3118   <p>The procedure for choosing a font for a given character in a run of text
  3119    consists of iterating over the font families named by the <a
  3120    href="#propdef-font-family" title="font-family!!property">‘<code
  3121    class=property>font-family</code>’</a> property, selecting a font face
  3122    with the appropriate style based on other font properties and then
  3123    determining whether a glyph exists for the given character. This is done
  3124    using the <dfn id=character-map>character map</dfn> of the font, data
  3125    which maps characters to the default glyph for that character. A font is
  3126    considered to <dfn id=support>support</dfn> a given character if (1) the
  3127    character is contained in the font's <a
  3128    href="#character-map"><em>character map</em></a> and (2) if required by
  3129    the containing script, shaping information is available for that
  3130    character.
  3132   <p>Some legacy fonts may include a given character in the <a
  3133    href="#character-map"><em>character map</em></a> but lack the shaping
  3134    information (e.g. <a
  3135    href="http://www.microsoft.com/typography/otspec/ttochap1.htm">OpenType
  3136    layout tables</a> or <a
  3137    href="http://scripts.sil.org/cms/scripts/page.php?site_id=projects&amp;item_id=graphite_techAbout">Graphite
  3138    tables</a>) necessary for correctly rendering text runs containing that
  3139    character.
  3141   <p>Codepoint sequences consisting of a base character followed by a
  3142    sequence of combining characters are treated slightly differently, see the
  3143    section on <a href="#cluster-matching">cluster matching</a> below.
  3145   <p>For this procedure, the <dfn id=default-face>default face</dfn> for a
  3146    given font family is defined to be the face that would be selected if all
  3147    font style properties were set to their initial value.
  3149   <ol id=fontmatchingalg>
  3150    <li>Using the computed font property values for a given element, the user
  3151     agent starts with the first family name specified by the <a
  3152     href="#propdef-font-family" title="font-family!!property">‘<code
  3153     class=property>font-family</code>’</a> property.
  3155    <li>If the family name is a generic family keyword, the user agent looks
  3156     up the appropriate font family name to be used. User agents may choose
  3157     the generic font family to use based on the language of the containing
  3158     element or the Unicode range of the character.
  3160    <li>For other family names, the user agent attempts to find the family
  3161     name among fonts defined via <a
  3162     href="#at-font-face-rule"><code>@font-face</code></a> rules and then
  3163     among available system fonts, matching names with a <a
  3164     href="#font-family-casing">case-insensitive comparison</a> as outlined in
  3165     the section above. On systems containing fonts with multiple localized
  3166     font family names, user agents must match any of these names independent
  3167     of the underlying system locale or platform API used. If the font
  3168     resources defined for a given face in an <a
  3169     href="#at-font-face-rule"><code>@font-face</code></a> rule are either not
  3170     available or contain invalid font data, then the face should be treated
  3171     as not present in the family. If no faces are present for a family
  3172     defined via <a href="#at-font-face-rule"><code>@font-face</code></a>
  3173     rules, the family should be treated as missing; matching a platform font
  3174     with the same name must not occur in this case.
  3176    <li>If a font family match occurs, the user agent assembles the set of
  3177     font faces in that family and then narrows the set to a single face using
  3178     other font properties in the order given below. A group of faces defined
  3179     via <a href="#at-font-face-rule"><code>@font-face</code></a> rules with
  3180     identical font descriptor values but differing ‘<a
  3181     href="#descdef-unicode-range"><code
  3182     class=property>unicode-range</code></a>’ values are considered to be a
  3183     single <dfn id=composite-face>composite face</dfn> for this step:
  3184     <ol id=fontstylematchingalg>
  3185      <li><a href="#propdef-font-stretch"
  3186       title="font-stretch!!property">‘<code
  3187       class=property>font-stretch</code>’</a> is tried first. If the
  3188       matching set contains faces with width values matching the <a
  3189       href="#propdef-font-stretch" title="font-stretch!!property">‘<code
  3190       class=property>font-stretch</code>’</a> value, faces with other width
  3191       values are removed from the matching set. If there is no face that
  3192       exactly matches the width value the nearest width is used instead. If
  3193       the value of <a href="#propdef-font-stretch"
  3194       title="font-stretch!!property">‘<code
  3195       class=property>font-stretch</code>’</a> is <a
  3196       href="#font-stretch-normal-value" title="normal!!font-stretch">‘<code
  3197       class=property>normal</code>’</a> or one of the condensed values,
  3198       narrower width values are checked first, then wider values. If the
  3199       value of <a href="#propdef-font-stretch"
  3200       title="font-stretch!!property">‘<code
  3201       class=property>font-stretch</code>’</a> is one of the expanded
  3202       values, wider values are checked first, followed by narrower values.
  3203       Once the closest matching width has been determined by this process,
  3204       faces with other widths are removed from the matching set.
  3206      <li><a href="#propdef-font-style" title="font-style!!property">‘<code
  3207       class=property>font-style</code>’</a> is tried next. If the value of
  3208       <a href="#propdef-font-style" title="font-style!!property">‘<code
  3209       class=property>font-style</code>’</a> is ‘<a href="#italic"><code
  3210       class=property>italic</code></a>’, italic faces are checked first,
  3211       then oblique, then normal faces. If the value is ‘<a
  3212       href="#oblique"><code class=property>oblique</code></a>’, oblique
  3213       faces are checked first, then italic faces and then normal faces. If
  3214       the value is <a href="#font-style-normal-value"
  3215       title="normal!!font-style">‘<code
  3216       class=property>normal</code>’</a>, normal faces are checked first,
  3217       then oblique faces, then italic faces. Faces with other style values
  3218       are excluded from the matching set. User agents are permitted to
  3219       distinguish between italic and oblique faces within platform font
  3220       families but this is not required, so all italic or oblique faces may
  3221       be treated as italic faces. However, within font families defined via
  3222       <a href="#at-font-face-rule"><code>@font-face</code></a> rules, italic
  3223       and oblique faces must be distinguished using the value of the <a
  3224       href="#descdef-font-style" title="font-style!!descriptor">‘<code
  3225       class=property>font-style</code>’</a> descriptor. For families that
  3226       lack any italic or oblique faces, users agents may create artificial
  3227       oblique faces, if this is permitted by the value of the ‘<a
  3228       href="#propdef-font-synthesis"><code
  3229       class=property>font-synthesis</code></a>’ property.
  3231      <li><a href="#propdef-font-weight"
  3232       title="font-weight!!property">‘<code
  3233       class=property>font-weight</code>’</a> is matched next, so it will
  3234       always reduce the matching set to a single font face. If bolder/lighter
  3235       relative weights are used, the effective weight is calculated based on
  3236       the inherited weight value, as described in the definition of the <a
  3237       href="#propdef-font-weight" title="font-weight!!property">‘<code
  3238       class=property>font-weight</code>’</a> property. Given the desired
  3239       weight and the weights of faces in the matching set after the steps
  3240       above, if the desired weight is available that face matches. Otherwise,
  3241       a weight is chosen using the rules below:
  3242       <ul>
  3243        <li>If the desired weight is less than 400, weights below the desired
  3244         weight are checked in descending order followed by weights above the
  3245         desired weight in ascending order until a match is found.
  3247        <li>If the desired weight is greater than 500, weights above the
  3248         desired weight are checked in ascending order followed by weights
  3249         below the desired weight in descending order until a match is found.
  3251        <li>If the desired weight is 400, 500 is checked first and then the
  3252         rule for desired weights less than 400 is used.
  3254        <li>If the desired weight is 500, 400 is checked first and then the
  3255         rule for desired weights less than 400 is used.
  3256       </ul>
  3258      <li><span class=property>‘<a href="#propdef-font-size"><code
  3259       class=property>font-size</code></a>’</span> must be matched within a
  3260       UA-dependent margin of tolerance. (Typically, sizes for scalable fonts
  3261       are rounded to the nearest whole pixel, while the tolerance for
  3262       bitmapped fonts could be as large as 20%.) Further computations, e.g.,
  3263       by ‘<code class=property>em</code>’ values in other properties, are
  3264       based on the <span class=property>‘<a href="#propdef-font-size"><code
  3265       class=property>font-size</code></a>’</span> value that is used, not
  3266       the one that is specified.
  3267     </ol>
  3269    <li>
  3270     <p>If the matched face is defined via <a
  3271      href="#at-font-face-rule"><code>@font-face</code></a> rules, user agents
  3272      must use the procedure below to select a single font:
  3274     <ol>
  3275      <li>If the font resource has not been loaded and the range of characters
  3276       defined by the ‘<a href="#descdef-unicode-range"><code
  3277       class=property>unicode-range</code></a>’ descriptor value includes
  3278       the character in question, load the font.
  3280      <li>After downloading, if the <a
  3281       href="#effective-character-map"><em>effective character map</em></a>
  3282       supports the character in question, select that font.
  3283     </ol>
  3285     <p>When the matched face is a <a href="#composite-face"><em>composite
  3286      face</em></a>, user agents must use the procedure above on each of the
  3287      faces in the <a href="#composite-face"><em>composite face</em></a> in
  3288      reverse order of <a
  3289      href="#at-font-face-rule"><code>@font-face</code></a> rule definition.</p>
  3291     <p>While the download occurs, user agents may either wait until the font
  3292      is downloaded or render once with substituted font metrics and render
  3293      again once the font is downloaded.</p>
  3295    <li>
  3296     <p>If no matching face exists or the matched face does not contain a
  3297      glyph for the character to be rendered, the next family name is selected
  3298      and the previous three steps repeated. Glyphs from other faces in the
  3299      family are not considered. The only exception is that user agents may
  3300      optionally substitute a synthetically obliqued version of the <a
  3301      href="#default-face"><em>default face</em></a> if that face supports a
  3302      given glyph and synthesis of these faces is permitted by the value of
  3303      the ‘<a href="#propdef-font-synthesis"><code
  3304      class=property>font-synthesis</code></a>’ property. For example, a
  3305      synthetic italic version of the regular face may be used if the italic
  3306      face doesn't support glyphs for Arabic.</p>
  3307     <!-- resolution on the above: http://lists.w3.org/Archives/Public/www-style/2012Nov/0292.html -->
  3310    <li>If there are no more font families to be evaluated and no matching
  3311     face has been found, then the user agent performs a <dfn
  3312     id=system-font-fallback>system font fallback</dfn> procedure to find the
  3313     best match for the character to be rendered. The result of this procedure
  3314     may vary across user agents.
  3316    <li>If a particular character cannot be displayed using any font, the user
  3317     agent should indicate by some means that a character is not being
  3318     displayed, displaying either a symbolic representation of the missing
  3319     glyph (e.g. using a <a
  3320     href="http://en.wikipedia.org/wiki/Last_resort_font">Last Resort
  3321     Font</a>) or using the missing character glyph from a default font.
  3322   </ol>
  3324   <p>Optimizations of this process are allowed provided that an
  3325    implementation behaves as if the algorithm had been followed exactly.
  3326    Matching occurs in a well-defined order to insure that the results are as
  3327    consistent as possible across user agents, given an identical set of
  3328    available fonts and rendering technology.
  3330   <p>The <dfn id=first-available-font>first available font</dfn>, used in the
  3331    definition of <a
  3332    href="http://www.w3.org/TR/css3-values/#font-relative-lengths"><em>font-relative
  3333    lengths</em></a> such as ‘<code class=property>ex</code>’ and ‘<code
  3334    class=property>ch</code>’, is defined to be the first available font
  3335    that would match any character given font families in the ‘<code
  3336    class=property>font-family</code>’ list (or a user agent's default font
  3337    if none are available).
  3339   <h3 id=cluster-matching><span class=secno>5.3 </span>Cluster matching</h3>
  3341   <p>When text contains characters such as combining marks, ideally the base
  3342    character should be rendered using the same font as the mark, this assures
  3343    proper placement of the mark. For this reason, the font matching algorithm
  3344    for clusters is more specialized than the general case of matching a
  3345    single character by itself. For sequences containing variation selectors,
  3346    which indicate the precise glyph to be used for a given character, user
  3347    agents always attempt <a href="#system-font-fallback"><em>system font
  3348    fallback</em></a> to find the appropriate glyph before using the default
  3349    glyph of the base character.
  3351   <p>A sequence of codepoints containing combining mark or other modifiers is
  3352    termed a grapheme cluster (see <a href="#CSS3TEXT"
  3353    rel=biblioentry>[CSS3TEXT]<!--{{CSS3TEXT}}--></a> for a more complete
  3354    description). For a given cluster containing a base character, <em>b</em>
  3355    and a sequence of combining characters <em>c1, c2…</em>, the entire
  3356    cluster is matched using these steps:
  3358   <ol>
  3359    <li>For each family in the font list, a face is chosen using the style
  3360     selection rules defined in the previous section.
  3361     <ol>
  3362      <li>If all characters in the sequence <em>b + c1 + c2 …</em> are
  3363       completely supported by the font, select this font for the sequence.
  3365      <li>If a sequence of multiple codepoints is canonically equivalent to a
  3366       single character and the font <a href="#support"><em
  3367       title=support>supports</em></a> that character, select this font for
  3368       the sequence.
  3369     </ol>
  3371    <li>If no font was found in the font list in step 1:
  3372     <ol>
  3373      <li>If <em>c1</em> is a variation selector, system fallback must be used
  3374       to find a font that <a href="#support"><em
  3375       title=support>supports</em></a> the full sequence of <em>b + c1</em>.
  3376       If no font on the system <a href="#support"><em
  3377       title=support>supports</em></a> the full sequence, match the single
  3378       character <em>b</em> using the normal procedure for matching single
  3379       characters and ignore the variation selector. Note: a sequence with
  3380       more than one variation selector must be treated as an encoding error
  3381       and the trailing selectors must be ignored. <a href="#UNICODE6"
  3382       rel=biblioentry>[UNICODE6]<!--{{!UNICODE6}}--></a>
  3384      <li>Otherwise, the user agent may optionally use system font fallback to
  3385       match a font that <a href="#support"><em
  3386       title=support>supports</em></a> the entire cluster.
  3387     </ol>
  3389    <li>If no font is found in step 2, use the matching sequence from step 1
  3390     to determine the longest sequence that is completely <a
  3391     href="#support"><em title=support>supported</em></a> by a font in the
  3392     font list and attempt to match the remaining combining characters
  3393     separately using the rules for single characters.
  3394   </ol>
  3396   <h3 id=char-handling-issues><span class=secno>5.4 </span>Character handling
  3397    issues</h3>
  3399   <p>CSS font matching is always performed on text runs containing Unicode
  3400    characters, so documents using legacy encodings are assumed to have been
  3401    transcoded before matching fonts. For fonts containing <a
  3402    href="#character-map"><em title="character map">character maps</em></a>
  3403    for both legacy encodings and Unicode, the contents of the legacy encoding
  3404    <a href="#character-map"><em>character map</em></a> must have no effect on
  3405    the results of the font matching process.
  3407   <p>The font matching process does not assume that text runs are in either
  3408    normalized or denormalized form (see <a href="#CHARMOD-NORM"
  3409    rel=biblioentry>[CHARMOD-NORM]<!--{{CHARMOD-NORM}}--></a> for more
  3410    details). Fonts may only support precomposed forms and not the decomposed
  3411    sequence of base character plus combining marks. Authors should always
  3412    tailor their choice of fonts to their content, including whether that
  3413    content contains normalized or denormalized character streams.
  3415   <p>If a given character is a Private-Use Area Unicode codepoint, user
  3416    agents must only match font families named in the ‘<code
  3417    class=property>font-family</code>’ list that are not generic families.
  3418    If none of the families named in the ‘<code
  3419    class=property>font-family</code>’ list contain a glyph for that
  3420    codepoint, user agents must display some form of missing glyph symbol for
  3421    that character rather than attempting <a
  3422    href="#system-font-fallback"><em>system font fallback</em></a> for that
  3423    codepoint. When matching the replacement character U+FFFD, user agents may
  3424    skip the font matching process and immediately display some form of
  3425    missing glyph symbol, they are not required to display the glyph from the
  3426    font that would be selected by the font matching process.
  3428   <p>In general, the fonts for a given family will all have the same or
  3429    similar <a href="#character-map"><em title="character map">character
  3430    maps</em></a>. The process outlined here is designed to handle even font
  3431    families containing faces with widely variant <a href="#character-map"><em
  3432    title="character map">character maps</em></a>. However, authors are
  3433    cautioned that the use of such families can lead to unexpected results.
  3435   <h3 id=font-matching-changes><span class=secno>5.5 </span>Font matching
  3436    changes since CSS 2.1</h3>
  3438   <p>The algorithm above is different from CSS 2.1 in a number of key places.
  3439    These changes were made to better reflect actual font matching behavior
  3440    across user agent implementations.
  3442   <p>Differences compared to the font matching algorithm in CSS 2.1:
  3444   <ul>
  3445    <li>The algorithm includes font-stretch matching.
  3447    <li>All possible font-style matching scenarios are delineated.
  3449    <li>Small-caps fonts are not matched as part of the font matching process,
  3450     they are now handled via font features.
  3452    <li>Unicode variation selector matching is required.
  3454    <li>Cluster sequences are matched as a unit.
  3455   </ul>
  3457   <h3 id=font-matching-examples><span class=secno>5.6 </span>Font matching
  3458    examples</h3>
  3460   <div class=example>
  3461    <p>It's useful to note that the CSS selector syntax may be used to create
  3462     language-sensitive typography. For example, some Chinese and Japanese
  3463     characters are unified to have the same Unicode code point, although the
  3464     abstract glyphs are not the same in the two languages.
  3466    <pre>*:lang(ja-jp) { font: 900 14pt/16pt &quot;Heisei Mincho W9&quot;, serif; }
  3467 *:lang(zh-tw) { font: 800 14pt/16.5pt &quot;Li Sung&quot;, serif; }
  3468 </pre>
  3470    <p>This selects any element that has the given language — Japanese or
  3471     Traditional Chinese — and uses the appropriate font.
  3472   </div>
  3474   <h2 id=font-rend-props><span class=secno>6 </span>Font Feature Properties</h2>
  3476   <p>Modern font technologies support a variety of advanced typographic and
  3477    language-specific font features. Using these features, a single font can
  3478    provide glyphs for a wide range of ligatures, contextual and stylistic
  3479    alternates, tabular and old-style figures, small capitals, automatic
  3480    fractions, swashes, and alternates specific to a given language. To allow
  3481    authors control over these font capabilities, the ‘<code
  3482    class=property>font-variant</code>’ property has been expanded for CSS3.
  3483    It now functions as a shorthand for a set of properties that provide
  3484    control over stylistic font features.
  3486   <h3 id=glyph-selection-positioning><span class=secno>6.1 </span>Glyph
  3487    selection and positioning</h3>
  3489   <p>Simple fonts used for displaying Latin text use a very basic processing
  3490    model. Fonts contain a <a href="#character-map"><em>character map</em></a>
  3491    which maps each character to a glyph for that character. Glyphs for
  3492    subsequent characters are simply placed one after the other along a run of
  3493    text. Modern font formats such as OpenType and AAT (Apple Advanced
  3494    Typography) use a richer processing model. The glyph for a given character
  3495    can be chosen and positioned not just based on the codepoint of the
  3496    character itself, but also on adjacent characters as well as the language,
  3497    script, and features enabled for the text. Font features may be required
  3498    for specific scripts, or recommended as enabled by default or they might
  3499    be stylistic features meant to be used under author control.
  3501   <p>For a good visual overview of these features, see the <a
  3502    href="#OPENTYPE-FONT-GUIDE"
  3503    rel=biblioentry>[OPENTYPE-FONT-GUIDE]<!--{{OPENTYPE-FONT-GUIDE}}--></a>.
  3504    For a detailed description of glyph processing for OpenType fonts, see <a
  3505    href="#WINDOWS-GLYPH-PROC"
  3506    rel=biblioentry>[WINDOWS-GLYPH-PROC]<!--{{WINDOWS-GLYPH-PROC}}--></a>.
  3508   <p>Stylistic font features can be classified into two broad categories:
  3509    ones that affect the harmonization of glyph shapes with the surrounding
  3510    context, such as kerning and ligature features, and ones such as the
  3511    small-caps, subscript/superscript and alternate features that affect shape
  3512    selection.
  3514   <p>The subproperties of <a href="#propdef-font-variant"
  3515    title="font-variant!!property">‘<code
  3516    class=property>font-variant</code>’</a> listed below are used to control
  3517    these stylistic font features. They do not control features that are
  3518    required for displaying certain scripts, such as the OpenType features
  3519    used when displaying Arabic or Indic language text. They affect glyph
  3520    selection and positioning, but do not affect font selection as described
  3521    in the font matching section (except in cases required for compatibility
  3522    with CSS 2.1).
  3524   <p>To assure consistent behavior across user agents, the equivalent
  3525    OpenType property settings are listed for individual properties and are
  3526    normative. When using other font formats these should be used as a
  3527    guideline to map CSS font feature property values to specific font
  3528    features.
  3530   <h3 id=language-specific-support><span class=secno>6.2
  3531    </span>Language-specific display</h3>
  3533   <p>OpenType also supports language-specific glyph selection and
  3534    positioning, so that text can be displayed correctly in cases where the
  3535    language dictates a specific display behavior. Many languages share a
  3536    common script, but the shape of certain letters can vary across those
  3537    languages. For example, certain Cyrillic letters have different shapes in
  3538    Russian text than in Bulgarian. In Latin text, it's common to render "fi"
  3539    with an explicit fi-ligature that lacks a dot on the "i". However, in
  3540    languages such as Turkish which uses both a dotted-i and a dotless-i, it's
  3541    important to not use this ligature or use a specialized version that
  3542    contains a dot over the "i". The example below shows language-specific
  3543    variations based on stylistic traditions found in Spanish, Italian and
  3544    French orthography:
  3546   <div class=featex><img alt="language specific forms, spanish"
  3547    src=locl-1.png></div>
  3549   <div class=featex><img alt="language specific forms, italian"
  3550    src=locl-2.png></div>
  3552   <div class=featex><img alt="language specific forms, french"
  3553    src=locl-3.png></div>
  3555   <p>If the content language of the element is known according to the rules
  3556    of the <a
  3557    href="http://www.w3.org/TR/CSS21/conform.html#doclanguage">document
  3558    language</a>, user agents are required to infer the OpenType language
  3559    system from the content language and use that when selecting and
  3560    positioning glyphs using an OpenType font.
  3562   <p>For OpenType fonts, in some cases it may be necessary to explicitly
  3563    declare the OpenType language to be used, for example when displaying text
  3564    in a given language that uses the typographic conventions of another
  3565    language or when the font does not explicitly support a given language but
  3566    supports a language that shares common typographic conventions. The ‘<a
  3567    href="#propdef-font-language-override"><code
  3568    class=property>font-language-override</code></a>’ property is used for
  3569    this purpose.</p>
  3570   <!-- prop: font-kerning -->
  3572   <h3 id=font-kerning-prop><span class=secno>6.3 </span>Kerning: the <a
  3573    href="#propdef-font-kerning">font-kerning</a> property</h3>
  3575   <table class=propdef id=namefont-kerningvalueauto-normal-noneini>
  3576    <tbody>
  3577     <tr>
  3578      <td>Name:
  3580      <td><dfn id=propdef-font-kerning>font-kerning</dfn>
  3582     <tr>
  3583      <td>Value:
  3585      <td><a href="#font-kerning-auto-value"
  3586       title="auto!!font-kerning">auto</a> | <a
  3587       href="#font-kerning-normal-value"
  3588       title="normal!!font-kerning">normal</a> | <a
  3589       href="#font-kerning-none-value" title="none!!font-kerning">none</a>
  3591     <tr>
  3592      <td>Initial:
  3594      <td>auto
  3596     <tr>
  3597      <td>Applies to:
  3599      <td>all elements
  3601     <tr>
  3602      <td>Inherited:
  3604      <td>yes
  3606     <tr>
  3607      <td>Percentages:
  3609      <td>N/A
  3611     <tr>
  3612      <td>Media:
  3614      <td>visual
  3616     <tr>
  3617      <td>Computed value:
  3619      <td>as specified
  3621     <tr>
  3622      <td>Animatable:
  3624      <td>no
  3625   </table>
  3627   <p>Kerning is the contextual adjustment of inter-glyph spacing. This
  3628    property controls metric kerning, kerning that utilizes adjustment data
  3629    contained in the font.
  3631   <dl>
  3632    <dt><dfn id=font-kerning-auto-value title="auto!!font-kerning">auto</dfn>
  3634    <dd>Specifies that kerning is applied at the discretion of the user agent
  3636    <dt><dfn id=font-kerning-normal-value
  3637     title="normal!!font-kerning">normal</dfn>
  3639    <dd>Specifies that kerning is applied
  3641    <dt><dfn id=font-kerning-none-value title="none!!font-kerning">none</dfn>
  3643    <dd>Specifies that kerning is not applied
  3644   </dl>
  3646   <p>For fonts that do not include kerning data this property will have no
  3647    visible effect. When rendering with OpenType fonts, the <a
  3648    href="#OPENTYPE" rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a>
  3649    specification suggests that kerning be enabled by default. When kerning is
  3650    enabled, the OpenType <span class=tag>kern</span> feature is enabled (for
  3651    vertical text runs the <span class=tag>vkrn</span> feature is enabled
  3652    instead). User agents must also support fonts that only support kerning
  3653    via data contained in a <span class=tag>kern</span> font table, as
  3654    detailed in the OpenType specification. If the ‘<code
  3655    class=property>letter-spacing</code>’ property is defined, kerning
  3656    adjustments are considered part of the default spacing and letter spacing
  3657    adjustments are made after kerning has been applied.
  3659   <p>When set to ‘<code class=property>auto</code>’, user agents can
  3660    determine whether to apply kerning or not based on a number of factors:
  3661    text size, script, or other factors that influence text processing speed.
  3662    Authors who want proper kerning should use <a
  3663    href="#font-kerning-normal-value" title="normal!!font-kerning">‘<code
  3664    class=property>normal</code>’</a> to explicitly enable kerning.
  3665    Likewise, some authors may prefer to disable kerning in situations where
  3666    performance is more important than precise appearance. However, in
  3667    well-designed modern implementations the use of kerning generally does not
  3668    have a large impact on text rendering speed.</p>
  3669   <!-- prop: font-variant-ligatures -->
  3671   <h3 id=font-variant-ligatures-prop><span class=secno>6.4 </span>Ligatures:
  3672    the <a href="#propdef-font-variant-ligatures">font-variant-ligatures</a>
  3673    property</h3>
  3675   <table class=propdef id=namefont-variant-ligaturesvaluenormal-no>
  3676    <tbody>
  3677     <tr>
  3678      <td>Name:
  3680      <td><dfn id=propdef-font-variant-ligatures>font-variant-ligatures</dfn>
  3682     <tr>
  3683      <td>Value:
  3685      <td><a href="#font-variant-ligatures-normal-value"
  3686       title="normal!!font-variant-ligatures">normal</a> | <a
  3687       href="#font-variant-ligatures-none-value"
  3688       title="none!!font-variant-ligatures">none</a> | [ <a
  3689       href="#common-lig-values"><var>&lt;common-lig-values&gt;</var></a> ||
  3690       <a
  3691       href="#discretionary-lig-values"><var>&lt;discretionary-lig-values&gt;</var></a>
  3692       || <a
  3693       href="#historical-lig-values"><var>&lt;historical-lig-values&gt;</var></a>
  3694       || <a
  3695       href="#contextual-alt-values"><var>&lt;contextual-alt-values&gt;</var></a>
  3698     <tr>
  3699      <td>Initial:
  3701      <td>normal
  3703     <tr>
  3704      <td>Applies to:
  3706      <td>all elements
  3708     <tr>
  3709      <td>Inherited:
  3711      <td>yes
  3713     <tr>
  3714      <td>Percentages:
  3716      <td>N/A
  3718     <tr>
  3719      <td>Media:
  3721      <td>visual
  3723     <tr>
  3724      <td>Computed value:
  3726      <td>as specified
  3728     <tr>
  3729      <td>Animatable:
  3731      <td>no
  3732   </table>
  3734   <p>Ligatures and contextual forms are ways of combining glyphs to produce
  3735    more harmonized forms.
  3737   <pre
  3738    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>
  3740   <pre
  3741    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>
  3743   <pre
  3744    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>
  3746   <pre
  3747    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>
  3749   <p>Individual values have the following meanings:
  3751   <dl>
  3752    <dt><dfn id=font-variant-ligatures-normal-value
  3753     title="normal!!font-variant-ligatures">normal</dfn>
  3755    <dd>A value of <a href="#font-variant-ligatures-normal-value"
  3756     title="normal!!font-variant-ligatures">‘<code
  3757     class=property>normal</code>’</a> specifies that common default
  3758     features are enabled, <a href="#font-feature-resolution">as described in
  3759     detail in the next section</a>. For OpenType fonts, common ligatures and
  3760     contextual forms are on by default, discretionary and historical
  3761     ligatures are not.
  3763    <dt><dfn id=font-variant-ligatures-none-value
  3764     title="none!!font-variant-ligatures">none</dfn>
  3766    <dd>Specifies that all types of ligatures and contextual forms covered by
  3767     this property are explicitly disabled. In situations where ligatures are
  3768     not considered necessary, this may improve the speed of text rendering.
  3770    <dt><dfn id=common-ligatures>common-ligatures</dfn>
  3772    <dd>Enables display of common ligatures (OpenType features: <span
  3773     class=tag>liga, clig</span>). For OpenType fonts, common ligatures are
  3774     enabled by default.
  3775   </dl>
  3777   <div class=featex><img alt="common ligature example" src=liga.png></div>
  3779   <dl>
  3780    <dt><dfn id=no-common-ligatures>no-common-ligatures</dfn>
  3782    <dd>Disables display of common ligatures (OpenType features: <span
  3783     class=tag>liga, clig</span>).
  3785    <dt><dfn id=discretionary-ligatures>discretionary-ligatures</dfn>
  3787    <dd>Enables display of discretionary ligatures (OpenType feature: <span
  3788     class=tag>dlig</span>). Which ligatures are discretionary or optional is
  3789     decided by the type designer, so authors will need to refer to the
  3790     documentation of a given font to understand which ligatures are
  3791     considered discretionary.
  3792   </dl>
  3794   <div class=featex><img alt="discretionary ligature example" src=dlig.png></div>
  3796   <dl>
  3797    <dt><dfn id=no-discretionary-ligatures>no-discretionary-ligatures</dfn>
  3799    <dd>Disables display of discretionary ligatures (OpenType feature: <span
  3800     class=tag>dlig</span>).
  3802    <dt><dfn id=historical-ligatures>historical-ligatures</dfn>
  3804    <dd>Enables display of historical ligatures (OpenType feature: <span
  3805     class=tag>hlig</span>).
  3806   </dl>
  3808   <div class=featex><img alt="historical ligature example" src=hlig.png></div>
  3810   <dl>
  3811    <dt><dfn id=no-historical-ligatures>no-historical-ligatures</dfn>
  3813    <dd>Disables display of historical ligatures (OpenType feature: <span
  3814     class=tag>hlig</span>).
  3816    <dt><dfn id=contextual>contextual</dfn>
  3818    <dd>Enables display of contextual alternates (OpenType feature: <span
  3819     class=tag>calt</span>). Although not strictly a ligature feature, like
  3820     ligatures this feature is commonly used to harmonize the shapes of glyphs
  3821     with the surrounding context. For OpenType fonts, this feature is on by
  3822     default.
  3823   </dl>
  3825   <div class=featex><img alt="contextual alternate example" src=calt.png></div>
  3827   <dl>
  3828    <dt><dfn id=no-contextual>no-contextual</dfn>
  3830    <dd>Disables display of contextual alternates (OpenType feature: <span
  3831     class=tag>calt</span>).
  3832   </dl>
  3834   <p>Required ligatures, needed for correctly rendering complex scripts, are
  3835    not affected by the settings above, including ‘<code
  3836    class=property>none</code>’ (OpenType feature: <span
  3837    class=tag>rlig</span>).</p>
  3838   <!-- prop: font-variant-position -->
  3840   <h3 id=font-variant-position-prop><span class=secno>6.5 </span>Subscript
  3841    and superscript forms: the <a
  3842    href="#propdef-font-variant-position">font-variant-position</a> property</h3>
  3844   <table class=propdef id=namefont-variant-positionvaluenormal-sub>
  3845    <tbody>
  3846     <tr>
  3847      <td>Name:
  3849      <td><dfn id=propdef-font-variant-position>font-variant-position</dfn>
  3851     <tr>
  3852      <td>Value:
  3854      <td><a href="#font-variant-position-normal-value"
  3855       title="normal!!font-variant-position">normal</a> | <a
  3856       href="#sub">sub</a> | <a href="#super">super</a>
  3858     <tr>
  3859      <td>Initial:
  3861      <td>normal
  3863     <tr>
  3864      <td>Applies to:
  3866      <td>all elements
  3868     <tr>
  3869      <td>Inherited:
  3871      <td>yes
  3873     <tr>
  3874      <td>Percentages:
  3876      <td>N/A
  3878     <tr>
  3879      <td>Media:
  3881      <td>visual
  3883     <tr>
  3884      <td>Computed value:
  3886      <td>as specified
  3888     <tr>
  3889      <td>Animatable:
  3891      <td>no
  3892   </table>
  3894   <p>This property is used to enable typographic subscript and superscript
  3895    glyphs. These are alternate glyphs designed within the same em-box as
  3896    default glyphs and are intended to be laid out on the same baseline as the
  3897    default glyphs, with no resizing or repositioning of the baseline. They
  3898    are explicitly designed to match the surrounding text and to be more
  3899    readable without affecting the line height.
  3901   <div class=figure><img alt="comparison between real subscript glyphs and
  3902    synthesized ones" src=realsubscripts.png>
  3903    <p class=caption>Subscript glyphs (top) vs. typical synthesized subscripts
  3904     (bottom)
  3905   </div>
  3907   <p>Individual values have the following meanings:
  3909   <dl>
  3910    <dt><dfn id=font-variant-position-normal-value
  3911     title="normal!!font-variant-position">normal</dfn>
  3913    <dd>None of the features listed below are enabled.
  3915    <dt><dfn id=sub>sub</dfn>
  3917    <dd>Enables display of subscript variants (OpenType feature: <span
  3918     class=tag>subs</span>).
  3920    <dt><dfn id=super>super</dfn>
  3922    <dd>Enables display of superscript variants (OpenType feature: <span
  3923     class=tag>sups</span>).
  3924   </dl>
  3926   <p>Because of the semantic nature of subscripts and superscripts, when the
  3927    value is either ‘<a href="#sub"><code class=property>sub</code></a>’
  3928    or ‘<a href="#super"><code class=property>super</code></a>’ for a
  3929    given contiguous run of text, if a variant glyph is not available for all
  3930    the characters in the run, simulated glyphs must be synthesized for all
  3931    characters using reduced forms of the glyphs that would be used without
  3932    this feature applied. This is done per run to avoid a mixture of variant
  3933    glyphs and synthesized ones that would not align correctly. In the case of
  3934    OpenType fonts that lack subscript or superscript glyphs for a given
  3935    character, user agents must use the appropriate subscript and superscript
  3936    metrics specified in the selected font's <a
  3937    href="http://www.microsoft.com/typography/otspec/os2.htm#subxs">OS/2
  3938    table</a> <a href="#OPENTYPE"
  3939    rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a> to calculate the size
  3940    and offset of the synthesized substitutes.
  3942   <div class=figure><img alt="alternate superscripts vs. glyphs synthesized
  3943    using superscript metrics" src=superscript-alt-synth.png>
  3944    <p class=caption>Superscript alternate glyph (left), synthesized
  3945     superscript glyphs (middle), and incorrect mixture of the two (right)
  3946   </div>
  3948   <p>In situations where text decorations are only applied to runs of text
  3949    containing superscript or subscript glyphs, the synthesized glyphs must be
  3950    used to avoid problems with the placement of decorations.
  3952   <p>In the past, user agents have used font-size and vertical-align to
  3953    simulate subscripts and superscripts for the <code title="HTML sub
  3954    element">sub</code> and <code title="HTML sup element">sup</code>
  3955    elements. To allow a backwards compatible way of defining subscripts and
  3956    superscripts, it is recommended that authors use conditional rules <a
  3957    href="#CSS3-CONDITIONAL"
  3958    rel=biblioentry>[CSS3-CONDITIONAL]<!--{{CSS3-CONDITIONAL}}--></a> so that
  3959    older user agents will still render subscripts and superscripts via the
  3960    older mechanism.
  3962   <p>Authors should note that fonts typically only provide subscript and
  3963    superscript glyphs for a subset of all characters supported by the font.
  3964    For example, while subscript and superscript glyphs are often available
  3965    for Latin numbers, glyphs for punctuation and letter characters are less
  3966    frequently provided. The synthetic fallback rules defined for this
  3967    property assure that subscripts and superscripts will always appear but
  3968    the appearance may not match author expectations if the font used does not
  3969    provide the appropriate alternate glyph for all characters contained in a
  3970    subscript or superscript.
  3972   <p>This property is not cumulative. Applying it to elements within a
  3973    subscript or superscript won't nest the placement of a subscript or
  3974    superscript glyph. Images contained within text runs where the value of
  3975    this property is ‘<a href="#sub"><code class=property>sub</code></a>’
  3976    or ‘<a href="#super"><code class=property>super</code></a>’ will be
  3977    drawn just as they would if the value was <a
  3978    href="#font-variant-position-normal-value"
  3979    title="normal!!font-variant-position">‘<code
  3980    class=property>normal</code>’</a>.</p>
  3981   <!-- due to lack of consensus, couldn't resolve on exact positioning of text decorations:
  3982 http://www.w3.org/2013/06/06-css-minutes.html#item03 -->
  3984   <p>Because of these limitations, ‘<a
  3985    href="#propdef-font-variant-position"><code
  3986    class=property>font-variant-position</code></a>’ is not recommended for
  3987    use in user agent stylesheets. Authors should use it in cases where
  3988    subscripts or superscripts will only contain the narrow range of
  3989    characters supported by the fonts specified.
  3991   <p class=note>The variant glyphs use the same baseline as the default
  3992    glyphs would use. There is no shift in the placement along the baseline,
  3993    so the use of variant glyphs doesn't affect the height of the inline box
  3994    or alter the height of the linebox. This makes superscript and subscript
  3995    variants ideal for situations where it's important that leading remain
  3996    constant, such as in multi-column layout.
  3998   <div class=example>
  3999    <p>A typical user agent default style for the <a class=tag
  4000     href="#sub">sub</a> element:</p>
  4002    <pre>sub {
  4003   vertical-align: sub;
  4004   font-size: smaller;
  4005   line-height: normal;
  4007 </pre>
  4009    <p>Using font-variant-position to specify typographic subscripts in a way
  4010     that will still show subscripts in older user agents:</p>
  4012    <pre>@supports ( font-variant-position: sub ) {
  4014   sub {
  4015     vertical-align: baseline;
  4016     font-size: 100%;
  4017     line-height: inherit;
  4018     font-variant-position: sub;
  4022 </pre>
  4024    <p>User agents that support the ‘<a
  4025     href="#propdef-font-variant-position"><code
  4026     class=property>font-variant-position</code></a>’ property will select a
  4027     subscript variant glyph and render this without adjusting the baseline or
  4028     font-size. Older user agents will ignore the ‘<a
  4029     href="#propdef-font-variant-position"><code
  4030     class=property>font-variant-position</code></a>’ property definition
  4031     and use the standard defaults for subscripts.</p>
  4032   </div>
  4033   <!-- prop: font-variant-caps -->
  4035   <h3 id=font-variant-caps-prop><span class=secno>6.6 </span>Capitalization:
  4036    the <a href="#propdef-font-variant-caps">font-variant-caps</a> property</h3>
  4038   <table class=propdef id=namefont-variant-capsvaluenormal-small-c>
  4039    <tbody>
  4040     <tr>
  4041      <td>Name:
  4043      <td><dfn id=propdef-font-variant-caps>font-variant-caps</dfn>
  4045     <tr>
  4046      <td>Value:
  4048      <td><a href="#font-variant-caps-normal-value"
  4049       title="normal!!font-variant-caps">normal</a> | <a
  4050       href="#small-caps">small-caps</a> | <a
  4051       href="#all-small-caps">all-small-caps</a> | <a
  4052       href="#petite-caps">petite-caps</a> | <a
  4053       href="#all-petite-caps">all-petite-caps</a> | <a
  4054       href="#unicase">unicase</a> | <a href="#titling-caps">titling-caps</a>
  4056     <tr>
  4057      <td>Initial:
  4059      <td>normal
  4061     <tr>
  4062      <td>Applies to:
  4064      <td>all elements
  4066     <tr>
  4067      <td>Inherited:
  4069      <td>yes
  4071     <tr>
  4072      <td>Percentages:
  4074      <td>N/A
  4076     <tr>
  4077      <td>Media:
  4079      <td>visual
  4081     <tr>
  4082      <td>Computed value:
  4084      <td>as specified
  4086     <tr>
  4087      <td>Animatable:
  4089      <td>no
  4090   </table>
  4092   <p>This property allows the selection of alternate glyphs used for small or
  4093    petite capitals or for titling. These glyphs are specifically designed to
  4094    blend well with the surrounding normal glyphs, to maintain the weight and
  4095    readability which suffers when text is simply resized to fit this purpose.
  4097   <p>Individual values have the following meanings:
  4099   <dl>
  4100    <dt><dfn id=font-variant-caps-normal-value
  4101     title="normal!!font-variant-caps">normal</dfn>
  4103    <dd>None of the features listed below are enabled.
  4105    <dt><dfn id=small-caps>small-caps</dfn>
  4107    <dd>Enables display of small capitals (OpenType feature: <span
  4108     class=tag>smcp</span>). Small-caps glyphs typically use the form of
  4109     uppercase letters but are reduced to the size of lowercase letters.
  4110   </dl>
  4112   <div class=featex><img alt="small-caps example" src=smcp.png></div>
  4114   <dl>
  4115    <dt><dfn id=all-small-caps>all-small-caps</dfn>
  4117    <dd>Enables display of small capitals for both upper and lowercase letters
  4118     (OpenType features: <span class=tag>c2sc, smcp</span>).
  4120    <dt><dfn id=petite-caps>petite-caps</dfn>
  4122    <dd>Enables display of petite capitals (OpenType feature: <span
  4123     class=tag>pcap</span>).
  4125    <dt><dfn id=all-petite-caps>all-petite-caps</dfn>
  4127    <dd>Enables display of petite capitals for both upper and lowercase
  4128     letters (OpenType features: <span class=tag>c2pc, pcap</span>).
  4130    <dt><dfn id=unicase>unicase</dfn>
  4132    <dd>Enables display of mixture of small capitals for uppercase letters
  4133     with normal lowercase letters (OpenType feature: <span
  4134     class=tag>unic</span>).
  4136    <dt><dfn id=titling-caps>titling-caps</dfn>
  4138    <dd>Enables display of titling capitals (OpenType feature: <span
  4139     class=tag>titl</span>). Uppercase letter glyphs are often designed for
  4140     use with lowercase letters. When used in all uppercase titling sequences
  4141     they can appear too strong. Titling capitals are designed specifically
  4142     for this situation.
  4143   </dl>
  4145   <p>The availability of these glyphs is based on whether a given feature is
  4146    defined or not in the feature list of the font. User agents can optionally
  4147    decide this on a per-script basis but should explicitly not decide this on
  4148    a per-character basis.
  4150   <p>Some fonts may only support a subset or none of the features described
  4151    for this property. For backwards compatibility with CSS 2.1, if ‘<a
  4152    href="#small-caps"><code class=property>small-caps</code></a>’ or ‘<a
  4153    href="#all-small-caps"><code class=property>all-small-caps</code></a>’
  4154    is specified but small-caps glyphs are not available for a given font,
  4155    user agents should simulate a small-caps font, for example by taking a
  4156    normal font and replacing the glyphs for lowercase letters with scaled
  4157    versions of the glyphs for uppercase characters (replacing the glyphs for
  4158    both upper and lowercase letters in the case of ‘<a
  4159    href="#all-small-caps"><code class=property>all-small-caps</code></a>’).
  4161   <div class=figure style="padding: 0; margin: auto;"><img alt="synthetic vs.
  4162    real small-caps" class=hires src=synthetic-vs-real-small-caps.png
  4163    width=512>
  4164    <p class=caption>Synthetic vs. real small-caps
  4165   </div>
  4167   <p>To match the surrounding text, a font may provide alternate glyphs for
  4168    caseless characters when these features are enabled but when a user agent
  4169    simulates small capitals, it must not attempt to simulate alternates for
  4170    codepoints which are considered caseless.
  4172   <div class=figure style="padding: 0; margin: auto;"><img alt="caseless
  4173    characters with small-caps, all-small-caps enabled" class=hires
  4174    src=small-capitals-variations.png width=418>
  4175    <p class=caption>Caseless characters with small-caps, all-small-caps
  4176     enabled
  4177   </div>
  4179   <p>If either ‘<a href="#petite-caps"><code
  4180    class=property>petite-caps</code></a>’ or ‘<a
  4181    href="#all-petite-caps"><code class=property>all-petite-caps</code></a>’
  4182    is specified for a font that doesn't support these features, the property
  4183    behaves as if ‘<a href="#small-caps"><code
  4184    class=property>small-caps</code></a>’ or ‘<a
  4185    href="#all-small-caps"><code class=property>all-small-caps</code></a>’,
  4186    respectively, had been specified. If ‘<a href="#unicase"><code
  4187    class=property>unicase</code></a>’ is specified for a font that doesn't
  4188    support that feature, the property behaves as if ‘<a
  4189    href="#small-caps"><code class=property>small-caps</code></a>’ was
  4190    applied only to lowercased uppercase letters. If ‘<a
  4191    href="#titling-caps"><code class=property>titling-caps</code></a>’ is
  4192    specified with a font that does not support this feature, this property
  4193    has no visible effect. When simulated small capital glyphs are used, for
  4194    scripts that lack uppercase and lowercase letters, ‘<a
  4195    href="#small-caps"><code class=property>small-caps</code></a>’, ‘<a
  4196    href="#all-small-caps"><code class=property>all-small-caps</code></a>’,
  4197    ‘<a href="#petite-caps"><code class=property>petite-caps</code></a>’,
  4198    ‘<a href="#all-petite-caps"><code
  4199    class=property>all-petite-caps</code></a>’ and ‘<a
  4200    href="#unicase"><code class=property>unicase</code></a>’ have no visible
  4201    effect.
  4203   <p>When casing transforms are used to simulate small capitals, the casing
  4204    transformations must match those used for the <span
  4205    class=property>‘<code class=property>text-transform</code>’</span>
  4206    property.
  4208   <p>As a last resort, unscaled uppercase letter glyphs in a normal font may
  4209    replace glyphs in a small-caps font so that the text appears in all
  4210    uppercase letters.
  4212   <div class=figure style="padding: 0; margin: auto;"><img alt="using
  4213    all-small-caps in acronym-laden text" class=hires
  4214    src=acronym-laden-text.png width=596>
  4215    <p class=caption>Using small capitals to improve readability in
  4216     acronym-laden text
  4217   </div>
  4219   <div class=example>
  4220    <p>Quotes rendered italicised, with small-caps on the first line:</p>
  4222    <pre>blockquote            { font-style: italic; }
  4223 blockquote:first-line { font-variant: small-caps; }
  4225 &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>
  4226 </pre>
  4227   </div>
  4228   <!-- prop: font-variant-numeric -->
  4230   <h3 id=font-variant-numeric-prop><span class=secno>6.7 </span>Numerical
  4231    formatting: the <a
  4232    href="#propdef-font-variant-numeric">font-variant-numeric</a> property</h3>
  4234   <table class=propdef id=namefont-variant-numericvaluenormal-ltnu>
  4235    <tbody>
  4236     <tr>
  4237      <td>Name:
  4239      <td><dfn id=propdef-font-variant-numeric>font-variant-numeric</dfn>
  4241     <tr>
  4242      <td>Value:
  4244      <td><a href="#font-variant-numeric-normal-value"
  4245       title="normal!!font-variant-numeric">normal</a> | [ <a
  4246       href="#numeric-figure-values"><var>&lt;numeric-figure-values&gt;</var></a>
  4247       || <a
  4248       href="#numeric-spacing-values"><var>&lt;numeric-spacing-values&gt;</var></a>
  4249       || <a
  4250       href="#numeric-fraction-values"><var>&lt;numeric-fraction-values&gt;</var></a>
  4251       || <a href="#ordinal">ordinal</a> || <a
  4252       href="#slashed-zero">slashed-zero</a> ]
  4254     <tr>
  4255      <td>Initial:
  4257      <td>normal
  4259     <tr>
  4260      <td>Applies to:
  4262      <td>all elements
  4264     <tr>
  4265      <td>Inherited:
  4267      <td>yes
  4269     <tr>
  4270      <td>Percentages:
  4272      <td>N/A
  4274     <tr>
  4275      <td>Media:
  4277      <td>visual
  4279     <tr>
  4280      <td>Computed value:
  4282      <td>as specified
  4284     <tr>
  4285      <td>Animatable:
  4287      <td>no
  4288   </table>
  4290   <p>Specifies control over numerical forms. The example below shows how some
  4291    of these values can be combined to influence the rendering of tabular data
  4292    with fonts that support these features. Within normal paragraph text,
  4293    proportional numbers are used while tabular numbers are used so that
  4294    columns of numbers line up properly:
  4296   <div class=figure style="padding: 0; margin: auto;"><img alt="combining
  4297    number styles" src=numberstyles.png>
  4298    <p class=caption>Using number styles
  4299   </div>
  4301   <p>Possible combinations:
  4303   <pre
  4304    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>
  4306   <pre
  4307    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>
  4309   <pre
  4310    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>
  4312   <p>Individual values have the following meanings:
  4314   <dl>
  4315    <dt><dfn id=font-variant-numeric-normal-value
  4316     title="normal!!font-variant-numeric">normal</dfn>
  4318    <dd>None of the features listed below are enabled.
  4320    <dt><dfn id=lining-nums>lining-nums</dfn>
  4322    <dd>Enables display of lining numerals (OpenType feature: <span
  4323     class=tag>lnum</span>).
  4325    <dt><dfn id=oldstyle-nums>oldstyle-nums</dfn>
  4327    <dd>Enables display of old-style numerals (OpenType feature: <span
  4328     class=tag>onum</span>).
  4330    <dt><dfn id=proportional-nums>proportional-nums</dfn>
  4332    <dd>Enables display of proportional numerals (OpenType feature: <span
  4333     class=tag>pnum</span>).
  4335    <dt><dfn id=tabular-nums>tabular-nums</dfn>
  4337    <dd>Enables display of tabular numerals (OpenType feature: <span
  4338     class=tag>tnum</span>).
  4340    <dt><dfn id=diagonal-fractions>diagonal-fractions</dfn>
  4342    <dd>Enables display of lining diagonal fractions (OpenType feature: <span
  4343     class=tag>frac</span>).
  4344   </dl>
  4346   <div class=featex><img alt="diagonal fraction example" src=frac.png></div>
  4348   <dl>
  4349    <dt><dfn id=stacked-fractions>stacked-fractions</dfn>
  4351    <dd>Enables display of lining stacked fractions (OpenType feature: <span
  4352     class=tag>afrc</span>).
  4353   </dl>
  4355   <div class=featex><img alt="stacked fraction example" src=afrc.png></div>
  4357   <dl>
  4358    <dt><dfn id=ordinal>ordinal</dfn>
  4360    <dd>Enables display of forms used with ordinal numbers (OpenType feature:
  4361     <span class=tag>ordn</span>).
  4363    <dt><dfn id=slashed-zero>slashed-zero</dfn>
  4365    <dd>Enables display of slashed zeros (OpenType feature: <span
  4366     class=tag>zero</span>).
  4367   </dl>
  4369   <div class=featex><img alt="slashed zero example" src=zero.png></div>
  4371   <div class=example id=steak-marinade>
  4372    <p>A simple flank steak marinade recipe, rendered with automatic fractions
  4373     and old-style numerals:</p>
  4375    <pre>.amount { font-variant-numeric: oldstyle-nums diagonal-fractions; }
  4377 &lt;h4>Steak marinade:&lt;/h4>
  4378 &lt;ul>
  4379   &lt;li>&lt;span class="amount">2&lt;/span> tbsp olive oil&lt;/li>
  4380   &lt;li>&lt;span class="amount">1&lt;/span> tbsp lemon juice&lt;/li>
  4381   &lt;li>&lt;span class="amount">1&lt;/span> tbsp soy sauce&lt;/li>
  4382   &lt;li>&lt;span class="amount">1 1/2&lt;/span> tbsp dry minced onion&lt;/li>
  4383   &lt;li>&lt;span class="amount">2 1/2&lt;/span> tsp italian seasoning&lt;/li>
  4384   &lt;li>Salt &amp;amp; pepper&lt;/li>
  4385 &lt;/ul>
  4387 &lt;p>Mix the meat with the marinade and let it sit covered in the refrigerator
  4388 for a few hours or overnight.&lt;/p>
  4389 </pre>
  4391    <p>Note that the fraction feature is only applied to values not the entire
  4392     paragraph. Fonts often implement this feature using contextual rules
  4393     based on the use of the slash (‘<code class=css>/</code>’) character.
  4394     As such, it's not suitable for use as a paragraph-level style.</p>
  4395   </div>
  4396   <!-- prop: font-variant-alternates -->
  4398   <h3 id=font-variant-alternates-prop><span class=secno>6.8 </span>Alternates
  4399    and swashes: the <a
  4400    href="#propdef-font-variant-alternates">font-variant-alternates</a>
  4401    property</h3>
  4403   <table class=propdef id=namefont-variant-alternatesvaluenormal-s>
  4404    <tbody>
  4405     <tr>
  4406      <td>Name:
  4408      <td><dfn
  4409       id=propdef-font-variant-alternates>font-variant-alternates</dfn>
  4411     <tr>
  4412      <td>Value:
  4414      <td>normal | [ <a href="#stylistic"
  4415       title=stylistic>stylistic(&lt;feature-value-name&gt;)</a> || <a
  4416       href="#historical-forms">historical-forms</a> || <a href="#styleset"
  4417       title=styleset>styleset(&lt;feature-value-name&gt; #)</a> || <a
  4418       href="#character-variant"
  4419       title=character-variant>character-variant(&lt;feature-value-name&gt;
  4420       #)</a> || <a href="#swash"
  4421       title=swash>swash(&lt;feature-value-name&gt;)</a> || <a
  4422       href="#ornaments"
  4423       title=ornaments>ornaments(&lt;feature-value-name&gt;)</a> || <a
  4424       href="#annotation"
  4425       title=annotation>annotation(&lt;feature-value-name&gt;)</a> ]
  4427     <tr>
  4428      <td>Initial:
  4430      <td>normal
  4432     <tr>
  4433      <td>Applies to:
  4435      <td>all elements
  4437     <tr>
  4438      <td>Inherited:
  4440      <td>yes
  4442     <tr>
  4443      <td>Percentages:
  4445      <td>N/A
  4447     <tr>
  4448      <td>Media:
  4450      <td>visual
  4452     <tr>
  4453      <td>Computed value:
  4455      <td>as specified
  4457     <tr>
  4458      <td>Animatable:
  4460      <td>no
  4461   </table>
  4463   <p>For any given character, fonts can provide a variety of alternate glyphs
  4464    in addition to the default glyph for that character. This property
  4465    provides control over the selection of these alternate glyphs.
  4467   <p>For many of the property values listed below, several different
  4468    alternate glyphs are available. How many alternates are available and what
  4469    they represent is font-specific, so these are each marked <dfn
  4470    id=font-specific>font specific</dfn> in the value definitions below.
  4471    Because the nature of these alternates is font-specific, the <a
  4472    href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
  4473    rule is used to define values for a specific font family or set of
  4474    families that associate a font-specific numeric
  4475    <code>&lt;feature-index&gt;</code> with a custom
  4476    <code>&lt;feature-value-name&gt;</code>, which is then used in this
  4477    property to select specific alternates:
  4479   <pre>@font-feature-values Noble Script { @swash { swishy: 1; flowing: 2; } }
  4481 p {
  4482   font-family: Noble Script;
  4483   font-variant-alternates: swash(flowing); /* use swash alternate #2 */
  4484 }</pre>
  4486   <p>When a particular <code>&lt;feature-value-name&gt;</code> has not been
  4487    defined for a given family or for a particular feature type, the computed
  4488    value must be the same as if it had been defined. However, property values
  4489    that contain these undefined <code>&lt;feature-value-name&gt;</code>
  4490    identifiers must be ignored when choosing glyphs.
  4492   <pre>/* these two style rules are effectively the same */
  4493 p { font-variant-alternates: swash(unknown-value); } /* not a defined value, ignored */
  4494 p { font-variant-alternates: normal; }
  4495 </pre>
  4497   <p>This allows values to be defined and used for a given set of font
  4498    families but ignored if fallback occurs, since the font family name would
  4499    be different. If a given value is outside the range supported by a given
  4500    font, the value is ignored. These values never apply to generic font
  4501    families.
  4503   <p>Individual values have the following meanings:
  4505   <dl>
  4506    <dt><dfn id=font-variant-alternates-normal-value
  4507     title="normal!!font-variant-alternates">normal</dfn>
  4509    <dd>None of the features listed below are enabled.
  4511    <dt><dfn id=historical-forms>historical-forms</dfn>
  4513    <dd>Enables display of historical forms (OpenType feature: <span
  4514     class=tag>hist</span>).
  4515   </dl>
  4517   <div class=featex><img alt="historical form example" src=hist.png></div>
  4519   <dl>
  4520    <dt><dfn id=stylistic
  4521     title=stylistic>stylistic(&lt;feature-value-name&gt;)</dfn>
  4523    <dd>Enables display of stylistic alternates (<a
  4524     href="#font-specific"><em>font specific</em></a>, OpenType feature: <span
  4525     class=tag>salt &lt;feature-index&gt;</span>).
  4526   </dl>
  4528   <div class=featex><img alt="stylistic alternate example" src=salt.png></div>
  4530   <dl>
  4531    <dt><dfn id=styleset title=styleset>styleset(&lt;feature-value-name&gt;
  4532     #)</dfn>
  4534    <dd>Enables display with stylistic sets (<a href="#font-specific"><em>font
  4535     specific</em></a>, OpenType feature: <span
  4536     class=tag>ss&lt;feature-index&gt;</span> OpenType currently defines <span
  4537     class=tag>ss01</span> through <span class=tag>ss20</span>).
  4538   </dl>
  4540   <div class=featex><img alt="styleset example" src=ssnn.png></div>
  4542   <dl>
  4543    <dt><dfn id=character-variant
  4544     title=character-variant>character-variant(&lt;feature-value-name&gt;
  4545     #)</dfn>
  4547    <dd>Enables display of specific character variants (<a
  4548     href="#font-specific"><em>font specific</em></a>, OpenType feature: <span
  4549     class=tag>cv&lt;feature-index&gt;</span> OpenType currently defines <span
  4550     class=tag>cv01</span> through <span class=tag>cv99</span>).
  4552    <dt><dfn id=swash title=swash>swash(&lt;feature-value-name&gt;)</dfn>
  4554    <dd>Enables display of swash glyphs (<a href="#font-specific"><em>font
  4555     specific</em></a>, OpenType feature: <span class=tag>swsh
  4556     &lt;feature-index&gt;, cswh &lt;feature-index&gt;</span>).
  4557   </dl>
  4559   <div class=featex><img alt="swash example" src=swsh.png></div>
  4561   <dl>
  4562    <dt><dfn id=ornaments
  4563     title=ornaments>ornaments(&lt;feature-value-name&gt;)</dfn>
  4565    <dd>Enables replacement of default glyphs with ornaments, if provided in
  4566     the font (<a href="#font-specific"><em>font specific</em></a>, OpenType
  4567     feature: <span class=tag>ornm &lt;feature-index&gt;</span>). Some fonts
  4568     may offer ornament glyphs as alternates for a wide collection of
  4569     characters; however, displaying arbitrary characters (e.g.,
  4570     alphanumerics) as ornaments is poor practice as it distorts the semantics
  4571     of the data. Font designers are encouraged to encode all ornaments
  4572     (except those explicitly encoded in the Unicode Dingbats blocks, etc.) as
  4573     alternates for the bullet character (U+2022) to allow authors to select
  4574     the desired glyph using ‘<a href="#ornaments"><code
  4575     class=property>ornaments</code></a>’.
  4576   </dl>
  4578   <div class=featex><img alt="ornaments example" src=ornm.png></div>
  4580   <dl>
  4581    <dt><dfn id=annotation
  4582     title=annotation>annotation(&lt;feature-value-name&gt;)</dfn>
  4584    <dd>Enables display of alternate annotation forms (<a
  4585     href="#font-specific"><em>font specific</em></a>, OpenType feature: <span
  4586     class=tag>nalt &lt;feature-index&gt;</span>).
  4587   </dl>
  4589   <div class=featex><img alt="alternate annotation form example"
  4590    src=nalt.png></div>
  4592   <h3 id=font-feature-values><span class=secno>6.9 </span>Defining font
  4593    specific alternates: the <dfn id=at-font-feature-values-rule
  4594    style="font-weight: inherit; font-style:
  4595    inherit"><code>@font-feature-values</code></dfn> rule</h3>
  4597   <p>Several of the possible values of ‘<a
  4598    href="#propdef-font-variant-alternates"><code
  4599    class=property>font-variant-alternates</code></a>’ listed above are
  4600    labeled as <a href="#font-specific"><em>font specific</em></a>. For these
  4601    features fonts may define not just a single glyph but a set of alternate
  4602    glyphs with an index to select a given alternate. Since these are font
  4603    family specific, the <a
  4604    href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
  4605    rule is used to define named values for these indices for a given family.
  4607   <p class=note>See the <a href="#om-fontfeaturevalues">object model
  4608    reference section</a> for a description of the interfaces used to modify
  4609    these rules via the CSS Object Model.
  4611   <div class=example>
  4612    <p>In the case of the swash Q in the example shown above, the swash could
  4613     be specified using these style rules:</p>
  4615    <pre>
  4617 @font-feature-values Jupiter Sans {
  4618   @swash {
  4619     delicate: 1;
  4620     flowing: 2;
  4624 h2 { font-family: Jupiter Sans, sans-serif; }
  4626 /* show the second swash variant in h2 headings */
  4627 h2:first-letter { font-variant-alternates: swash(flowing); }
  4629 &lt;h2>Quick&lt;/h2></pre>
  4631    <p>When Jupiter Sans is present, the second alternate swash alternate will
  4632     be displayed. When not present, no swash character will be shown, since
  4633     the specific named value "flowing" is only defined for the Jupiter Sans
  4634     family. The @-mark indicates the name of the property value for which a
  4635     named value can be used. The name "flowing" is chosen by the author. The
  4636     index that represents each alternate is defined within a given font's
  4637     data.</p>
  4638   </div>
  4640   <h4 id=basic-syntax><span class=secno>6.9.1 </span>Basic syntax</h4>
  4642   <p>An <a
  4643    href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
  4644    rule is composed of a list of font families followed by a block containing
  4645    individual <a href="#featurevalueblock"><i
  4646    title="feature_value_block">feature value blocks</i></a> that take the
  4647    form of @-rules. Each block defines a set of named values for a specific
  4648    font feature when a given set of font families is used. Effectively, they
  4649    define a mapping of ⟨family, feature, ident⟩ → ⟨values⟩ where
  4650    ⟨values⟩ are the numeric indices used for specific features defined
  4651    for a given font.
  4653   <p>In terms of the grammar, this specification defines the following
  4654    productions:
  4656   <pre><dfn id=fontfeaturevaluesrule>font_feature_values_rule</dfn>
  4657   : <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>*
  4658     '{' <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>*
  4661 <dfn id=fontfamilynamelist>font_family_name_list</dfn>
  4662   : <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> ]*
  4665 <dfn id=fontfamilyname>font_family_name</dfn>
  4666   : <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> ]* ]
  4669 <dfn id=featurevalueblock>feature_value_block</dfn>
  4670   : <a href="#featuretype"><i>feature_type</i></a> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>*
  4671     '{' <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>*
  4674 <dfn id=featuretype>feature_type</dfn>:
  4675   <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>ATKEYWORD</i></a>
  4678 <dfn id=featurevaluedefinition>feature_value_definition</dfn>
  4679   : <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> ]*
  4681 </pre>
  4683   <p>The following new token is introduced:
  4685   <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>;}
  4686 </pre>
  4688   <p><a href="#featurevalueblock"><i title="feature_value_block">Feature
  4689    value blocks</i></a> are handled as <a
  4690    href="http://www.w3.org/TR/CSS2/syndata.html#at-rules">at-rules</a>, they
  4691    consist of everything up to the next block or semi-colon, whichever comes
  4692    first.
  4694   <p>The <a href="#fontfamilynamelist"><i title="font_family_name_list">font
  4695    family list</i></a> is a comma-delimited list of <a
  4696    href="#fontfamilyname"><i title="font_family_name">font family
  4697    names</i></a> that match the definition of <a
  4698    href="#family-name-value"><var>&lt;family-name&gt;</var></a> for the <a
  4699    href="#propdef-font-family" title="font-family!!property">‘<code
  4700    class=property>font-family</code>’</a> property. This means that only
  4701    named font families are allowed, rules that include generic or system
  4702    fonts in the list of font families are syntax errors. However, if a user
  4703    agent defines a generic font to be a specific named font (e.g. Helvetica),
  4704    the settings associated with that family name will be used. If syntax
  4705    errors occur within the font family list, the entire rule must be ignored.
  4707   <p>Within <a href="#featurevalueblock"><i
  4708    title="feature_value_block">feature value blocks</i></a>, the <a
  4709    href="#featuretype"><i title="feature_type">feature type</i></a> is
  4710    ‘<code class=css>@</code>’ followed by the name of one of the <a
  4711    href="#font-specific"><em>font specific</em></a> property values of ‘<a
  4712    href="#propdef-font-variant-alternates"><code
  4713    class=property>font-variant-alternates</code></a>’ (e.g. <a
  4714    href="#swash"><code>@swash</code></a>). The identifiers used within
  4715    feature value definitions follow the rules of CSS user identifiers and are
  4716    case-sensitive. They are unique only for a given set of font families and
  4717    <a href="#featuretype"><i title="feature_type">feature type</i></a>. The
  4718    same identifier used with a different <a href="#featuretype"><i
  4719    title="feature_type">feature type</i></a> is treated as a separate and
  4720    distinct value. If the same identifier is defined mulitple times for a
  4721    given <a href="#featuretype"><i title="feature_type">feature type</i></a>
  4722    and font family, the last defined value is used. Values associated with a
  4723    given identifier are limited to integer values 0 or greater.
  4725   <p>When syntax errors occur within a <a href="#featurevaluedefinition"><i
  4726    title="feature_value_definition">feature value definition</i></a>, such as
  4727    invalid identifiers or values, the entire <a
  4728    href="#featurevaluedefinition"><i title="feature_value_definition">feature
  4729    value definition</i></a> must be omitted, just as syntax errors in style
  4730    declarations are handled. When the <a href="#featuretype"><i
  4731    title="feature_type">feature type</i></a> is invalid, the entire
  4732    associated <a href="#featurevalueblock"><i
  4733    title="feature_value_block">feature value block</i></a> must be ignored.
  4735   <div class=example>
  4736    <p>Rules that are equivalent given syntax error handling:</p>
  4738    <pre>@font-feature-values Bongo {
  4739   @swash { ornate: 1; }
  4740   annotation { boxed: 4; } /* should be @annotation! */
  4741   @swash { double-loops: 1; flowing: -1; } /* negative value */
  4742   @ornaments ; /* incomplete definition */
  4743   @styleset { double-W: 14; sharp-terminals: 16 1 } /* missing ; */
  4744   <a href="http://www.angryalien.com/0504/shiningbunnies.html" style="text-decoration: none; border: none;">redrum</a>  /* random editing mistake */
  4745 }</pre>
  4747    <p>The example above is equivalent to:</p>
  4749    <pre>@font-feature-values Bongo {
  4750   @swash { ornate: 1; }
  4751   @swash { double-loops: 1; }
  4752   @styleset { double-W: 14; sharp-terminals: 16 1; }
  4753 }</pre>
  4754   </div>
  4756   <p>If multiple <a
  4757    href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
  4758    rules are defined for a given family, the resulting values definitions are
  4759    the union of the definitions contained within these rules. This allows a
  4760    set of named values to be defined for a given font family globally for a
  4761    site and specific additions made per-page.
  4763   <div class=example>
  4764    <p>Using both site-wide and per-page feature values:</p>
  4766    <pre>
  4767 site.css:
  4769   @font-feature-values Mercury Serif {
  4770     @styleset {
  4771       stacked-g: 3; /* "two-storey" versions of g, a */
  4772       stacked-a: 4;
  4776 page.css:
  4778   @font-feature-values Mercury Serif {
  4779     @styleset {
  4780       geometric-m: 7; /* alternate version of m */
  4784   body {
  4785     font-family: Mercury Serif, serif;
  4787     /* enable both the use of stacked g and alternate m */
  4788     font-variant-alternates: styleset(stacked-g, geometric-m);
  4789   }</pre>
  4790   </div>
  4792   <div class=example>
  4793    <p>Using a commonly named value allows authors to use a single style rule
  4794     to cover a set of fonts for which the underlying selector is different
  4795     for each font. If either font in the example below is found, a circled
  4796     number glyph will be used:</p>
  4798    <pre>@font-feature-values Taisho Gothic {
  4799   @annotation { boxed: 1; circled: 4; }
  4802 @font-feature-values Otaru Kisa {
  4803   @annotation { circled: 1; black-boxed: 3; }
  4806 h3.title {
  4807   /* circled form defined for both fonts */
  4808   font-family: Taisho Gothic, Otaru Kisa;
  4809   font-variant: annotation(circled);
  4810 }</pre>
  4811   </div>
  4813   <h4 id=multi-valued-feature-value-definitions><span class=secno>6.9.2
  4814    </span>Multi-valued feature value definitions</h4>
  4816   <p>Most <a href="#font-specific"><em>font specific</em></a> ‘<a
  4817    href="#propdef-font-variant-alternates"><code
  4818    class=property>font-variant-alternates</code></a>’ property values take
  4819    a single value (e.g. ‘<a href="#swash"><code
  4820    class=property>swash</code></a>’). The ‘<a
  4821    href="#character-variant"><code
  4822    class=property>character-variant</code></a>’ property value allows two
  4823    values and ‘<a href="#styleset"><code
  4824    class=property>styleset</code></a>’ allows an unlimited number.
  4826   <p>For the styleset property value, multiple values indicate the style sets
  4827    to be enabled. Values between 1 and 99 enable OpenType features <span
  4828    class=tag>ss01</span> through <span class=tag>ss99</span>. However, the
  4829    OpenType standard only officially defines <span class=tag>ss01</span>
  4830    through <span class=tag>ss20</span>. For OpenType fonts, values greater
  4831    than 99 or equal to 0 do not generate a syntax error when parsed but
  4832    enable no OpenType features.
  4834   <pre>@font-feature-values Mars Serif {
  4835   @styleset {
  4836     alt-g: 1;        /* implies ss01 = 1 */
  4837     curly-quotes: 3; /* implies ss03 = 1 */
  4838     code: 4 5;       /* implies ss04 = 1, ss05 = 1 */
  4841   @styleset {
  4842     dumb: 125;        /* &gt;99, ignored */
  4845   @swash {
  4846     swishy: 3 5;     /* more than 1 value for swash, syntax error */
  4850 p.codeblock {
  4851   /* implies ss03 = 1, ss04 = 1, ss05 = 1 */
  4852   font-variant-alternates: styleset(curly-quotes, code);
  4853 }</pre>
  4855   <p>For character-variant, a single value between 1 and 99 indicates the
  4856    enabling of OpenType feature <span class=tag>cv01</span> through <span
  4857    class=tag>cv99</span>. For OpenType fonts, values greater than 99 or equal
  4858    to 0 are ignored but do not generate a syntax error when parsed but enable
  4859    no OpenType features. When two values are listed, the first value
  4860    indicates the feature used and the second the value passed for that
  4861    feature. If more than two values are assigned to a given name, a syntax
  4862    error occurs and the entire <a href="#featurevaluedefinition"><i
  4863    title="feature_value_definition">feature value definition</i></a> is
  4864    ignored.
  4866   <pre>@font-feature-values MM Greek {
  4867   @character-variant { alpha-2: 1 2; }   /* implies cv01 = 2 */
  4868   @character-variant { beta-3: 2 3; }    /* implies cv02 = 3 */
  4869   @character-variant { epsilon: 5 3 6; } /* more than 2 values, syntax error, definition ignored */
  4870   @character-variant { gamma: 12; }      /* implies cv12 = 1 */
  4871   @character-variant { zeta:   20 3; }   /* implies cv20 = 3 */
  4872   @character-variant { zeta-2: 20 2; }   /* implies cv20 = 2 */
  4873   @character-variant { silly: 105; }     /* &gt;99, ignored */
  4874   @character-variant { dumb: 323 3; }    /* &gt;99, ignored */
  4877 #title {
  4878   /* use the third alternate beta, first alternate gamma */
  4879   font-variant-alternates: character-variant(beta-3, gamma);
  4882 p {
  4883   /* zeta-2 follows zeta, implies cv20 = 2  */
  4884   font-variant-alternates: character-variant(zeta, zeta-2);
  4887 .special {
  4888   /* zeta follows zeta-2, implies cv20 = 3  */
  4889   font-variant-alternates: character-variant(zeta-2, zeta);
  4890 }</pre>
  4892   <div class=figure><img alt="Matching text on Byzantine seals using
  4893    character variants" src=byzantineseal.png>
  4894    <p class=caption>Byzantine seal text displayed with character variants
  4895   </div>
  4897   <div class=example>
  4898    <p>In the figure above, the text in red is rendered using a font
  4899     containing character variants that mimic the character forms found on a
  4900     Byzantine seal from the 8th century A.D. Two lines below is the same text
  4901     displayed in a font without variants. Note the two variants for U and N
  4902     used on the seal.</p>
  4904    <pre>@font-feature-values Athena Ruby {
  4905   @character-variant {
  4906     leo-B: 2 1;
  4907     leo-M: 13 3;
  4908     leo-alt-N: 14 1;
  4909     leo-N: 14 2;
  4910     leo-T: 20 1;
  4911     leo-U: 21 2;
  4912     leo-alt-U: 21 4;
  4916 p {
  4917   font-variant: discretionary-ligatures,
  4918                 character-variant(leo-B, leo-M, leo-N, leo-T, leo-U);
  4921 span.alt-N {
  4922   font-variant-alternates: character-variant(leo-alt-N);
  4925 span.alt-U {
  4926   font-variant-alternates: character-variant(leo-alt-U);
  4929 &lt;p>ENO....UP͞RSTU&lt;span class="alt-U">U&lt;/span>͞&lt;span class="alt-U">U&lt;/span>ΚΑΙTỤẠG̣IUPNS&lt;/p>
  4931 &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>
  4932 </pre>
  4933   </div>
  4935   <h3 id=font-variant-east-asian-prop><span class=secno>6.10 </span>East
  4936    Asian text rendering: the <a
  4937    href="#propdef-font-variant-east-asian">font-variant-east-asian</a>
  4938    property</h3>
  4940   <table class=propdef id=namefont-variant-east-asianvaluenormal-l>
  4941    <tbody>
  4942     <tr>
  4943      <td>Name:
  4945      <td><dfn
  4946       id=propdef-font-variant-east-asian>font-variant-east-asian</dfn>
  4948     <tr>
  4949      <td>Value:
  4951      <td><a href="#font-variant-east-asian-normal-value"
  4952       title="normal!!font-variant-east-asian">normal</a> | [ <a
  4953       href="#east-asian-variant-values"><var>&lt;east-asian-variant-values&gt;</var></a>
  4954       || <a
  4955       href="#east-asian-width-values"><var>&lt;east-asian-width-values&gt;</var></a>
  4956       || <a href="#ruby">ruby</a> ]
  4958     <tr>
  4959      <td>Initial:
  4961      <td>normal
  4963     <tr>
  4964      <td>Applies to:
  4966      <td>all elements
  4968     <tr>
  4969      <td>Inherited:
  4971      <td>yes
  4973     <tr>
  4974      <td>Percentages:
  4976      <td>N/A
  4978     <tr>
  4979      <td>Media:
  4981      <td>visual
  4983     <tr>
  4984      <td>Computed value:
  4986      <td>as specified
  4988     <tr>
  4989      <td>Animatable:
  4991      <td>no
  4992   </table>
  4994   <p>Allows control of glyph substitution and sizing in East Asian text.
  4996   <pre
  4997    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>
  4999   <pre
  5000    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>
  5002   <p>Individual values have the following meanings:
  5004   <dl>
  5005    <dt><dfn id=font-variant-east-asian-normal-value
  5006     title="normal!!font-variant-east-asian">normal</dfn>
  5008    <dd>None of the features listed below are enabled.
  5010    <dt><dfn id=jis78>jis78</dfn>
  5012    <dd>Enables rendering of JIS78 forms (OpenType feature: <span
  5013     class=tag>jp78</span>).
  5014   </dl>
  5016   <div class=featex><img alt="JIS78 form example" src=jp78.png></div>
  5018   <dl>
  5019    <dt><dfn id=jis83>jis83</dfn>
  5021    <dd>Enables rendering of JIS83 forms (OpenType feature: <span
  5022     class=tag>jp83</span>).
  5024    <dt><dfn id=jis90>jis90</dfn>
  5026    <dd>Enables rendering of JIS90 forms (OpenType feature: <span
  5027     class=tag>jp90</span>).
  5029    <dt><dfn id=jis04>jis04</dfn>
  5031    <dd>Enables rendering of JIS2004 forms (OpenType feature: <span
  5032     class=tag>jp04</span>).
  5033     <p>The various JIS variants reflect the glyph forms defined in different
  5034      Japanese national standards. Fonts generally include glyphs defined by
  5035      the most recent national standard but it's sometimes necessary to use
  5036      older variants, to match signage for example.</p>
  5038    <dt><dfn id=simplified>simplified</dfn>
  5040    <dd>Enables rendering of simplified forms (OpenType feature: <span
  5041     class=tag>smpl</span>).
  5043    <dt><dfn id=traditional>traditional</dfn>
  5045    <dd>Enables rendering of traditional forms (OpenType feature: <span
  5046     class=tag>trad</span>).
  5047   </dl>
  5049   <p>The ‘<a href="#simplified"><code
  5050    class=property>simplified</code></a>’ and ‘<a
  5051    href="#traditional"><code class=property>traditional</code></a>’ values
  5052    allow control over the glyph forms for characters which have been
  5053    simplified over time but for which the older, traditional form is still
  5054    used in some contexts. The exact set of characters and glyph forms will
  5055    vary to some degree by context for which a given font was designed.
  5057   <div class=featex><img alt="tradtional form example" src=trad.png></div>
  5059   <dl>
  5060    <dt><dfn id=full-width>full-width</dfn>
  5062    <dd>Enables rendering of full-width variants (OpenType feature: <span
  5063     class=tag>fwid</span>).
  5065    <dt><dfn id=proportional-width>proportional-width</dfn>
  5067    <dd>Enables rendering of proportionally-spaced variants (OpenType feature:
  5068     <span class=tag>pwid</span>).
  5069   </dl>
  5071   <div class=featex><img alt="proportionally spaced Japanese example"
  5072    src=pwid.png></div>
  5074   <dl>
  5075    <dt><dfn id=ruby>ruby</dfn>
  5077    <dd>Enables display of ruby variant glyphs (OpenType feature: <span
  5078     class=tag>ruby</span>). Since ruby text is generally smaller than the
  5079     associated body text, font designers can design special glyphs for use
  5080     with ruby that are more readable than scaled down versions of the default
  5081     glyphs. Only glyph selection is affected, there is no associated font
  5082     scaling or other change that affects line layout. The red ruby text below
  5083     is shown with default glyphs (top) and with ruby variant glyphs (bottom).
  5084     Note the slight difference in stroke thickness.
  5085   </dl>
  5087   <div class=featex><img alt="ruby variant example" src=rubyshinkansen.png></div>
  5089   <h3 id=font-variant-prop><span class=secno>6.11 </span>Overall shorthand
  5090    for font rendering: the <a href="#propdef-font-variant">font-variant</a>
  5091    property</h3>
  5093   <table class=propdef id=namefont-variantvaluenormal-none-ltcommo>
  5094    <tbody>
  5095     <tr>
  5096      <td>Name:
  5098      <td><dfn id=propdef-font-variant
  5099       title="font-variant!!property">font-variant</dfn>
  5101     <tr>
  5102      <td>Value:
  5104      <td><a href="#font-variant-normal-value"
  5105       title="normal!!font-variant">normal</a> | <a
  5106       href="#font-variant-none-value" title="none!!font-variant">none</a> | [
  5107       <a href="#common-lig-values"><var>&lt;common-lig-values&gt;</var></a>
  5108       || <a
  5109       href="#discretionary-lig-values"><var>&lt;discretionary-lig-values&gt;</var></a>
  5110       || <a
  5111       href="#historical-lig-values"><var>&lt;historical-lig-values&gt;</var></a>
  5112       || <a
  5113       href="#contextual-alt-values"><var>&lt;contextual-alt-values&gt;</var></a>
  5114       || <a href="#stylistic"><var
  5115       title=stylistic>stylistic(&lt;feature-value-name&gt;)</var></a> || <a
  5116       href="#historical-forms"><var>historical-forms</var></a> || <a
  5117       href="#styleset"><var
  5118       title=styleset>styleset(&lt;feature-value-name&gt; #)</var></a> || <a
  5119       href="#character-variant"><var
  5120       title=character-variant>character-variant(&lt;feature-value-name&gt;
  5121       #)</var></a> || <a href="#swash"><var
  5122       title=swash>swash(&lt;feature-value-name&gt;)</var></a> || <a
  5123       href="#ornaments"><var
  5124       title=ornaments>ornaments(&lt;feature-value-name&gt;)</var></a> || <a
  5125       href="#annotation"><var
  5126       title=annotation>annotation(&lt;feature-value-name&gt;)</var></a> || [
  5127       <a href="#small-caps"><i>small-caps</i></a> | <a
  5128       href="#all-small-caps"><i>all-small-caps</i></a> | <a
  5129       href="#petite-caps"><i>petite-caps</i></a> | <a
  5130       href="#all-petite-caps"><i>all-petite-caps</i></a> | <a
  5131       href="#unicase"><i>unicase</i></a> | <a
  5132       href="#titling-caps"><i>titling-caps</i></a> ] || <a
  5133       href="#numeric-figure-values"><var>&lt;numeric-figure-values&gt;</var></a>
  5134       || <a
  5135       href="#numeric-spacing-values"><var>&lt;numeric-spacing-values&gt;</var></a>
  5136       || <a
  5137       href="#numeric-fraction-values"><var>&lt;numeric-fraction-values&gt;</var></a>
  5138       || <a href="#ordinal"><i>ordinal</i></a> || <a
  5139       href="#slashed-zero"><i>slashed-zero</i></a> || <a
  5140       href="#east-asian-variant-values"><var>&lt;east-asian-variant-values&gt;</var></a>
  5141       || <a
  5142       href="#east-asian-width-values"><var>&lt;east-asian-width-values&gt;</var></a>
  5143       || <a href="#ruby"><i>ruby</i></a> ]
  5145     <tr>
  5146      <td>Initial:
  5148      <td>normal
  5150     <tr>
  5151      <td>Applies to:
  5153      <td>all elements
  5155     <tr>
  5156      <td>Inherited:
  5158      <td>yes
  5160     <tr>
  5161      <td>Percentages:
  5163      <td>see individual properties
  5165     <tr>
  5166      <td>Media:
  5168      <td>visual
  5170     <tr>
  5171      <td>Computed value:
  5173      <td>see individual properties
  5175     <tr>
  5176      <td>Animatable:
  5178      <td>see individual properties
  5179   </table>
  5181   <p>The <a href="#propdef-font-variant"
  5182    title="font-variant!!property">‘<code
  5183    class=property>font-variant</code>’</a> property is a shorthand for all
  5184    font-variant subproperties. The value <dfn id=font-variant-normal-value
  5185    title="normal!!font-variant">‘<code
  5186    class=property>normal</code>’</dfn> resets all subproperties of <a
  5187    href="#propdef-font-variant" title="font-variant!!property">‘<code
  5188    class=property>font-variant</code>’</a> to their inital value. The <dfn
  5189    id=font-variant-none-value title="none!!font-variant">‘<code
  5190    class=property>none</code>’</dfn> value sets ‘<a
  5191    href="#propdef-font-variant-ligatures"><code
  5192    class=property>font-variant-ligatures</code></a>’ to ‘<code
  5193    class=property>none</code>’ and resets all other font feature properties
  5194    to their initial value. Like other shorthands, using <a
  5195    href="#propdef-font-variant" title="font-variant!!property">‘<code
  5196    class=property>font-variant</code>’</a> resets unspecified <a
  5197    href="#propdef-font-variant" title="font-variant!!property">‘<code
  5198    class=property>font-variant</code>’</a> subproperties to their initial
  5199    values. It does not reset the values of either ‘<a
  5200    href="#propdef-font-language-override"><code
  5201    class=property>font-language-override</code></a>’ or <a
  5202    href="#propdef-font-feature-settings"
  5203    title="font-feature-settings!!property">‘<code
  5204    class=property>font-feature-settings</code>’</a>.
  5206   <h3 id=font-feature-settings-prop><span class=secno>6.12 </span>Low-level
  5207    font feature settings control: the <a
  5208    href="#propdef-font-feature-settings">font-feature-settings</a> property</h3>
  5210   <table class=propdef id=namefont-feature-settingsvaluenormal-ltf>
  5211    <tbody>
  5212     <tr>
  5213      <td>Name:
  5215      <td><dfn id=propdef-font-feature-settings
  5216       title="font-feature-settings!!property">font-feature-settings</dfn>
  5218     <tr>
  5219      <td>Value:
  5221      <td><a href="#font-feature-settings-normal-value"
  5222       title="normal!!font-feature-settings">normal</a> | <a
  5223       href="#feature-tag-value"><var>&lt;feature-tag-value&gt;</var></a> #
  5225     <tr>
  5226      <td>Initial:
  5228      <td>normal
  5230     <tr>
  5231      <td>Applies to:
  5233      <td>all elements
  5235     <tr>
  5236      <td>Inherited:
  5238      <td>yes
  5240     <tr>
  5241      <td>Percentages:
  5243      <td>N/A
  5245     <tr>
  5246      <td>Media:
  5248      <td>visual
  5250     <tr>
  5251      <td>Computed value:
  5253      <td>as specified
  5255     <tr>
  5256      <td>Animatable:
  5258      <td>no
  5259   </table>
  5261   <p>This property provides low-level control over OpenType font features. It
  5262    is intended as a way of providing access to font features that are not
  5263    widely used but are needed for a particular use case.
  5265   <p>Authors should generally use <a href="#propdef-font-variant"
  5266    title="font-variant!!property">‘<code
  5267    class=property>font-variant</code>’</a> and its related subproperties
  5268    whenever possible and only use this property for special cases where its
  5269    use is the only way of accessing a particular infrequently used font
  5270    feature.
  5272   <pre>/* enable small caps and use second swash alternate */
  5273 font-feature-settings: "smcp", "swsh" 2;</pre>
  5275   <p>A value of <dfn id=font-feature-settings-normal-value
  5276    title="normal!!font-feature-settings">‘<code
  5277    class=property>normal</code>’</dfn> means that no change in glyph
  5278    selection or positioning occurs due to this property.
  5280   <p>Feature tag values have the following syntax:
  5282   <pre
  5283    class=prod><dfn id=feature-tag-value><var>&lt;feature-tag-value&gt;</var></dfn> = &lt;string&gt; [ &lt;integer&gt; | on | off ]?</pre>
  5285   <p>The &lt;string&gt; is a case-sensitive OpenType feature tag. As
  5286    specified in the OpenType specification, feature tags contain four ASCII
  5287    characters. Tag strings longer or shorter than four characters, or
  5288    containing characters outside the U+20–7E codepoint range are invalid.
  5289    Feature tags need only match a feature tag defined in the font, so they
  5290    are not limited to explicitly registered OpenType features. Fonts defining
  5291    custom feature tags should follow the <a
  5292    href="http://www.microsoft.com/typography/otspec/featuretags.htm">tag name
  5293    rules</a> defined in the OpenType specification <a
  5294    href="#OPENTYPE-FEATURES"
  5295    rel=biblioentry>[OPENTYPE-FEATURES]<!--{{!OPENTYPE-FEATURES}}--></a>.
  5297   <p>Feature tags not present in the font are ignored; a user agent must not
  5298    attempt to synthesize fallback behavior based on these feature tags. The
  5299    one exception is that user agents may synthetically support the <span
  5300    class=tag>kern</span> feature with fonts that contain kerning data in the
  5301    form of a ‘<code class=property>kern</code>’ table but lack <span
  5302    class=tag>kern</span> feature support in the ‘<code
  5303    class=property>GPOS</code>’ table.
  5305   <p class=note>In general, authors should use the ‘<a
  5306    href="#propdef-font-kerning"><code
  5307    class=property>font-kerning</code></a>’ property to explicitly enable or
  5308    disable kerning since this property always affects fonts with either type
  5309    of kerning data.
  5311   <p>If present, a value indicates an index used for glyph selection. An
  5312    &lt;integer&gt; value must be 0 or greater. A value of 0 indicates that
  5313    the feature is disabled. For boolean features, a value of 1 enables the
  5314    feature. For non-boolean features, a value of 1 or greater enables the
  5315    feature and indicates the feature selection index. A value of ‘<code
  5316    class=property>on</code>’ is synonymous with 1 and ‘<code
  5317    class=property>off</code>’ is synonymous with 0. If the value is
  5318    omitted, a value of 1 is assumed.
  5320   <pre>
  5321 font-feature-settings: "dlig" 1;       /* dlig=1 enable discretionary ligatures */
  5322 font-feature-settings: "smcp" on;      /* smcp=1 enable small caps */
  5323 font-feature-settings: 'c2sc';         /* c2sc=1 enable caps to small caps */
  5324 font-feature-settings: "liga" off;     /* liga=0 no common ligatures */
  5325 font-feature-settings: "tnum", 'hist'; /* tnum=1, hist=1 enable tabular numbers and historical forms */
  5326 font-feature-settings: "tnum" "hist";  /* invalid, need a comma-delimited list */
  5327 font-feature-settings: "silly" off;    /* invalid, tag too long */
  5328 font-feature-settings: "PKRN";         /* PKRN=1 enable custom feature */
  5329 font-feature-settings: dlig;           /* invalid, tag must be a string */
  5330 </pre>
  5332   <p>When values greater than the range supported by the font are specified,
  5333    the behavior is explicitly undefined. For boolean features, in general
  5334    these will enable the feature. For non-boolean features, out of range
  5335    values will in general be equivalent to a 0 value. However, in both cases
  5336    the exact behavior will depend upon the way the font is designed
  5337    (specifically, which type of lookup is used to define the feature).
  5339   <p>Although specifically defined for OpenType feature tags, feature tags
  5340    for other modern font formats that support font features may be added in
  5341    the future. Where possible, features defined for other font formats should
  5342    attempt to follow the pattern of registered OpenType tags.
  5344   <div class=example>
  5345    <p>The Japanese text below will be rendered with half-width kana
  5346     characters:</p>
  5348    <pre lang=ja>
  5349 body { font-feature-settings: "hwid"; /* Half-width OpenType feature */ }
  5351 &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>
  5352 </pre>
  5353   </div>
  5355   <h3 id=font-language-override-prop><span class=secno>6.13 </span>Font
  5356    language override: the <a
  5357    href="#propdef-font-language-override">font-language-override</a> property</h3>
  5359   <table class=propdef id=namefont-language-overridevaluenormal-lt>
  5360    <tbody>
  5361     <tr>
  5362      <td>Name:
  5364      <td><dfn id=propdef-font-language-override>font-language-override</dfn>
  5366     <tr>
  5367      <td>Value:
  5369      <td><a href="#font-language-override-normal-value"
  5370       title="normal!!font-language-override">normal</a> | <a
  5371       href="#font-language-override-string-value"><var>&lt;string&gt;</var></a>
  5373     <tr>
  5374      <td>Initial:
  5376      <td><a href="#font-language-override-normal-value"
  5377       title="normal!!font-language-override">normal</a>
  5379     <tr>
  5380      <td>Applies to:
  5382      <td>all elements
  5384     <tr>
  5385      <td>Inherited:
  5387      <td>yes
  5389     <tr>
  5390      <td>Percentages:
  5392      <td>N/A
  5394     <tr>
  5395      <td>Media:
  5397      <td>visual
  5399     <tr>
  5400      <td>Computed value:
  5402      <td>as specified
  5404     <tr>
  5405      <td>Animatable:
  5407      <td>no
  5408   </table>
  5410   <p>Normally, authors can control the use of language-specific glyph
  5411    substitutions and positioning by setting the content language of an
  5412    element, as <a href="#language-specific-support">described above</a>:
  5414   <pre>&lt;!-- Display text using S'gaw Karen specific features -->
  5415 &lt;p lang="ksw">...&lt;/p></pre>
  5417   <p>In some cases, authors may need to specify a language system that
  5418    differs from the content language, for example due to the need to mimic
  5419    another language's typographic traditions. The ‘<a
  5420    href="#propdef-font-language-override"><code
  5421    class=property>font-language-override</code></a>’ property allows
  5422    authors to explicitly specify the language system of the font, overriding
  5423    the language system implied by the content language.
  5425   <p>Values have the following meanings:
  5427   <dl>
  5428    <dt><dfn id=font-language-override-normal-value
  5429     title="normal!!font-language-override">normal</dfn>
  5431    <dd>specifies that when rendering with OpenType fonts, the content
  5432     language of the element is used to infer the OpenType language system
  5434    <dt><dfn
  5435     id=font-language-override-string-value><var>&lt;string&gt;</var></dfn>
  5437    <dd>single three-letter case-sensitive OpenType <a
  5438     href="http://www.microsoft.com/typography/otspec/languagetags.htm">language
  5439     system tag</a>, specifies the OpenType language system to be used instead
  5440     of the language system implied by the language of the element
  5441   </dl>
  5442   <!-- For this level, string represents a single language code, there's no concept of "fallback" 
  5443 http://www.w3.org/2013/06/07-css-minutes.html#item04 -->
  5445   <p>Use of invalid OpenType language system tags must not generate a parse
  5446    error but must be ignored when doing glyph selection and placement.
  5448   <div class=example>
  5449    <p>The <a href="http://www.un.org/en/documents/udhr/index.shtml">Universal
  5450     Declaration of Human Rights</a> has been translated into a wide variety
  5451     of languages. In Turkish, Article 9 of this document might be marked up
  5452     as below:</p>
  5454    <pre lang=tr>&lt;body lang="tr">
  5456 &lt;h4>Madde 9&lt;/h4>
  5457 &lt;p>Hiç kimse keyfi olarak tutuklanamaz, alıkonulanamaz veya sürülemez.&lt;/p>
  5458 </pre>
  5460    <p>Here the user agent uses the value of the ‘<code
  5461     class=property>lang</code>’ attribute when rendering text and
  5462     appropriately renders this text without ‘<code
  5463     class=property>fi</code>’ ligatures. There is no need to use the ‘<a
  5464     href="#propdef-font-language-override"><code
  5465     class=property>font-language-override</code></a>’ property.</p>
  5467    <p>However, a given font may lack support for a specific language. In this
  5468     situation authors may need to use the typographic conventions of a
  5469     related language that are supported by that font:</p>
  5471    <pre lang=mk>&lt;body lang="mk">     &lt;!-- Macedonian lang code --&gt;
  5473 body { font-language-override: "SRB"; /* Serbian OpenType language tag */ }
  5475 &lt;h4>Члeн 9&lt;/h4>
  5476 &lt;p>Никoj чoвeк нeмa дa бидe пoдлoжeн нa прoизвoлнo aпсeњe, притвoр или прoгoнувaњe.&lt;/p>
  5478 </pre>
  5480    <p>The Macedonian text here will be rendered using Serbian typographic
  5481     conventions, with the assumption that the font specified supports
  5482     Serbian.</p>
  5483   </div>
  5485   <p><a id=rendering-considerations></a>
  5487   <h2 id=font-feature-resolution><span class=secno>7 </span>Font Feature
  5488    Resolution</h2>
  5490   <p>As described in the previous section, font features can be enabled in a
  5491    variety of ways, either via the use of <a href="#propdef-font-variant"
  5492    title="font-variant!!property">‘<code
  5493    class=property>font-variant</code>’</a> or <a
  5494    href="#propdef-font-feature-settings"
  5495    title="font-feature-settings!!property">‘<code
  5496    class=property>font-feature-settings</code>’</a> in a style rule or
  5497    within an <a href="#at-font-face-rule"><code>@font-face</code></a> rule.
  5498    The resolution order for the union of these settings is defined below.
  5499    Features defined via CSS properties are applied on top of layout engine
  5500    default features.
  5502   <h3 id=default-features><span class=secno>7.1 </span>Default features</h3>
  5504   <p>For OpenType fonts, user agents must enable the default features defined
  5505    in the OpenType documentation for a given script and writing mode.
  5506    Required ligatures, common ligatures and contextual forms must be enabled
  5507    by default (OpenType features: <span class=tag>rlig, liga, clig,
  5508    calt</span>), along with localized forms (OpenType feature: <span
  5509    class=tag>locl</span>), and features required for proper display of
  5510    composed characters and marks (OpenType features: <span class=tag>ccmp,
  5511    mark, mkmk</span>). These features must always be enabled, even when the
  5512    value of the <a href="#propdef-font-variant"
  5513    title="font-variant!!property">‘<code
  5514    class=property>font-variant</code>’</a> and <a
  5515    href="#propdef-font-feature-settings"
  5516    title="font-feature-settings!!property">‘<code
  5517    class=property>font-feature-settings</code>’</a> properties is <span
  5518    title="normal value">‘<code class=property>normal</code>’</span>.
  5519    Individual features are only disabled when explicitly overridden by the
  5520    author, as when ‘<a href="#propdef-font-variant-ligatures"><code
  5521    class=property>font-variant-ligatures</code></a>’ is set to ‘<a
  5522    href="#no-common-ligatures"><code
  5523    class=property>no-common-ligatures</code></a>’. For handling complex
  5524    scripts such as <a
  5525    href="http://www.microsoft.com/typography/otfntdev/arabicot/features.aspx">Arabic</a>,
  5526    <a
  5527    href="http://www.microsoft.com/typography/otfntdev/mongolot/features.htm">Mongolian</a>
  5528    or <a
  5529    href="http://www.microsoft.com/typography/otfntdev/devanot/features.aspx">Devanagari</a>
  5530    additional features are required. For upright text within vertical text
  5531    runs, vertical alternates (OpenType feature: <span class=tag>vert</span>)
  5532    must be enabled.
  5534   <h3 id=feature-precedence><span class=secno>7.2 </span>Feature precedence</h3>
  5536   <p>General and <a href="#font-specific"><em>font specific</em></a> font
  5537    feature property settings are resolved in the order below, in ascending
  5538    order of precedence. This ordering is used to construct a combined list of
  5539    font features that affect a given text run.
  5541   <ol>
  5542    <li>Font features enabled by default, including features required for a
  5543     given script.
  5545    <li>If the font is defined via an <a
  5546     href="#at-font-face-rule"><code>@font-face</code></a> rule, the font
  5547     features implied by the font-variant descriptor in the <a
  5548     href="#at-font-face-rule"><code>@font-face</code></a> rule.
  5550    <li>If the font is defined via an <a
  5551     href="#at-font-face-rule"><code>@font-face</code></a> rule, the font
  5552     features implied by the font-feature-settings descriptor in the <a
  5553     href="#at-font-face-rule"><code>@font-face</code></a> rule.
  5555    <li>Font features implied by the value of the <a
  5556     href="#propdef-font-variant" title="font-variant!!property">‘<code
  5557     class=property>font-variant</code>’</a> property, the related <a
  5558     href="#propdef-font-variant" title="font-variant!!property">‘<code
  5559     class=property>font-variant</code>’</a> subproperties and any other CSS
  5560     property that uses OpenType features (e.g. the ‘<a
  5561     href="#propdef-font-kerning"><code
  5562     class=property>font-kerning</code></a>’ property).</li>
  5563    <!-- other CSS props override 'font-variant' but not 'font-feature-settings' -->
  5564    <!-- http://lists.w3.org/Archives/Public/www-style/2013Aug/0110.html -->
  5566    <li>Feature settings determined by properties other than <a
  5567     href="#propdef-font-variant" title="font-variant!!property">‘<code
  5568     class=property>font-variant</code>’</a> or <a
  5569     href="#propdef-font-feature-settings"
  5570     title="font-feature-settings!!property">‘<code
  5571     class=property>font-feature-settings</code>’</a>. For example, setting
  5572     a non-default value for the ‘<code
  5573     class=property>letter-spacing</code>’ property disables common
  5574     ligatures.
  5576    <li>Font features implied by the value of <a
  5577     href="#propdef-font-feature-settings"
  5578     title="font-feature-settings!!property">‘<code
  5579     class=property>font-feature-settings</code>’</a> property.
  5580   </ol>
  5582   <p>This ordering allows authors to set up a general set of defaults for
  5583    fonts within their <a
  5584    href="#at-font-face-rule"><code>@font-face</code></a> rules, then override
  5585    them with property settings for specific elements. General property
  5586    settings override the settings in <a
  5587    href="#at-font-face-rule"><code>@font-face</code></a> rules and low-level
  5588    font feature settings override <a href="#propdef-font-variant"
  5589    title="font-variant!!property">‘<code
  5590    class=property>font-variant</code>’</a> property settings.
  5592   <p>For situations where the combined list of font feature settings contains
  5593    more than one value for the same feature, the last value is used. When a
  5594    font lacks support for a given underlying font feature, text is simply
  5595    rendered as if that font feature was not enabled; font fallback does not
  5596    occur and no attempt is made to synthesize the feature except where
  5597    explicitly defined for specific properties.
  5599   <h3 id=feature-precedence-examples><span class=secno>7.3 </span>Feature
  5600    precedence examples</h3>
  5602   <div class=example>
  5603    <p>With the styles below, numbers are rendered proportionally when used
  5604     within a paragraph but are shown in tabular form within tables of prices:</p>
  5606    <pre>body {
  5607   font-variant-numeric: proportional-nums;
  5610 table.prices td {
  5611   font-variant-numeric: tabular-nums;
  5613 </pre>
  5614   </div>
  5616   <div class=example>
  5617    <p>When the <a href="#descdef-font-variant"
  5618     title="font-variant!!descriptor">font-variant</a> descriptor is used
  5619     within an <a href="#at-font-face-rule"><code>@font-face</code></a> rule,
  5620     it only applies to the font defined by that rule.</p>
  5622    <pre>@font-face {
  5623   font-family: MainText;
  5624   src: url(http://example.com/font.woff);
  5625   font-variant: oldstyle-nums proportional-nums styleset(1,3);
  5628 body {
  5629   font-family: MainText, Helvetica;
  5632 table.prices td {
  5633   font-variant-numeric: tabular-nums;
  5635 </pre>
  5637    <p>In this case, old-style numerals will be used throughout but only where
  5638     the font "MainText" is used. Just as in the previous example, tabular
  5639     values will be used in price tables since ‘<a
  5640     href="#tabular-nums"><code class=property>tabular-nums</code></a>’
  5641     appears in a general style rule and its use is mutually exclusive with
  5642     ‘<a href="#proportional-nums"><code
  5643     class=property>proportional-nums</code></a>’. Stylistic alternate sets
  5644     will only be used where MainText is used.</p>
  5645   </div>
  5647   <div class=example>
  5648    <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule can
  5649     also be used to access font features in locally available fonts via the
  5650     use of <code>local()</code> in the ‘<a href="#descdef-src"><code
  5651     class=property>src</code></a>’ descriptor of the <a
  5652     href="#at-font-face-rule"><code>@font-face</code></a> definition:</p>
  5654    <pre>@font-face {
  5655   font-family: BodyText;
  5656   src: local("HiraMaruPro-W4");
  5657   font-variant: proportional-width;
  5658   font-feature-settings: "ital"; /* Latin italics within CJK text feature */
  5661 body { font-family: BodyText, serif; }
  5662 </pre>
  5664    <p>If available, a Japanese font "Hiragino Maru Gothic" will be used. When
  5665     text rendering occurs, Japanese kana will be proportionally spaced and
  5666     Latin text will be italicised. Text rendered with the fallback serif font
  5667     will use default rendering properties.</p>
  5668   </div>
  5670   <div class=example>
  5671    <p>In the example below, discretionary ligatures are enabled only for a
  5672     downloadable font but are disabled within spans of class "special":</p>
  5674    <pre>@font-face {
  5675   font-family: main;
  5676   src: url(fonts/ffmeta.woff) format("woff");
  5677   font-variant: discretionary-ligatures;
  5680 body         { font-family: main, Helvetica; }
  5681 span.special { font-variant-ligatures: no-discretionary-ligatures; }
  5682 </pre>
  5684    <p>Suppose one adds a rule using ‘<code
  5685     class=property>font-feature-settings</code>’ to enable discretionary
  5686     ligatures:</p>
  5688    <pre>body         { font-family: main, Helvetica; }
  5689 span         { font-feature-settings: "dlig"; }
  5690 span.special { font-variant-ligatures: no-discretionary-ligatures; }
  5691 </pre>
  5693    <p>In this case, discretionary ligatures <em>will</em> be rendered within
  5694     spans of class "special". This is because both the <a
  5695     href="#propdef-font-feature-settings"
  5696     title="font-feature-settings!!property">‘<code
  5697     class=property>font-feature-settings</code>’</a> and ‘<a
  5698     href="#propdef-font-variant-ligatures"><code
  5699     class=property>font-variant-ligatures</code></a>’ properties apply to
  5700     these spans. Although the ‘<code class=css>no-discretionary
  5701     ligatures</code>’ setting of ‘<a
  5702     href="#propdef-font-variant-ligatures"><code
  5703     class=property>font-variant-ligatures</code></a>’ effectively disables
  5704     the OpenType <span class=tag>dlig</span> feature, because the <a
  5705     href="#propdef-font-feature-settings"
  5706     title="font-feature-settings!!property">‘<code
  5707     class=property>font-feature-settings</code>’</a> is resolved after
  5708     that, the ‘<code class=property>dlig</code>’ value reenables
  5709     discretionary ligatures.</p>
  5710   </div>
  5712   <h2 id=object-model><span class=secno>8 </span>Object Model</h2>
  5714   <p>The contents of <a href="#at-font-face-rule"><code>@font-face</code></a>
  5715    and <a
  5716    href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
  5717    rules can be accessed via the following extensions to the CSS Object
  5718    Model.
  5720   <h3 id=om-fontface><span class=secno>8.1 </span>The <a
  5721    href="#cssfontfacerule"><code>CSSFontFaceRule</code></a> interface</h3>
  5723   <p>The <dfn id=cssfontfacerule>CSSFontFaceRule</dfn> interface represents a
  5724    <a href="#at-font-face-rule"><code>@font-face</code></a> rule.
  5726   <pre class=idl>
  5727 interface CSSFontFaceRule : CSSRule {
  5728   attribute DOMString family;
  5729   attribute DOMString src;
  5730   attribute DOMString style;
  5731   attribute DOMString weight;
  5732   attribute DOMString stretch;
  5733   attribute DOMString unicodeRange;
  5734   attribute DOMString variant;
  5735   attribute DOMString featureSettings;
  5736 }</pre>
  5738   <p>The DOM Level 2 Style specification <a href="#DOM-LEVEL-2-STYLE"
  5739    rel=biblioentry>[DOM-LEVEL-2-STYLE]<!--{{DOM-LEVEL-2-STYLE}}--></a>
  5740    defined a different variant of this rule. This definition supercedes that
  5741    one.
  5743   <h3 id=om-fontfeaturevalues><span class=secno>8.2 </span>The <a
  5744    href="#cssfontfeaturevaluesrule"><code>CSSFontFeatureValuesRule</code></a>
  5745    interface</h3>
  5747   <p>The <code>CSSRule</code> interface is extended as follows:
  5749   <pre class=idl>partial interface CSSRule {
  5750   const unsigned short FONT_FEATURE_VALUES_RULE = 14;
  5751 }</pre>
  5753   <p>The <dfn id=cssfontfeaturevaluesrule>CSSFontFeatureValuesRule</dfn>
  5754    interface represents a <a
  5755    href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
  5756    rule.
  5758   <pre class=idl>interface CSSFontFeatureValuesRule : CSSRule {
  5759   attribute DOMString fontFamily;
  5760   readonly attribute CSSFontFeatureValuesMap annotation;
  5761   readonly attribute CSSFontFeatureValuesMap ornaments;
  5762   readonly attribute CSSFontFeatureValuesMap stylistic;
  5763   readonly attribute CSSFontFeatureValuesMap swash;
  5764   readonly attribute CSSFontFeatureValuesMap characterVariant;
  5765   readonly attribute CSSFontFeatureValuesMap styleset;
  5768 [MapClass(DOMString, sequence&lt;unsigned long&gt;)]
  5769 interface CSSFontFeatureValuesMap {
  5770   void set(DOMString featureValueName,
  5771            (unsigned long or sequence&lt;unsigned long&gt;) values);
  5772 }</pre>
  5774   <dl class=idl-attributes>
  5775    <dt><var>fontFamily</var> of type <code>DOMString</code>
  5777    <dd>The list of one or more font families for which a given set of feature
  5778     values is defined.
  5780    <dt>value maps of type <code>CSSFontFeatureValuesMap</code>, readonly
  5782    <dd>Maps of feature values associated with feature value names for a given
  5783     ‘<a href="#propdef-font-variant-alternates"><code
  5784     class=property>font-variant-alternates</code></a>’ value type
  5785   </dl>
  5787   <p>Each value map attribute of <a
  5788    href="#cssfontfeaturevaluesrule"><code>CSSFontFeatureValuesRule</code></a>
  5789    reflects the values defined via a corresponding <a
  5790    href="#featurevalueblock"><i title="feature_value_block">feature value
  5791    block</i></a>. Thus, the <var title="annotation
  5792    attribute">annotation</var> attribute contains the values contained within
  5793    a <code title="@annotation">@annotation</code> <a
  5794    href="#featurevalueblock"><i title="feature_value_block">feature value
  5795    block</i></a>, the <var title="ornaments attribute">ornaments</var>
  5796    attribute contains the values contained with a <code
  5797    title="@ornaments">@ornaments</code> <a href="#featurevalueblock"><i
  5798    title="feature_value_block">feature value block</i></a> and so forth.
  5800   <p>The <code>CSSFontFeatureValuesMap</code> interface uses the <a
  5801    href="http://dev.w3.org/2006/webapi/WebIDL/#es-map-members">default map
  5802    class methods</a> but the <code>set</code> method has different behavior.
  5803    It takes a sequence of unsigned integers and associates it with a given
  5804    <code>featureValueName</code>. The method behaves the same as the default
  5805    map class method except that a single unsigned long value is treated as a
  5806    sequence of a single value. The method throws an exception if an invalid
  5807    number of values is passed in. If the associated <a
  5808    href="#featurevalueblock"><i title="feature_value_block">feature value
  5809    block</i></a> only allows a limited number of values, the <code>set</code>
  5810    method throws an <code>InvalidAccessError</code> exception when the input
  5811    sequence to <code>set</code> contains more than the limited number of
  5812    values. See the description of <a
  5813    href="#multi-valued-feature-value-definitions">multi-valued feature value
  5814    definitions</a> for details on the maximum number of values allowed for a
  5815    given type of <a href="#featurevalueblock"><i
  5816    title="feature_value_block">feature value block</i></a>. The
  5817    <code>get</code> method always returns a sequence of values, even if the
  5818    sequence only contains a single value.
  5820   <h2 class=no-num id=platform-props-to-css>Appendix A: Mapping platform font
  5821    properties to CSS properties</h2>
  5823   <p><em>This appendix is included as background for some of the problems and
  5824    situations that are described in other sections. It should be viewed as
  5825    informative only.</em>
  5827   <p>Font properties in CSS are designed to be independent of the underlying
  5828    font formats used; they can be used to specify bitmap fonts, Type1 fonts,
  5829    SVG fonts in addition to the common TrueType and OpenType fonts. But there
  5830    are facets of the TrueType and OpenType formats that often cause confusion
  5831    for authors and present challenges to implementers on different platforms.
  5833   <p>Originally developed at Apple, TrueType was designed as an outline font
  5834    format for both screen and print. Microsoft joined Apple in developing the
  5835    TrueType format and both platforms have supported TrueType fonts since
  5836    then. Font data in the TrueType format consists of a set of tables
  5837    distinguished with common four-letter tag names, each containing a
  5838    specific type of data. For example, naming information, including
  5839    copyright and license information, is stored in the ‘<code
  5840    class=property>name</code>’ table. The <a
  5841    href="#character-map"><em>character map</em></a> (‘<code
  5842    class=property>cmap</code>’) table contains a mapping of character
  5843    encodings to glyphs. Apple later added additional tables for supporting
  5844    enhanced typographic functionality; these are now called Apple Advanced
  5845    Typography, or AAT, fonts. Microsoft and Adobe developed a separate set of
  5846    tables for advanced typography and called their format OpenType <a
  5847    href="#OPENTYPE" rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a>.
  5849   <p>In many cases the font data used under Microsoft Windows or Linux is
  5850    slightly different from the data used under Apple's Mac OS X because the
  5851    TrueType format allowed for explicit variation across platforms. This
  5852    includes font metrics, names and <a href="#character-map"><em>character
  5853    map</em></a> data.
  5855   <p>Specifically, font family name data is handled differently across
  5856    platforms. For TrueType and OpenType fonts these names are contained in
  5857    the ‘<code class=property>name</code>’ table, in name records with
  5858    name ID 1. Mulitple names can be stored for different locales, but
  5859    Microsoft recommends fonts always include at least a US English version of
  5860    the name. On Windows, Microsoft made the decision for backwards
  5861    compatibility to limit this family name to a maximum of four faces; for
  5862    larger groupings the "preferred family" (name ID 16) or "WWS family" (name
  5863    ID 21) can be used. Other platforms such as OSX don't have this
  5864    limitation, so the family name is used to define all possible groupings.
  5866   <p>Other name table data provides names used to uniquely identify a
  5867    specific face within a family. The full font name (name ID 4) and the
  5868    Postscript name (name ID 6) describe a single face uniquely. For example,
  5869    the bold face of the Gill Sans family has a fullname of "Gill Sans Bold"
  5870    and a Postscript name of "GillSans-Bold". There can be multiple localized
  5871    versions of the fullname for a given face, but the Postscript name is
  5872    always a unique name made from a limited set of ASCII characters.
  5874   <p>On various platforms, different names are used to search for a font. For
  5875    example, with the Windows GDI CreateIndirectFont API, either a family or
  5876    fullname can be used to lookup a face, while on Mac OS X the
  5877    CTFontCreateWithName API call is used to lookup a given face using the
  5878    fullname and Postscript name. Under Linux, the fontconfig API allows fonts
  5879    to be searched using any of these names. In situations where platform
  5880    API's automatically substitute other font choices, it may be necessary to
  5881    verify a returned font matches a given name.
  5883   <p>The weight of a given face can be determined via the usWeightClass field
  5884    of the OS/2 table or inferred from the style name (name ID 2). Likewise,
  5885    the width can be determined via the usWidthClass of the OS/2 table or
  5886    inferred from the style name. For historical reasons related to synthetic
  5887    bolding at weights 200 or lower with the Windows GDI API, font designers
  5888    have sometimes skewed values in the OS/2 table to avoid these weights.
  5890   <p>Rendering complex scripts that use contextual shaping such as Thai,
  5891    Arabic and Devanagari requires features present only in OpenType or AAT
  5892    fonts. Currently, complex script rendering is supported on Windows and
  5893    Linux using OpenType font features while both OpenType and AAT font
  5894    features are used under Mac OS X.
  5896   <h2 class=no-num id=ch-ch-ch-changes>Changes</h2>
  5898   <h3 class=no-num id=recent-changes> Changes from the <a
  5899    href="http://www.w3.org/TR/2013/WD-css-fonts-3-20130711/">July 2013 CSS3
  5900    Fonts Last Call Working Draft</a></h3>
  5902   <p>Major changes include:
  5904   <ul>
  5905    <li>reorder feature precedence such that features implied by other CSS
  5906     properties override ‘<code class=property>font-variant</code>’
  5907     settings
  5909    <li>switched examples to use .woff files
  5911    <li>revised wording of font fetching algorithm
  5913    <li>minor editorial cleanups
  5914   </ul>
  5916   <h2 class=no-num id=acknowledgments>Acknowledgments</h2>
  5918   <p>I'd like to thank Tal Leming, Jonathan Kew and Christopher Slye for all
  5919    their help and feedback. John Hudson was kind enough to take the time to
  5920    explain the subtleties of OpenType language tags and provided the example
  5921    of character variant usage for displaying text on Byzantine seals. Ken
  5922    Lunde and Eric Muller provided valuable feedback on CJK OpenType features
  5923    and Unicode variation selectors. The idea for supporting font features by
  5924    using <a href="#propdef-font-variant"
  5925    title="font-variant!!property">‘<code
  5926    class=property>font-variant</code>’</a> subproperties originated with
  5927    Håkon Wium Lie, Adam Twardoch and Tal Leming. Elika Etemad supplied some
  5928    of the initial design ideas for the <a
  5929    href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
  5930    rule. Thanks also to House Industries for allowing the use of Ed Interlock
  5931    in the discretionary ligatures example.
  5933   <p>A special thanks to Robert Bringhurst for the sublime mind expansion
  5934    that is <em>The Elements of Typographic Style</em>.
  5936   <h2 class=no-num id=conformance> Conformance</h2>
  5938   <h3 class=no-num id=conventions> Document Conventions</h3>
  5940   <p>Conformance requirements are expressed with a combination of descriptive
  5941    assertions and RFC 2119 terminology. The key words “MUST”, “MUST
  5942    NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”,
  5943    “SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL” in the
  5944    normative parts of this document are to be interpreted as described in RFC
  5945    2119. However, for readability, these words do not appear in all uppercase
  5946    letters in this specification.
  5948   <p>All of the text of this specification is normative except sections
  5949    explicitly marked as non-normative, examples, and notes. <a
  5950    href="#RFC2119" rel=biblioentry>[RFC2119]<!--{{!RFC2119}}--></a>
  5952   <p>Examples in this specification are introduced with the words “for
  5953    example” or are set apart from the normative text with
  5954    <code>class="example"</code>, like this:
  5956   <div class=example>
  5957    <p>This is an example of an informative example.
  5958   </div>
  5960   <p>Informative notes begin with the word “Note” and are set apart from
  5961    the normative text with <code>class="note"</code>, like this:
  5963   <p class=note>Note, this is an informative note.
  5965   <h3 class=no-num id=conformance-classes> Conformance Classes</h3>
  5967   <p>Conformance to CSS Fonts Level 3 Module is defined for three conformance
  5968    classes:
  5970   <dl>
  5971    <dt><dfn id=style-sheet title="style sheet!!as conformance class">style
  5972     sheet</dfn>
  5974    <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#style-sheet">CSS
  5975     style sheet</a>.
  5977    <dt><dfn id=renderer>renderer</dfn>
  5979    <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
  5980     that interprets the semantics of a style sheet and renders documents that
  5981     use them.
  5983    <dt><dfn id=authoring-tool>authoring tool</dfn>
  5985    <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
  5986     that writes a style sheet.
  5987   </dl>
  5989   <p>A style sheet is conformant to CSS Fonts Level 3 Module if all of its
  5990    declarations that use properties defined in this module have values that
  5991    are valid according to the generic CSS grammar and the individual grammars
  5992    of each property as given in this module.
  5994   <p>A renderer is conformant to CSS Fonts Level 3 Module if, in addition to
  5995    interpreting the style sheet as defined by the appropriate specifications,
  5996    it supports all the features defined by CSS Fonts Level 3 Module by
  5997    parsing them correctly and rendering the document accordingly. However,
  5998    the inability of a UA to correctly render a document due to limitations of
  5999    the device does not make the UA non-conformant. (For example, a UA is not
  6000    required to render color on a monochrome monitor.)
  6002   <p>An authoring tool is conformant to CSS Fonts Level 3 Module if it writes
  6003    style sheets that are syntactically correct according to the generic CSS
  6004    grammar and the individual grammars of each feature in this module, and
  6005    meet all other conformance requirements of style sheets as described in
  6006    this module.
  6008   <h3 class=no-num id=partial> Partial Implementations</h3>
  6010   <p>So that authors can exploit the forward-compatible parsing rules to
  6011    assign fallback values, CSS renderers <strong>must</strong> treat as
  6012    invalid (and <a
  6013    href="http://www.w3.org/TR/CSS21/conform.html#ignore">ignore as
  6014    appropriate</a>) any at-rules, properties, property values, keywords, and
  6015    other syntactic constructs for which they have no usable level of support.
  6016    In particular, user agents <strong>must not</strong> selectively ignore
  6017    unsupported component values and honor supported values in a single
  6018    multi-value property declaration: if any value is considered invalid (as
  6019    unsupported values must be), CSS requires that the entire declaration be
  6020    ignored.
  6022   <h3 class=no-num id=experimental> Experimental Implementations</h3>
  6024   <p>To avoid clashes with future CSS features, the CSS2.1 specification
  6025    reserves a <a
  6026    href="http://www.w3.org/TR/CSS21/syndata.html#vendor-keywords">prefixed
  6027    syntax</a> for proprietary and experimental extensions to CSS.
  6029   <p>Prior to a specification reaching the Candidate Recommendation stage in
  6030    the W3C process, all implementations of a CSS feature are considered
  6031    experimental. The CSS Working Group recommends that implementations use a
  6032    vendor-prefixed syntax for such features, including those in W3C Working
  6033    Drafts. This avoids incompatibilities with future changes in the draft.
  6035   <h3 class=no-num id=testing> Non-Experimental Implementations</h3>
  6037   <p>Once a specification reaches the Candidate Recommendation stage,
  6038    non-experimental implementations are possible, and implementors should
  6039    release an unprefixed implementation of any CR-level feature they can
  6040    demonstrate to be correctly implemented according to spec.
  6042   <p>To establish and maintain the interoperability of CSS across
  6043    implementations, the CSS Working Group requests that non-experimental CSS
  6044    renderers submit an implementation report (and, if necessary, the
  6045    testcases used for that implementation report) to the W3C before releasing
  6046    an unprefixed implementation of any CSS features. Testcases submitted to
  6047    W3C are subject to review and correction by the CSS Working Group.
  6049   <p>Further information on submitting testcases and implementation reports
  6050    can be found from on the CSS Working Group's website at <a
  6051    href="http://www.w3.org/Style/CSS/Test/">http://www.w3.org/Style/CSS/Test/</a>.
  6052    Questions should be directed to the <a
  6053    href="http://lists.w3.org/Archives/Public/public-css-testsuite">public-css-testsuite@w3.org</a>
  6054    mailing list.
  6056   <h2 class=no-num id=references>References</h2>
  6058   <h3 class=no-num id=normative-references>Normative References</h3>
  6059   <!--begin-normative-->
  6060   <!-- Sorted by label -->
  6062   <dl class=bibliography>
  6063    <dd style="display: none"><!-- keeps the doc valid if the DL is empty -->
  6064     <!---->
  6066    <dt id=CHARMOD>[CHARMOD]
  6068    <dd>Martin J. Dürst; et al. <a
  6069     href="http://www.w3.org/TR/2005/REC-charmod-20050215/"><cite>Character
  6070     Model for the World Wide Web 1.0: Fundamentals.</cite></a> 15 February
  6071     2005. W3C Recommendation. URL: <a
  6072     href="http://www.w3.org/TR/2005/REC-charmod-20050215/">http://www.w3.org/TR/2005/REC-charmod-20050215/</a>
  6073     </dd>
  6074    <!---->
  6076    <dt id=CORS>[CORS]
  6078    <dd>Anne van Kesteren. <a
  6079     href="http://www.w3.org/TR/2013/CR-cors-20130129/"><cite>Cross-Origin
  6080     Resource Sharing.</cite></a> 29 January 2013. W3C Candidate
  6081     Recommendation. (Work in progress.) URL: <a
  6082     href="http://www.w3.org/TR/2013/CR-cors-20130129/">http://www.w3.org/TR/2013/CR-cors-20130129/</a>
  6083     </dd>
  6084    <!---->
  6086    <dt id=CSS21>[CSS21]
  6088    <dd>Bert Bos; et al. <a
  6089     href="http://www.w3.org/TR/2011/REC-CSS2-20110607"><cite>Cascading Style
  6090     Sheets Level 2 Revision 1 (CSS 2.1) Specification.</cite></a> 7 June
  6091     2011. W3C Recommendation. URL: <a
  6092     href="http://www.w3.org/TR/2011/REC-CSS2-20110607">http://www.w3.org/TR/2011/REC-CSS2-20110607</a>
  6093     </dd>
  6094    <!---->
  6096    <dt id=CSS3VAL>[CSS3VAL]
  6098    <dd>Håkon Wium Lie; Tab Atkins; Elika J. Etemad. <a
  6099     href="http://www.w3.org/TR/2013/CR-css3-values-20130404/"><cite>CSS
  6100     Values and Units Module Level 3.</cite></a> 4 April 2013. W3C Candidate
  6101     Recommendation. (Work in progress.) URL: <a
  6102     href="http://www.w3.org/TR/2013/CR-css3-values-20130404/">http://www.w3.org/TR/2013/CR-css3-values-20130404/</a>
  6103     </dd>
  6104    <!---->
  6106    <dt id=HTML5>[HTML5]
  6108    <dd>Ian Hickson. <a
  6109     href="http://www.w3.org/TR/2012/CR-html5-20121217/"><cite>HTML5.</cite></a>
  6110     17 December 2012. W3C Candidate Recommendation. (Work in progress.) URL:
  6111     <a
  6112     href="http://www.w3.org/TR/2012/CR-html5-20121217/">http://www.w3.org/TR/2012/CR-html5-20121217/</a>
  6113     </dd>
  6114    <!---->
  6116    <dt id=OPEN-FONT-FORMAT>[OPEN-FONT-FORMAT]
  6118    <dd><a
  6119     href="http://www.iso.org/iso/home/store/catalogue_ics/catalogue_detail_ics.htm?csnumber=52136"><cite>Information
  6120     technology — Coding of audio-visual objects — Part 22: Open Font
  6121     Format.</cite></a> International Organization for Standardization.
  6122     ISO/IEC 14496-22:2009. URL: <a
  6123     href="http://www.iso.org/iso/home/store/catalogue_ics/catalogue_detail_ics.htm?csnumber=52136">http://www.iso.org/iso/home/store/catalogue_ics/catalogue_detail_ics.htm?csnumber=52136</a>
  6124     </dd>
  6125    <!---->
  6127    <dt id=OPENTYPE>[OPENTYPE]
  6129    <dd><a
  6130     href="http://www.microsoft.com/typography/otspec/default.htm"><cite>OpenType
  6131     specification.</cite></a> Microsoft. URL: <a
  6132     href="http://www.microsoft.com/typography/otspec/default.htm">http://www.microsoft.com/typography/otspec/default.htm</a>
  6133     </dd>
  6134    <!---->
  6136    <dt id=OPENTYPE-FEATURES>[OPENTYPE-FEATURES]
  6138    <dd><a
  6139     href="http://www.microsoft.com/typography/otspec/featurelist.htm"><cite>OpenType
  6140     feature registry.</cite></a> Microsoft. URL: <a
  6141     href="http://www.microsoft.com/typography/otspec/featurelist.htm">http://www.microsoft.com/typography/otspec/featurelist.htm</a>
  6142     </dd>
  6143    <!---->
  6145    <dt id=RFC2119>[RFC2119]
  6147    <dd>S. Bradner. <a href="http://www.ietf.org/rfc/rfc2119.txt"><cite>Key
  6148     words for use in RFCs to Indicate Requirement Levels.</cite></a> Internet
  6149     RFC 2119. URL: <a
  6150     href="http://www.ietf.org/rfc/rfc2119.txt">http://www.ietf.org/rfc/rfc2119.txt</a>
  6151     </dd>
  6152    <!---->
  6154    <dt id=UAX15>[UAX15]
  6156    <dd>Mark Davis; Ken Whistler. <a
  6157     href="http://www.unicode.org/reports/tr15/"><cite>Unicode Normalization
  6158     Forms.</cite></a> 31 August 2012. Unicode Standard Annex #15. URL: <a
  6159     href="http://www.unicode.org/reports/tr15/">http://www.unicode.org/reports/tr15/</a>
  6160     </dd>
  6161    <!---->
  6163    <dt id=UAX29>[UAX29]
  6165    <dd>Mark Davis. <a
  6166     href="http://www.unicode.org/reports/tr29/"><cite>Unicode Text
  6167     Segmentation.</cite></a> 12 September 2012. Unicode Standard Annex #29.
  6168     URL: <a
  6169     href="http://www.unicode.org/reports/tr29/">http://www.unicode.org/reports/tr29/</a>
  6170     </dd>
  6171    <!---->
  6173    <dt id=UNICODE6>[UNICODE6]
  6175    <dd>The Unicode Consortium. <a
  6176     href="http://www.unicode.org/versions/Unicode6.2.0/"><cite>The Unicode
  6177     Standard, Version 6.2.0.</cite></a> Defined by: The Unicode Standard,
  6178     Version 6.2.0 URL: <a
  6179     href="http://www.unicode.org/versions/Unicode6.2.0/">http://www.unicode.org/versions/Unicode6.2.0/</a>
  6180     </dd>
  6181    <!---->
  6182   </dl>
  6183   <!--end-normative-->
  6184   <!--{{!CSS21}}-->
  6185   <!--{{!CSS3VAL}}-->
  6186   <!--{{!OPENTYPE}}-->
  6187   <!--{{!OPENTYPE-FEATURES}}-->
  6188   <!--{{!OPEN-FONT-FORMAT}}-->
  6189   <!--{{!UNICODE6}}-->
  6190   <!--{{!UAX15}}-->
  6191   <!--{{!UAX29}}-->
  6192   <!--{{!CORS}}-->
  6193   <!--{{!HTML5}}-->
  6194   <!--{{!CHARMOD}}-->
  6196   <h3 class=no-num id=other-references>Other References</h3>
  6197   <!--begin-informative-->
  6198   <!-- Sorted by label -->
  6200   <dl class=bibliography>
  6201    <dd style="display: none"><!-- keeps the doc valid if the DL is empty -->
  6202     <!---->
  6204    <dt id=AAT-FEATURES>[AAT-FEATURES]
  6206    <dd><a href="http://developer.apple.com/fonts/registry/"><cite>Apple
  6207     Advanced Typography font feature registry.</cite></a> Apple. URL: <a
  6208     href="http://developer.apple.com/fonts/registry/">http://developer.apple.com/fonts/registry/</a>
  6209     </dd>
  6210    <!---->
  6212    <dt id=ARABIC-TYPO>[ARABIC-TYPO]
  6214    <dd>Huda Smitshuijzen AbiFares. <cite>Arabic Typography: A Comprehensive
  6215     Sourcebook.</cite> Saqi Books. 2001. ISBN 0-86356-347-3.</dd>
  6216    <!---->
  6218    <dt id=CHARMOD-NORM>[CHARMOD-NORM]
  6220    <dd>François Yergeau; et al. <a
  6221     href="http://www.w3.org/TR/2012/WD-charmod-norm-20120501/"><cite>Character
  6222     Model for the World Wide Web 1.0: Normalization.</cite></a> 1 May 2012.
  6223     W3C Working Draft. (Work in progress.) URL: <a
  6224     href="http://www.w3.org/TR/2012/WD-charmod-norm-20120501/">http://www.w3.org/TR/2012/WD-charmod-norm-20120501/</a>
  6225     </dd>
  6226    <!---->
  6228    <dt id=CJKV-INFO-PROCESSING>[CJKV-INFO-PROCESSING]
  6230    <dd>Ken Lunde. <cite>CJKV Information Processing, Second Edition.</cite>
  6231     O'Reilly Media, Inc. 2009. ISBN 0-596-51447-1.</dd>
  6232    <!---->
  6234    <dt id=CSS3-CONDITIONAL>[CSS3-CONDITIONAL]
  6236    <dd>L. David Baron. <a
  6237     href="http://www.w3.org/TR/2013/CR-css3-conditional-20130404/"><cite>CSS
  6238     Conditional Rules Module Level 3.</cite></a> 4 April 2013. W3C Candidate
  6239     Recommendation. (Work in progress.) URL: <a
  6240     href="http://www.w3.org/TR/2013/CR-css3-conditional-20130404/">http://www.w3.org/TR/2013/CR-css3-conditional-20130404/</a>
  6241     </dd>
  6242    <!---->
  6244    <dt id=CSS3TEXT>[CSS3TEXT]
  6246    <dd>Elika J. Etemad; Koji Ishii. <a
  6247     href="http://www.w3.org/TR/2012/WD-css3-text-20121113/"><cite>CSS Text
  6248     Module Level 3.</cite></a> 13 November 2012. W3C Working Draft. (Work in
  6249     progress.) URL: <a
  6250     href="http://www.w3.org/TR/2012/WD-css3-text-20121113/">http://www.w3.org/TR/2012/WD-css3-text-20121113/</a>
  6251     </dd>
  6252    <!---->
  6254    <dt id=DIGITAL-TYPOGRAPHY>[DIGITAL-TYPOGRAPHY]
  6256    <dd>Richard Rubinstein. <cite>Digital Typography, An Introduction to Type
  6257     and Composition for Computer System Design.</cite> Addison-Wesley. 1988.
  6258     ISBN 0-201-17633-5.</dd>
  6259    <!---->
  6261    <dt id=DOM-LEVEL-2-STYLE>[DOM-LEVEL-2-STYLE]
  6263    <dd>Chris Wilson; Philippe Le Hégaret; Vidur Apparao. <a
  6264     href="http://www.w3.org/TR/2000/REC-DOM-Level-2-Style-20001113/"><cite>Document
  6265     Object Model (DOM) Level 2 Style Specification.</cite></a> 13 November
  6266     2000. W3C Recommendation. URL: <a
  6267     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>
  6268     </dd>
  6269    <!---->
  6271    <dt id=ELEMTYPO>[ELEMTYPO]
  6273    <dd>Robert Bringhurst. <cite>The Elements of Typographic Style, Version
  6274     4.</cite> Hartley &amp; Marks. 2013. ISBN 0-88179-212-8.</dd>
  6275    <!---->
  6277    <dt id=LANGCULTTYPE>[LANGCULTTYPE]
  6279    <dd>John D. Berry, Ed. <cite>Language Culture Type.</cite> Graphis. 2001.
  6280     ISBN 1-932026-01-0.</dd>
  6281    <!---->
  6283    <dt id=OPENTYPE-FONT-GUIDE>[OPENTYPE-FONT-GUIDE]
  6285    <dd><a
  6286     href="https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf"><cite>OpenType
  6287     User Guide.</cite></a> FontShop International. URL: <a
  6288     href="https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf">https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf</a>
  6289     </dd>
  6290    <!---->
  6292    <dt id=RASTER-TRAGEDY>[RASTER-TRAGEDY]
  6294    <dd>Beat Stamm. <a href="http://www.rastertragedy.com/"><cite>The Raster
  6295     Tragedy at Low-Resolution Revisited.</cite></a> 7 December 2011. URL: <a
  6296     href="http://www.rastertragedy.com/">http://www.rastertragedy.com/</a></dd>
  6297    <!---->
  6299    <dt id=WINDOWS-GLYPH-PROC>[WINDOWS-GLYPH-PROC]
  6301    <dd>John Hudson. <a
  6302     href="http://www.microsoft.com/typography/developers/opentype/default.htm"><cite>Windows
  6303     Glyph Processing.</cite></a> Microsoft Typogrraphy. URL: <a
  6304     href="http://www.microsoft.com/typography/developers/opentype/default.htm">http://www.microsoft.com/typography/developers/opentype/default.htm</a>
  6305     </dd>
  6306    <!---->
  6307   </dl>
  6308   <!--end-informative-->
  6309   <!--{{ARABIC-TYPO}}-->
  6310   <!--{{CJKV-INFO-PROCESSING}}-->
  6311   <!--{{DIGITAL-TYPOGRAPHY}}-->
  6312   <!--{{DOM-LEVEL-2-STYLE}}-->
  6313   <!--{{ELEMTYPO}}-->
  6314   <!--{{LANGCULTTYPE}}-->
  6315   <!--{{OPENTYPE-FONT-GUIDE}}-->
  6316   <!--{{RASTER-TRAGEDY}}-->
  6317   <!--{{WINDOWS-GLYPH-PROC}}-->
  6318   <!--{{CHARMOD-NORM}}-->
  6319   <!--{{AAT-FEATURES}}-->
  6320   <!--{{CSS3-CONDITIONAL}}-->
  6321   <!--{{CSS3TEXT}}-->
  6323   <h2 class=no-num id=index>Index</h2>
  6324   <!--begin-index-->
  6326   <ul class=indexlist>
  6327    <li>100...900 weight values, <a href="#font-weight-numeric-values"
  6328     title="100...900 weight values"><strong>3.2</strong></a>
  6330    <li><var>&lt;absolute-size&gt;</var>, <a href="#absolute-size-value"
  6331     title="&lt;absolute-size&gt;"><strong>3.5</strong></a>
  6333    <li><var>&lt;common-lig-values&gt;</var>, <a href="#common-lig-values"
  6334     title="&lt;common-lig-values&gt;"><strong>6.4</strong></a>
  6336    <li><var>&lt;contextual-alt-values&gt;</var>, <a
  6337     href="#contextual-alt-values"
  6338     title="&lt;contextual-alt-values&gt;"><strong>6.4</strong></a>
  6340    <li><var>&lt;discretionary-lig-values&gt;</var>, <a
  6341     href="#discretionary-lig-values"
  6342     title="&lt;discretionary-lig-values&gt;"><strong>6.4</strong></a>
  6344    <li><var>&lt;east-asian-variant-values&gt;</var>, <a
  6345     href="#east-asian-variant-values"
  6346     title="&lt;east-asian-variant-values&gt;"><strong>6.10</strong></a>
  6348    <li><var>&lt;east-asian-width-values&gt;</var>, <a
  6349     href="#east-asian-width-values"
  6350     title="&lt;east-asian-width-values&gt;"><strong>6.10</strong></a>
  6352    <li><var>&lt;family-name&gt;</var>, <a href="#family-name-value"
  6353     title="&lt;family-name&gt;"><strong>3.1</strong></a>
  6355    <li><var>&lt;feature-tag-value&gt;</var>, <a href="#feature-tag-value"
  6356     title="&lt;feature-tag-value&gt;"><strong>6.12</strong></a>
  6358    <li><var>&lt;font-face-name&gt;</var>, <a href="#font-face-name-value"
  6359     title="&lt;font-face-name&gt;"><strong>4.3</strong></a>
  6361    <li><var>&lt;font-variant-css21&gt;</var>, <a
  6362     href="#font-variant-css21-values"
  6363     title="&lt;font-variant-css21&gt;"><strong>3.7</strong></a>
  6365    <li><var>&lt;generic-family&gt;</var>, <a href="#generic-family-value"
  6366     title="&lt;generic-family&gt;"><strong>3.1</strong></a>
  6368    <li><var>&lt;historical-lig-values&gt;</var>, <a
  6369     href="#historical-lig-values"
  6370     title="&lt;historical-lig-values&gt;"><strong>6.4</strong></a>
  6372    <li><var>&lt;length&gt;</var>, <a href="#length-size-value"
  6373     title="&lt;length&gt;"><strong>3.5</strong></a>
  6375    <li><var>&lt;number&gt;</var>, <a href="#aspect-ratio-value"
  6376     title="&lt;number&gt;"><strong>3.6</strong></a>
  6378    <li><var>&lt;numeric-figure-values&gt;</var>, <a
  6379     href="#numeric-figure-values"
  6380     title="&lt;numeric-figure-values&gt;"><strong>6.7</strong></a>
  6382    <li><var>&lt;numeric-fraction-values&gt;</var>, <a
  6383     href="#numeric-fraction-values"
  6384     title="&lt;numeric-fraction-values&gt;"><strong>6.7</strong></a>
  6386    <li><var>&lt;numeric-spacing-values&gt;</var>, <a
  6387     href="#numeric-spacing-values"
  6388     title="&lt;numeric-spacing-values&gt;"><strong>6.7</strong></a>
  6390    <li><var>&lt;percentage&gt;</var>, <a href="#percentage-size-value"
  6391     title="&lt;percentage&gt;"><strong>3.5</strong></a>
  6393    <li><var>&lt;relative-size&gt;</var>, <a href="#relative-size-value"
  6394     title="&lt;relative-size&gt;"><strong>3.5</strong></a>
  6396    <li><var>&lt;string&gt;</var>, <a
  6397     href="#font-language-override-string-value"
  6398     title="&lt;string&gt;"><strong>6.13</strong></a>
  6400    <li><var>&lt;urange&gt;</var>, <a href="#urange-value"
  6401     title="&lt;urange&gt;"><strong>4.5</strong></a>
  6403    <li><code>@font-face</code>, <a href="#at-font-face-rule"
  6404     title="@font-face"><strong>4.1</strong></a>
  6406    <li><code>@font-feature-values</code>, <a
  6407     href="#at-font-feature-values-rule"
  6408     title="@font-feature-values"><strong>6.9</strong></a>
  6410    <li>all-petite-caps, <a href="#all-petite-caps"
  6411     title=all-petite-caps><strong>6.6</strong></a>
  6413    <li>all-small-caps, <a href="#all-small-caps"
  6414     title=all-small-caps><strong>6.6</strong></a>
  6416    <li>annotation, <a href="#annotation"
  6417     title=annotation><strong>6.8</strong></a>
  6419    <li>aspect value, <a href="#aspect-value0" title="aspect
  6420     value"><strong>3.6</strong></a>
  6422    <li>authoring tool, <a href="#authoring-tool" title="authoring
  6423     tool"><strong>#</strong></a>
  6425    <li>auto
  6426     <ul>
  6427      <li>font-kerning, <a href="#font-kerning-auto-value" title="auto,
  6428       font-kerning"><strong>6.3</strong></a>
  6430      <li>font-size-adjust, <a href="#font-size-adjust-auto-value"
  6431       title="auto, font-size-adjust"><strong>3.6</strong></a>
  6432     </ul>
  6434    <li>bold, <a href="#bold" title=bold><strong>3.2</strong></a>
  6436    <li>bolder, <a href="#bolder" title=bolder><strong>3.2</strong></a>
  6438    <li>character map, <a href="#character-map" title="character
  6439     map"><strong>5.2</strong></a>
  6441    <li>character-variant, <a href="#character-variant"
  6442     title=character-variant><strong>6.8</strong></a>
  6444    <li>common-ligatures, <a href="#common-ligatures"
  6445     title=common-ligatures><strong>6.4</strong></a>
  6447    <li>composite face, <a href="#composite-face" title="composite
  6448     face"><strong>5.2</strong></a>
  6450    <li>condensed, <a href="#condensed"
  6451     title=condensed><strong>3.3</strong></a>
  6453    <li>contextual, <a href="#contextual"
  6454     title=contextual><strong>6.4</strong></a>
  6456    <li>CSSFontFaceRule, <a href="#cssfontfacerule"
  6457     title=CSSFontFaceRule><strong>8.1</strong></a>
  6459    <li>CSSFontFeatureValuesRule, <a href="#cssfontfeaturevaluesrule"
  6460     title=CSSFontFeatureValuesRule><strong>8.2</strong></a>
  6462    <li>cursive, definition of, <a href="#cursive0" title="cursive, definition
  6463     of"><strong>#</strong></a>
  6465    <li>default face, <a href="#default-face" title="default
  6466     face"><strong>5.2</strong></a>
  6468    <li>descriptor_declaration, <a href="#descriptordeclaration"
  6469     title="descriptor_declaration"><strong>4.1</strong></a>
  6471    <li>diagonal-fractions, <a href="#diagonal-fractions"
  6472     title=diagonal-fractions><strong>6.7</strong></a>
  6474    <li>discretionary-ligatures, <a href="#discretionary-ligatures"
  6475     title=discretionary-ligatures><strong>6.4</strong></a>
  6477    <li>effective character map, <a href="#effective-character-map"
  6478     title="effective character map"><strong>4.5</strong></a>
  6480    <li>expanded, <a href="#expanded" title=expanded><strong>3.3</strong></a>
  6482    <li>extra-condensed, <a href="#extra-condensed"
  6483     title=extra-condensed><strong>3.3</strong></a>
  6485    <li>extra-expanded, <a href="#extra-expanded"
  6486     title=extra-expanded><strong>3.3</strong></a>
  6488    <li>fantasy, definition of, <a href="#fantasy0" title="fantasy, definition
  6489     of"><strong>#</strong></a>
  6491    <li>feature_type, <a href="#featuretype"
  6492     title="feature_type"><strong>6.9.1</strong></a>
  6494    <li>feature_value_block, <a href="#featurevalueblock"
  6495     title="feature_value_block"><strong>6.9.1</strong></a>
  6497    <li>feature_value_definition, <a href="#featurevaluedefinition"
  6498     title="feature_value_definition"><strong>6.9.1</strong></a>
  6500    <li>first available font, <a href="#first-available-font" title="first
  6501     available font"><strong>5.2</strong></a>
  6503    <li>font, <a href="#propdef-font" title=font><strong>3.7</strong></a>
  6505    <li>font specific, <a href="#font-specific" title="font
  6506     specific"><strong>6.8</strong></a>
  6508    <li>font-family
  6509     <ul>
  6510      <li>descriptor, <a href="#descdef-font-family" title="font-family,
  6511       descriptor"><strong>4.2</strong></a>
  6513      <li>property, <a href="#propdef-font-family" title="font-family,
  6514       property"><strong>3.1</strong></a>
  6515     </ul>
  6517    <li>font-feature-settings
  6518     <ul>
  6519      <li>descriptor, <a href="#descdef-font-feature-settings"
  6520       title="font-feature-settings, descriptor"><strong>4.7</strong></a>
  6522      <li>property, <a href="#propdef-font-feature-settings"
  6523       title="font-feature-settings, property"><strong>6.12</strong></a>
  6524     </ul>
  6526    <li>font-kerning, <a href="#propdef-font-kerning"
  6527     title=font-kerning><strong>6.3</strong></a>
  6529    <li>font-language-override, <a href="#propdef-font-language-override"
  6530     title=font-language-override><strong>6.13</strong></a>
  6532    <li>font-size, <a href="#propdef-font-size"
  6533     title=font-size><strong>3.5</strong></a>
  6535    <li>font-size-adjust, <a href="#propdef-font-size-adjust"
  6536     title=font-size-adjust><strong>3.6</strong></a>
  6538    <li>font-stretch
  6539     <ul>
  6540      <li>descriptor, <a href="#descdef-font-stretch" title="font-stretch,
  6541       descriptor"><strong>4.4</strong></a>
  6543      <li>property, <a href="#propdef-font-stretch" title="font-stretch,
  6544       property"><strong>3.3</strong></a>
  6545     </ul>
  6547    <li>font-style
  6548     <ul>
  6549      <li>descriptor, <a href="#descdef-font-style" title="font-style,
  6550       descriptor"><strong>4.4</strong></a>
  6552      <li>property, <a href="#propdef-font-style" title="font-style,
  6553       property"><strong>3.4</strong></a>
  6554     </ul>
  6556    <li>font-synthesis, <a href="#propdef-font-synthesis"
  6557     title=font-synthesis><strong>3.8</strong></a>
  6559    <li>font-variant
  6560     <ul>
  6561      <li>descriptor, <a href="#descdef-font-variant" title="font-variant,
  6562       descriptor"><strong>4.7</strong></a>
  6564      <li>property, <a href="#propdef-font-variant" title="font-variant,
  6565       property"><strong>6.11</strong></a>
  6566     </ul>
  6568    <li>font-variant-alternates, <a href="#propdef-font-variant-alternates"
  6569     title=font-variant-alternates><strong>6.8</strong></a>
  6571    <li>font-variant-caps, <a href="#propdef-font-variant-caps"
  6572     title=font-variant-caps><strong>6.6</strong></a>
  6574    <li>font-variant-east-asian, <a href="#propdef-font-variant-east-asian"
  6575     title=font-variant-east-asian><strong>6.10</strong></a>
  6577    <li>font-variant-ligatures, <a href="#propdef-font-variant-ligatures"
  6578     title=font-variant-ligatures><strong>6.4</strong></a>
  6580    <li>font-variant-numeric, <a href="#propdef-font-variant-numeric"
  6581     title=font-variant-numeric><strong>6.7</strong></a>
  6583    <li>font-variant-position, <a href="#propdef-font-variant-position"
  6584     title=font-variant-position><strong>6.5</strong></a>
  6586    <li>font-weight
  6587     <ul>
  6588      <li>descriptor, <a href="#descdef-font-weight" title="font-weight,
  6589       descriptor"><strong>4.4</strong></a>
  6591      <li>property, <a href="#propdef-font-weight" title="font-weight,
  6592       property"><strong>3.2</strong></a>
  6593     </ul>
  6595    <li>font_face_rule, <a href="#fontfacerule"
  6596     title="font_face_rule"><strong>4.1</strong></a>
  6598    <li>FONT_FACE_SYM, <a href="#fontfacesym"
  6599     title="FONT_FACE_SYM"><strong>4.1</strong></a>
  6601    <li>font_family_name, <a href="#fontfamilyname"
  6602     title="font_family_name"><strong>6.9.1</strong></a>
  6604    <li>font_family_name_list, <a href="#fontfamilynamelist"
  6605     title="font_family_name_list"><strong>6.9.1</strong></a>
  6607    <li>font_feature_values_rule, <a href="#fontfeaturevaluesrule"
  6608     title="font_feature_values_rule"><strong>6.9.1</strong></a>
  6610    <li>FONT_FEATURE_VALUES_SYM, <a href="#fontfeaturevaluessym"
  6611     title="FONT_FEATURE_VALUES_SYM"><strong>6.9.1</strong></a>
  6613    <li>full-width, <a href="#full-width"
  6614     title=full-width><strong>6.10</strong></a>
  6616    <li>historical-forms, <a href="#historical-forms"
  6617     title=historical-forms><strong>6.8</strong></a>
  6619    <li>historical-ligatures, <a href="#historical-ligatures"
  6620     title=historical-ligatures><strong>6.4</strong></a>
  6622    <li>italic, <a href="#italic" title=italic><strong>3.4</strong></a>
  6624    <li>jis04, <a href="#jis04" title=jis04><strong>6.10</strong></a>
  6626    <li>jis78, <a href="#jis78" title=jis78><strong>6.10</strong></a>
  6628    <li>jis83, <a href="#jis83" title=jis83><strong>6.10</strong></a>
  6630    <li>jis90, <a href="#jis90" title=jis90><strong>6.10</strong></a>
  6632    <li>lighter, <a href="#lighter" title=lighter><strong>3.2</strong></a>
  6634    <li>lining-nums, <a href="#lining-nums"
  6635     title=lining-nums><strong>6.7</strong></a>
  6637    <li>monospace, definition of, <a href="#monospace0" title="monospace,
  6638     definition of"><strong>#</strong></a>
  6640    <li>no-common-ligatures, <a href="#no-common-ligatures"
  6641     title=no-common-ligatures><strong>6.4</strong></a>
  6643    <li>no-contextual, <a href="#no-contextual"
  6644     title=no-contextual><strong>6.4</strong></a>
  6646    <li>no-discretionary-ligatures, <a href="#no-discretionary-ligatures"
  6647     title=no-discretionary-ligatures><strong>6.4</strong></a>
  6649    <li>no-historical-ligatures, <a href="#no-historical-ligatures"
  6650     title=no-historical-ligatures><strong>6.4</strong></a>
  6652    <li>none
  6653     <ul>
  6654      <li>font-kerning, <a href="#font-kerning-none-value" title="none,
  6655       font-kerning"><strong>6.3</strong></a>
  6657      <li>font-size-adjust, <a href="#font-size-adjust-none-value"
  6658       title="none, font-size-adjust"><strong>3.6</strong></a>
  6660      <li>font-variant, <a href="#font-variant-none-value" title="none,
  6661       font-variant"><strong>6.11</strong></a>
  6663      <li>font-variant-ligatures, <a href="#font-variant-ligatures-none-value"
  6664       title="none, font-variant-ligatures"><strong>6.4</strong></a>
  6665     </ul>
  6667    <li>normal
  6668     <ul>
  6669      <li>font-feature-settings, <a href="#font-feature-settings-normal-value"
  6670       title="normal, font-feature-settings"><strong>6.12</strong></a>
  6672      <li>font-kerning, <a href="#font-kerning-normal-value" title="normal,
  6673       font-kerning"><strong>6.3</strong></a>
  6675      <li>font-language-override, <a
  6676       href="#font-language-override-normal-value" title="normal,
  6677       font-language-override"><strong>6.13</strong></a>
  6679      <li>font-stretch, <a href="#font-stretch-normal-value" title="normal,
  6680       font-stretch"><strong>3.3</strong></a>
  6682      <li>font-style, <a href="#font-style-normal-value" title="normal,
  6683       font-style"><strong>3.4</strong></a>
  6685      <li>font-variant, <a href="#font-variant-normal-value" title="normal,
  6686       font-variant"><strong>6.11</strong></a>
  6688      <li>font-variant-alternates, <a
  6689       href="#font-variant-alternates-normal-value" title="normal,
  6690       font-variant-alternates"><strong>6.8</strong></a>
  6692      <li>font-variant-caps, <a href="#font-variant-caps-normal-value"
  6693       title="normal, font-variant-caps"><strong>6.6</strong></a>
  6695      <li>font-variant-east-asian, <a
  6696       href="#font-variant-east-asian-normal-value" title="normal,
  6697       font-variant-east-asian"><strong>6.10</strong></a>
  6699      <li>font-variant-ligatures, <a
  6700       href="#font-variant-ligatures-normal-value" title="normal,
  6701       font-variant-ligatures"><strong>6.4</strong></a>
  6703      <li>font-variant-numeric, <a href="#font-variant-numeric-normal-value"
  6704       title="normal, font-variant-numeric"><strong>6.7</strong></a>
  6706      <li>font-variant-position, <a href="#font-variant-position-normal-value"
  6707       title="normal, font-variant-position"><strong>6.5</strong></a>
  6709      <li>font-weight, <a href="#font-weight-normal-value" title="normal,
  6710       font-weight"><strong>3.2</strong></a>
  6711     </ul>
  6713    <li>oblique, <a href="#oblique" title=oblique><strong>3.4</strong></a>
  6715    <li>oldstyle-nums, <a href="#oldstyle-nums"
  6716     title=oldstyle-nums><strong>6.7</strong></a>
  6718    <li>ordinal, <a href="#ordinal" title=ordinal><strong>6.7</strong></a>
  6720    <li>ornaments, <a href="#ornaments"
  6721     title=ornaments><strong>6.8</strong></a>
  6723    <li>petite-caps, <a href="#petite-caps"
  6724     title=petite-caps><strong>6.6</strong></a>
  6726    <li>proportional-nums, <a href="#proportional-nums"
  6727     title=proportional-nums><strong>6.7</strong></a>
  6729    <li>proportional-width, <a href="#proportional-width"
  6730     title=proportional-width><strong>6.10</strong></a>
  6732    <li>renderer, <a href="#renderer" title=renderer><strong>#</strong></a>
  6734    <li>ruby, <a href="#ruby" title=ruby><strong>6.10</strong></a>
  6736    <li>sans-serif, definition of, <a href="#sans-serif0" title="sans-serif,
  6737     definition of"><strong>#</strong></a>
  6739    <li>semi-condensed, <a href="#semi-condensed-"
  6740     title=semi-condensed><strong>3.3</strong></a>
  6742    <li>semi-expanded, <a href="#semi-expanded"
  6743     title=semi-expanded><strong>3.3</strong></a>
  6745    <li>serif, definition of, <a href="#serif0" title="serif, definition
  6746     of"><strong>#</strong></a>
  6748    <li>simplified, <a href="#simplified"
  6749     title=simplified><strong>6.10</strong></a>
  6751    <li>slashed-zero, <a href="#slashed-zero"
  6752     title=slashed-zero><strong>6.7</strong></a>
  6754    <li>small-caps, <a href="#small-caps"
  6755     title=small-caps><strong>6.6</strong></a>
  6757    <li>src, <a href="#descdef-src" title=src><strong>4.3</strong></a>
  6759    <li>stacked-fractions, <a href="#stacked-fractions"
  6760     title=stacked-fractions><strong>6.7</strong></a>
  6762    <li>style sheet
  6763     <ul>
  6764      <li>as conformance class, <a href="#style-sheet" title="style sheet, as
  6765       conformance class"><strong>#</strong></a>
  6766     </ul>
  6768    <li>styleset, <a href="#styleset" title=styleset><strong>6.8</strong></a>
  6770    <li>stylistic, <a href="#stylistic"
  6771     title=stylistic><strong>6.8</strong></a>
  6773    <li>sub, <a href="#sub" title=sub><strong>6.5</strong></a>
  6775    <li>super, <a href="#super" title=super><strong>6.5</strong></a>
  6777    <li>support, <a href="#support" title=support><strong>5.2</strong></a>
  6779    <li>swash, <a href="#swash" title=swash><strong>6.8</strong></a>
  6781    <li>system font fallback, <a href="#system-font-fallback" title="system
  6782     font fallback"><strong>5.2</strong></a>
  6784    <li>tabular-nums, <a href="#tabular-nums"
  6785     title=tabular-nums><strong>6.7</strong></a>
  6787    <li>titling-caps, <a href="#titling-caps"
  6788     title=titling-caps><strong>6.6</strong></a>
  6790    <li>traditional, <a href="#traditional"
  6791     title=traditional><strong>6.10</strong></a>
  6793    <li>ultra-condensed, <a href="#ultra-condensed"
  6794     title=ultra-condensed><strong>3.3</strong></a>
  6796    <li>ultra-expanded, <a href="#ultra-expanded"
  6797     title=ultra-expanded><strong>3.3</strong></a>
  6799    <li>unicase, <a href="#unicase" title=unicase><strong>6.6</strong></a>
  6801    <li>unicode-range, <a href="#descdef-unicode-range"
  6802     title=unicode-range><strong>4.5</strong></a>
  6804    <li>weight, <a href="#weight" title=weight><strong>2</strong></a>
  6806    <li>width, <a href="#width" title=width><strong>2</strong></a>
  6807   </ul>
  6808   <!--end-index-->
  6810   <h2 class=no-num id=property-index>Property index</h2>
  6811   <!--begin-properties-->
  6813   <table class=proptable>
  6814    <thead>
  6815     <tr>
  6816      <th>Property
  6818      <th>Values
  6820      <th>Initial
  6822      <th>Applies to
  6824      <th>Inh.
  6826      <th>Percentages
  6828      <th>Media
  6830    <tbody>
  6831     <tr>
  6832      <th><a class=property href="#propdef-font">font</a>
  6834      <td>[ [ &lt;‘font-style’&gt; || &lt;font-variant-css21&gt; ||
  6835       &lt;‘font-weight’&gt; || &lt;‘font-stretch’ ]?
  6836       &lt;‘font-size’&gt; [ / &lt;‘line-height’&gt; ]?
  6837       &lt;‘font-family’&gt; ] | caption | icon | menu | message-box |
  6838       small-caption | status-bar
  6840      <td>see individual properties
  6842      <td>all elements
  6844      <td>yes
  6846      <td>see individual properties
  6848      <td>visual
  6850     <tr>
  6851      <th><span class=property>font-family</span>
  6853      <td>[ &lt;family-name&gt; | &lt;generic-family&gt; ] #
  6855      <td>depends on user agent
  6857      <td>all elements
  6859      <td>yes
  6861      <td>N/A
  6863      <td>visual
  6865     <tr>
  6866      <th><span class=property>font-feature-settings</span>
  6868      <td>normal | &lt;feature-tag-value&gt; #
  6870      <td>normal
  6872      <td>all elements
  6874      <td>yes
  6876      <td>N/A
  6878      <td>visual
  6880     <tr>
  6881      <th><a class=property href="#propdef-font-kerning">font-kerning</a>
  6883      <td>auto | normal | none
  6885      <td>auto
  6887      <td>all elements
  6889      <td>yes
  6891      <td>N/A
  6893      <td>visual
  6895     <tr>
  6896      <th><a class=property
  6897       href="#propdef-font-language-override">font-language-override</a>
  6899      <td>normal | &lt;string&gt;
  6901      <td>normal
  6903      <td>all elements
  6905      <td>yes
  6907      <td>N/A
  6909      <td>visual
  6911     <tr>
  6912      <th><a class=property href="#propdef-font-size">font-size</a>
  6914      <td>&lt;absolute-size&gt; | &lt;relative-size&gt; | &lt;length&gt; |
  6915       &lt;percentage&gt;
  6917      <td>medium
  6919      <td>all elements
  6921      <td>yes
  6923      <td>refer to parent element's font size
  6925      <td>visual
  6927     <tr>
  6928      <th><a class=property
  6929       href="#propdef-font-size-adjust">font-size-adjust</a>
  6931      <td>none | auto | &lt;number&gt;
  6933      <td>none
  6935      <td>all elements
  6937      <td>yes
  6939      <td>N/A
  6941      <td>visual
  6943     <tr>
  6944      <th><span class=property>font-stretch</span>
  6946      <td>normal | ultra-condensed | extra-condensed | condensed |
  6947       semi-condensed | semi-expanded | expanded | extra-expanded |
  6948       ultra-expanded
  6950      <td>normal
  6952      <td>all elements
  6954      <td>yes
  6956      <td>N/A
  6958      <td>visual
  6960     <tr>
  6961      <th><span class=property>font-style</span>
  6963      <td>normal | italic | oblique
  6965      <td>normal
  6967      <td>all elements
  6969      <td>yes
  6971      <td>N/A
  6973      <td>visual
  6975     <tr>
  6976      <th><a class=property href="#propdef-font-synthesis">font-synthesis</a>
  6978      <td>none | [ weight || style ]
  6980      <td>weight style
  6982      <td>all elements
  6984      <td>yes
  6986      <td>N/A
  6988      <td>visual
  6990     <tr>
  6991      <th><span class=property>font-variant</span>
  6993      <td>normal | none | [ &lt;common-lig-values&gt; ||
  6994       &lt;discretionary-lig-values&gt; || &lt;historical-lig-values&gt; ||
  6995       &lt;contextual-alt-values&gt; || stylistic(&lt;feature-value-name&gt;)
  6996       || historical-forms || styleset(&lt;feature-value-name&gt; #) ||
  6997       character-variant(&lt;feature-value-name&gt; #) ||
  6998       swash(&lt;feature-value-name&gt;) ||
  6999       ornaments(&lt;feature-value-name&gt;) ||
  7000       annotation(&lt;feature-value-name&gt;) || [ small-caps | all-small-caps
  7001       | petite-caps | all-petite-caps | unicase | titling-caps ] ||
  7002       &lt;numeric-figure-values&gt; || &lt;numeric-spacing-values&gt; ||
  7003       &lt;numeric-fraction-values&gt; || ordinal || slashed-zero ||
  7004       &lt;east-asian-variant-values&gt; || &lt;east-asian-width-values&gt; ||
  7005       ruby ]
  7007      <td>normal
  7009      <td>all elements
  7011      <td>yes
  7013      <td>see individual properties
  7015      <td>visual
  7017     <tr>
  7018      <th><a class=property
  7019       href="#propdef-font-variant-alternates">font-variant-alternates</a>
  7021      <td>normal | [ stylistic(&lt;feature-value-name&gt;) || historical-forms
  7022       || styleset(&lt;feature-value-name&gt; #) ||
  7023       character-variant(&lt;feature-value-name&gt; #) ||
  7024       swash(&lt;feature-value-name&gt;) ||
  7025       ornaments(&lt;feature-value-name&gt;) ||
  7026       annotation(&lt;feature-value-name&gt;) ]
  7028      <td>normal
  7030      <td>all elements
  7032      <td>yes
  7034      <td>N/A
  7036      <td>visual
  7038     <tr>
  7039      <th><a class=property
  7040       href="#propdef-font-variant-caps">font-variant-caps</a>
  7042      <td>normal | small-caps | all-small-caps | petite-caps | all-petite-caps
  7043       | unicase | titling-caps
  7045      <td>normal
  7047      <td>all elements
  7049      <td>yes
  7051      <td>N/A
  7053      <td>visual
  7055     <tr>
  7056      <th><a class=property
  7057       href="#propdef-font-variant-east-asian">font-variant-east-asian</a>
  7059      <td>normal | [ &lt;east-asian-variant-values&gt; ||
  7060       &lt;east-asian-width-values&gt; || ruby ]
  7062      <td>normal
  7064      <td>all elements
  7066      <td>yes
  7068      <td>N/A
  7070      <td>visual
  7072     <tr>
  7073      <th><a class=property
  7074       href="#propdef-font-variant-ligatures">font-variant-ligatures</a>
  7076      <td>normal | none | [ &lt;common-lig-values&gt; ||
  7077       &lt;discretionary-lig-values&gt; || &lt;historical-lig-values&gt; ||
  7078       &lt;contextual-alt-values&gt; ]
  7080      <td>normal
  7082      <td>all elements
  7084      <td>yes
  7086      <td>N/A
  7088      <td>visual
  7090     <tr>
  7091      <th><a class=property
  7092       href="#propdef-font-variant-numeric">font-variant-numeric</a>
  7094      <td>normal | [ &lt;numeric-figure-values&gt; ||
  7095       &lt;numeric-spacing-values&gt; || &lt;numeric-fraction-values&gt; ||
  7096       ordinal || slashed-zero ]
  7098      <td>normal
  7100      <td>all elements
  7102      <td>yes
  7104      <td>N/A
  7106      <td>visual
  7108     <tr>
  7109      <th><a class=property
  7110       href="#propdef-font-variant-position">font-variant-position</a>
  7112      <td>normal | sub | super
  7114      <td>normal
  7116      <td>all elements
  7118      <td>yes
  7120      <td>N/A
  7122      <td>visual
  7124     <tr>
  7125      <th><span class=property>font-weight</span>
  7127      <td>normal | bold | bolder | lighter | 100 | 200 | 300 | 400 | 500 | 600
  7128       | 700 | 800 | 900
  7130      <td>normal
  7132      <td>all elements
  7134      <td>yes
  7136      <td>N/A
  7138      <td>visual
  7139   </table>
  7140   <!--end-properties-->
  7141   <!--begin-descriptors-->
  7143   <table class=proptable>
  7144    <thead>
  7145     <tr>
  7146      <th>Descriptor
  7148      <th>Value
  7150      <th>Initial
  7152      <th>Percentages
  7154      <th>Media
  7156    <tbody>
  7157     <tr>
  7158      <th><span class=property>font-family</span>
  7160      <td>&lt;family-name&gt;
  7162      <td>N/A
  7164     <tr>
  7165      <th><span class=property>font-feature-settings</span>
  7167      <td>normal | &lt;feature-tag-value&gt; #
  7169      <td>normal
  7171     <tr>
  7172      <th><span class=property>font-stretch</span>
  7174      <td>normal | ultra-condensed | extra-condensed | condensed |
  7175       semi-condensed | semi-expanded | expanded | extra-expanded |
  7176       ultra-expanded
  7178      <td>normal
  7180     <tr>
  7181      <th><span class=property>font-style</span>
  7183      <td>normal | italic | oblique
  7185      <td>normal
  7187     <tr>
  7188      <th><span class=property>font-variant</span>
  7190      <td>normal | none | [ &lt;common-lig-values&gt; ||
  7191       &lt;discretionary-lig-values&gt; || &lt;historical-lig-values&gt; ||
  7192       &lt;contextual-alt-values&gt; || stylistic(&lt;feature-value-name&gt;)
  7193       || historical-forms || styleset(&lt;feature-value-name&gt; #) ||
  7194       character-variant(&lt;feature-value-name&gt; #) ||
  7195       swash(&lt;feature-value-name&gt;) ||
  7196       ornaments(&lt;feature-value-name&gt;) ||
  7197       annotation(&lt;feature-value-name&gt;) || [ small-caps | all-small-caps
  7198       | petite-caps | all-petite-caps | unicase | titling-caps ] ||
  7199       &lt;numeric-figure-values&gt; || &lt;numeric-spacing-values&gt; ||
  7200       &lt;numeric-fraction-values&gt; || ordinal || slashed-zero ||
  7201       &lt;east-asian-variant-values&gt; || &lt;east-asian-width-values&gt; ||
  7202       ruby ]
  7204      <td>normal
  7206     <tr>
  7207      <th><span class=property>font-weight</span>
  7209      <td>normal | bold | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900
  7211      <td>normal
  7213     <tr>
  7214      <th><a class=property href="#descdef-src">src</a>
  7216      <td>[ &lt;url> [format(&lt;string> #)]? | &lt;font-face-name&gt; ] #
  7218      <td>N/A
  7220     <tr>
  7221      <th><a class=property href="#descdef-unicode-range">unicode-range</a>
  7223      <td>&lt;urange&gt; #
  7225      <td>U+0-10FFFF
  7226   </table>
  7227   <!--end-descriptors-->
  7228   <script type="text/javascript">
  7229 window.onload = function () {
  7230   if (!("devicePixelRatio" in window && window.devicePixelRatio > 1)) return;
  7231   var i, hiresElements = document.getElementsByClassName("hires");
  7232   for (i = 0; i < hiresElements.length; i++) {
  7233     var h = hiresElements[i];
  7234     if (h.tagName != "IMG") continue;
  7235     var src = h.getAttribute("src");
  7236     var src2x = src.replace(/\.\w+$/, function(m) { return "@2x" + m; });
  7237     h.src = src2x;
  7240 </script>
  7241 </html>
  7242 <!-- Keep this comment at the end of the file
  7243 Local variables:
  7244 mode: sgml
  7245 sgml-declaration:"~/SGML/HTML4.decl"
  7246 sgml-default-doctype-name:"html"
  7247 sgml-minimize-attributes:t
  7248 sgml-nofill-elements:("pre" "style" "br")
  7249 sgml-live-element-indicator:t
  7250 sgml-omittag:nil
  7251 sgml-shorttag:nil
  7252 sgml-namecase-general:t
  7253 sgml-general-insert-case:lower
  7254 sgml-always-quote-attributes:t
  7255 sgml-indent-step:nil
  7256 sgml-indent-data:t
  7257 sgml-parent-document:nil
  7258 sgml-exposed-tags:nil
  7259 sgml-local-catalogs:nil
  7260 sgml-local-ecat-files:nil
  7261 End:
  7262 -->
  7263 <!--
  7265 to do:
  7267 - wording of OpenType family name handling
  7268 - handling combining sequences in the font matching algorithm
  7269 - fix-up fi ligature example
  7271 -->

mercurial