Tue, 17 Sep 2013 15:52:29 +0900
[css3-fonts] fix up redirected links
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-17-september-2013>Editor's
119 Draft 17 September 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-3-20130917/">http://www.w3.org/TR/2013/ED-css-fonts-3-20130917/</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&product=CSS&component=Fonts&bug_status=NEW&bug_status=ASSIGNED&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>Test Suite:
167 <dd><a
168 href="http://test.csswg.org/suites/css3-fonts/nightly-unstable/">http://test.csswg.org/suites/css3-fonts/nightly-unstable/</a>
171 <dt>Editor:
173 <dd><a href="mailto:jdaggett@mozilla.com">John Daggett (Mozilla)</a>
174 </dl>
175 <!--begin-copyright-->
176 <p class=copyright><a
177 href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright"
178 rel=license>Copyright</a> © 2013 <a href="http://www.w3.org/"><abbr
179 title="World Wide Web Consortium">W3C</abbr></a><sup>®</sup> (<a
180 href="http://www.csail.mit.edu/"><abbr title="Massachusetts Institute of
181 Technology">MIT</abbr></a>, <a href="http://www.ercim.eu/"><abbr
182 title="European Research Consortium for Informatics and
183 Mathematics">ERCIM</abbr></a>, <a href="http://www.keio.ac.jp/">Keio</a>,
184 <a href="http://ev.buaa.edu.cn/">Beihang</a>), All Rights Reserved. W3C
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186 href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>,
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188 href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a>
189 and <a
190 href="http://www.w3.org/Consortium/Legal/copyright-documents">document
191 use</a> rules apply.</p>
192 <!--end-copyright-->
193 <hr title="Separator for header">
194 </div>
196 <h2 class="no-num no-toc" id=abstract>Abstract</h2>
198 <p>This CSS3 module describes how font properties are specified and how
199 font resources are loaded dynamically. The contents of this specification
200 are a consolidation of content previously divided into <a
201 href="http://www.w3.org/TR/2002/WD-css3-fonts-20020802/">CSS3 Fonts</a>
202 and <a href="http://www.w3.org/TR/2002/WD-css3-webfonts-20020802/">CSS3
203 Web Fonts</a> modules. The description of font load events was moved into
204 the <a href="http://dev.w3.org/csswg/css-font-load-events/">CSS3 Font Load
205 Events</a> module.
207 <h2 class="no-num no-toc" id=status>Status of this document</h2>
208 <!--begin-status-->
210 <p>This is a public copy of the editors' draft. It is provided for
211 discussion only and may change at any moment. Its publication here does
212 not imply endorsement of its contents by W3C. Don't cite this document
213 other than as work in progress.
215 <p>The (<a
216 href="http://lists.w3.org/Archives/Public/www-style/">archived</a>) public
217 mailing list <a
218 href="mailto:www-style@w3.org?Subject=%5Bcss3-fonts%5D%20PUT%20SUBJECT%20HERE">
219 www-style@w3.org</a> (see <a
220 href="http://www.w3.org/Mail/Request">instructions</a>) is preferred for
221 discussion of this specification. When sending e-mail, please put the text
222 “css3-fonts” in the subject, preferably like this:
223 “[<!---->css3-fonts<!---->] <em>…summary of comment…</em>”
225 <p>This document was produced by the <a
226 href="http://www.w3.org/Style/CSS/members">CSS Working Group</a> (part of
227 the <a href="http://www.w3.org/Style/">Style Activity</a>).
229 <p>This document was produced by a group operating under the <a
230 href="http://www.w3.org/Consortium/Patent-Policy-20040205/">5 February
231 2004 W3C Patent Policy</a>. W3C maintains a <a
232 href="http://www.w3.org/2004/01/pp-impl/32061/status"
233 rel=disclosure>public list of any patent disclosures</a> made in
234 connection with the deliverables of the group; that page also includes
235 instructions for disclosing a patent. An individual who has actual
236 knowledge of a patent which the individual believes contains <a
237 href="http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">Essential
238 Claim(s)</a> must disclose the information in accordance with <a
239 href="http://www.w3.org/Consortium/Patent-Policy-20040205/#sec-Disclosure">section
240 6 of the W3C Patent Policy</a>.</p>
241 <!--end-status-->
243 <h3 class="no-num no-toc" id=atrisk>Features at risk</h3>
245 <p>The following features are at risk and may be removed when exiting CR:
247 <ul>
248 <li>fallback handling for text decoration in superscript/subscript variant
249 glyphs (‘<a href="#propdef-font-variant-position"><code
250 class=property>font-variant-position</code></a>’)
252 <li>‘<a href="#propdef-font-language-override"><code
253 class=property>font-language-override</code></a>’ property
254 </ul>
255 <!--
256 <p>This draft is a <strong>Last Call Working Draft</strong>.
257 Please send comments to the
258 <a href="http://lists.w3.org/Archives/Public/www-style/">www-style mailing list</a>
259 as described above. The <strong>deadline for comments</strong>
260 is six weeks after the date of publication in the header, 22 August 2013.</p>
261 -->
263 <h2 class="no-num no-toc" id=contents>Table of contents</h2>
264 <!--begin-toc-->
266 <ul class=toc>
267 <li><a href="#introduction"><span class=secno>1 </span>Introduction</a>
269 <li><a href="#typography-background"><span class=secno>2 </span>Typography
270 Background</a>
272 <li><a href="#basic-font-props"><span class=secno>3 </span>Basic Font
273 Properties</a>
274 <ul class=toc>
275 <li><a href="#font-family-prop"><span class=secno>3.1 </span>Font
276 family: the font-family property</a>
277 <ul class=toc>
278 <li><a href="#generic-font-families"><span class=secno>3.1.1
279 </span>Generic font families</a>
280 </ul>
282 <li><a href="#font-weight-prop"><span class=secno>3.2 </span>Font
283 weight: the font-weight property</a>
285 <li><a href="#font-stretch-prop"><span class=secno>3.3 </span>Font
286 width: the font-stretch property</a>
288 <li><a href="#font-style-prop"><span class=secno>3.4 </span>Font style:
289 the font-style property</a>
291 <li><a href="#font-size-prop"><span class=secno>3.5 </span>Font size:
292 the font-size property</a>
294 <li><a href="#font-size-adjust-prop"><span class=secno>3.6
295 </span>Relative sizing: the font-size-adjust property</a>
297 <li><a href="#font-prop"><span class=secno>3.7 </span>Shorthand font
298 property: the font property</a>
300 <li><a href="#font-synthesis-prop"><span class=secno>3.8
301 </span>Controlling synthetic faces: the font-synthesis property</a>
302 </ul>
304 <li><a href="#font-resources"><span class=secno>4 </span>Font
305 Resources</a>
306 <ul class=toc>
307 <li><a href="#font-face-rule"><span class=secno>4.1 </span>The
308 <code>@font-face</code> rule</a>
310 <li><a href="#font-family-desc"><span class=secno>4.2 </span>Font
311 family: the font-family descriptor</a>
313 <li><a href="#src-desc"><span class=secno>4.3 </span>Font reference: the
314 src descriptor</a>
316 <li><a href="#font-prop-desc"><span class=secno>4.4 </span>Font property
317 descriptors: the font-style, font-weight, font-stretch descriptors</a>
319 <li><a href="#unicode-range-desc"><span class=secno>4.5 </span>Character
320 range: the unicode-range descriptor</a>
322 <li><a href="#composite-fonts"><span class=secno>4.6 </span>Using
323 character ranges to define composite fonts</a>
325 <li><a href="#font-rend-desc"><span class=secno>4.7 </span>Font
326 features: the font-variant and font-feature-settings descriptors</a>
328 <li><a href="#font-face-loading"><span class=secno>4.8 </span>Font
329 loading guidelines</a>
331 <li><a href="#font-fetching-requirements"><span class=secno>4.9
332 </span>Font fetching requirements</a>
333 </ul>
335 <li><a href="#font-matching-algorithm"><span class=secno>5 </span>Font
336 Matching Algorithm</a>
337 <ul class=toc>
338 <li><a href="#font-family-casing"><span class=secno>5.1 </span>Case
339 sensitivity of font family names</a>
341 <li><a href="#font-style-matching"><span class=secno>5.2 </span>Matching
342 font styles</a>
344 <li><a href="#cluster-matching"><span class=secno>5.3 </span>Cluster
345 matching</a>
347 <li><a href="#char-handling-issues"><span class=secno>5.4
348 </span>Character handling issues</a>
350 <li><a href="#font-matching-changes"><span class=secno>5.5 </span>Font
351 matching changes since CSS 2.1</a>
353 <li><a href="#font-matching-examples"><span class=secno>5.6 </span>Font
354 matching examples</a>
355 </ul>
357 <li><a href="#font-rend-props"><span class=secno>6 </span>Font Feature
358 Properties</a>
359 <ul class=toc>
360 <li><a href="#glyph-selection-positioning"><span class=secno>6.1
361 </span>Glyph selection and positioning</a>
363 <li><a href="#language-specific-support"><span class=secno>6.2
364 </span>Language-specific display</a>
366 <li><a href="#font-kerning-prop"><span class=secno>6.3 </span>Kerning:
367 the font-kerning property</a>
369 <li><a href="#font-variant-ligatures-prop"><span class=secno>6.4
370 </span>Ligatures: the font-variant-ligatures property</a>
372 <li><a href="#font-variant-position-prop"><span class=secno>6.5
373 </span>Subscript and superscript forms: the font-variant-position
374 property</a>
376 <li><a href="#font-variant-caps-prop"><span class=secno>6.6
377 </span>Capitalization: the font-variant-caps property</a>
379 <li><a href="#font-variant-numeric-prop"><span class=secno>6.7
380 </span>Numerical formatting: the font-variant-numeric property</a>
382 <li><a href="#font-variant-alternates-prop"><span class=secno>6.8
383 </span>Alternates and swashes: the font-variant-alternates property</a>
386 <li><a href="#font-feature-values"><span class=secno>6.9 </span>Defining
387 font specific alternates: the <code>@font-feature-values</code>
388 rule</a>
389 <ul class=toc>
390 <li><a href="#basic-syntax"><span class=secno>6.9.1 </span>Basic
391 syntax</a>
393 <li><a href="#multi-valued-feature-value-definitions"><span
394 class=secno>6.9.2 </span>Multi-valued feature value definitions</a>
395 </ul>
397 <li><a href="#font-variant-east-asian-prop"><span class=secno>6.10
398 </span>East Asian text rendering: the font-variant-east-asian
399 property</a>
401 <li><a href="#font-variant-prop"><span class=secno>6.11 </span>Overall
402 shorthand for font rendering: the font-variant property</a>
404 <li><a href="#font-feature-settings-prop"><span class=secno>6.12
405 </span>Low-level font feature settings control: the
406 font-feature-settings property</a>
408 <li><a href="#font-language-override-prop"><span class=secno>6.13
409 </span>Font language override: the font-language-override property</a>
410 </ul>
412 <li><a href="#font-feature-resolution"><span class=secno>7 </span>Font
413 Feature Resolution </a>
414 <ul class=toc>
415 <li><a href="#default-features"><span class=secno>7.1 </span>Default
416 features</a>
418 <li><a href="#feature-precedence"><span class=secno>7.2 </span>Feature
419 precedence</a>
421 <li><a href="#feature-precedence-examples"><span class=secno>7.3
422 </span>Feature precedence examples</a>
423 </ul>
425 <li><a href="#object-model"><span class=secno>8 </span>Object Model</a>
426 <ul class=toc>
427 <li><a href="#om-fontface"><span class=secno>8.1 </span>The
428 <code>CSSFontFaceRule</code> interface</a>
430 <li><a href="#om-fontfeaturevalues"><span class=secno>8.2 </span>The
431 <code>CSSFontFeatureValuesRule</code> interface</a>
432 </ul>
434 <li class=no-num><a href="#platform-props-to-css">Appendix A: Mapping
435 platform font properties to CSS properties</a>
437 <li class=no-num><a href="#ch-ch-ch-changes">Changes</a>
438 <ul class=toc>
439 <li class=no-num><a href="#recent-changes"> Changes from the July 2013
440 CSS3 Fonts Last Call Working Draft</a>
441 </ul>
443 <li class=no-num><a href="#acknowledgments">Acknowledgments</a>
445 <li class=no-num><a href="#conformance"> Conformance</a>
446 <ul class=toc>
447 <li class=no-num><a href="#conventions"> Document Conventions</a>
449 <li class=no-num><a href="#conformance-classes"> Conformance Classes</a>
452 <li class=no-num><a href="#partial"> Partial Implementations</a>
454 <li class=no-num><a href="#experimental"> Experimental
455 Implementations</a>
457 <li class=no-num><a href="#testing"> Non-Experimental
458 Implementations</a>
459 </ul>
461 <li class=no-num><a href="#references">References</a>
462 <ul class=toc>
463 <li class=no-num><a href="#normative-references">Normative
464 References</a>
466 <li class=no-num><a href="#other-references">Other References</a>
467 </ul>
469 <li class=no-num><a href="#index">Index</a>
471 <li class=no-num><a href="#property-index">Property index</a>
472 </ul>
473 <!--end-toc-->
475 <h2 id=introduction><span class=secno>1 </span>Introduction</h2>
477 <p>A font provides a resource containing the visual representation of
478 characters. At the simplest level it contains information that maps
479 character codes to shapes (called glyphs) that represent these characters.
480 Fonts sharing a common design style are commonly grouped into font
481 families classified by a set of standard font properties. Within a family,
482 the shape displayed for a given character can vary by stroke weight, slant
483 or relative width, among others. An individual font face is described by a
484 unique combination of these properties. For a given range of text, CSS
485 font properties are used to select a font family and a specific font face
486 within that family to be used when rendering that text. As a simple
487 example, to use the bold form of Helvetica one could use:
489 <pre>body {
490 font-family: Helvetica;
491 font-weight: bold;
492 }</pre>
494 <p>Font resources may be installed locally on the system on which a user
495 agent is running or downloadable. For local font resources descriptive
496 information can be obtained directly from the font resource. For
497 downloadable font resources (sometimes referred to as web fonts), the
498 descriptive information is included with the reference to the font
499 resource.
501 <p>Families of fonts typically don't contain a single face for each
502 possible variation of font properties. The CSS font selection mechanism
503 describes how to match a given set of CSS font properties to a single font
504 face.
506 <h2 id=typography-background><span class=secno>2 </span>Typography
507 Background</h2>
509 <p><em>This section is non-normative.</em>
511 <p> Typographic traditions vary across the globe, so there is no unique way
512 to classify all fonts across languages and cultures. For even common Latin
513 letters, wide variations are possible:
515 <div class=figure><img alt="variations in glyphs for a single character"
516 src=aaaaaa.png>
517 <p class=caption>One character, many glyph variations
518 </div>
520 <p>Differences in the anatomy of letterforms is one way to distinguish
521 fonts. For Latin fonts, flourishes at the ends of a character's main
522 strokes, or serifs, can distinguish a font from those without. Similar
523 comparisons exist in non-Latin fonts between fonts with tapered strokes
524 and those using primarily uniform strokes:
526 <div class=figure><img alt="serif vs. non-serifs" src=serifvssansserif.png>
527 <p class=caption>Letterforms with and without serifs
528 </div>
530 <div class=figure><img alt="serif vs. non-serifs for japanese"
531 src=minchovsgothic.png>
532 <p class=caption>Similar groupings for Japanese typefaces
533 </div>
535 <p>Fonts contain letterforms and the data needed to map characters to these
536 letterforms. Often this may be a simple one-to-one mapping, but more
537 complex mappings are also possible. The use of combining diacritic marks
538 creates many variations for an underlying letterform:
540 <div class=figure><img alt="diacritic marks" src=aaaaaa-diacritics.png>
541 <p class=caption>Variations with diacritic marks
542 </div>
544 <p>A sequence of characters can be represented by a single glyph known as a
545 ligature:
547 <div class=figure><img alt="example of a fi ligature"
548 src=final-ligature.png>
549 <p class=caption>Ligature example
550 </div>
552 <p>Visual transformations based on textual context are often stylistic
553 option in European languages. They are required to correctly render
554 languages like Arabic, the lam and alef characters below <em>must</em> be
555 combined when they exist in sequence:
557 <div class=figure><img alt="lam alef ligature" src=lamaleflig.png>
558 <p class=caption>Required Arabic ligature
559 </div>
561 <p>The relative complexity of these shaping transformations requires
562 additional data within the font.
564 <p>Sets of font faces with various stylistic variations are often grouped
565 together into font families. In the simplest case a regular face is
566 supplemented with bold and italic faces, but much more extensive groupings
567 are possible. Variations in the thickness of letterform strokes, the <dfn
568 id=weight>weight</dfn>, and the overall proportions of the letterform, the
569 <dfn id=width>width</dfn>, are most common. In the example below, each
570 letter uses a different font face within the Univers font family. The
571 width used increases from top to bottom and the weight increases from left
572 to right:
574 <div class=figure><img alt="various width and weight variations within a
575 single family" src=weightwidthvariations.png>
576 <p class=caption>Weight and width variations within a single font family
577 </div>
579 <p>Creating fonts that support multiple scripts is a difficult task;
580 designers need to understand the cultural traditions surrounding the use
581 of type in different scripts and come up with letterforms that somehow
582 share a common theme. Many languages often share a common script and each
583 of these languages may have noticeable stylistic differences. For example,
584 the Arabic script, when used for Persian and Urdu, exhibits significant
585 and systematic differences in letterforms, as does Cyrillic when used with
586 languages such as Serbian and Russian.
588 <p>The <a href="#character-map"><em>character map</em></a> of a font
589 defines the mapping of characters to glyphs for that font. If a document
590 contains characters not supported by the <a href="#character-map"><em
591 title="character map">character maps</em></a> of the fonts contained in a
592 font family list, a user agent may use a <a
593 href="#system-font-fallback"><em>system font fallback</em></a> procedure
594 to locate an appropriate font that does. If no appropriate font can be
595 found, some form of "missing glyph" character will be rendered by the user
596 agent. System fallback can occur when the specified list of font families
597 does not include a font that supports a given character.
599 <p>Although the <a href="#character-map"><em>character map</em></a> of a
600 font maps a given character to a glyph for that character, modern font
601 technologies such as OpenType and AAT (Apple Advanced Typography) provide
602 ways of mapping a character to different glyphs based upon feature
603 settings. Fonts in these formats allow these features to be embedded in
604 the font itself and controlled by applications. Common typographic
605 features which can be specified this way include ligatures, swashes,
606 contextual alternates, proportional and tabular figures, and automatic
607 fractions, to list just a few. For a visual overview of OpenType features,
608 see the <a href="#OPENTYPE-FONT-GUIDE"
609 rel=biblioentry>[OPENTYPE-FONT-GUIDE]<!--{{OPENTYPE-FONT-GUIDE}}--></a>.
611 <h2 id=basic-font-props><span class=secno>3 </span>Basic Font Properties</h2>
613 <p>The particular font face used to render a character is determined by the
614 font family and other font properties that apply to a given element. This
615 structure allows settings to be varied independent of each other.</p>
616 <!-- prop: font-family -->
618 <h3 id=font-family-prop><span class=secno>3.1 </span>Font family: the <a
619 href="#propdef-font-family">font-family</a> property</h3>
621 <table class=propdef id=namefont-familyvalue-ltfamily-namegt-ltg>
622 <tbody>
623 <tr>
624 <td>Name:
626 <td><dfn id=propdef-font-family
627 title="font-family!!property">font-family</dfn>
629 <tr>
630 <td>Value:
632 <td>[ <a href="#family-name-value"><var><family-name></var></a> |
633 <a href="#generic-family-value"><var><generic-family></var></a> ]
634 #
636 <tr>
637 <td>Initial:
639 <td>depends on user agent
641 <tr>
642 <td>Applies to:
644 <td>all elements
646 <tr>
647 <td>Inherited:
649 <td>yes
651 <tr>
652 <td>Percentages:
654 <td>N/A
656 <tr>
657 <td>Media:
659 <td>visual
661 <tr>
662 <td>Computed value:
664 <td>as specified
666 <tr>
667 <td>Animatable:
669 <td>no
670 </table>
672 <p>This property specifies a prioritized list of font family names or
673 generic family names. A font family defines a set of faces that vary in
674 weight, width or slope. CSS uses the combination of a family name with
675 other style attributes to select an individual face. Using this selection
676 mechanism, rather than selecting a face via the style name as is often
677 done in design applications, allows some degree of regularity in textual
678 display when fallback occurs.
680 <p class=note>Designers should note that the CSS definition of font
681 attributes used for selection are explicitly not intended to define a font
682 taxonomy. A type designer's idea of a family may often extend to a set of
683 faces that vary along axes other than just the standard axes of weight,
684 width and slope. A family may extend to include both a set of serif faces
685 and a set of sans-serif faces or vary along axes that are unique to that
686 family. The CSS font selection mechanism merely provides a way to
687 determine the “closest” substitute when substitution is necessary.
689 <p>Unlike other CSS properties, component values are a comma-separated list
690 indicating alternatives. A user agent iterates through the list of family
691 names until it matches an available font that contains a glyph for the
692 character to be rendered. This allows for differences in available fonts
693 across platforms and for differences in the range of characters supported
694 by individual fonts.
696 <p>A font family name only specifies a name given to a set of font faces,
697 it does not specify an individual face. For example, given the
698 availability of the fonts below, Futura would match but Futura Medium
699 would not:
701 <div class=figure><img alt="family and face names"
702 src=familyvsfacename.png>
703 <p class=caption>Family and individual face names
704 </div>
706 <p>Consider the example below:
708 <div class=example>
709 <pre>body {
710 font-family: Helvetica, Verdana, sans-serif;
711 }</pre>
713 <p>If Helvetica is available it will be used when rendering. If neither
714 Helvetica nor Verdana is present, then the user-agent-defined sans serif
715 font will be used.</p>
716 </div>
718 <p>There are two types of font family names:
720 <dl>
721 <dt><dfn id=family-name-value><var><family-name></var></dfn>
723 <dd>The name of a font family of choice such as Helvetica or Verdana in
724 the previous example.
726 <dt><dfn id=generic-family-value><var><generic-family></var></dfn>
728 <dd> The following generic family keywords are defined: ‘<a
729 href="#serif"><code class=property>serif</code></a>’, ‘<a
730 href="#sans-serif"><code class=property>sans-serif</code></a>’, ‘<a
731 href="#cursive"><code class=property>cursive</code></a>’, ‘<a
732 href="#fantasy"><code class=property>fantasy</code></a>’, and ‘<a
733 href="#monospace"><code class=property>monospace</code></a>’. These
734 keywords can be used as a general fallback mechanism when an author's
735 desired font choices are not available. As keywords, they must not be
736 quoted. Authors are encouraged to append a generic font family as a last
737 alternative for improved robustness.
738 </dl>
740 <p>Font family names other than generic families must either be given
741 quoted as <a
742 href="http://www.w3.org/TR/CSS21/syndata.html#strings">strings,</a> or
743 unquoted as a sequence of one or more <a
744 href="http://www.w3.org/TR/CSS21/syndata.html#value-def-identifier">identifiers.</a>
745 This means most punctuation characters and digits at the start of each
746 token must be escaped in unquoted font family names.
748 <p>To illustrate this, the following declarations are invalid:
750 <pre>
751 font-family: Red/Black, sans-serif;
752 font-family: "Lucida" Grande, sans-serif;
753 font-family: Ahem!, sans-serif;
754 font-family: test@foo, sans-serif;
755 font-family: #POUND, sans-serif;
756 font-family: Hawaii 5-0, sans-serif;
757 </pre>
759 <p>If a sequence of identifiers is given as a font family name, the
760 computed value is the name converted to a string by joining all the
761 identifiers in the sequence by single spaces.
763 <p>To avoid mistakes in escaping, it is recommended to quote font family
764 names that contain white space, digits, or punctuation characters other
765 than hyphens:
767 <pre>
768 body { font-family: "New Century Schoolbook", serif }
770 <BODY STYLE="font-family: '21st Century', fantasy">
771 </pre>
773 <p>Font family <em>names</em> that happen to be the same as a keyword value
774 (‘<code class=property>inherit</code>’, ‘<a href="#serif"><code
775 class=property>serif</code></a>’, ‘<a href="#sans-serif"><code
776 class=property>sans-serif</code></a>’, ‘<a href="#monospace"><code
777 class=property>monospace</code></a>’, ‘<a href="#fantasy"><code
778 class=property>fantasy</code></a>’, and ‘<a href="#cursive"><code
779 class=property>cursive</code></a>’) must be quoted to prevent confusion
780 with the keywords with the same names. The keywords ‘<code
781 class=property>initial</code>’ and ‘<code
782 class=property>default</code>’ are reserved for future use and must also
783 be quoted when used as font names. UAs must not consider these keywords as
784 matching the <a
785 href="#family-name-value"><var><family-name></var></a> type.
787 <p>The precise way a set of fonts are grouped into font families varies
788 depending upon the platform font management API's. The Windows GDI API
789 only allows four faces to be grouped into a family while the DirectWrite
790 API and API's on OSX and other platforms support font families with a
791 variety of weights, widths and slopes (see <a
792 href="#platform-props-to-css">Appendix A</a> for more details).
794 <p>Some font formats allow fonts to carry multiple localizations of the
795 family name. User agents must recognize and correctly match all of these
796 names independent of the underlying platform localization, system API used
797 or document encoding:
799 <div class=figure><img alt="examples of localized family names"
800 src=localizedfamilynames.png>
801 <p class=caption>Localized family names
802 </div>
804 <p>The details of localized font family name matching and the corresponding
805 issues of case sensitivity are described below in the <a
806 href="#font-family-casing">font matching</a> section.
808 <h4 id=generic-font-families><span class=secno>3.1.1 </span>Generic font
809 families</h4>
811 <p>All five generic font families are defined to exist in all CSS
812 implementations (they need not necessarily map to five distinct actual
813 fonts). User agents should provide reasonable default choices for the
814 generic font families, which express the characteristics of each family as
815 well as possible within the limits allowed by the underlying technology.
816 User agents are encouraged to allow users to select alternative choices
817 for the generic fonts.
819 <h5 class="no-num no-toc"> <span class=index-def id=serif0 title="serif,
820 definition of"><a name=serif-def><dfn id=serif>serif</dfn></a></span></h5>
822 <p>Serif fonts represent the formal text style for a script. This often
823 means but is not limited to glyphs that have finishing strokes, flared or
824 tapering ends, or have actual serifed endings (including slab serifs).
825 Serif fonts are typically proportionately-spaced. They often display a
826 greater variation between thick and thin strokes than fonts from the ‘<a
827 href="#sans-serif"><code class=property>sans-serif</code></a>’ generic
828 font family. CSS uses the term ‘<a href="#serif"><code
829 class=property>serif</code></a>’ to apply to a font for any script,
830 although other names may be more familiar for particular scripts, such as
831 Mincho (Japanese), Sung, Song or Kai (Chinese), Batang (Korean). For
832 Arabic, the Naskh style would correspond to ‘<a href="#serif"><code
833 class=property>serif</code></a>’ more due to its typographic role rather
834 than its actual design style. Any font that is so described may be used to
835 represent the generic ‘<a href="#serif"><code
836 class=property>serif</code></a>’ family.
838 <div class=figure><img alt="sample serif fonts" src=serifexamples.png>
839 <p class=caption>Sample serif fonts
840 </div>
842 <h5 class="no-num no-toc"> <span class=index-def id=sans-serif0
843 title="sans-serif, definition of"> <a name=sans-serif-def><dfn
844 id=sans-serif>sans-serif</dfn></a></span></h5>
846 <p>Glyphs in sans-serif fonts, as the term is used in CSS, are generally
847 low contrast (vertical and horizontal stems have the close to the same
848 thickness) and have stroke endings that are plain -- without any flaring,
849 cross stroke, or other ornamentation. Sans-serif fonts are typically
850 proportionately-spaced. They often have little variation between thick and
851 thin strokes, compared to fonts from the ‘<a href="#serif"><code
852 class=property>serif</code></a>’ family. CSS uses the term ‘<a
853 href="#sans-serif"><code class=property>sans-serif</code></a>’ to apply
854 to a font for any script, although other names may be more familiar for
855 particular scripts, such as Gothic (Japanese), Hei (Chinese), or Gulim
856 (Korean). Any font that is so described may be used to represent the
857 generic ‘<a href="#sans-serif"><code
858 class=property>sans-serif</code></a>’ family.
860 <div class=figure><img alt="sample sans-serif fonts"
861 src=sansserifexamples.png>
862 <p class=caption>Sample sans-serif fonts
863 </div>
865 <h5 class="no-num no-toc"> <span class=index-def id=cursive0
866 title="cursive, definition of"> <a name=cursive-def><dfn
867 id=cursive>cursive</dfn></a></span></h5>
869 <p>Glyphs in cursive fonts generally use a more informal script style, and
870 the result looks more like handwritten pen or brush writing than printed
871 letterwork. CSS uses the term ‘<a href="#cursive"><code
872 class=property>cursive</code></a>’ to apply to a font for any script,
873 although other names such as Chancery, Brush, Swing and Script are also
874 used in font names.
876 <div class=figure><img alt="sample cursive fonts" src=cursiveexamples.png>
877 <p class=caption>Sample cursive fonts
878 </div>
880 <h5 class="no-num no-toc"> <span class=index-def id=fantasy0
881 title="fantasy, definition of"> <a name=fantasy-def><dfn
882 id=fantasy>fantasy</dfn></a></span></h5>
884 <p>Fantasy fonts are primarily decorative or expressive fonts that contain
885 decorative or expressive representations of characters. These do not
886 include Pi or Picture fonts which do not represent actual characters.
888 <div class=figure><img alt="sample fantasy fonts" src=fantasyexamples.png>
889 <p class=caption>Sample fantasy fonts
890 </div>
892 <h5 class="no-num no-toc"> <span class=index-def id=monospace0
893 title="monospace, definition of"> <a name=monospace-def><dfn
894 id=monospace>monospace</dfn></a></span></h5>
896 <p>The sole criterion of a monospace font is that all glyphs have the same
897 fixed width. This is often used to render samples of computer code.
899 <div class=figure><img alt="sample monospace fonts"
900 src=monospaceexamples.png>
901 <p class=caption>Sample monospace fonts
902 </div>
903 <!-- prop: font-weight -->
905 <h3 id=font-weight-prop><span class=secno>3.2 </span>Font weight: the <a
906 href="#propdef-font-weight">font-weight</a> property</h3>
908 <table class=propdef id=namefont-weightvaluenormal-bold-bolder-l>
909 <tbody>
910 <tr>
911 <td>Name:
913 <td><dfn id=propdef-font-weight
914 title="font-weight!!property">font-weight</dfn>
916 <tr>
917 <td>Value:
919 <td><a href="#font-weight-normal-value"
920 title="normal!!font-weight">normal</a> | <a href="#bold">bold</a> | <a
921 href="#bolder">bolder</a> | <a href="#lighter">lighter</a> | <a
922 href="#font-weight-numeric-values" title="100...900 weight
923 values">100</a> | <a href="#font-weight-numeric-values"
924 title="100...900 weight values">200</a> | <a
925 href="#font-weight-numeric-values" title="100...900 weight
926 values">300</a> | <a href="#font-weight-numeric-values"
927 title="100...900 weight values">400</a> | <a
928 href="#font-weight-numeric-values" title="100...900 weight
929 values">500</a> | <a href="#font-weight-numeric-values"
930 title="100...900 weight values">600</a> | <a
931 href="#font-weight-numeric-values" title="100...900 weight
932 values">700</a> | <a href="#font-weight-numeric-values"
933 title="100...900 weight values">800</a> | <a
934 href="#font-weight-numeric-values" title="100...900 weight
935 values">900</a>
937 <tr>
938 <td>Initial:
940 <td>normal
942 <tr>
943 <td>Applies to:
945 <td>all elements
947 <tr>
948 <td>Inherited:
950 <td>yes
952 <tr>
953 <td>Percentages:
955 <td>N/A
957 <tr>
958 <td>Media:
960 <td>visual
962 <tr>
963 <td>Computed value:
965 <td>numeric weight value (see description)
967 <tr>
968 <td>Animatable:
970 <td>as <a
971 href="http://dev.w3.org/csswg/css-transitions/#animtype-font-weight">font
972 weight</a>
973 </table>
975 <p>The <a href="#propdef-font-weight"
976 title="font-weight!!property">‘<code
977 class=property>font-weight</code>’</a> property specifies the weight of
978 glyphs in the font, their degree of blackness or stroke thickness.
980 <p>Values have the following meanings:
982 <dl>
983 <dt><dfn id=font-weight-numeric-values title="100...900 weight values">100
984 to 900</dfn>
986 <dd>These values form an ordered sequence, where each number indicates a
987 weight that is at least as dark as its predecessor. These roughly
988 correspond to the commonly used weight names below:
989 </dl>
991 <ul>
992 <li>100 - Thin
994 <li>200 - Extra Light (Ultra Light)
996 <li>300 - Light
998 <li>400 - Normal
1000 <li>500 - Medium
1002 <li>600 - Semi Bold (Demi Bold)
1004 <li>700 - Bold
1006 <li>800 - Extra Bold (Ultra Bold)
1008 <li>900 - Black (Heavy)
1009 </ul>
1011 <dl>
1012 <dt><dfn id=font-weight-normal-value
1013 title="normal!!font-weight">normal</dfn>
1015 <dd>Same as ‘<code class=css>400</code>’.
1017 <dt><dfn id=bold>bold</dfn>
1019 <dd>Same as ‘<code class=css>700</code>’.
1021 <dt><dfn id=bolder>bolder</dfn>
1023 <dd>Specifies a bolder weight than the inherited value.
1025 <dt><dfn id=lighter>lighter</dfn>
1027 <dd>Specifies a lighter weight than the inherited value.
1028 </dl>
1030 <p>Font formats that use a scale other than a nine-step scale should map
1031 their scale onto the CSS scale so that 400 roughly corresponds with a face
1032 that would be labeled as Regular, Book, Roman and 700 roughly matches a
1033 face that would be labeled as Bold. Or weights may be inferred from the
1034 style names, ones that correspond roughly with the scale above. The scale
1035 is relative, so a face with a larger weight value must never appear
1036 lighter. If style names are used to infer weights, care should be taken to
1037 handle variations in style names across locales.
1039 <p>Quite often there are only a few weights available for a particular font
1040 family. When a weight is specified for which no face exists, a face with a
1041 nearby weight is used. In general, bold weights map to faces with heavier
1042 weights and light weights map to faces with lighter weights (see the <a
1043 href="#font-matching-algorithm">font matching section below</a> for a
1044 precise definition). The examples here illustrate which face is used for
1045 different weights, grey indicates a face for that weight does not exist so
1046 a face with a nearby weight is used:
1048 <div class=figure><img alt="weight mappings for a family with 400, 700 and
1049 900 weights" src=optimaweights.png>
1050 <p class=caption>Weight mappings for a font family with 400, 700 and 900
1051 weight faces
1052 </div>
1054 <div class=figure><img alt="weight mappings for a family with 300, 600
1055 weights" src=hiraginoweights.png>
1056 <p class=caption>Weight mappings for a font family with 300 and 600 weight
1057 faces
1058 </div>
1060 <p>Although the practice is not well-loved by typographers, bold faces are
1061 often synthesized by user agents for faces that lack actual bold faces.
1062 For the purposes of style matching, these faces must be treated as if they
1063 exist within the family. Authors can explicitly avoid this behavior by
1064 using the ‘<a href="#propdef-font-synthesis"><code
1065 class=property>font-synthesis</code></a>’ property.
1067 <p>Specified values of ‘<a href="#bolder"><code
1068 class=property>bolder</code></a>’ and ‘<a href="#lighter"><code
1069 class=property>lighter</code></a>’ indicate weights relative to the
1070 weight of the parent element. The computed weight is calculated based on
1071 the inherited <a href="#propdef-font-weight"
1072 title="font-weight!!property">‘<code
1073 class=property>font-weight</code>’</a> value using the chart below.
1075 <table class=data id=bolderlighter summary="Bolder/lighter mappings">
1076 <thead>
1077 <tr>
1078 <th>Inherited value
1080 <th>bolder
1082 <th>lighter
1084 <tbody>
1085 <tr>
1086 <th>100
1088 <td>400
1090 <td>100
1092 <tr>
1093 <th>200
1095 <td>400
1097 <td>100
1099 <tr>
1100 <th>300
1102 <td>400
1104 <td>100
1106 <tr>
1107 <th>400
1109 <td>700
1111 <td>100
1113 <tr>
1114 <th>500
1116 <td>700
1118 <td>100
1120 <tr>
1121 <th>600
1123 <td>900
1125 <td>400
1127 <tr>
1128 <th>700
1130 <td>900
1132 <td>400
1134 <tr>
1135 <th>800
1137 <td>900
1139 <td>700
1141 <tr>
1142 <th>900
1144 <td>900
1146 <td>700
1147 </table>
1149 <p>The table above is equivalent to selecting the next relative bolder or
1150 lighter face, given a font family containing normal and bold faces along
1151 with a thin and a heavy face. Authors who desire finer control over the
1152 exact weight values used for a given element may use numerical values
1153 instead of relative weights.</p>
1154 <!-- prop: font-stretch -->
1156 <h3 id=font-stretch-prop><span class=secno>3.3 </span>Font width: the <a
1157 href="#propdef-font-stretch">font-stretch</a> property</h3>
1159 <table class=propdef id=namefont-stretchvalue-normal-ultra-conde>
1160 <tbody>
1161 <tr>
1162 <td>Name:
1164 <td><dfn id=propdef-font-stretch
1165 title="font-stretch!!property">font-stretch</dfn>
1167 <tr>
1168 <td>Value:
1170 <td> <a href="#font-stretch-normal-value"
1171 title="normal!!font-stretch">normal</a> | <a
1172 href="#ultra-condensed">ultra-condensed</a> | <a
1173 href="#extra-condensed">extra-condensed</a> | <a
1174 href="#condensed">condensed</a> | <a
1175 href="#semi-condensed-">semi-condensed</a> | <a
1176 href="#semi-expanded">semi-expanded</a> | <a
1177 href="#expanded">expanded</a> | <a
1178 href="#extra-expanded">extra-expanded</a> | <a
1179 href="#ultra-expanded">ultra-expanded</a>
1181 <tr>
1182 <td>Initial:
1184 <td>normal
1186 <tr>
1187 <td>Applies to:
1189 <td>all elements
1191 <tr>
1192 <td>Inherited:
1194 <td>yes
1196 <tr>
1197 <td>Percentages:
1199 <td>N/A
1201 <tr>
1202 <td>Media:
1204 <td>visual
1206 <tr>
1207 <td>Computed value:
1209 <td>as specified
1211 <tr>
1212 <td>Animatable:
1214 <td>as <a href="#font-stretch-animation">font stretch</a>
1215 </table>
1217 <p>The <a href="#propdef-font-stretch"
1218 title="font-stretch!!property">‘<code
1219 class=property>font-stretch</code>’</a> property selects a normal,
1220 condensed, or expanded face from a font family. Absolute keyword values
1221 have the following ordering, from narrowest to widest:
1223 <ul>
1224 <li><dfn id=ultra-condensed>ultra-condensed</dfn>
1226 <li><dfn id=extra-condensed>extra-condensed</dfn>
1228 <li><dfn id=condensed>condensed</dfn>
1230 <li><dfn id=semi-condensed->semi-condensed </dfn>
1232 <li><dfn id=font-stretch-normal-value
1233 title="normal!!font-stretch">normal</dfn>
1235 <li><dfn id=semi-expanded>semi-expanded</dfn>
1237 <li><dfn id=expanded>expanded</dfn>
1239 <li><dfn id=extra-expanded>extra-expanded</dfn>
1241 <li><dfn id=ultra-expanded>ultra-expanded</dfn>
1242 </ul>
1244 <p>When a face does not exist for a given width, normal or condensed values
1245 map to a narrower face, otherwise a wider face. Conversely, expanded
1246 values map to a wider face, otherwise a narrower face. The figure below
1247 shows how the nine font-stretch property settings affect font selection
1248 for font family containing a variety of widths, grey indicates a width for
1249 which no face exists and a different width is substituted:
1251 <div class=figure><img alt="width mappings for a family with condensed,
1252 normal and expanded faces" src=universwidths.png>
1253 <p class=caption>Width mappings for a font family with condensed, normal
1254 and expanded width faces
1255 </div>
1257 <p id=font-stretch-animation>Animation of font stretch: Font stretch is
1258 interpolated in discrete steps. The interpolation happens as though the
1259 ordered values are equally spaced real numbers. The interpolation result
1260 is rounded to the nearest value, with values exactly halfway between two
1261 values rounded towards the later value in the list above.</p>
1262 <!-- prop: font-style -->
1264 <h3 id=font-style-prop><span class=secno>3.4 </span>Font style: the <a
1265 href="#propdef-font-style">font-style</a> property</h3>
1267 <table class=propdef id=namefont-stylevaluenormal-italic-oblique>
1268 <tbody>
1269 <tr>
1270 <td>Name:
1272 <td><dfn id=propdef-font-style
1273 title="font-style!!property">font-style</dfn>
1275 <tr>
1276 <td>Value:
1278 <td><a href="#font-style-normal-value"
1279 title="normal!!font-style">normal</a> | <a href="#italic">italic</a> |
1280 <a href="#oblique">oblique</a>
1282 <tr>
1283 <td>Initial:
1285 <td>normal
1287 <tr>
1288 <td>Applies to:
1290 <td>all elements
1292 <tr>
1293 <td>Inherited:
1295 <td>yes
1297 <tr>
1298 <td>Percentages:
1300 <td>N/A
1302 <tr>
1303 <td>Media:
1305 <td>visual
1307 <tr>
1308 <td>Computed value:
1310 <td>as specified
1312 <tr>
1313 <td>Animatable:
1315 <td>no
1316 </table>
1318 <p>The <a href="#propdef-font-style" title="font-style!!property">‘<code
1319 class=property>font-style</code>’</a> property allows italic or oblique
1320 faces to be selected. Italic forms are generally cursive in nature while
1321 oblique faces are typically sloped versions of the regular face. Oblique
1322 faces can be simulated by artificially sloping the glyphs of the regular
1323 face. Compare the artificially sloped renderings of Palatino ‘<code
1324 class=property>a</code>’ and Baskerville ‘<code
1325 class=property>N</code>’ in grey with the actual italic versions:
1327 <div class=figure><img alt="artificial sloping vs. real italics"
1328 src=realvsfakeitalics.png>
1329 <p class=caption>Artificial sloping versus real italics
1330 </div>
1332 <p>Values have the following meanings:
1334 <dl>
1335 <dt><dfn id=font-style-normal-value
1336 title="normal!!font-style">normal</dfn>
1338 <dd>selects a face that is classified as a normal face, one that is
1339 neither italic or obliqued
1341 <dt><dfn id=italic>italic</dfn>
1343 <dd>selects a font that is labeled as an italic face, or an oblique face
1344 if one is not
1346 <dt><dfn id=oblique>oblique</dfn>
1348 <dd>selects a font that is labeled as an oblique face, or an italic face
1349 if one is not
1350 </dl>
1352 <p>If no italic or oblique face is available, oblique faces can be
1353 synthesized by rendering non-obliqued faces with an artificial obliquing
1354 operation. The use of these artificially obliqued faces can be disabled
1355 using the ‘<a href="#propdef-font-synthesis"><code
1356 class=property>font-synthesis</code></a>’ property. The details of the
1357 obliquing operation are not explicitly defined.
1359 <p class=note>Authors should also be aware that synthesized approaches may
1360 not be suitable for scripts like Cyrillic, where italic forms are very
1361 different in shape. It is always better to use an actual italic font
1362 rather than rely on a synthetic version.</p>
1363 <!-- resolution on the "undefined" nature of synthetics: http://www.w3.org/2013/06/06-css-minutes.html#item03 -->
1365 <p>Many scripts lack the tradition of mixing a cursive form within text
1366 rendered with a normal face. Chinese, Japanese and Korean fonts almost
1367 always lack italic or oblique faces. Fonts that support a mixture of
1368 scripts will sometimes omit specific scripts such as Arabic from the set
1369 of glyphs supported in the italic face. User agents should be careful
1370 about making <a href="#character-map"><em>character map</em></a>
1371 assumptions across faces when implementing support for <a
1372 href="#system-font-fallback"><em>system font fallback</em></a>.</p>
1373 <!-- prop: font-size -->
1375 <h3 id=font-size-prop><span class=secno>3.5 </span>Font size: the <a
1376 href="#propdef-font-size">font-size</a> property</h3>
1378 <table class=propdef id=namefont-sizevalueltabsolute-sizegt-ltre>
1379 <tbody>
1380 <tr>
1381 <td>Name:
1383 <td><dfn id=propdef-font-size>font-size</dfn>
1385 <tr>
1386 <td>Value:
1388 <td><a href="#absolute-size-value"><var><absolute-size></var></a>
1389 | <a href="#relative-size-value"><var><relative-size></var></a> |
1390 <a href="#length-size-value"><var><length></var></a> | <a
1391 href="#percentage-size-value"><var><percentage></var></a>
1393 <tr>
1394 <td>Initial:
1396 <td>medium
1398 <tr>
1399 <td>Applies to:
1401 <td>all elements
1403 <tr>
1404 <td>Inherited:
1406 <td>yes
1408 <tr>
1409 <td>Percentages:
1411 <td>refer to parent element's font size
1413 <tr>
1414 <td>Media:
1416 <td>visual
1418 <tr>
1419 <td>Computed value:
1421 <td>absolute length
1423 <tr>
1424 <td>Animatable:
1426 <td>as <a
1427 href="http://dev.w3.org/csswg/css-transitions/#animtype-length">length</a>
1428 </table>
1430 <p>This property indicates the desired height of glyphs from the font. For
1431 scalable fonts, the font-size is a scale factor applied to the EM unit of
1432 the font. (Note that certain glyphs may bleed outside their EM box.) For
1433 non-scalable fonts, the font-size is converted into absolute units and
1434 matched against the declared font-size of the font, using the same
1435 absolute coordinate space for both of the matched values. Values have the
1436 following meanings:
1438 <dl>
1439 <dt><dfn id=absolute-size-value><var><absolute-size></var></dfn>
1441 <dd> An <a
1442 href="#absolute-size-value"><var><absolute-size></var></a> keyword
1443 refers to an entry in a table of font sizes computed and kept by the user
1444 agent. Possible values are:
1445 <p> [ xx-small | x-small | small | medium | large | x-large | xx-large ]</p>
1447 <dt><dfn id=relative-size-value><var><relative-size></var></dfn>
1449 <dd> A <a href="#relative-size-value"><var><relative-size></var></a>
1450 keyword is interpreted relative to the table of font sizes and the
1451 computed ‘<a href="#propdef-font-size"><code
1452 class=property>font-size</code></a>’ of the parent element. Possible
1453 values are:
1454 <p> [ larger | smaller ]
1456 <p> For example, if the parent element has a font size of ‘<code
1457 class=property>medium</code>’, a value of ‘<code
1458 class=property>larger</code>’ will make the font size of the current
1459 element be ‘<code class=property>large</code>’. If the parent
1460 element's size is not close to a table entry, the user agent is free to
1461 interpolate between table entries or round off to the closest one. The
1462 user agent may have to extrapolate table values if the numerical value
1463 goes beyond the keywords.
1465 <dt><dfn id=length-size-value><var><length></var></dfn>
1467 <dd>A length value specifies an absolute font size (independent of the
1468 user agent's font table). Negative lengths are illegal.
1470 <dt><dfn id=percentage-size-value><var><percentage></var></dfn>
1472 <dd>A percentage value specifies an absolute font size relative to the
1473 parent element's font size. Use of percentage values, or values in
1474 ‘<code class=property>em</code>’s, leads to more robust and
1475 cascadable style sheets.
1476 </dl>
1478 <p>The following table provides user agent guidelines for the absolute-size
1479 scaling factor and their mapping to HTML heading and absolute font-sizes.
1480 The ‘<code class=property>medium</code>’ value is used as the
1481 reference middle value. The user agent may fine-tune these values for
1482 different fonts or different types of display devices.
1484 <table class=data>
1485 <thead>
1486 <tr>
1487 <th>CSS absolute-size values
1489 <th>xx-small
1491 <th>x-small
1493 <th>small
1495 <th>medium
1497 <th>large
1499 <th>x-large
1501 <th>xx-large
1503 <th>
1505 <tbody>
1506 <tr>
1507 <th>scaling factor
1509 <td>3/5
1511 <td>3/4
1513 <td>8/9
1515 <td>1
1517 <td>6/5
1519 <td>3/2
1521 <td>2/1
1523 <td>3/1
1525 <tr>
1526 <th>HTML headings
1528 <td>h6
1530 <td>
1532 <td>h5
1534 <td>h4
1536 <td>h3
1538 <td>h2
1540 <td>h1
1542 <td>
1544 <tr>
1545 <th>HTML font sizes
1547 <td>1
1549 <td>
1551 <td>2
1553 <td>3
1555 <td>4
1557 <td>5
1559 <td>6
1561 <td>7
1562 </table>
1564 <p class=note><em><strong>Note 1.</strong> To preserve readability, an UA
1565 applying these guidelines should nevertheless avoid creating font-size
1566 resulting in less than 9 device pixels per EM unit on a computer
1567 display.</em>
1569 <p class=note><em><strong>Note 2.</strong> In CSS1, the suggested scaling
1570 factor between adjacent indexes was 1.5 which user experience proved to be
1571 too large. In CSS2, the suggested scaling factor for computer screen
1572 between adjacent indexes was 1.2 which still created issues for the small
1573 sizes. The new scaling factor varies between each index to provide a
1574 better readability.</em>
1576 <p>The actual value of this property may differ from the computed value due
1577 a numerical value on ‘<a href="#propdef-font-size-adjust"><code
1578 class=property>font-size-adjust</code></a>’ and the unavailability of
1579 certain font sizes.
1581 <p>Child elements inherit the computed <a class=noxref
1582 href="#font-size-prop"> <span class=property>‘<code
1583 class=property>font-size</code>’</span></a> value (otherwise, the effect
1584 of <a class=noxref href="#font-size-adjust-prop"><span
1585 class=property>‘<code
1586 class=property>font-size-adjust</code>’</span></a> would compound).
1588 <div class=example>
1589 <p style="display:none">Example(s):</p>
1591 <pre>p { font-size: 12pt; }
1592 blockquote { font-size: larger }
1593 em { font-size: 150% }
1594 em { font-size: 1.5em }
1595 </pre>
1596 </div>
1597 <!-- prop: font-size-adjust -->
1599 <h3 id=font-size-adjust-prop><span class=secno>3.6 </span>Relative sizing:
1600 the <a href="#propdef-font-size-adjust">font-size-adjust</a> property</h3>
1602 <table class=propdef id=namefont-size-adjustvaluenone-ltnumbergt>
1603 <tbody>
1604 <tr>
1605 <td>Name:
1607 <td><dfn id=propdef-font-size-adjust>font-size-adjust</dfn>
1609 <tr>
1610 <td>Value:
1612 <td><a href="#font-size-adjust-none-value"
1613 title="none!!font-size-adjust">none</a> | <a
1614 href="#aspect-ratio-value"><var><number></var></a>
1616 <tr>
1617 <td>Initial:
1619 <td>none
1621 <tr>
1622 <td>Applies to:
1624 <td>all elements
1626 <tr>
1627 <td>Inherited:
1629 <td>yes
1631 <tr>
1632 <td>Percentages:
1634 <td>N/A
1636 <tr>
1637 <td>Media:
1639 <td>visual
1641 <tr>
1642 <td>Computed value:
1644 <td>as specified
1646 <tr>
1647 <td>Animatable:
1649 <td>as <a
1650 href="http://dev.w3.org/csswg/css-transitions/#animtype-number">number</a>
1651 </table>
1653 <p>For any given font size, the apparent size and legibility of text varies
1654 across fonts. For scripts such as Latin or Cyrillic that distinguish
1655 between upper and lowercase letters, the relative height of lowercase
1656 letters compared to their uppercase counterparts is a determining factor
1657 of legibility. This is commonly referred to as the <a class=index-def
1658 href="#aspect-value" id=aspect-value0 title="aspect value"><dfn
1659 id=aspect-value>aspect value</dfn></a>. Precisely defined, it is equal to
1660 the x-height of a font divided by the font size.
1662 <p>In situations where font fallback occurs, fallback fonts may not share
1663 the same aspect value as the desired font family and will thus appear less
1664 readable. The ‘<a href="#propdef-font-size-adjust"><code
1665 class=property>font-size-adjust</code></a>’ property is a way to
1666 preserve the readability of text when font fallback occurs. It does this
1667 by adjusting the font-size so that the x-height is the same regardless of
1668 the font used.
1670 <div class=example>
1671 <p>The style defined below defines Verdana as the desired font family, but
1672 if Verdana is not available Futura or Times will be used.</p>
1674 <pre>p {
1675 font-family: Verdana, Futura, Times;
1676 }
1678 <p>Lorem ipsum dolor sit amet, ...</p>
1679 </pre>
1681 <p>Verdana has a relatively high aspect value, lowercase letters are
1682 relatively tall compared to uppercase letters, so at small sizes text
1683 appears legible. Times has a lower aspect value and so if fallback
1684 occurs, the text will be less legible at small sizes than Verdana.</p>
1685 </div>
1687 <p>How text rendered in each of these fonts compares is shown below, the
1688 columns show text rendered in Verdana, Futura and Times. The same
1689 font-size value is used across cells within each row and red lines are
1690 included to show the differences in x-height. In the upper half each row
1691 is rendered in the same font-size value. The same is true for the lower
1692 half but in this half the ‘<a href="#propdef-font-size-adjust"><code
1693 class=property>font-size-adjust</code></a>’ property is also set so that
1694 the actual font size is adjusted to preserve the x-height across each row.
1695 Note how small text remains relatively legible across each row in the
1696 lower half.
1698 <div class=figure><img alt="text with and without 'font-size-adjust'"
1699 src=fontsizeadjust.png>
1700 <p class=caption>Text with and without the use of ‘<a
1701 href="#propdef-font-size-adjust"><code
1702 class=property>font-size-adjust</code></a>’
1703 </div>
1705 <p>This property allows authors to specify an <a
1706 href="#aspect-value"><i>aspect value</i></a> for an element that will
1707 effectively preserve the x-height of the first choice font, whether it is
1708 substituted or not. Values have the following meanings:
1710 <dl>
1711 <dt><dfn id=font-size-adjust-none-value
1712 title="none!!font-size-adjust">none</dfn>
1714 <dd>Do not preserve the font's x-height.
1716 <dt><dfn id=aspect-ratio-value><var><number></var></dfn>
1718 <dd>Specifies the <a href="#aspect-value"><i>aspect value</i></a> used in
1719 the calculation below to calculate the adjusted font size:
1720 <pre>c = ( a / a' ) s
1721 </pre>
1723 <p>where:</p>
1725 <pre>s = font-size value
1726 a = <a href="#aspect-value"><i>aspect value</i></a> as specified by the 'font-size-adjust' property
1727 a' = <a href="#aspect-value"><i>aspect value</i></a> of actual font
1728 c = adjusted font-size to use
1729 </pre>
1731 <p>This value applies to any font that is selected but in typical usage
1732 it should be based on the <a href="#aspect-value"><i>aspect
1733 value</i></a> of the first font in the font-family list. If this is
1734 specified accurately, the <tt>(a/a')</tt> term in the formula above is
1735 effectively 1 for the first font and no adjustment occurs. If the value
1736 is specified inaccurately, text rendered using the first font in the
1737 family list will display differently in older user agents that don't
1738 support ‘<a href="#propdef-font-size-adjust"><code
1739 class=property>font-size-adjust</code></a>’.</p>
1740 </dl>
1742 <p>The value of ‘<a href="#propdef-font-size-adjust"><code
1743 class=property>font-size-adjust</code></a>’ affects the used value of
1744 ‘<a href="#propdef-font-size"><code
1745 class=property>font-size</code></a>’ but does not affect the computed
1746 value. It affects the size of relative units that are based on font
1747 metrics of the <a href="#first-available-font"><i>first available
1748 font</i></a> such as <code>ex</code> and <code>ch</code> but does not
1749 affect the size of <code>em</code> units. Since numeric values of <a
1750 href="http://www.w3.org/TR/CSS2/visudet.html#propdef-line-height">‘<code
1751 class=property>line-height</code>’</a> refer to the computed size of
1752 ‘<a href="#propdef-font-size"><code
1753 class=property>font-size</code></a>’, ‘<a
1754 href="#propdef-font-size-adjust"><code
1755 class=property>font-size-adjust</code></a>’ does not affect the used
1756 value of <a
1757 href="http://www.w3.org/TR/CSS2/visudet.html#propdef-line-height">‘<code
1758 class=property>line-height</code>’</a>.
1760 <p class=note>In CSS, authors often specify <a
1761 href="http://www.w3.org/TR/CSS2/visudet.html#propdef-line-height">‘<code
1762 class=property>line-height</code>’</a> as a multiple of the ‘<a
1763 href="#propdef-font-size"><code class=property>font-size</code></a>’.
1764 Since the ‘<a href="#propdef-font-size-adjust"><code
1765 class=property>font-size-adjust</code></a>’ property affects the used
1766 value of ‘<a href="#propdef-font-size"><code
1767 class=property>font-size</code></a>’, authors should take care setting
1768 the line height when ‘<a href="#propdef-font-size-adjust"><code
1769 class=property>font-size-adjust</code></a>’ is used. Setting the line
1770 height too tightly can result in overlapping lines of text in this
1771 situation.
1773 <p>Authors can calculate the <a href="#aspect-value"><i>aspect
1774 value</i></a> for a given font by comparing spans with the same content
1775 but different ‘<a href="#propdef-font-size-adjust"><code
1776 class=property>font-size-adjust</code></a>’ properties. If the same
1777 font-size is used, the spans will match when the ‘<a
1778 href="#propdef-font-size-adjust"><code
1779 class=property>font-size-adjust</code></a>’ value is accurate for the
1780 given font.
1782 <div class=example>
1783 <p>Two spans with borders are used to determine the <a
1784 href="#aspect-value"><i>aspect value</i></a> of a font. The ‘<a
1785 href="#propdef-font-size"><code class=property>font-size</code></a>’ is
1786 the same for both spans but the ‘<a
1787 href="#propdef-font-size-adjust"><code
1788 class=property>font-size-adjust</code></a>’ property is specified only
1789 for the right span. Starting with a value of 0.5, the aspect value can be
1790 adjusted until the borders around the two letters line up.</p>
1792 <pre>p {
1793 font-family: Futura;
1794 font-size: 500px;
1795 }
1797 span {
1798 border: solid 1px red;
1799 }
1801 .adjust {
1802 font-size-adjust: 0.5;
1803 }
1805 <p><span>b</span><span class="adjust">b</span></p>
1806 </pre>
1808 <div class=figure><img alt="Futura with an <i>aspect value</i> of 0.5"
1809 src=beforefontsizeadjust.png>
1810 <p class=caption>Futura with an <a href="#aspect-value"><i>aspect
1811 value</i></a> of 0.5
1812 </div>
1814 <p>The box on the right is a bit bigger than the one on the left, so the
1815 <a href="#aspect-value"><i>aspect value</i></a> of this font is something
1816 less than 0.5. Adjust the value until the boxes align.</p>
1817 </div>
1818 <!-- prop: font -->
1820 <h3 id=font-prop><span class=secno>3.7 </span>Shorthand font property: the
1821 <a href="#propdef-font">font</a> property</h3>
1823 <table class=propdef id=namefontvalue-ltlsquofont-stylersquogt-l>
1824 <tbody>
1825 <tr>
1826 <td>Name:
1828 <td><dfn id=propdef-font>font</dfn>
1830 <tr>
1831 <td>Value:
1833 <td>[ [ <var><<a href="#propdef-font-style"
1834 title="font-style!!property">‘<code
1835 class=property>font-style</code>’</a>></var> || <a
1836 href="#font-variant-css21-values"><var><font-variant-css21></var></a>
1837 || <var><<a href="#propdef-font-weight"
1838 title="font-weight!!property">‘<code
1839 class=property>font-weight</code>’</a>></var> || <var><<a
1840 href="#propdef-font-stretch" title="font-stretch!!property">‘<code
1841 class=property>font-stretch</code>’</a></var> ]? <var><‘<a
1842 href="#propdef-font-size"><code
1843 class=property>font-size</code></a>’></var> [ / <var><‘<code
1844 class=property>line-height</code>’></var> ]? <var><<a
1845 href="#propdef-font-family" title="font-family!!property">‘<code
1846 class=property>font-family</code>’</a>></var> ] | caption | icon |
1847 menu | message-box | small-caption | status-bar
1849 <tr>
1850 <td>Initial:
1852 <td>see individual properties
1854 <tr>
1855 <td>Applies to:
1857 <td>all elements
1859 <tr>
1860 <td>Inherited:
1862 <td>yes
1864 <tr>
1865 <td>Percentages:
1867 <td>see individual properties
1869 <tr>
1870 <td>Media:
1872 <td>visual
1874 <tr>
1875 <td>Computed value:
1877 <td>see individual properties
1879 <tr>
1880 <td>Animatable:
1882 <td>see individual properties
1883 </table>
1885 <p>The <span class=property>‘<a href="#propdef-font"><code
1886 class=property>font</code></a>’</span> property is, except as described
1887 below, a shorthand property for setting <a href="#propdef-font-style"
1888 title="font-style!!property">‘<code
1889 class=property>font-style</code>’</a>, <a href="#propdef-font-variant"
1890 title="font-variant!!property">‘<code
1891 class=property>font-variant</code>’</a>, <a href="#propdef-font-weight"
1892 title="font-weight!!property">‘<code
1893 class=property>font-weight</code>’</a>, <a href="#propdef-font-stretch"
1894 title="font-stretch!!property">‘<code
1895 class=property>font-stretch</code>’</a>, <span class=property>‘<a
1896 href="#propdef-font-size"><code
1897 class=property>font-size</code></a>’</span>, <a class=property
1898 href="http://www.w3.org/TR/CSS2/visudet.html#propdef-line-height">‘<code
1899 class=property>line-height</code>’</a>, <a href="#propdef-font-family"
1900 title="font-family!!property">‘<code
1901 class=property>font-family</code>’</a> at the same place in the
1902 stylesheet. Values for the <a href="#propdef-font-variant"
1903 title="font-variant!!property">‘<code
1904 class=property>font-variant</code>’</a> property may also be included
1905 but only those supported in CSS 2.1, none of the <a
1906 href="#propdef-font-variant" title="font-variant!!property">‘<code
1907 class=property>font-variant</code>’</a> values added in this
1908 specification can be used in the <span class=property>‘<a
1909 href="#propdef-font"><code class=property>font</code></a>’</span>
1910 shorthand:
1912 <pre
1913 class=prod><dfn id=font-variant-css21-values><var><font-variant-css21></var></dfn> = [normal | small-caps]</pre>
1915 <p>The syntax of this property is based on a traditional typographical
1916 shorthand notation to set multiple properties related to fonts.
1918 <p>All subproperties of the ‘<a href="#propdef-font"><code
1919 class=property>font</code></a>’ property are first reset to their
1920 initial values, including those listed above plus <span
1921 class=property>‘<a href="#propdef-font-size-adjust"><code
1922 class=property>font-size-adjust</code></a>’</span>, <span
1923 class=property>‘<a href="#propdef-font-kerning"><code
1924 class=property>font-kerning</code></a>’</span>, subproperties of <a
1925 href="#propdef-font-variant" title="font-variant!!property">‘<code
1926 class=property>font-variant</code>’</a> and and <span>‘<a
1927 href="#propdef-font-language-override"><code
1928 class=property>font-language-override</code></a>’</span>. Then, those
1929 properties that are given explicit values in the <span
1930 class=property>‘<a href="#propdef-font"><code
1931 class=property>font</code></a>’</span> shorthand are set to those
1932 values. For a definition of allowed and initial values, see the previously
1933 defined properties. For reasons of backwards compatibility, it is not
1934 possible to set <span class=property>‘<a
1935 href="#propdef-font-size-adjust"><code
1936 class=property>font-size-adjust</code></a>’</span> to anything other
1937 than its initial value using the <span class=property>‘<a
1938 href="#propdef-font"><code class=property>font</code></a>’</span>
1939 shorthand property; instead, use the individual property.
1941 <div class=example>
1942 <p style="display:none">Example(s):</p>
1944 <pre>p { font: 12pt/14pt sans-serif }
1945 p { font: 80% sans-serif }
1946 p { font: x-large/110% "new century schoolbook", serif }
1947 p { font: bold italic large Palatino, serif }
1948 p { font: normal small-caps 120%/120% fantasy }
1949 p { font: condensed oblique 12pt "Helvetica Neue", serif; }
1950 </pre>
1952 <p> In the second rule, the font size percentage value (‘<code
1953 class=css>80%</code>’) refers to the computed ‘<a
1954 href="#propdef-font-size"><code class=property>font-size</code></a>’ of
1955 the parent element. In the third rule, the line height percentage
1956 (‘<code class=css>110%</code>’) refers to the font size of the
1957 element itself.
1959 <p>The first three rules do not specify the <a
1960 href="#propdef-font-variant" title="font-variant!!property">‘<code
1961 class=property>font-variant</code>’</a> and <a
1962 href="#propdef-font-weight" title="font-weight!!property">‘<code
1963 class=property>font-weight</code>’</a> explicitly, so these properties
1964 receive their initial values (<span title="normal value">‘<code
1965 class=property>normal</code>’</span>). Notice that the font family name
1966 "new century schoolbook", which contains spaces, is enclosed in quotes.
1967 The fourth rule sets the <a href="#propdef-font-weight"
1968 title="font-weight!!property">‘<code
1969 class=property>font-weight</code>’</a> to ‘<a href="#bold"><code
1970 class=property>bold</code></a>’, the <a href="#propdef-font-style"
1971 title="font-style!!property">‘<code
1972 class=property>font-style</code>’</a> to ‘<a href="#italic"><code
1973 class=property>italic</code></a>’, and implicitly sets <a
1974 href="#propdef-font-variant" title="font-variant!!property">‘<code
1975 class=property>font-variant</code>’</a> to <a
1976 href="#font-variant-normal-value" title="normal!!font-variant">‘<code
1977 class=property>normal</code>’</a>.
1979 <p> The fifth rule sets the <a href="#propdef-font-variant"
1980 title="font-variant!!property">‘<code
1981 class=property>font-variant</code>’</a> (‘<a href="#small-caps"><code
1982 class=property>small-caps</code></a>’), the <span class=property>‘<a
1983 href="#propdef-font-size"><code
1984 class=property>font-size</code></a>’</span> (120% of the parent's font
1985 size), the <a class=property
1986 href="http://www.w3.org/TR/CSS2/visudet.html#propdef-line-height">‘<code
1987 class=property>line-height</code>’</a> (120% of the font size) and the
1988 <a href="#propdef-font-family" title="font-family!!property">‘<code
1989 class=property>font-family</code>’</a> (‘<a href="#fantasy"><code
1990 class=property>fantasy</code></a>’). It follows that the keyword <span
1991 title="normal value">‘<code class=property>normal</code>’</span>
1992 applies to the two remaining properties: <a href="#propdef-font-style"
1993 title="font-style!!property">‘<code
1994 class=property>font-style</code>’</a> and <a
1995 href="#propdef-font-weight" title="font-weight!!property">‘<code
1996 class=property>font-weight</code>’</a>.
1998 <p>The sixth rule sets the <a href="#propdef-font-style"
1999 title="font-style!!property">‘<code
2000 class=property>font-style</code>’</a>, <a href="#propdef-font-stretch"
2001 title="font-stretch!!property">‘<code
2002 class=property>font-stretch</code>’</a>, <span class=property>‘<a
2003 href="#propdef-font-size"><code
2004 class=property>font-size</code></a>’</span>, and <a
2005 href="#propdef-font-family" title="font-family!!property">‘<code
2006 class=property>font-family</code>’</a>, the other font properties being
2007 set to their initial values.
2008 </div>
2010 <p>Since the <a href="#propdef-font-stretch"
2011 title="font-stretch!!property">‘<code
2012 class=property>font-stretch</code>’</a> property was not defined in CSS
2013 2.1, when using <a href="#propdef-font-stretch"
2014 title="font-stretch!!property">‘<code
2015 class=property>font-stretch</code>’</a> values within ‘<a
2016 href="#propdef-font"><code class=property>font</code></a>’ rules,
2017 authors should include a extra version compatible with older user agents:
2019 <pre>p {
2020 font: 80% sans-serif; /* for older user agents */
2021 font: condensed 80% sans-serif;
2022 }</pre>
2024 <p>The following values refer to system fonts:
2026 <dl>
2027 <dt><strong>caption</strong>
2029 <dd>The font used for captioned controls (e.g., buttons, drop-downs,
2030 etc.).
2032 <dt><strong>icon</strong>
2034 <dd>The font used to label icons.
2036 <dt><strong>menu</strong>
2038 <dd>The font used in menus (e.g., dropdown menus and menu lists).
2040 <dt><strong>message-box</strong>
2042 <dd>The font used in dialog boxes.
2044 <dt><strong>small-caption</strong>
2046 <dd>The font used for labeling small controls.
2048 <dt><strong>status-bar</strong>
2050 <dd>The font used in window status bars.
2051 </dl>
2053 <p>System fonts may only be set as a whole; that is, the font family, size,
2054 weight, style, etc. are all set at the same time. These values may then be
2055 altered individually if desired. If no font with the indicated
2056 characteristics exists on a given platform, the user agent should either
2057 intelligently substitute (e.g., a smaller version of the ‘<code
2058 class=property>caption</code>’ font might be used for the ‘<code
2059 class=property>small-caption</code>’ font), or substitute a user agent
2060 default font. As for regular fonts, if, for a system font, any of the
2061 individual properties are not part of the operating system's available
2062 user preferences, those properties should be set to their initial values.
2064 <p>That is why this property is "almost" a shorthand property: system fonts
2065 can only be specified with this property, not with <a
2066 href="#propdef-font-family" title="font-family!!property">‘<code
2067 class=property>font-family</code>’</a> itself, so <span
2068 class=property>‘<a href="#propdef-font"><code
2069 class=property>font</code></a>’</span> allows authors to do more than
2070 the sum of its subproperties. However, the individual properties such as
2071 <a href="#propdef-font-weight" title="font-weight!!property">‘<code
2072 class=property>font-weight</code>’</a> are still given values taken from
2073 the system font, which can be independently varied.
2075 <p>Note that the keywords used for the system fonts listed above are only
2076 treated as keywords when they occur in the initial position, in other
2077 positions the same string is treated as part of the font family name:
2079 <pre> font: menu; /* use the font settings for system menus */
2080 font: large menu; /* use a font family named "menu" */</pre>
2082 <div class=example>
2083 <p style="display:none">Example(s):</p>
2085 <pre>button { font: 300 italic 1.3em/1.7em "FB Armada", sans-serif }
2086 button p { font: menu }
2087 button p em { font-weight: bolder }
2088 </pre>
2090 <p>If the font used for dropdown menus on a particular system happened to
2091 be, for example, 9-point Charcoal, with a weight of 600, then P elements
2092 that were descendants of BUTTON would be displayed as if this rule were
2093 in effect:
2095 <pre>button p { font: 600 9pt Charcoal }
2096 </pre>
2098 <p>Because the <span class=property>‘<a href="#propdef-font"><code
2099 class=property>font</code></a>’</span> shorthand resets to its initial
2100 value any property not explicitly given a value, this has the same effect
2101 as this declaration:
2103 <pre>button p {
2104 font-style: normal;
2105 font-variant: normal;
2106 font-weight: 600;
2107 font-size: 9pt;
2108 line-height: normal;
2109 font-family: Charcoal
2110 }
2111 </pre>
2112 </div>
2113 <!-- prop: font-synthesis -->
2115 <h3 id=font-synthesis-prop><span class=secno>3.8 </span>Controlling
2116 synthetic faces: the <a href="#propdef-font-synthesis">font-synthesis</a>
2117 property</h3>
2119 <table class=propdef id=namefont-synthesisvaluenone-weight-style>
2120 <tbody>
2121 <tr>
2122 <td>Name:
2124 <td><dfn id=propdef-font-synthesis>font-synthesis</dfn>
2126 <tr>
2127 <td>Value:
2129 <td>none | [ weight || style ]
2131 <tr>
2132 <td>Initial:
2134 <td>weight style
2136 <tr>
2137 <td>Applies to:
2139 <td>all elements
2141 <tr>
2142 <td>Inherited:
2144 <td>yes
2146 <tr>
2147 <td>Percentages:
2149 <td>N/A
2151 <tr>
2152 <td>Media:
2154 <td>visual
2156 <tr>
2157 <td>Computed value:
2159 <td>as specified
2161 <tr>
2162 <td>Animatable:
2164 <td>no
2165 </table>
2167 <p>This property controls whether user agents are allowed to synthesize
2168 bold or oblique font faces when a font family lacks bold or italic faces.
2169 If ‘<a href="#weight"><code class=property>weight</code></a>’ is not
2170 specified, user agents must not synthesize bold faces and if ‘<code
2171 class=property>style</code>’ is not specified user agents must not
2172 synthesize italic faces. A value of ‘<code class=property>none</code>’
2173 disallows all synthetic faces.
2175 <div class=example>
2176 <p>The style rule below disables the use of synthetically obliqued Arabic:</p>
2178 <pre>*:lang(ar) { font-synthesis: none; }
2179 </pre>
2180 </div>
2182 <h2 id=font-resources><span class=secno>4 </span>Font Resources</h2>
2184 <h3 id=font-face-rule><span class=secno>4.1 </span>The <dfn
2185 id=at-font-face-rule style="font-weight: inherit; font-style:
2186 inherit"><code>@font-face</code></dfn> rule</h3>
2188 <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule allows
2189 for linking to fonts that are automatically fetched and activated when
2190 needed. This allows authors to select a font that closely matches the
2191 design goals for a given page rather than limiting the font choice to a
2192 set of fonts available on a given platform. A set of font descriptors
2193 define the location of a font resource, either locally or externally,
2194 along with the style characteristics of an individual face. Multiple <a
2195 href="#at-font-face-rule"><code>@font-face</code></a> rules can be used to
2196 construct font families with a variety of faces. Using CSS font matching
2197 rules, a user agent can selectively download only those faces that are
2198 needed for a given piece of text.
2200 <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule
2201 consists of the <a href="#at-font-face-rule"><code>@font-face</code></a>
2202 at-keyword followed by a block of descriptor declarations. In terms of the
2203 grammar, this specification defines the following productions:
2205 <pre><dfn id=fontfacerule>font_face_rule</dfn>
2206 : <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>*
2207 ;
2209 <dfn id=descriptordeclaration>descriptor_declaration</dfn>
2210 : <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>
2211 ;</pre>
2213 <p>The following new definitions are introduced:
2215 <pre>- -|\\0{0,4}2d(\r\n|[ \t\r\n\f])?
2216 F f|\\0{0,4}(46|66)(\r\n|[ \t\r\n\f])?</pre>
2218 <p>The following new token is introduced:
2220 <pre>@{F}{O}{N}{T}{-}{F}{A}{C}{E} {return <dfn id=fontfacesym>FONT_FACE_SYM</dfn>;}</pre>
2222 <p>Each <a href="#at-font-face-rule"><code>@font-face</code></a> rule
2223 specifies a value for every font descriptor, either implicitly or
2224 explicitly. Those not given explicit values in the rule take the initial
2225 value listed with each descriptor in this specification. These descriptors
2226 apply solely within the context of the <a
2227 href="#at-font-face-rule"><code>@font-face</code></a> rule in which they
2228 are defined, and do not apply to document language elements. There is no
2229 notion of which elements the descriptors apply to or whether the values
2230 are inherited by child elements. When a given descriptor occurs multiple
2231 times in a given <a href="#at-font-face-rule"><code>@font-face</code></a>
2232 rule, only the last descriptor declaration is used and all prior
2233 declarations for that descriptor are ignored.
2235 <div class=example>
2236 <p>To use a downloadable font called Gentium:</p>
2238 <pre>
2239 @font-face {
2240 font-family: Gentium;
2241 src: url(http://example.com/fonts/Gentium.woff);
2242 }
2244 p { font-family: Gentium, serif; }
2245 </pre>
2247 <p>The user agent will download Gentium and use it when rendering text
2248 within paragraph elements. If for some reason the site serving the font
2249 is unavailable, the default serif font will be used.</p>
2250 </div>
2252 <p>A given set of <a href="#at-font-face-rule"><code>@font-face</code></a>
2253 rules define a set of fonts available for use within the documents that
2254 contain these rules. When font matching is done, fonts defined using these
2255 rules are considered before other available fonts on a system.
2257 <p>Downloaded fonts are only available to documents that reference them.
2258 The process of activating these fonts must not make them available to
2259 other applications or to documents that don't directly link to the same
2260 font. User agent implementers might consider it convenient to use
2261 downloaded fonts when rendering characters in other documents for which no
2262 other available font exists as part of the <a
2263 href="#system-font-fallback"><em>system font fallback</em></a> procedure.
2264 However, this would cause a security leak since the contents of one page
2265 would be able to affect other pages, something an attacker could use as an
2266 attack vector. These restrictions do not affect caching behavior, fonts
2267 are cached the same way other web resources are cached.
2269 <p>This at-rule follows the forward-compatible parsing rules of CSS. Like
2270 properties in a declaration block, declarations of any descriptors that
2271 are not supported by the user agent must be ignored. <a
2272 href="#at-font-face-rule"><code>@font-face</code></a> rules require a
2273 font-family and src descriptor; if either of these are missing, the <a
2274 href="#at-font-face-rule"><code>@font-face</code></a> rule is invalid and
2275 must be ignored entirely.
2277 <p>In cases where user agents have limited platform resources or implement
2278 the ability to disable downloadable font resources, <a
2279 href="#at-font-face-rule"><code>@font-face</code></a> rules must simply be
2280 ignored; the behavior of individual descriptors as defined in this
2281 specification should not be altered.
2283 <h3 id=font-family-desc><span class=secno>4.2 </span>Font family: the <a
2284 href="#descdef-font-family">font-family</a> descriptor</h3>
2286 <table class=descdef>
2287 <tbody>
2288 <tr>
2289 <td>Name:
2291 <td><dfn id=descdef-font-family
2292 title="font-family!!descriptor">font-family</dfn>
2294 <tr>
2295 <td>Value:
2297 <td><a href="#family-name-value"><var><family-name></var></a>
2299 <tr>
2300 <td><em>Initial:</em>
2302 <td>N/A
2303 </table>
2305 <p>This descriptor defines the font family name that will be used in all
2306 CSS font family name matching. It is required for the <a
2307 href="#at-font-face-rule"><code>@font-face</code></a> rule to be valid. It
2308 overrides the font family names contained in the underlying font data. If
2309 the font family name is the same as a font family available in a given
2310 user's environment, it effectively hides the underlying font for documents
2311 that use the stylesheet. This permits a web author to freely choose
2312 font-family names without worrying about conflicts with font family names
2313 present in a given user's environment. Likewise, platform substitutions
2314 for a given font family name must not be used.
2316 <h3 id=src-desc><span class=secno>4.3 </span>Font reference: the <a
2317 href="#descdef-src">src</a> descriptor</h3>
2319 <table class=descdef>
2320 <tbody>
2321 <tr>
2322 <td>Name:
2324 <td><dfn id=descdef-src>src</dfn>
2326 <tr>
2327 <td>Value:
2329 <td>[ <url> [format(<string> #)]? | <a
2330 href="#font-face-name-value"><var><font-face-name></var></a> ] #
2332 <tr>
2333 <td><em>Initial:</em>
2335 <td>N/A
2336 </table>
2338 <p>This descriptor specifies the resource containing font data. It is
2339 required for the <a href="#at-font-face-rule"><code>@font-face</code></a>
2340 rule to be valid. Its value is a prioritized, comma-separated list of
2341 external references or locally-installed font face names. When a font is
2342 needed the user agent iterates over the set of references listed, using
2343 the first one it can successfully activate. Fonts containing invalid data
2344 or local font faces that are not found are ignored and the user agent
2345 loads the next font in the list.
2347 <p>As with other URLs in CSS, the URL may be relative, in which case it is
2348 resolved relative to the location of the style sheet containing the <a
2349 href="#at-font-face-rule"><code>@font-face</code></a> rule. In the case of
2350 SVG fonts, the URL points to an element within a document containing SVG
2351 font definitions. If the element reference is omitted, a reference to the
2352 first defined font is implied. Similarly, font container formats that can
2353 contain more than one font must load one and only one of the fonts for a
2354 given <a href="#at-font-face-rule"><code>@font-face</code></a> rule.
2355 Fragment identifiers are used to indicate which font to load. If a
2356 container format lacks a defined fragment identifier scheme,
2357 implementations should use a simple 1-based indexing scheme (e.g.
2358 "font-collection#1" for the first font, "font-collection#2" for the second
2359 font).
2361 <pre>
2362 src: url(fonts/simple.woff); /* load simple.woff relative to stylesheet location */
2363 src: url(/fonts/simple.woff); /* load simple.woff from absolute location */
2364 src: url(fonts.svg#simple); /* load SVG font with id 'simple' */
2365 </pre>
2367 <p>External references consist of a URL, followed by an optional hint
2368 describing the format of the font resource referenced by that URL. The
2369 format hint contains a comma-separated list of format strings that denote
2370 well-known font formats. Conformant user agents must skip downloading a
2371 font resource if the format hints indicate only unsupported or unknown
2372 font formats. If no format hints are supplied, the user agent should
2373 download the font resource.
2375 <pre>
2376 /* load WOFF font if possible, otherwise use OpenType font */
2377 @font-face {
2378 font-family: bodytext;
2379 src: url(ideal-sans-serif.woff) format("woff"),
2380 url(basic-sans-serif.ttf) format("opentype");
2381 }
2382 </pre>
2384 <p>Format strings defined by this specification:
2386 <table class=data id=fontformats>
2387 <thead>
2388 <tr>
2389 <th>String
2391 <th>Font Format
2393 <th>Common extensions
2395 <tbody>
2396 <tr>
2397 <th>"woff"
2399 <td><a href="http://www.w3.org/TR/WOFF/">WOFF (Web Open Font Format)</a>
2401 <td>.woff
2403 <tr>
2404 <th>"truetype"
2406 <td><a
2407 href="http://www.microsoft.com/typography/otspec/default.htm">TrueType</a>
2409 <td>.ttf
2411 <tr>
2412 <th>"opentype"
2414 <td><a
2415 href="http://www.microsoft.com/typography/otspec/default.htm">OpenType</a>
2417 <td>.ttf, .otf
2419 <tr>
2420 <th>"embedded-opentype"
2422 <td><a
2423 href="http://www.w3.org/Submission/2008/SUBM-EOT-20080305/">Embedded
2424 OpenType</a>
2426 <td>.eot
2428 <tr>
2429 <th>"svg"
2431 <td><a href="http://www.w3.org/TR/SVG/fonts.html">SVG Font</a>
2433 <td>.svg, .svgz
2434 </table>
2436 <p>Given the overlap in common usage between TrueType and OpenType, the
2437 format hints "truetype" and "opentype" must be considered as synonymous; a
2438 format hint of "opentype" does not imply that the font contains Postscript
2439 CFF style glyph data or that it contains OpenType layout information (see
2440 <a href="#platform-props-to-css">Appendix A</a> for more background on
2441 this).
2443 <p>When authors would prefer to use a locally available copy of a given
2444 font and download it if it's not, <code>local()</code> can be used. The
2445 locally-installed <dfn
2446 id=font-face-name-value><var><font-face-name></var></dfn> argument
2447 to <code>local()</code> is a format-specific string that uniquely
2448 identifies a single font face within a larger family. The syntax for a <a
2449 href="#font-face-name-value"><var><font-face-name></var></a> is a
2450 unique font face name enclosed by "local(" and ")". The name can
2451 optionally be enclosed in quotes. If unquoted, the unquoted font family
2452 name processing conventions apply; the name must be a sequence of
2453 identifiers separated by whitespace which is converted to a string by
2454 joining the identifiers together separated by a single space.
2456 <pre>
2457 /* regular face of Gentium */
2458 @font-face {
2459 font-family: MyGentium;
2460 src: local(Gentium), /* use locally available Gentium */
2461 url(Gentium.woff); /* otherwise, download it */
2462 }
2463 </pre>
2465 <p>For OpenType and TrueType fonts, this string is used to match only the
2466 Postscript name or the full font name in the name table of locally
2467 available fonts. Which type of name is used varies by platform and font,
2468 so authors should include both of these names to assure proper matching
2469 across platforms. Platform substitutions for a given font name must not be
2470 used.
2472 <pre>
2473 /* bold face of Gentium */
2474 @font-face {
2475 font-family: MyGentium;
2476 src: local(Gentium Bold), /* full font name */
2477 local(Gentium-Bold), /* Postscript name */
2478 url(GentiumBold.woff); /* otherwise, download it */
2479 font-weight: bold;
2480 }
2481 </pre>
2483 <p>Just as a <a href="#at-font-face-rule"><code>@font-face</code></a> rule
2484 specifies the characteristics of a single font within a family, the unique
2485 name used with <code>local()</code> specifies a single font, not an entire
2486 font family. Defined in terms of OpenType font data, the Postscript name
2487 is found in the font's <a
2488 href="http://www.microsoft.com/typography/otspec/name.htm">name table</a>,
2489 in the name record with nameID = 6 (see <a href="#OPENTYPE"
2490 rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a> for more details). The
2491 Postscript name is the commonly used key for all fonts on OSX and for
2492 Postscript CFF fonts under Windows. The full font name (nameID = 4) is
2493 used as a unique key for fonts with TrueType glyphs on Windows.
2495 <p>For OpenType fonts with multiple localizations of the full font name,
2496 the US English version is used (language ID = 0x409 for Windows and
2497 language ID = 0 for Macintosh) or the first localization when a US English
2498 full font name is not available (the OpenType specification recommends
2499 that <a href="http://www.microsoft.com/typography/otspec/recom.htm">all
2500 fonts minimally include US English names</a>). User agents that also match
2501 other full font names, e.g. matching the Dutch name when the current
2502 system locale is set to Dutch, are considered non-conformant. This is done
2503 not to prefer English but to avoid matching inconsistencies across font
2504 versions and OS localizations, since font style names (e.g. "Bold") are
2505 frequently localized into many languages and the set of localizations
2506 available varies widely across platform and font version. User agents that
2507 match a concatenation of family name (nameID = 1) with style name (nameID
2508 = 2) are considered non-conformant.
2510 <p>This also allows for referencing faces that belong to larger families
2511 that cannot otherwise be referenced.
2513 <div class=example>
2514 <p>Use a local font or reference an SVG font in another document:</p>
2516 <pre>
2517 @font-face {
2518 font-family: Headline;
2519 src: local(Futura-Medium),
2520 url(fonts.svg#MyGeometricModern) format("svg");
2521 }
2522 </pre>
2524 <p>Create an alias for local Japanese fonts on different platforms:</p>
2526 <pre>
2527 @font-face {
2528 font-family: jpgothic;
2529 src: local(HiraKakuPro-W3), local(Meiryo), local(IPAPGothic);
2530 }
2531 </pre>
2533 <p>Reference a font face that cannot be matched within a larger family:</p>
2535 <pre>
2536 @font-face {
2537 font-family: Hoefler Text Ornaments;
2538 /* has the same font properties as Hoefler Text Regular */
2539 src: local(HoeflerText-Ornaments);
2540 }
2541 </pre>
2543 <p>Since localized fullnames never match, a document with the header style
2544 rules below would always render using the default serif font, regardless
2545 whether a particular system locale parameter is set to Finnish or not:</p>
2547 <pre>
2548 @font-face {
2549 font-family: SectionHeader;
2550 src: local("Arial Lihavoitu"); /* Finnish fullname for Arial Bold, should fail */
2551 font-weight: bold;
2552 }
2554 h2 { font-family: SectionHeader, serif; }
2555 </pre>
2557 <p>A conformant user agent would never load the font ‘<code
2558 class=css>gentium.eot</code>’ in the example below, since it is
2559 included in the first definition of the ‘<a href="#descdef-src"><code
2560 class=property>src</code></a>’ descriptor which is overridden by the
2561 second definition in the same <a
2562 href="#at-font-face-rule"><code>@font-face</code></a> rule:</p>
2564 <pre>
2565 @font-face {
2566 font-family: MainText;
2567 src: url(gentium.eot); /* for use with older user agents */
2568 src: local("Gentium"), url(gentium.woff); /* Overrides src definition */
2569 }
2570 </pre>
2571 </div>
2573 <h3 id=font-prop-desc><span class=secno>4.4 </span>Font property
2574 descriptors: the <a href="#descdef-font-style">font-style</a>, <a
2575 href="#descdef-font-weight">font-weight</a>, <a
2576 href="#descdef-font-stretch">font-stretch</a> descriptors</h3>
2578 <table class=descdef>
2579 <tbody>
2580 <tr>
2581 <td>Name:
2583 <td><dfn id=descdef-font-style
2584 title="font-style!!descriptor">font-style</dfn>
2586 <tr>
2587 <td>Value:
2589 <td>normal | italic | oblique
2591 <tr>
2592 <td><em>Initial:</em>
2594 <td>normal
2595 </table>
2597 <table class=descdef>
2598 <tbody>
2599 <tr>
2600 <td>Name:
2602 <td><dfn id=descdef-font-weight
2603 title="font-weight!!descriptor">font-weight</dfn>
2605 <tr>
2606 <td>Value:
2608 <td>normal | bold | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900
2610 <tr>
2611 <td><em>Initial:</em>
2613 <td>normal
2614 </table>
2616 <table class=descdef>
2617 <tbody>
2618 <tr>
2619 <td>Name:
2621 <td><dfn id=descdef-font-stretch
2622 title="font-stretch!!descriptor">font-stretch</dfn>
2624 <tr>
2625 <td>Value:
2627 <td>normal | ultra-condensed | extra-condensed | condensed |
2628 semi-condensed | semi-expanded | expanded | extra-expanded |
2629 ultra-expanded
2631 <tr>
2632 <td><em>Initial:</em>
2634 <td>normal
2635 </table>
2637 <p>These descriptors define the characteristics of a font face and are used
2638 in the process of matching styles to specific faces. For a font family
2639 defined with several <a
2640 href="#at-font-face-rule"><code>@font-face</code></a> rules, user agents
2641 can either download all faces in the family or use these descriptors to
2642 selectively download font faces that match actual styles used in document.
2643 The values for these descriptors are the same as those for the
2644 corresponding font properties except that relative keywords are not
2645 allowed, ‘<a href="#bolder"><code class=property>bolder</code></a>’
2646 and ‘<a href="#lighter"><code class=property>lighter</code></a>’. If
2647 these descriptors are omitted, initial values are assumed.
2649 <p>The value for these font face style attributes is used in place of the
2650 style implied by the underlying font data. This allows authors to combine
2651 faces in flexible combinations, even in situations where the original font
2652 data was arranged differently. User agents that implement synthetic
2653 bolding and obliquing must only apply synthetic styling in cases where the
2654 font descriptors imply this is needed, rather than based on the style
2655 attributes implied by the font data.
2657 <h3 id=unicode-range-desc><span class=secno>4.5 </span>Character range: the
2658 <a href="#descdef-unicode-range">unicode-range</a> descriptor</h3>
2660 <table class=descdef>
2661 <tbody>
2662 <tr>
2663 <td>Name:
2665 <td><dfn id=descdef-unicode-range>unicode-range</dfn>
2667 <tr>
2668 <td>Value:
2670 <td><a href="#urange-value"><var><urange></var></a> #
2672 <tr>
2673 <td><em>Initial:</em>
2675 <td>U+0-10FFFF
2676 </table>
2678 <p>This descriptor defines the set of Unicode codepoints that may be
2679 supported by the font face for which it is declared. The descriptor value
2680 is a comma-delimited list of Unicode range (<a
2681 href="#urange-value"><var><urange></var></a>) values. The union of
2682 these ranges defines the set of codepoints that serves as a hint for user
2683 agents when deciding whether or not to download a font resource for a
2684 given text run.
2686 <p>Each <dfn id=urange-value><var><urange></var></dfn> value is a <a
2687 href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><code
2688 title="UNICODE-RANGE token">UNICODE-RANGE</code></a> token made up of a
2689 "U+" or "u+" prefix followed by a codepoint range in one of the three
2690 forms listed below. Ranges that do not fit one of the these forms are
2691 invalid and cause the declaration to be ignored.
2693 <dl>
2694 <dt>single codepoint (e.g. U+416)
2696 <dd>a Unicode codepoint, represented as one to six hexadecimal digits
2698 <dt>interval range (e.g. U+400-4ff)
2700 <dd>represented as two hyphen-separated Unicode codepoints indicating the
2701 inclusive start and end codepoints of a range
2703 <dt>wildcard range (e.g. U+4??)
2705 <dd>defined by the set of codepoints implied when trailing ‘<code
2706 class=css>?</code>’ characters signify any hexadeximal digit
2707 </dl>
2709 <p>Individual codepoints are written using hexadecimal values that
2710 correspond to <a href="http://www.unicode.org/charts/">Unicode character
2711 codepoints</a>. Unicode codepoint values must be between 0 and 10FFFF
2712 inclusive. Digit values of codepoints are ASCII case-insensitive. For
2713 interval ranges, the start and end codepoints must be within the range
2714 noted above and the end codepoint must be greater than or equal to the
2715 start codepoint.
2717 <p>Wildcard ranges specified with ‘?’ that lack an initial digit (e.g.
2718 "U+???") are valid and equivalent to a wildcard range with an initial zero
2719 digit (e.g. "U+0???" = "U+0000-0FFF"). Wildcard ranges that extend beyond
2720 the range of Unicode codepoints are invalid. Because of this, the maximum
2721 number of trailing ‘<code class=css>?</code>’ wildcard characters is
2722 five, even though the <a
2723 href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><code
2724 title="UNICODE-RANGE token">UNICODE-RANGE</code></a> token accepts six.
2726 <p>Within the comma-delimited list of Unicode ranges in a ‘<a
2727 href="#descdef-unicode-range"><code
2728 class=property>unicode-range</code></a>’ descriptor declaration, ranges
2729 may overlap. The union of these ranges defines the set of codepoints for
2730 which the corresponding font may be used. User agents must not download or
2731 use the font for codepoints outside this set. User agents may normalize
2732 the list of ranges into a list that is different but represents the same
2733 set of codepoints.
2735 <p>The associated font might not contain glyphs for the entire set of
2736 codepoints defined by the ‘<a href="#descdef-unicode-range"><code
2737 class=property>unicode-range</code></a>’ descriptor. When the font is
2738 used, the <dfn id=effective-character-map>effective character map</dfn> is
2739 the intersection of the codepoints defined by ‘<a
2740 href="#descdef-unicode-range"><code
2741 class=property>unicode-range</code></a>’ with the font's <a
2742 href="#character-map"><em>character map</em></a>. This allows authors to
2743 define supported ranges in terms of broad ranges without worrying about
2744 the precise codepoint ranges supported by the underlying font.
2746 <h3 id=composite-fonts><span class=secno>4.6 </span>Using character ranges
2747 to define composite fonts</h3>
2749 <p>Multiple <a href="#at-font-face-rule"><code>@font-face</code></a> rules
2750 with different unicode ranges for the same family and style descriptor
2751 values can be used to create composite fonts that mix the glyphs from
2752 different fonts for different scripts. This can be used to combine fonts
2753 that only contain glyphs for a single script (e.g. Latin, Greek, Cyrillic)
2754 or it can be used by authors as a way of segmenting a font into fonts for
2755 commonly used characters and less frequently used characters. Since the
2756 user agent will only pull down the fonts it needs this helps reduce page
2757 bandwidth.
2759 <p>If the unicode ranges overlap for a set of <a
2760 href="#at-font-face-rule"><code>@font-face</code></a> rules with the same
2761 family and style descriptor values, the rules are ordered in the reverse
2762 order they were defined; the last rule defined is the first to be checked
2763 for a given character.
2765 <p>Example ranges for specific languages or characters:
2767 <dl>
2768 <dt>unicode-range: U+A5;
2770 <dd>a single code point, the yen/yuan symbol
2772 <dt>unicode-range: U+0-7F;
2774 <dd>code range for basic ASCII characters
2776 <dt>unicode-range: U+590-5ff;
2778 <dd>code range for Hebrew characters
2780 <dt>unicode-range: U+A5, U+4E00-9FFF, U+30??, U+FF00-FF9F;
2782 <dd>code range for Japanese kanji, hiragana and katakana characters plus
2783 yen/yuan symbol
2784 </dl>
2786 <div class=example>
2787 <p>The BBC provides news services in a wide variety of languages, many
2788 that are not well supported across all platforms. Using an <a
2789 href="#at-font-face-rule"><code>@font-face</code></a> rule, the BBC could
2790 provide a font for any of these languages, as it already does via a
2791 manual font download.</p>
2793 <pre>
2794 @font-face {
2795 font-family: BBCBengali;
2796 src: url(fonts/BBCBengali.woff) format("woff");
2797 unicode-range: U+00-FF, U+980-9FF;
2798 }
2799 </pre>
2800 </div>
2802 <div class=example>
2803 <p>Technical documents often require a wide range of symbols. The STIX
2804 Fonts project is one project aimed at providing fonts to support a wide
2805 range of technical typesetting in a standardized way. The example below
2806 shows the use of a font that provides glyphs for many of the mathematical
2807 and technical symbol ranges within Unicode:</p>
2809 <pre>
2810 @font-face {
2811 font-family: STIXGeneral;
2812 src: local(STIXGeneral), url(/stixfonts/STIXGeneral.otf);
2813 unicode-range: U+000-49F, U+2000-27FF, U+2900-2BFF, U+1D400-1D7FF;
2814 }
2815 </pre>
2816 </div>
2818 <div class=example>
2819 <p>This example shows how an author can override the glyphs used for Latin
2820 characters in a Japanese font with glyphs from a different font. The
2821 first rule specifies no range so it defaults to the entire range. The
2822 range specified in the second rule overlaps but takes precedence because
2823 it is defined later.</p>
2825 <pre>
2826 @font-face {
2827 font-family: JapaneseWithGentium;
2828 src: local(MSMincho);
2829 /* no range specified, defaults to entire range */
2830 }
2832 @font-face {
2833 font-family: JapaneseWithGentium;
2834 src: url(../fonts/Gentium.woff);
2835 unicode-range: U+0-2FF;
2836 }
2837 </pre>
2838 </div>
2840 <div class=example>
2841 <p>Consider a family constructed to optimize bandwidth by separating out
2842 Latin, Japanese and other characters into different font files:</p>
2844 <pre>
2845 /* fallback font - size: 4.5MB */
2846 @font-face {
2847 font-family: DroidSans;
2848 src: url(DroidSansFallback.woff);
2849 /* no range specified, defaults to entire range */
2850 }
2852 /* Japanese glyphs - size: 1.2MB */
2853 @font-face {
2854 font-family: DroidSans;
2855 src: url(DroidSansJapanese.woff);
2856 unicode-range: U+3000-9FFF, U+ff??;
2857 }
2859 /* Latin, Greek, Cyrillic along with some
2860 punctuation and symbols - size: 190KB */
2861 @font-face {
2862 font-family: DroidSans;
2863 src: url(DroidSans.woff);
2864 unicode-range: U+000-5FF, U+1e00-1fff, U+2000-2300;
2865 }
2866 </pre>
2868 <p>For simple Latin text, only the font for Latin characters is
2869 downloaded:</p>
2871 <pre>
2872 body { font-family: DroidSans; }
2874 <p>This is that</p>
2875 </pre>
2877 <p>In this case the user agent first checks the unicode-range for the font
2878 containing Latin characters (DroidSans.woff). Since all the characters
2879 above are in the range U+0-5FF, the user agent downloads the font and
2880 renders the text with that font.</p>
2882 <p>Next, consider text that makes use of an arrow character (⇨):</p>
2884 <pre>
2885 <p>This &#x21e8; that<p>
2886 </pre>
2888 <p>The user agent again first checks the unicode-range of the font
2889 containing Latin characters. Since U+2000-2300 includes the arrow code
2890 point (U+21E8), the user agent downloads the font. For this character
2891 however the Latin font does not have a matching glyph, so the effective
2892 unicode-range used for font matching excludes this code point. Next, the
2893 user agent evaluates the Japanese font. The unicode-range for the
2894 Japanese font, U+3000-9FFF and U+ff??, does not include U+21E8, so the
2895 user agent does not download the Japanese font. Next the fallback font is
2896 considered. The <a href="#at-font-face-rule"><code>@font-face</code></a>
2897 rule for the fallback font does not define unicode-range so its value
2898 defaults to the range of all Unicode code points. The fallback font is
2899 downloaded and used to render the arrow character.</p>
2900 </div>
2902 <h3 id=font-rend-desc><span class=secno>4.7 </span>Font features: the <a
2903 href="#descdef-font-variant">font-variant</a> and <a
2904 href="#descdef-font-feature-settings">font-feature-settings</a>
2905 descriptors</h3>
2907 <table class=descdef>
2908 <tbody>
2909 <tr>
2910 <td>Name:
2912 <td><dfn id=descdef-font-variant
2913 title="font-variant!!descriptor">font-variant</dfn>
2915 <tr>
2916 <td>Value:
2918 <td><a href="#font-variant-normal-value"
2919 title="normal!!font-variant">normal</a> | <a
2920 href="#font-variant-none-value" title="none!!font-variant">none</a> | [
2921 <a href="#common-lig-values"><var><common-lig-values></var></a>
2922 || <a
2923 href="#discretionary-lig-values"><var><discretionary-lig-values></var></a>
2924 || <a
2925 href="#historical-lig-values"><var><historical-lig-values></var></a>
2926 || <a
2927 href="#contextual-alt-values"><var><contextual-alt-values></var></a>
2928 || <a href="#stylistic"><var
2929 title=stylistic>stylistic(<feature-value-name>)</var></a> || <a
2930 href="#historical-forms"><var>historical-forms</var></a> || <a
2931 href="#styleset"><var
2932 title=styleset>styleset(<feature-value-name> #)</var></a> || <a
2933 href="#character-variant"><var
2934 title=character-variant>character-variant(<feature-value-name>
2935 #)</var></a> || <a href="#swash"><var
2936 title=swash>swash(<feature-value-name>)</var></a> || <a
2937 href="#ornaments"><var
2938 title=ornaments>ornaments(<feature-value-name>)</var></a> || <a
2939 href="#annotation"><var
2940 title=annotation>annotation(<feature-value-name>)</var></a> || [
2941 <a href="#small-caps"><i>small-caps</i></a> | <a
2942 href="#all-small-caps"><i>all-small-caps</i></a> | <a
2943 href="#petite-caps"><i>petite-caps</i></a> | <a
2944 href="#all-petite-caps"><i>all-petite-caps</i></a> | <a
2945 href="#unicase"><i>unicase</i></a> | <a
2946 href="#titling-caps"><i>titling-caps</i></a> ] || <a
2947 href="#numeric-figure-values"><var><numeric-figure-values></var></a>
2948 || <a
2949 href="#numeric-spacing-values"><var><numeric-spacing-values></var></a>
2950 || <a
2951 href="#numeric-fraction-values"><var><numeric-fraction-values></var></a>
2952 || <a href="#ordinal"><i>ordinal</i></a> || <a
2953 href="#slashed-zero"><i>slashed-zero</i></a> || <a
2954 href="#east-asian-variant-values"><var><east-asian-variant-values></var></a>
2955 || <a
2956 href="#east-asian-width-values"><var><east-asian-width-values></var></a>
2957 || <a href="#ruby"><i>ruby</i></a> ]
2959 <tr>
2960 <td><em>Initial:</em>
2962 <td>normal
2963 </table>
2965 <table class=descdef>
2966 <tbody>
2967 <tr>
2968 <td>Name:
2970 <td><dfn id=descdef-font-feature-settings
2971 title="font-feature-settings!!descriptor">font-feature-settings</dfn>
2973 <tr>
2974 <td>Value:
2976 <td><a href="#font-feature-settings-normal-value"
2977 title="normal!!font-feature-settings">normal</a> | <a
2978 href="#feature-tag-value"><var><feature-tag-value></var></a> #
2980 <tr>
2981 <td><em>Initial:</em>
2983 <td>normal
2984 </table>
2986 <p>These descriptors define initial settings that apply when the font
2987 defined by an <a href="#at-font-face-rule"><code>@font-face</code></a>
2988 rule is rendered. They do not affect font selection. Values are identical
2989 to those defined for the corresponding <a href="#propdef-font-variant"
2990 title="font-variant!!property">‘<code
2991 class=property>font-variant</code>’</a> and <a
2992 href="#propdef-font-feature-settings"
2993 title="font-feature-settings!!property">‘<code
2994 class=property>font-feature-settings</code>’</a> properties defined
2995 below except that the value ‘<code class=property>inherit</code>’ is
2996 omitted. When multiple font feature descriptors or properties are used,
2997 the cumulative effect on text rendering is detailed in the section <a
2998 href="#font-feature-resolution">Font Feature Resolution</a> below. In
2999 cases where specific values define synthesized fallback for certain <a
3000 href="#propdef-font-variant" title="font-variant!!property">‘<code
3001 class=property>font-variant</code>’</a> subproperties, the same
3002 synthesized fallback applies when used within those values are used with
3003 the <a href="#descdef-font-style" title="font-style!!descriptor">‘<code
3004 class=property>font-variant</code>’</a> descriptor.
3006 <h3 id=font-face-loading><span class=secno>4.8 </span>Font loading
3007 guidelines</h3>
3009 <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule is
3010 designed to allow lazy loading of font resources that are only downloaded
3011 when used within a document. A stylesheet can include <a
3012 href="#at-font-face-rule"><code>@font-face</code></a> rules for a library
3013 of fonts of which only a select set are used; user agents must only
3014 download those fonts that are referred to within the style rules
3015 applicable to a given page. User agents that download all fonts defined in
3016 <a href="#at-font-face-rule"><code>@font-face</code></a> rules without
3017 considering whether those fonts are in fact used within a page are
3018 considered non-conformant. In cases where a font might be downloaded in
3019 character fallback cases, user agents may download a font if it's
3020 contained within the computed value of <a href="#propdef-font-family"
3021 title="font-family!!property">‘<code
3022 class=property>font-family</code>’</a> for a given text run.
3024 <pre>
3025 @font-face {
3026 font-family: GeometricModern;
3027 src: url(font.woff);
3028 }
3030 p {
3031 /* font will be downloaded for pages with p elements */
3032 font-family: GeometricModern, sans-serif;
3033 }
3035 h2 {
3036 /* font may be downloaded for pages with h2 elements, even if Futura is available locally */
3037 font-family: Futura, GeometricModern, sans-serif;
3038 }
3039 </pre>
3041 <p>In cases where textual content is loaded before downloadable fonts are
3042 available, user agents may render text as it would be rendered if
3043 downloadable font resources are not available or they may render text
3044 transparently with fallback fonts to avoid a flash of text using a
3045 fallback font. In cases where the font download fails user agents must
3046 display text, simply leaving transparent text is considered non-conformant
3047 behavior. Authors are advised to use fallback fonts in their font lists
3048 that closely match the metrics of the downloadable fonts to avoid large
3049 page reflows where possible.
3051 <p><a id=same-origin-restriction> </a><a
3052 id=allowing-cross-origin-font-loading> </a>
3054 <h3 id=font-fetching-requirements><span class=secno>4.9 </span>Font
3055 fetching requirements</h3>
3056 <!-- TPAC 2011 Resolution to require same-origin restriction for loading fonts:
3057 http://lists.w3.org/Archives/Public/www-style/2011Nov/0711.html
3058 http://www.w3.org/2011/10/31-webapps-minutes.html#item02
3059 -->
3061 <p>For font loads, user agents must use the <a
3062 href="http://www.w3.org/TR/html5/infrastructure.html#cors-enabled-fetch">potentially
3063 CORS-enabled fetch</a> method defined by the <a href="#HTML5"
3064 rel=biblioentry>[HTML5]<!--{{!HTML5}}--></a> specification for URL's
3065 defined within @font-face rules. When fetching, user agents must use
3066 "Anonymous" mode, set the referrer source to the stylesheet's URL and set
3067 the origin to the URL of the containing document.
3069 <p class=note>The implications of this for authors are that fonts will
3070 typically not be loaded cross-origin unless authors specifically takes
3071 steps to permit cross-origin loads. Sites can explicitly allow cross-site
3072 loading of font data using the <code>Access-Control-Allow-Origin</code>
3073 HTTP header. For other schemes, no explicit mechanism to allow
3074 cross-origin loading, beyond what is permitted by the <a
3075 href="http://www.w3.org/TR/html5/infrastructure.html#cors-enabled-fetch">potentially
3076 CORS-enabled fetch</a> method, is defined or required.
3078 <div class=example> For the examples given below, assume that a document is
3079 located at <code>http://example.com/page.html</code> and all URL's link to
3080 valid font resources supported by the user agent. Fonts defined with the
3081 ‘<a href="#descdef-src"><code class=property>src</code></a>’
3082 descriptor values below will be loaded:
3083 <pre>/* same origin (i.e. domain, scheme, port match document) */
3084 src: url(fonts/simple.woff);
3086 /* data url's with no redirects are treated as same origin */
3087 src: url("data:application/font-woff;base64,...");
3089 /* cross origin, different domain */
3090 /* Access-Control-Allow-Origin response header set to '*' */
3091 src: url(http://another.example.com/fonts/simple.woff);
3092 </pre>
3093 Fonts defined with the ‘<a href="#descdef-src"><code
3094 class=property>src</code></a>’ descriptor values below will fail to
3095 load:
3096 <pre>/* cross origin, different scheme */
3097 /* no Access-Control-xxx headers in response */
3098 src: url(https://example.com/fonts/simple.woff);
3100 /* cross origin, different domain */
3101 /* no Access-Control-xxx headers in response */
3102 src: url(http://another.example.com/fonts/simple.woff);
3103 </pre>
3104 </div>
3106 <h2 id=font-matching-algorithm><span class=secno>5 </span>Font Matching
3107 Algorithm</h2>
3109 <p>The algorithm below describes how fonts are associated with individual
3110 runs of text. For each character in the run a font family is chosen and a
3111 particular font face is selected containing a glyph for that character.
3113 <h3 id=font-family-casing><span class=secno>5.1 </span>Case sensitivity of
3114 font family names</h3>
3116 <p>As part of the font matching algorithm outlined below, user agents must
3117 match font family names used in style rules with actual font family names
3118 contained in fonts available in a given environment or with font family
3119 names defined in <a href="#at-font-face-rule"><code>@font-face</code></a>
3120 rules. User agents must match these names case insensitively, using the
3121 "Default Caseless Matching" algorithm outlined in the Unicode
3122 specification <a href="#UNICODE"
3123 rel=biblioentry>[UNICODE]<!--{{!UNICODE}}--></a>. This algorithm is
3124 detailed in section 3.13 entitled "Default Case Algorithms". Specifically,
3125 the algorithm must be applied without normalizing the strings involved and
3126 without applying any language-specific tailorings. The case folding method
3127 specified by this algorithm uses the case mappings with status field
3128 ‘<code class=property>C</code>’ or ‘<code class=property>F</code>’
3129 in the CaseFolding.txt file of the Unicode Character Database.
3131 <p class=note> For authors this means that font family names are matched
3132 case insensitively, whether those names exist in a platform font or in the
3133 <a href="#at-font-face-rule"><code>@font-face</code></a> rules contained
3134 in a stylesheet. Authors should take care to ensure that names use a
3135 character sequence consistent with the actual font family name,
3136 particularly when using combining characters such as diacritical marks.
3137 For example, a family name that contains an uppercase A (U+0041) followed
3138 by a combining ring (U+030A) will <strong>not</strong> match a name that
3139 looks identical but which uses the precomposed lowercase a-ring character
3140 (U+00E5) instead of the combining sequence.
3142 <p class=note> Implementors should take care to verify that a given
3143 caseless string comparison implementation uses this precise algorithm and
3144 not assume that a given platform string matching routine follows it, as
3145 many of these have locale-specific behavior or use some level of string
3146 normalization.
3148 <h3 id=font-style-matching><span class=secno>5.2 </span>Matching font
3149 styles</h3>
3151 <p>The procedure for choosing a font for a given character in a run of text
3152 consists of iterating over the font families named by the <a
3153 href="#propdef-font-family" title="font-family!!property">‘<code
3154 class=property>font-family</code>’</a> property, selecting a font face
3155 with the appropriate style based on other font properties and then
3156 determining whether a glyph exists for the given character. This is done
3157 using the <dfn id=character-map>character map</dfn> of the font, data
3158 which maps characters to the default glyph for that character. A font is
3159 considered to <dfn id=support>support</dfn> a given character if (1) the
3160 character is contained in the font's <a
3161 href="#character-map"><em>character map</em></a> and (2) if required by
3162 the containing script, shaping information is available for that
3163 character.
3165 <p>Some legacy fonts may include a given character in the <a
3166 href="#character-map"><em>character map</em></a> but lack the shaping
3167 information (e.g. <a
3168 href="http://www.microsoft.com/typography/otspec/ttochap1.htm">OpenType
3169 layout tables</a> or <a
3170 href="http://scripts.sil.org/cms/scripts/page.php?site_id=projects&item_id=graphite_techAbout">Graphite
3171 tables</a>) necessary for correctly rendering text runs containing that
3172 character.
3174 <p>Codepoint sequences consisting of a base character followed by a
3175 sequence of combining characters are treated slightly differently, see the
3176 section on <a href="#cluster-matching">cluster matching</a> below.
3178 <p>For this procedure, the <dfn id=default-face>default face</dfn> for a
3179 given font family is defined to be the face that would be selected if all
3180 font style properties were set to their initial value.
3182 <ol id=fontmatchingalg>
3183 <li>Using the computed font property values for a given element, the user
3184 agent starts with the first family name specified by the <a
3185 href="#propdef-font-family" title="font-family!!property">‘<code
3186 class=property>font-family</code>’</a> property.
3188 <li>If the family name is a generic family keyword, the user agent looks
3189 up the appropriate font family name to be used. User agents may choose
3190 the generic font family to use based on the language of the containing
3191 element or the Unicode range of the character.
3193 <li>For other family names, the user agent attempts to find the family
3194 name among fonts defined via <a
3195 href="#at-font-face-rule"><code>@font-face</code></a> rules and then
3196 among available system fonts, matching names with a <a
3197 href="#font-family-casing">case-insensitive comparison</a> as outlined in
3198 the section above. On systems containing fonts with multiple localized
3199 font family names, user agents must match any of these names independent
3200 of the underlying system locale or platform API used. If the font
3201 resources defined for a given face in an <a
3202 href="#at-font-face-rule"><code>@font-face</code></a> rule are either not
3203 available or contain invalid font data, then the face should be treated
3204 as not present in the family. If no faces are present for a family
3205 defined via <a href="#at-font-face-rule"><code>@font-face</code></a>
3206 rules, the family should be treated as missing; matching a platform font
3207 with the same name must not occur in this case.
3209 <li>If a font family match occurs, the user agent assembles the set of
3210 font faces in that family and then narrows the set to a single face using
3211 other font properties in the order given below. A group of faces defined
3212 via <a href="#at-font-face-rule"><code>@font-face</code></a> rules with
3213 identical font descriptor values but differing ‘<a
3214 href="#descdef-unicode-range"><code
3215 class=property>unicode-range</code></a>’ values are considered to be a
3216 single <dfn id=composite-face>composite face</dfn> for this step:
3217 <ol id=fontstylematchingalg>
3218 <li><a href="#propdef-font-stretch"
3219 title="font-stretch!!property">‘<code
3220 class=property>font-stretch</code>’</a> is tried first. If the
3221 matching set contains faces with width values matching the <a
3222 href="#propdef-font-stretch" title="font-stretch!!property">‘<code
3223 class=property>font-stretch</code>’</a> value, faces with other width
3224 values are removed from the matching set. If there is no face that
3225 exactly matches the width value the nearest width is used instead. If
3226 the value of <a href="#propdef-font-stretch"
3227 title="font-stretch!!property">‘<code
3228 class=property>font-stretch</code>’</a> is <a
3229 href="#font-stretch-normal-value" title="normal!!font-stretch">‘<code
3230 class=property>normal</code>’</a> or one of the condensed values,
3231 narrower width values are checked first, then wider values. If the
3232 value of <a href="#propdef-font-stretch"
3233 title="font-stretch!!property">‘<code
3234 class=property>font-stretch</code>’</a> is one of the expanded
3235 values, wider values are checked first, followed by narrower values.
3236 Once the closest matching width has been determined by this process,
3237 faces with other widths are removed from the matching set.
3239 <li><a href="#propdef-font-style" title="font-style!!property">‘<code
3240 class=property>font-style</code>’</a> is tried next. If the value of
3241 <a href="#propdef-font-style" title="font-style!!property">‘<code
3242 class=property>font-style</code>’</a> is ‘<a href="#italic"><code
3243 class=property>italic</code></a>’, italic faces are checked first,
3244 then oblique, then normal faces. If the value is ‘<a
3245 href="#oblique"><code class=property>oblique</code></a>’, oblique
3246 faces are checked first, then italic faces and then normal faces. If
3247 the value is <a href="#font-style-normal-value"
3248 title="normal!!font-style">‘<code
3249 class=property>normal</code>’</a>, normal faces are checked first,
3250 then oblique faces, then italic faces. Faces with other style values
3251 are excluded from the matching set. User agents are permitted to
3252 distinguish between italic and oblique faces within platform font
3253 families but this is not required, so all italic or oblique faces may
3254 be treated as italic faces. However, within font families defined via
3255 <a href="#at-font-face-rule"><code>@font-face</code></a> rules, italic
3256 and oblique faces must be distinguished using the value of the <a
3257 href="#descdef-font-style" title="font-style!!descriptor">‘<code
3258 class=property>font-style</code>’</a> descriptor. For families that
3259 lack any italic or oblique faces, users agents may create artificial
3260 oblique faces, if this is permitted by the value of the ‘<a
3261 href="#propdef-font-synthesis"><code
3262 class=property>font-synthesis</code></a>’ property.
3264 <li><a href="#propdef-font-weight"
3265 title="font-weight!!property">‘<code
3266 class=property>font-weight</code>’</a> is matched next, so it will
3267 always reduce the matching set to a single font face. If bolder/lighter
3268 relative weights are used, the effective weight is calculated based on
3269 the inherited weight value, as described in the definition of the <a
3270 href="#propdef-font-weight" title="font-weight!!property">‘<code
3271 class=property>font-weight</code>’</a> property. Given the desired
3272 weight and the weights of faces in the matching set after the steps
3273 above, if the desired weight is available that face matches. Otherwise,
3274 a weight is chosen using the rules below:
3275 <ul>
3276 <li>If the desired weight is less than 400, weights below the desired
3277 weight are checked in descending order followed by weights above the
3278 desired weight in ascending order until a match is found.
3280 <li>If the desired weight is greater than 500, weights above the
3281 desired weight are checked in ascending order followed by weights
3282 below the desired weight in descending order until a match is found.
3284 <li>If the desired weight is 400, 500 is checked first and then the
3285 rule for desired weights less than 400 is used.
3287 <li>If the desired weight is 500, 400 is checked first and then the
3288 rule for desired weights less than 400 is used.
3289 </ul>
3291 <li><span class=property>‘<a href="#propdef-font-size"><code
3292 class=property>font-size</code></a>’</span> must be matched within a
3293 UA-dependent margin of tolerance. (Typically, sizes for scalable fonts
3294 are rounded to the nearest whole pixel, while the tolerance for
3295 bitmapped fonts could be as large as 20%.) Further computations, e.g.,
3296 by ‘<code class=property>em</code>’ values in other properties, are
3297 based on the <span class=property>‘<a href="#propdef-font-size"><code
3298 class=property>font-size</code></a>’</span> value that is used, not
3299 the one that is specified.
3300 </ol>
3302 <li>
3303 <p>If the matched face is defined via <a
3304 href="#at-font-face-rule"><code>@font-face</code></a> rules, user agents
3305 must use the procedure below to select a single font:
3307 <ol>
3308 <li>If the font resource has not been loaded and the range of characters
3309 defined by the ‘<a href="#descdef-unicode-range"><code
3310 class=property>unicode-range</code></a>’ descriptor value includes
3311 the character in question, load the font.
3313 <li>After downloading, if the <a
3314 href="#effective-character-map"><em>effective character map</em></a>
3315 supports the character in question, select that font.
3316 </ol>
3318 <p>When the matched face is a <a href="#composite-face"><em>composite
3319 face</em></a>, user agents must use the procedure above on each of the
3320 faces in the <a href="#composite-face"><em>composite face</em></a> in
3321 reverse order of <a
3322 href="#at-font-face-rule"><code>@font-face</code></a> rule definition.</p>
3324 <p>While the download occurs, user agents may either wait until the font
3325 is downloaded or render once with substituted font metrics and render
3326 again once the font is downloaded.</p>
3328 <li>
3329 <p>If no matching face exists or the matched face does not contain a
3330 glyph for the character to be rendered, the next family name is selected
3331 and the previous three steps repeated. Glyphs from other faces in the
3332 family are not considered. The only exception is that user agents may
3333 optionally substitute a synthetically obliqued version of the <a
3334 href="#default-face"><em>default face</em></a> if that face supports a
3335 given glyph and synthesis of these faces is permitted by the value of
3336 the ‘<a href="#propdef-font-synthesis"><code
3337 class=property>font-synthesis</code></a>’ property. For example, a
3338 synthetic italic version of the regular face may be used if the italic
3339 face doesn't support glyphs for Arabic.</p>
3340 <!-- resolution on the above: http://lists.w3.org/Archives/Public/www-style/2012Nov/0292.html -->
3343 <li>If there are no more font families to be evaluated and no matching
3344 face has been found, then the user agent performs a <dfn
3345 id=system-font-fallback>system font fallback</dfn> procedure to find the
3346 best match for the character to be rendered. The result of this procedure
3347 may vary across user agents.
3349 <li>If a particular character cannot be displayed using any font, the user
3350 agent should indicate by some means that a character is not being
3351 displayed, displaying either a symbolic representation of the missing
3352 glyph (e.g. using a <a
3353 href="http://en.wikipedia.org/wiki/Last_resort_font">Last Resort
3354 Font</a>) or using the missing character glyph from a default font.
3355 </ol>
3357 <p>Optimizations of this process are allowed provided that an
3358 implementation behaves as if the algorithm had been followed exactly.
3359 Matching occurs in a well-defined order to ensure that the results are as
3360 consistent as possible across user agents, given an identical set of
3361 available fonts and rendering technology.
3363 <p>The <dfn id=first-available-font>first available font</dfn>, used in the
3364 definition of <a
3365 href="http://www.w3.org/TR/css3-values/#font-relative-lengths"><em>font-relative
3366 lengths</em></a> such as ‘<code class=property>ex</code>’ and ‘<code
3367 class=property>ch</code>’, is defined to be the first available font
3368 that would match any character given font families in the ‘<code
3369 class=property>font-family</code>’ list (or a user agent's default font
3370 if none are available).
3372 <h3 id=cluster-matching><span class=secno>5.3 </span>Cluster matching</h3>
3374 <p>When text contains characters such as combining marks, ideally the base
3375 character should be rendered using the same font as the mark, this assures
3376 proper placement of the mark. For this reason, the font matching algorithm
3377 for clusters is more specialized than the general case of matching a
3378 single character by itself. For sequences containing variation selectors,
3379 which indicate the precise glyph to be used for a given character, user
3380 agents always attempt <a href="#system-font-fallback"><em>system font
3381 fallback</em></a> to find the appropriate glyph before using the default
3382 glyph of the base character.
3384 <p>A sequence of codepoints containing combining mark or other modifiers is
3385 termed a grapheme cluster (see <a href="#CSS3TEXT"
3386 rel=biblioentry>[CSS3TEXT]<!--{{CSS3TEXT}}--></a> for a more complete
3387 description). For a given cluster containing a base character, <em>b</em>
3388 and a sequence of combining characters <em>c1, c2…</em>, the entire
3389 cluster is matched using these steps:
3391 <ol>
3392 <li>For each family in the font list, a face is chosen using the style
3393 selection rules defined in the previous section.
3394 <ol>
3395 <li>If all characters in the sequence <em>b + c1 + c2 …</em> are
3396 completely supported by the font, select this font for the sequence.
3398 <li>If a sequence of multiple codepoints is canonically equivalent to a
3399 single character and the font <a href="#support"><em
3400 title=support>supports</em></a> that character, select this font for
3401 the sequence and use the glyph associated with the canonically
3402 equiavlent character for the entire cluster.
3403 </ol>
3405 <li>If no font was found in the font list in step 1:
3406 <ol>
3407 <li>If <em>c1</em> is a variation selector, system fallback must be used
3408 to find a font that <a href="#support"><em
3409 title=support>supports</em></a> the full sequence of <em>b + c1</em>.
3410 If no font on the system <a href="#support"><em
3411 title=support>supports</em></a> the full sequence, match the single
3412 character <em>b</em> using the normal procedure for matching single
3413 characters and ignore the variation selector. Note: a sequence with
3414 more than one variation selector must be treated as an encoding error
3415 and the trailing selectors must be ignored. <a href="#UNICODE"
3416 rel=biblioentry>[UNICODE]<!--{{!UNICODE}}--></a>
3418 <li>Otherwise, the user agent may optionally use system font fallback to
3419 match a font that <a href="#support"><em
3420 title=support>supports</em></a> the entire cluster.
3421 </ol>
3423 <li>If no font is found in step 2, use the matching sequence from step 1
3424 to determine the longest sequence that is completely <a
3425 href="#support"><em title=support>supported</em></a> by a font in the
3426 font list and attempt to match the remaining combining characters
3427 separately using the rules for single characters.
3428 </ol>
3430 <h3 id=char-handling-issues><span class=secno>5.4 </span>Character handling
3431 issues</h3>
3433 <p>CSS font matching is always performed on text runs containing Unicode
3434 characters, so documents using legacy encodings are assumed to have been
3435 transcoded before matching fonts. For fonts containing <a
3436 href="#character-map"><em title="character map">character maps</em></a>
3437 for both legacy encodings and Unicode, the contents of the legacy encoding
3438 <a href="#character-map"><em>character map</em></a> must have no effect on
3439 the results of the font matching process.
3441 <p>The font matching process does not assume that text runs are in either
3442 normalized or denormalized form (see <a href="#CHARMOD-NORM"
3443 rel=biblioentry>[CHARMOD-NORM]<!--{{CHARMOD-NORM}}--></a> for more
3444 details). Fonts may only support precomposed forms and not the decomposed
3445 sequence of base character plus combining marks. Authors should always
3446 tailor their choice of fonts to their content, including whether that
3447 content contains normalized or denormalized character streams.
3449 <p>If a given character is a Private-Use Area Unicode codepoint, user
3450 agents must only match font families named in the ‘<code
3451 class=property>font-family</code>’ list that are not generic families.
3452 If none of the families named in the ‘<code
3453 class=property>font-family</code>’ list contain a glyph for that
3454 codepoint, user agents must display some form of missing glyph symbol for
3455 that character rather than attempting <a
3456 href="#system-font-fallback"><em>system font fallback</em></a> for that
3457 codepoint. When matching the replacement character U+FFFD, user agents may
3458 skip the font matching process and immediately display some form of
3459 missing glyph symbol, they are not required to display the glyph from the
3460 font that would be selected by the font matching process.
3462 <p>In general, the fonts for a given family will all have the same or
3463 similar <a href="#character-map"><em title="character map">character
3464 maps</em></a>. The process outlined here is designed to handle even font
3465 families containing faces with widely variant <a href="#character-map"><em
3466 title="character map">character maps</em></a>. However, authors are
3467 cautioned that the use of such families can lead to unexpected results.
3469 <h3 id=font-matching-changes><span class=secno>5.5 </span>Font matching
3470 changes since CSS 2.1</h3>
3472 <p>The algorithm above is different from CSS 2.1 in a number of key places.
3473 These changes were made to better reflect actual font matching behavior
3474 across user agent implementations.
3476 <p>Differences compared to the font matching algorithm in CSS 2.1:
3478 <ul>
3479 <li>The algorithm includes font-stretch matching.
3481 <li>All possible font-style matching scenarios are delineated.
3483 <li>Small-caps fonts are not matched as part of the font matching process,
3484 they are now handled via font features.
3486 <li>Unicode variation selector matching is required.
3488 <li>Cluster sequences are matched as a unit.
3489 </ul>
3491 <h3 id=font-matching-examples><span class=secno>5.6 </span>Font matching
3492 examples</h3>
3494 <div class=example>
3495 <p>It's useful to note that the CSS selector syntax may be used to create
3496 language-sensitive typography. For example, some Chinese and Japanese
3497 characters are unified to have the same Unicode code point, although the
3498 abstract glyphs are not the same in the two languages.
3500 <pre>*:lang(ja) { font: 900 14pt/16pt "Heisei Mincho W9", serif; }
3501 *:lang(zh-Hant-TW) { font: 800 14pt/16.5pt "Li Sung", serif; }
3502 </pre>
3504 <p>This selects any element that has the given language — Japanese or
3505 Traditional Chinese as used in Taiwan — and uses the appropriate font.
3507 </div>
3509 <h2 id=font-rend-props><span class=secno>6 </span>Font Feature Properties</h2>
3511 <p>Modern font technologies support a variety of advanced typographic and
3512 language-specific font features. Using these features, a single font can
3513 provide glyphs for a wide range of ligatures, contextual and stylistic
3514 alternates, tabular and old-style figures, small capitals, automatic
3515 fractions, swashes, and alternates specific to a given language. To allow
3516 authors control over these font capabilities, the ‘<code
3517 class=property>font-variant</code>’ property has been expanded for CSS3.
3518 It now functions as a shorthand for a set of properties that provide
3519 control over stylistic font features.
3521 <h3 id=glyph-selection-positioning><span class=secno>6.1 </span>Glyph
3522 selection and positioning</h3>
3524 <p>Simple fonts used for displaying Latin text use a very basic processing
3525 model. Fonts contain a <a href="#character-map"><em>character map</em></a>
3526 which maps each character to a glyph for that character. Glyphs for
3527 subsequent characters are simply placed one after the other along a run of
3528 text. Modern font formats such as OpenType and AAT (Apple Advanced
3529 Typography) use a richer processing model. The glyph for a given character
3530 can be chosen and positioned not just based on the codepoint of the
3531 character itself, but also on adjacent characters as well as the language,
3532 script, and features enabled for the text. Font features may be required
3533 for specific scripts, or recommended as enabled by default or they might
3534 be stylistic features meant to be used under author control.
3536 <p>For a good visual overview of these features, see the <a
3537 href="#OPENTYPE-FONT-GUIDE"
3538 rel=biblioentry>[OPENTYPE-FONT-GUIDE]<!--{{OPENTYPE-FONT-GUIDE}}--></a>.
3539 For a detailed description of glyph processing for OpenType fonts, see <a
3540 href="#WINDOWS-GLYPH-PROC"
3541 rel=biblioentry>[WINDOWS-GLYPH-PROC]<!--{{WINDOWS-GLYPH-PROC}}--></a>.
3543 <p>Stylistic font features can be classified into two broad categories:
3544 ones that affect the harmonization of glyph shapes with the surrounding
3545 context, such as kerning and ligature features, and ones such as the
3546 small-caps, subscript/superscript and alternate features that affect shape
3547 selection.
3549 <p>The subproperties of <a href="#propdef-font-variant"
3550 title="font-variant!!property">‘<code
3551 class=property>font-variant</code>’</a> listed below are used to control
3552 these stylistic font features. They do not control features that are
3553 required for displaying certain scripts, such as the OpenType features
3554 used when displaying Arabic or Indic language text. They affect glyph
3555 selection and positioning, but do not affect font selection as described
3556 in the font matching section (except in cases required for compatibility
3557 with CSS 2.1).
3559 <p>To assure consistent behavior across user agents, the equivalent
3560 OpenType property settings are listed for individual properties and are
3561 normative. When using other font formats these should be used as a
3562 guideline to map CSS font feature property values to specific font
3563 features.
3565 <h3 id=language-specific-support><span class=secno>6.2
3566 </span>Language-specific display</h3>
3568 <p>OpenType also supports language-specific glyph selection and
3569 positioning, so that text can be displayed correctly in cases where the
3570 language dictates a specific display behavior. Many languages share a
3571 common script, but the shape of certain letters can vary across those
3572 languages. For example, certain Cyrillic letters have different shapes in
3573 Russian text than in Bulgarian. In Latin text, it's common to render "fi"
3574 with an explicit fi-ligature that lacks a dot on the "i". However, in
3575 languages such as Turkish which uses both a dotted-i and a dotless-i, it's
3576 important to not use this ligature or use a specialized version that
3577 contains a dot over the "i". The example below shows language-specific
3578 variations based on stylistic traditions found in Spanish, Italian and
3579 French orthography:
3581 <div class=featex><img alt="language specific forms, spanish"
3582 src=locl-1.png></div>
3584 <div class=featex><img alt="language specific forms, italian"
3585 src=locl-2.png></div>
3587 <div class=featex><img alt="language specific forms, french"
3588 src=locl-3.png></div>
3590 <p>If the content language of the element is known according to the rules
3591 of the <a
3592 href="http://www.w3.org/TR/CSS21/conform.html#doclanguage">document
3593 language</a>, user agents are required to infer the OpenType language
3594 system from the content language and use that when selecting and
3595 positioning glyphs using an OpenType font.
3597 <p>For OpenType fonts, in some cases it may be necessary to explicitly
3598 declare the OpenType language to be used, for example when displaying text
3599 in a given language that uses the typographic conventions of another
3600 language or when the font does not explicitly support a given language but
3601 supports a language that shares common typographic conventions. The ‘<a
3602 href="#propdef-font-language-override"><code
3603 class=property>font-language-override</code></a>’ property is used for
3604 this purpose.</p>
3605 <!-- prop: font-kerning -->
3607 <h3 id=font-kerning-prop><span class=secno>6.3 </span>Kerning: the <a
3608 href="#propdef-font-kerning">font-kerning</a> property</h3>
3610 <table class=propdef id=namefont-kerningvalueauto-normal-noneini>
3611 <tbody>
3612 <tr>
3613 <td>Name:
3615 <td><dfn id=propdef-font-kerning>font-kerning</dfn>
3617 <tr>
3618 <td>Value:
3620 <td><a href="#font-kerning-auto-value"
3621 title="auto!!font-kerning">auto</a> | <a
3622 href="#font-kerning-normal-value"
3623 title="normal!!font-kerning">normal</a> | <a
3624 href="#font-kerning-none-value" title="none!!font-kerning">none</a>
3626 <tr>
3627 <td>Initial:
3629 <td>auto
3631 <tr>
3632 <td>Applies to:
3634 <td>all elements
3636 <tr>
3637 <td>Inherited:
3639 <td>yes
3641 <tr>
3642 <td>Percentages:
3644 <td>N/A
3646 <tr>
3647 <td>Media:
3649 <td>visual
3651 <tr>
3652 <td>Computed value:
3654 <td>as specified
3656 <tr>
3657 <td>Animatable:
3659 <td>no
3660 </table>
3662 <p>Kerning is the contextual adjustment of inter-glyph spacing. This
3663 property controls metric kerning, kerning that utilizes adjustment data
3664 contained in the font.
3666 <dl>
3667 <dt><dfn id=font-kerning-auto-value title="auto!!font-kerning">auto</dfn>
3669 <dd>Specifies that kerning is applied at the discretion of the user agent
3671 <dt><dfn id=font-kerning-normal-value
3672 title="normal!!font-kerning">normal</dfn>
3674 <dd>Specifies that kerning is applied
3676 <dt><dfn id=font-kerning-none-value title="none!!font-kerning">none</dfn>
3678 <dd>Specifies that kerning is not applied
3679 </dl>
3681 <p>For fonts that do not include kerning data this property will have no
3682 visible effect. When rendering with OpenType fonts, the <a
3683 href="#OPENTYPE" rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a>
3684 specification suggests that kerning be enabled by default. When kerning is
3685 enabled, the OpenType <span class=tag>kern</span> feature is enabled (for
3686 vertical text runs the <span class=tag>vkrn</span> feature is enabled
3687 instead). User agents must also support fonts that only support kerning
3688 via data contained in a <span class=tag>kern</span> font table, as
3689 detailed in the OpenType specification. If the ‘<code
3690 class=property>letter-spacing</code>’ property is defined, kerning
3691 adjustments are considered part of the default spacing and letter spacing
3692 adjustments are made after kerning has been applied.
3694 <p>When set to ‘<code class=property>auto</code>’, user agents can
3695 determine whether to apply kerning or not based on a number of factors:
3696 text size, script, or other factors that influence text processing speed.
3697 Authors who want proper kerning should use <a
3698 href="#font-kerning-normal-value" title="normal!!font-kerning">‘<code
3699 class=property>normal</code>’</a> to explicitly enable kerning.
3700 Likewise, some authors may prefer to disable kerning in situations where
3701 performance is more important than precise appearance. However, in
3702 well-designed modern implementations the use of kerning generally does not
3703 have a large impact on text rendering speed.</p>
3704 <!-- prop: font-variant-ligatures -->
3706 <h3 id=font-variant-ligatures-prop><span class=secno>6.4 </span>Ligatures:
3707 the <a href="#propdef-font-variant-ligatures">font-variant-ligatures</a>
3708 property</h3>
3710 <table class=propdef id=namefont-variant-ligaturesvaluenormal-no>
3711 <tbody>
3712 <tr>
3713 <td>Name:
3715 <td><dfn id=propdef-font-variant-ligatures>font-variant-ligatures</dfn>
3717 <tr>
3718 <td>Value:
3720 <td><a href="#font-variant-ligatures-normal-value"
3721 title="normal!!font-variant-ligatures">normal</a> | <a
3722 href="#font-variant-ligatures-none-value"
3723 title="none!!font-variant-ligatures">none</a> | [ <a
3724 href="#common-lig-values"><var><common-lig-values></var></a> ||
3725 <a
3726 href="#discretionary-lig-values"><var><discretionary-lig-values></var></a>
3727 || <a
3728 href="#historical-lig-values"><var><historical-lig-values></var></a>
3729 || <a
3730 href="#contextual-alt-values"><var><contextual-alt-values></var></a>
3731 ]
3733 <tr>
3734 <td>Initial:
3736 <td>normal
3738 <tr>
3739 <td>Applies to:
3741 <td>all elements
3743 <tr>
3744 <td>Inherited:
3746 <td>yes
3748 <tr>
3749 <td>Percentages:
3751 <td>N/A
3753 <tr>
3754 <td>Media:
3756 <td>visual
3758 <tr>
3759 <td>Computed value:
3761 <td>as specified
3763 <tr>
3764 <td>Animatable:
3766 <td>no
3767 </table>
3769 <p>Ligatures and contextual forms are ways of combining glyphs to produce
3770 more harmonized forms.
3772 <pre
3773 class=prod><dfn id=common-lig-values><var><common-lig-values></var></dfn> = [ <a href="#common-ligatures">common-ligatures</a> | <a href="#no-common-ligatures">no-common-ligatures</a> ]</pre>
3775 <pre
3776 class=prod><dfn id=discretionary-lig-values><var><discretionary-lig-values></var></dfn> = [ <a href="#discretionary-ligatures">discretionary-ligatures</a> | <a href="#no-discretionary-ligatures">no-discretionary-ligatures</a> ]</pre>
3778 <pre
3779 class=prod><dfn id=historical-lig-values><var><historical-lig-values></var></dfn> = [ <a href="#historical-ligatures">historical-ligatures</a> | <a href="#no-historical-ligatures">no-historical-ligatures</a> ]</pre>
3781 <pre
3782 class=prod><dfn id=contextual-alt-values><var><contextual-alt-values></var></dfn> = [ <a href="#contextual">contextual</a> | <a href="#no-contextual">no-contextual</a> ]</pre>
3784 <p>Individual values have the following meanings:
3786 <dl>
3787 <dt><dfn id=font-variant-ligatures-normal-value
3788 title="normal!!font-variant-ligatures">normal</dfn>
3790 <dd>A value of <a href="#font-variant-ligatures-normal-value"
3791 title="normal!!font-variant-ligatures">‘<code
3792 class=property>normal</code>’</a> specifies that common default
3793 features are enabled, <a href="#font-feature-resolution">as described in
3794 detail in the next section</a>. For OpenType fonts, common ligatures and
3795 contextual forms are on by default, discretionary and historical
3796 ligatures are not.
3798 <dt><dfn id=font-variant-ligatures-none-value
3799 title="none!!font-variant-ligatures">none</dfn>
3801 <dd>Specifies that all types of ligatures and contextual forms covered by
3802 this property are explicitly disabled. In situations where ligatures are
3803 not considered necessary, this may improve the speed of text rendering.
3805 <dt><dfn id=common-ligatures>common-ligatures</dfn>
3807 <dd>Enables display of common ligatures (OpenType features: <span
3808 class=tag>liga, clig</span>). For OpenType fonts, common ligatures are
3809 enabled by default.
3810 </dl>
3812 <div class=featex><img alt="common ligature example" src=liga.png></div>
3814 <dl>
3815 <dt><dfn id=no-common-ligatures>no-common-ligatures</dfn>
3817 <dd>Disables display of common ligatures (OpenType features: <span
3818 class=tag>liga, clig</span>).
3820 <dt><dfn id=discretionary-ligatures>discretionary-ligatures</dfn>
3822 <dd>Enables display of discretionary ligatures (OpenType feature: <span
3823 class=tag>dlig</span>). Which ligatures are discretionary or optional is
3824 decided by the type designer, so authors will need to refer to the
3825 documentation of a given font to understand which ligatures are
3826 considered discretionary.
3827 </dl>
3829 <div class=featex><img alt="discretionary ligature example" src=dlig.png></div>
3831 <dl>
3832 <dt><dfn id=no-discretionary-ligatures>no-discretionary-ligatures</dfn>
3834 <dd>Disables display of discretionary ligatures (OpenType feature: <span
3835 class=tag>dlig</span>).
3837 <dt><dfn id=historical-ligatures>historical-ligatures</dfn>
3839 <dd>Enables display of historical ligatures (OpenType feature: <span
3840 class=tag>hlig</span>).
3841 </dl>
3843 <div class=featex><img alt="historical ligature example" src=hlig.png></div>
3845 <dl>
3846 <dt><dfn id=no-historical-ligatures>no-historical-ligatures</dfn>
3848 <dd>Disables display of historical ligatures (OpenType feature: <span
3849 class=tag>hlig</span>).
3851 <dt><dfn id=contextual>contextual</dfn>
3853 <dd>Enables display of contextual alternates (OpenType feature: <span
3854 class=tag>calt</span>). Although not strictly a ligature feature, like
3855 ligatures this feature is commonly used to harmonize the shapes of glyphs
3856 with the surrounding context. For OpenType fonts, this feature is on by
3857 default.
3858 </dl>
3860 <div class=featex><img alt="contextual alternate example" src=calt.png></div>
3862 <dl>
3863 <dt><dfn id=no-contextual>no-contextual</dfn>
3865 <dd>Disables display of contextual alternates (OpenType feature: <span
3866 class=tag>calt</span>).
3867 </dl>
3869 <p>Required ligatures, needed for correctly rendering complex scripts, are
3870 not affected by the settings above, including ‘<code
3871 class=property>none</code>’ (OpenType feature: <span
3872 class=tag>rlig</span>).</p>
3873 <!-- prop: font-variant-position -->
3875 <h3 id=font-variant-position-prop><span class=secno>6.5 </span>Subscript
3876 and superscript forms: the <a
3877 href="#propdef-font-variant-position">font-variant-position</a> property</h3>
3879 <table class=propdef id=namefont-variant-positionvaluenormal-sub>
3880 <tbody>
3881 <tr>
3882 <td>Name:
3884 <td><dfn id=propdef-font-variant-position>font-variant-position</dfn>
3886 <tr>
3887 <td>Value:
3889 <td><a href="#font-variant-position-normal-value"
3890 title="normal!!font-variant-position">normal</a> | <a
3891 href="#sub">sub</a> | <a href="#super">super</a>
3893 <tr>
3894 <td>Initial:
3896 <td>normal
3898 <tr>
3899 <td>Applies to:
3901 <td>all elements
3903 <tr>
3904 <td>Inherited:
3906 <td>yes
3908 <tr>
3909 <td>Percentages:
3911 <td>N/A
3913 <tr>
3914 <td>Media:
3916 <td>visual
3918 <tr>
3919 <td>Computed value:
3921 <td>as specified
3923 <tr>
3924 <td>Animatable:
3926 <td>no
3927 </table>
3929 <p>This property is used to enable typographic subscript and superscript
3930 glyphs. These are alternate glyphs designed within the same em-box as
3931 default glyphs and are intended to be laid out on the same baseline as the
3932 default glyphs, with no resizing or repositioning of the baseline. They
3933 are explicitly designed to match the surrounding text and to be more
3934 readable without affecting the line height.
3936 <div class=figure><img alt="comparison between real subscript glyphs and
3937 synthesized ones" src=realsubscripts.png>
3938 <p class=caption>Subscript glyphs (top) vs. typical synthesized subscripts
3939 (bottom)
3940 </div>
3942 <p>Individual values have the following meanings:
3944 <dl>
3945 <dt><dfn id=font-variant-position-normal-value
3946 title="normal!!font-variant-position">normal</dfn>
3948 <dd>None of the features listed below are enabled.
3950 <dt><dfn id=sub>sub</dfn>
3952 <dd>Enables display of subscript variants (OpenType feature: <span
3953 class=tag>subs</span>).
3955 <dt><dfn id=super>super</dfn>
3957 <dd>Enables display of superscript variants (OpenType feature: <span
3958 class=tag>sups</span>).
3959 </dl>
3961 <p>Because of the semantic nature of subscripts and superscripts, when the
3962 value is either ‘<a href="#sub"><code class=property>sub</code></a>’
3963 or ‘<a href="#super"><code class=property>super</code></a>’ for a
3964 given contiguous run of text, if a variant glyph is not available for all
3965 the characters in the run, simulated glyphs must be synthesized for all
3966 characters using reduced forms of the glyphs that would be used without
3967 this feature applied. This is done per run to avoid a mixture of variant
3968 glyphs and synthesized ones that would not align correctly. In the case of
3969 OpenType fonts that lack subscript or superscript glyphs for a given
3970 character, user agents must use the appropriate subscript and superscript
3971 metrics specified in the selected font's <a
3972 href="http://www.microsoft.com/typography/otspec/os2.htm#subxs">OS/2
3973 table</a> <a href="#OPENTYPE"
3974 rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a> to calculate the size
3975 and offset of the synthesized substitutes.
3977 <div class=figure><img alt="alternate superscripts vs. glyphs synthesized
3978 using superscript metrics" src=superscript-alt-synth.png>
3979 <p class=caption>Superscript alternate glyph (left), synthesized
3980 superscript glyphs (middle), and incorrect mixture of the two (right)
3981 </div>
3983 <p>In situations where text decorations are only applied to runs of text
3984 containing superscript or subscript glyphs, the synthesized glyphs must be
3985 used to avoid problems with the placement of decorations.
3987 <p>In the past, user agents have used font-size and vertical-align to
3988 simulate subscripts and superscripts for the <code title="HTML sub
3989 element">sub</code> and <code title="HTML sup element">sup</code>
3990 elements. To allow a backwards compatible way of defining subscripts and
3991 superscripts, it is recommended that authors use conditional rules <a
3992 href="#CSS3-CONDITIONAL"
3993 rel=biblioentry>[CSS3-CONDITIONAL]<!--{{CSS3-CONDITIONAL}}--></a> so that
3994 older user agents will still render subscripts and superscripts via the
3995 older mechanism.
3997 <p>Authors should note that fonts typically only provide subscript and
3998 superscript glyphs for a subset of all characters supported by the font.
3999 For example, while subscript and superscript glyphs are often available
4000 for Latin numbers, glyphs for punctuation and letter characters are less
4001 frequently provided. The synthetic fallback rules defined for this
4002 property assure that subscripts and superscripts will always appear but
4003 the appearance may not match author expectations if the font used does not
4004 provide the appropriate alternate glyph for all characters contained in a
4005 subscript or superscript.
4007 <p>This property is not cumulative. Applying it to elements within a
4008 subscript or superscript won't nest the placement of a subscript or
4009 superscript glyph. Images contained within text runs where the value of
4010 this property is ‘<a href="#sub"><code class=property>sub</code></a>’
4011 or ‘<a href="#super"><code class=property>super</code></a>’ will be
4012 drawn just as they would if the value was <a
4013 href="#font-variant-position-normal-value"
4014 title="normal!!font-variant-position">‘<code
4015 class=property>normal</code>’</a>.</p>
4016 <!-- due to lack of consensus, couldn't resolve on exact positioning of text decorations:
4017 http://www.w3.org/2013/06/06-css-minutes.html#item03 -->
4019 <p>Because of these limitations, ‘<a
4020 href="#propdef-font-variant-position"><code
4021 class=property>font-variant-position</code></a>’ is not recommended for
4022 use in user agent stylesheets. Authors should use it in cases where
4023 subscripts or superscripts will only contain the narrow range of
4024 characters supported by the fonts specified.
4026 <p class=note>The variant glyphs use the same baseline as the default
4027 glyphs would use. There is no shift in the placement along the baseline,
4028 so the use of variant glyphs doesn't affect the height of the inline box
4029 or alter the height of the linebox. This makes superscript and subscript
4030 variants ideal for situations where it's important that leading remain
4031 constant, such as in multi-column layout.
4033 <div class=example>
4034 <p>A typical user agent default style for the <a class=tag
4035 href="#sub">sub</a> element:</p>
4037 <pre>sub {
4038 vertical-align: sub;
4039 font-size: smaller;
4040 line-height: normal;
4041 }
4042 </pre>
4044 <p>Using font-variant-position to specify typographic subscripts in a way
4045 that will still show subscripts in older user agents:</p>
4047 <pre>@supports ( font-variant-position: sub ) {
4049 sub {
4050 vertical-align: baseline;
4051 font-size: 100%;
4052 line-height: inherit;
4053 font-variant-position: sub;
4054 }
4056 }
4057 </pre>
4059 <p>User agents that support the ‘<a
4060 href="#propdef-font-variant-position"><code
4061 class=property>font-variant-position</code></a>’ property will select a
4062 subscript variant glyph and render this without adjusting the baseline or
4063 font-size. Older user agents will ignore the ‘<a
4064 href="#propdef-font-variant-position"><code
4065 class=property>font-variant-position</code></a>’ property definition
4066 and use the standard defaults for subscripts.</p>
4067 </div>
4068 <!-- prop: font-variant-caps -->
4070 <h3 id=font-variant-caps-prop><span class=secno>6.6 </span>Capitalization:
4071 the <a href="#propdef-font-variant-caps">font-variant-caps</a> property</h3>
4073 <table class=propdef id=namefont-variant-capsvaluenormal-small-c>
4074 <tbody>
4075 <tr>
4076 <td>Name:
4078 <td><dfn id=propdef-font-variant-caps>font-variant-caps</dfn>
4080 <tr>
4081 <td>Value:
4083 <td><a href="#font-variant-caps-normal-value"
4084 title="normal!!font-variant-caps">normal</a> | <a
4085 href="#small-caps">small-caps</a> | <a
4086 href="#all-small-caps">all-small-caps</a> | <a
4087 href="#petite-caps">petite-caps</a> | <a
4088 href="#all-petite-caps">all-petite-caps</a> | <a
4089 href="#unicase">unicase</a> | <a href="#titling-caps">titling-caps</a>
4091 <tr>
4092 <td>Initial:
4094 <td>normal
4096 <tr>
4097 <td>Applies to:
4099 <td>all elements
4101 <tr>
4102 <td>Inherited:
4104 <td>yes
4106 <tr>
4107 <td>Percentages:
4109 <td>N/A
4111 <tr>
4112 <td>Media:
4114 <td>visual
4116 <tr>
4117 <td>Computed value:
4119 <td>as specified
4121 <tr>
4122 <td>Animatable:
4124 <td>no
4125 </table>
4127 <p>This property allows the selection of alternate glyphs used for small or
4128 petite capitals or for titling. These glyphs are specifically designed to
4129 blend well with the surrounding normal glyphs, to maintain the weight and
4130 readability which suffers when text is simply resized to fit this purpose.
4132 <p>Individual values have the following meanings:
4134 <dl>
4135 <dt><dfn id=font-variant-caps-normal-value
4136 title="normal!!font-variant-caps">normal</dfn>
4138 <dd>None of the features listed below are enabled.
4140 <dt><dfn id=small-caps>small-caps</dfn>
4142 <dd>Enables display of small capitals (OpenType feature: <span
4143 class=tag>smcp</span>). Small-caps glyphs typically use the form of
4144 uppercase letters but are reduced to the size of lowercase letters.
4145 </dl>
4147 <div class=featex><img alt="small-caps example" src=smcp.png></div>
4149 <dl>
4150 <dt><dfn id=all-small-caps>all-small-caps</dfn>
4152 <dd>Enables display of small capitals for both upper and lowercase letters
4153 (OpenType features: <span class=tag>c2sc, smcp</span>).
4155 <dt><dfn id=petite-caps>petite-caps</dfn>
4157 <dd>Enables display of petite capitals (OpenType feature: <span
4158 class=tag>pcap</span>).
4160 <dt><dfn id=all-petite-caps>all-petite-caps</dfn>
4162 <dd>Enables display of petite capitals for both upper and lowercase
4163 letters (OpenType features: <span class=tag>c2pc, pcap</span>).
4165 <dt><dfn id=unicase>unicase</dfn>
4167 <dd>Enables display of mixture of small capitals for uppercase letters
4168 with normal lowercase letters (OpenType feature: <span
4169 class=tag>unic</span>).
4171 <dt><dfn id=titling-caps>titling-caps</dfn>
4173 <dd>Enables display of titling capitals (OpenType feature: <span
4174 class=tag>titl</span>). Uppercase letter glyphs are often designed for
4175 use with lowercase letters. When used in all uppercase titling sequences
4176 they can appear too strong. Titling capitals are designed specifically
4177 for this situation.
4178 </dl>
4180 <p>The availability of these glyphs is based on whether a given feature is
4181 defined or not in the feature list of the font. User agents can optionally
4182 decide this on a per-script basis but should explicitly not decide this on
4183 a per-character basis.
4185 <p>Some fonts may only support a subset or none of the features described
4186 for this property. For backwards compatibility with CSS 2.1, if ‘<a
4187 href="#small-caps"><code class=property>small-caps</code></a>’ or ‘<a
4188 href="#all-small-caps"><code class=property>all-small-caps</code></a>’
4189 is specified but small-caps glyphs are not available for a given font,
4190 user agents should simulate a small-caps font, for example by taking a
4191 normal font and replacing the glyphs for lowercase letters with scaled
4192 versions of the glyphs for uppercase characters (replacing the glyphs for
4193 both upper and lowercase letters in the case of ‘<a
4194 href="#all-small-caps"><code class=property>all-small-caps</code></a>’).
4196 <div class=figure style="padding: 0; margin: auto;"><img alt="synthetic vs.
4197 real small-caps" class=hires src=synthetic-vs-real-small-caps.png
4198 width=512>
4199 <p class=caption>Synthetic vs. real small-caps
4200 </div>
4202 <p>To match the surrounding text, a font may provide alternate glyphs for
4203 caseless characters when these features are enabled but when a user agent
4204 simulates small capitals, it must not attempt to simulate alternates for
4205 codepoints which are considered caseless.
4207 <div class=figure style="padding: 0; margin: auto;"><img alt="caseless
4208 characters with small-caps, all-small-caps enabled" class=hires
4209 src=small-capitals-variations.png width=418>
4210 <p class=caption>Caseless characters with small-caps, all-small-caps
4211 enabled
4212 </div>
4214 <p>If either ‘<a href="#petite-caps"><code
4215 class=property>petite-caps</code></a>’ or ‘<a
4216 href="#all-petite-caps"><code class=property>all-petite-caps</code></a>’
4217 is specified for a font that doesn't support these features, the property
4218 behaves as if ‘<a href="#small-caps"><code
4219 class=property>small-caps</code></a>’ or ‘<a
4220 href="#all-small-caps"><code class=property>all-small-caps</code></a>’,
4221 respectively, had been specified. If ‘<a href="#unicase"><code
4222 class=property>unicase</code></a>’ is specified for a font that doesn't
4223 support that feature, the property behaves as if ‘<a
4224 href="#small-caps"><code class=property>small-caps</code></a>’ was
4225 applied only to lowercased uppercase letters. If ‘<a
4226 href="#titling-caps"><code class=property>titling-caps</code></a>’ is
4227 specified with a font that does not support this feature, this property
4228 has no visible effect. When simulated small capital glyphs are used, for
4229 scripts that lack uppercase and lowercase letters, ‘<a
4230 href="#small-caps"><code class=property>small-caps</code></a>’, ‘<a
4231 href="#all-small-caps"><code class=property>all-small-caps</code></a>’,
4232 ‘<a href="#petite-caps"><code class=property>petite-caps</code></a>’,
4233 ‘<a href="#all-petite-caps"><code
4234 class=property>all-petite-caps</code></a>’ and ‘<a
4235 href="#unicase"><code class=property>unicase</code></a>’ have no visible
4236 effect.
4238 <p>When casing transforms are used to simulate small capitals, the casing
4239 transformations must match those used for the <span
4240 class=property>‘<code class=property>text-transform</code>’</span>
4241 property.
4243 <p>As a last resort, unscaled uppercase letter glyphs in a normal font may
4244 replace glyphs in a small-caps font so that the text appears in all
4245 uppercase letters.
4247 <div class=figure style="padding: 0; margin: auto;"><img alt="using
4248 all-small-caps in acronym-laden text" class=hires
4249 src=acronym-laden-text.png width=596>
4250 <p class=caption>Using small capitals to improve readability in
4251 acronym-laden text
4252 </div>
4254 <div class=example>
4255 <p>Quotes rendered italicised, with small-caps on the first line:</p>
4257 <pre>blockquote { font-style: italic; }
4258 blockquote:first-line { font-variant: small-caps; }
4260 <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></blockquote>
4261 </pre>
4262 </div>
4263 <!-- prop: font-variant-numeric -->
4265 <h3 id=font-variant-numeric-prop><span class=secno>6.7 </span>Numerical
4266 formatting: the <a
4267 href="#propdef-font-variant-numeric">font-variant-numeric</a> property</h3>
4269 <table class=propdef id=namefont-variant-numericvaluenormal-ltnu>
4270 <tbody>
4271 <tr>
4272 <td>Name:
4274 <td><dfn id=propdef-font-variant-numeric>font-variant-numeric</dfn>
4276 <tr>
4277 <td>Value:
4279 <td><a href="#font-variant-numeric-normal-value"
4280 title="normal!!font-variant-numeric">normal</a> | [ <a
4281 href="#numeric-figure-values"><var><numeric-figure-values></var></a>
4282 || <a
4283 href="#numeric-spacing-values"><var><numeric-spacing-values></var></a>
4284 || <a
4285 href="#numeric-fraction-values"><var><numeric-fraction-values></var></a>
4286 || <a href="#ordinal">ordinal</a> || <a
4287 href="#slashed-zero">slashed-zero</a> ]
4289 <tr>
4290 <td>Initial:
4292 <td>normal
4294 <tr>
4295 <td>Applies to:
4297 <td>all elements
4299 <tr>
4300 <td>Inherited:
4302 <td>yes
4304 <tr>
4305 <td>Percentages:
4307 <td>N/A
4309 <tr>
4310 <td>Media:
4312 <td>visual
4314 <tr>
4315 <td>Computed value:
4317 <td>as specified
4319 <tr>
4320 <td>Animatable:
4322 <td>no
4323 </table>
4325 <p>Specifies control over numerical forms. The example below shows how some
4326 of these values can be combined to influence the rendering of tabular data
4327 with fonts that support these features. Within normal paragraph text,
4328 proportional numbers are used while tabular numbers are used so that
4329 columns of numbers line up properly:
4331 <div class=figure style="padding: 0; margin: auto;"><img alt="combining
4332 number styles" src=numberstyles.png>
4333 <p class=caption>Using number styles
4334 </div>
4336 <p>Possible combinations:
4338 <pre
4339 class=prod><dfn id=numeric-figure-values><var><numeric-figure-values></var></dfn> = [ <a href="#lining-nums">lining-nums</a> | <a href="#oldstyle-nums">oldstyle-nums</a> ]</pre>
4341 <pre
4342 class=prod><dfn id=numeric-spacing-values><var><numeric-spacing-values></var></dfn> = [ <a href="#proportional-nums">proportional-nums</a> | <a href="#tabular-nums">tabular-nums</a> ]</pre>
4344 <pre
4345 class=prod><dfn id=numeric-fraction-values><var><numeric-fraction-values></var></dfn> = [ <a href="#diagonal-fractions">diagonal-fractions</a> | <a href="#stacked-fractions">stacked-fractions</a> ]</pre>
4347 <p>Individual values have the following meanings:
4349 <dl>
4350 <dt><dfn id=font-variant-numeric-normal-value
4351 title="normal!!font-variant-numeric">normal</dfn>
4353 <dd>None of the features listed below are enabled.
4355 <dt><dfn id=lining-nums>lining-nums</dfn>
4357 <dd>Enables display of lining numerals (OpenType feature: <span
4358 class=tag>lnum</span>).
4360 <dt><dfn id=oldstyle-nums>oldstyle-nums</dfn>
4362 <dd>Enables display of old-style numerals (OpenType feature: <span
4363 class=tag>onum</span>).
4365 <dt><dfn id=proportional-nums>proportional-nums</dfn>
4367 <dd>Enables display of proportional numerals (OpenType feature: <span
4368 class=tag>pnum</span>).
4370 <dt><dfn id=tabular-nums>tabular-nums</dfn>
4372 <dd>Enables display of tabular numerals (OpenType feature: <span
4373 class=tag>tnum</span>).
4375 <dt><dfn id=diagonal-fractions>diagonal-fractions</dfn>
4377 <dd>Enables display of lining diagonal fractions (OpenType feature: <span
4378 class=tag>frac</span>).
4379 </dl>
4381 <div class=featex><img alt="diagonal fraction example" src=frac.png></div>
4383 <dl>
4384 <dt><dfn id=stacked-fractions>stacked-fractions</dfn>
4386 <dd>Enables display of lining stacked fractions (OpenType feature: <span
4387 class=tag>afrc</span>).
4388 </dl>
4390 <div class=featex><img alt="stacked fraction example" src=afrc.png></div>
4392 <dl>
4393 <dt><dfn id=ordinal>ordinal</dfn>
4395 <dd>Enables display of letter forms used with ordinal numbers (OpenType
4396 feature: <span class=tag>ordn</span>).
4397 </dl>
4399 <div class=featex><img alt="ordinals example" src=ordinals.png></div>
4401 <dl>
4402 <dt><dfn id=slashed-zero>slashed-zero</dfn>
4404 <dd>Enables display of slashed zeros (OpenType feature: <span
4405 class=tag>zero</span>).
4406 </dl>
4408 <div class=featex><img alt="slashed zero example" src=zero.png></div>
4410 <div class=example id=ordinal-example>
4411 <p>In the case of ‘<a href="#ordinal"><code
4412 class=property>ordinal</code></a>’, although ordinal forms are often
4413 the same as superscript forms, they are marked up differently.</p>
4415 <p>For superscripts, the variant property is only applied to the
4416 sub-element containing the superscript:</p>
4418 <pre>
4419 sup { font-variant-position: super; }
4420 x<sup>2</sup>
4421 </pre>
4423 <p>For ordinals, the variant property is applied to the entire ordinal
4424 number rather than just to the suffix (or to the containing paragraph):</p>
4426 <pre>
4427 .ordinal { font-variant-numeric: ordinal; }
4428 <span class="ordinal">17th</span>
4429 </pre>
4431 <p>In this case only the "th" will appear in ordinal form, the digits will
4432 remain unchanged. Depending upon the typographic traditions used in a
4433 given language, ordinal forms may differ from superscript forms. In
4434 Italian, for example, ordinal forms sometimes include an underline in the
4435 ordinal design.</p>
4436 </div>
4438 <div class=example id=steak-marinade>
4439 <p>A simple flank steak marinade recipe, rendered with automatic fractions
4440 and old-style numerals:</p>
4442 <pre>.amount { font-variant-numeric: oldstyle-nums diagonal-fractions; }
4444 <h4>Steak marinade:</h4>
4445 <ul>
4446 <li><span class="amount">2</span> tbsp olive oil</li>
4447 <li><span class="amount">1</span> tbsp lemon juice</li>
4448 <li><span class="amount">1</span> tbsp soy sauce</li>
4449 <li><span class="amount">1 1/2</span> tbsp dry minced onion</li>
4450 <li><span class="amount">2 1/2</span> tsp italian seasoning</li>
4451 <li>Salt &amp; pepper</li>
4452 </ul>
4454 <p>Mix the meat with the marinade and let it sit covered in the refrigerator
4455 for a few hours or overnight.</p>
4456 </pre>
4458 <p>Note that the fraction feature is only applied to values not the entire
4459 paragraph. Fonts often implement this feature using contextual rules
4460 based on the use of the slash (‘<code class=css>/</code>’) character.
4461 As such, it's not suitable for use as a paragraph-level style.</p>
4462 </div>
4463 <!-- prop: font-variant-alternates -->
4465 <h3 id=font-variant-alternates-prop><span class=secno>6.8 </span>Alternates
4466 and swashes: the <a
4467 href="#propdef-font-variant-alternates">font-variant-alternates</a>
4468 property</h3>
4470 <table class=propdef id=namefont-variant-alternatesvaluenormal-s>
4471 <tbody>
4472 <tr>
4473 <td>Name:
4475 <td><dfn
4476 id=propdef-font-variant-alternates>font-variant-alternates</dfn>
4478 <tr>
4479 <td>Value:
4481 <td>normal | [ <a href="#stylistic"
4482 title=stylistic>stylistic(<feature-value-name>)</a> || <a
4483 href="#historical-forms">historical-forms</a> || <a href="#styleset"
4484 title=styleset>styleset(<feature-value-name> #)</a> || <a
4485 href="#character-variant"
4486 title=character-variant>character-variant(<feature-value-name>
4487 #)</a> || <a href="#swash"
4488 title=swash>swash(<feature-value-name>)</a> || <a
4489 href="#ornaments"
4490 title=ornaments>ornaments(<feature-value-name>)</a> || <a
4491 href="#annotation"
4492 title=annotation>annotation(<feature-value-name>)</a> ]
4494 <tr>
4495 <td>Initial:
4497 <td>normal
4499 <tr>
4500 <td>Applies to:
4502 <td>all elements
4504 <tr>
4505 <td>Inherited:
4507 <td>yes
4509 <tr>
4510 <td>Percentages:
4512 <td>N/A
4514 <tr>
4515 <td>Media:
4517 <td>visual
4519 <tr>
4520 <td>Computed value:
4522 <td>as specified
4524 <tr>
4525 <td>Animatable:
4527 <td>no
4528 </table>
4530 <p>For any given character, fonts can provide a variety of alternate glyphs
4531 in addition to the default glyph for that character. This property
4532 provides control over the selection of these alternate glyphs.
4534 <p>For many of the property values listed below, several different
4535 alternate glyphs are available. How many alternates are available and what
4536 they represent is font-specific, so these are each marked <dfn
4537 id=font-specific>font specific</dfn> in the value definitions below.
4538 Because the nature of these alternates is font-specific, the <a
4539 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
4540 rule is used to define values for a specific font family or set of
4541 families that associate a font-specific numeric
4542 <code><feature-index></code> with a custom
4543 <code><feature-value-name></code>, which is then used in this
4544 property to select specific alternates:
4546 <pre>@font-feature-values Noble Script { @swash { swishy: 1; flowing: 2; } }
4548 p {
4549 font-family: Noble Script;
4550 font-variant-alternates: swash(flowing); /* use swash alternate #2 */
4551 }</pre>
4553 <p>When a particular <code><feature-value-name></code> has not been
4554 defined for a given family or for a particular feature type, the computed
4555 value must be the same as if it had been defined. However, property values
4556 that contain these undefined <code><feature-value-name></code>
4557 identifiers must be ignored when choosing glyphs.
4559 <pre>/* these two style rules are effectively the same */
4560 p { font-variant-alternates: swash(unknown-value); } /* not a defined value, ignored */
4561 p { font-variant-alternates: normal; }
4562 </pre>
4564 <p>This allows values to be defined and used for a given set of font
4565 families but ignored if fallback occurs, since the font family name would
4566 be different. If a given value is outside the range supported by a given
4567 font, the value is ignored. These values never apply to generic font
4568 families.
4570 <p>Individual values have the following meanings:
4572 <dl>
4573 <dt><dfn id=font-variant-alternates-normal-value
4574 title="normal!!font-variant-alternates">normal</dfn>
4576 <dd>None of the features listed below are enabled.
4578 <dt><dfn id=historical-forms>historical-forms</dfn>
4580 <dd>Enables display of historical forms (OpenType feature: <span
4581 class=tag>hist</span>).
4582 </dl>
4584 <div class=featex><img alt="historical form example" src=hist.png></div>
4586 <dl>
4587 <dt><dfn id=stylistic
4588 title=stylistic>stylistic(<feature-value-name>)</dfn>
4590 <dd>Enables display of stylistic alternates (<a
4591 href="#font-specific"><em>font specific</em></a>, OpenType feature: <span
4592 class=tag>salt <feature-index></span>).
4593 </dl>
4595 <div class=featex><img alt="stylistic alternate example" src=salt.png></div>
4597 <dl>
4598 <dt><dfn id=styleset title=styleset>styleset(<feature-value-name>
4599 #)</dfn>
4601 <dd>Enables display with stylistic sets (<a href="#font-specific"><em>font
4602 specific</em></a>, OpenType feature: <span
4603 class=tag>ss<feature-index></span> OpenType currently defines <span
4604 class=tag>ss01</span> through <span class=tag>ss20</span>).
4605 </dl>
4607 <div class=featex><img alt="styleset example" src=ssnn.png></div>
4609 <dl>
4610 <dt><dfn id=character-variant
4611 title=character-variant>character-variant(<feature-value-name>
4612 #)</dfn>
4614 <dd>Enables display of specific character variants (<a
4615 href="#font-specific"><em>font specific</em></a>, OpenType feature: <span
4616 class=tag>cv<feature-index></span> OpenType currently defines <span
4617 class=tag>cv01</span> through <span class=tag>cv99</span>).
4619 <dt><dfn id=swash title=swash>swash(<feature-value-name>)</dfn>
4621 <dd>Enables display of swash glyphs (<a href="#font-specific"><em>font
4622 specific</em></a>, OpenType feature: <span class=tag>swsh
4623 <feature-index>, cswh <feature-index></span>).
4624 </dl>
4626 <div class=featex><img alt="swash example" src=swsh.png></div>
4628 <dl>
4629 <dt><dfn id=ornaments
4630 title=ornaments>ornaments(<feature-value-name>)</dfn>
4632 <dd>Enables replacement of default glyphs with ornaments, if provided in
4633 the font (<a href="#font-specific"><em>font specific</em></a>, OpenType
4634 feature: <span class=tag>ornm <feature-index></span>). Some fonts
4635 may offer ornament glyphs as alternates for a wide collection of
4636 characters; however, displaying arbitrary characters (e.g.,
4637 alphanumerics) as ornaments is poor practice as it distorts the semantics
4638 of the data. Font designers are encouraged to encode all ornaments
4639 (except those explicitly encoded in the Unicode Dingbats blocks, etc.) as
4640 alternates for the bullet character (U+2022) to allow authors to select
4641 the desired glyph using ‘<a href="#ornaments"><code
4642 class=property>ornaments</code></a>’.
4643 </dl>
4645 <div class=featex><img alt="ornaments example" src=ornm.png></div>
4647 <dl>
4648 <dt><dfn id=annotation
4649 title=annotation>annotation(<feature-value-name>)</dfn>
4651 <dd>Enables display of alternate annotation forms (<a
4652 href="#font-specific"><em>font specific</em></a>, OpenType feature: <span
4653 class=tag>nalt <feature-index></span>).
4654 </dl>
4656 <div class=featex><img alt="alternate annotation form example"
4657 src=nalt.png></div>
4659 <h3 id=font-feature-values><span class=secno>6.9 </span>Defining font
4660 specific alternates: the <dfn id=at-font-feature-values-rule
4661 style="font-weight: inherit; font-style:
4662 inherit"><code>@font-feature-values</code></dfn> rule</h3>
4664 <p>Several of the possible values of ‘<a
4665 href="#propdef-font-variant-alternates"><code
4666 class=property>font-variant-alternates</code></a>’ listed above are
4667 labeled as <a href="#font-specific"><em>font specific</em></a>. For these
4668 features fonts may define not just a single glyph but a set of alternate
4669 glyphs with an index to select a given alternate. Since these are font
4670 family specific, the <a
4671 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
4672 rule is used to define named values for these indices for a given family.
4674 <p class=note>See the <a href="#om-fontfeaturevalues">object model
4675 reference section</a> for a description of the interfaces used to modify
4676 these rules via the CSS Object Model.
4678 <div class=example>
4679 <p>In the case of the swash Q in the example shown above, the swash could
4680 be specified using these style rules:</p>
4682 <pre>
4684 @font-feature-values Jupiter Sans {
4685 @swash {
4686 delicate: 1;
4687 flowing: 2;
4688 }
4689 }
4691 h2 { font-family: Jupiter Sans, sans-serif; }
4693 /* show the second swash variant in h2 headings */
4694 h2:first-letter { font-variant-alternates: swash(flowing); }
4696 <h2>Quick</h2></pre>
4698 <p>When Jupiter Sans is present, the second alternate swash alternate will
4699 be displayed. When not present, no swash character will be shown, since
4700 the specific named value "flowing" is only defined for the Jupiter Sans
4701 family. The @-mark indicates the name of the property value for which a
4702 named value can be used. The name "flowing" is chosen by the author. The
4703 index that represents each alternate is defined within a given font's
4704 data.</p>
4705 </div>
4707 <h4 id=basic-syntax><span class=secno>6.9.1 </span>Basic syntax</h4>
4709 <p>An <a
4710 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
4711 rule is composed of a list of font families followed by a block containing
4712 individual <a href="#featurevalueblock"><i
4713 title="feature_value_block">feature value blocks</i></a> that take the
4714 form of @-rules. Each block defines a set of named values for a specific
4715 font feature when a given set of font families is used. Effectively, they
4716 define a mapping of ⟨family, feature, ident⟩ → ⟨values⟩ where
4717 ⟨values⟩ are the numeric indices used for specific features defined
4718 for a given font.
4720 <p>In terms of the grammar, this specification defines the following
4721 productions:
4723 <pre><dfn id=fontfeaturevaluesrule>font_feature_values_rule</dfn>
4724 : <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>*
4725 '{' <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>*
4726 ;
4728 <dfn id=fontfamilynamelist>font_family_name_list</dfn>
4729 : <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> ]*
4730 ;
4732 <dfn id=fontfamilyname>font_family_name</dfn>
4733 : <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> ]* ]
4734 ;
4736 <dfn id=featurevalueblock>feature_value_block</dfn>
4737 : <a href="#featuretype"><i>feature_type</i></a> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>*
4738 '{' <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>*
4739 ;
4741 <dfn id=featuretype>feature_type</dfn>:
4742 <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>ATKEYWORD</i></a>
4743 ;
4745 <dfn id=featurevaluedefinition>feature_value_definition</dfn>
4746 : <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> ]*
4747 ;
4748 </pre>
4750 <p>The following new token is introduced:
4752 <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>;}
4753 </pre>
4755 <p><a href="#featurevalueblock"><i title="feature_value_block">Feature
4756 value blocks</i></a> are handled as <a
4757 href="http://www.w3.org/TR/CSS2/syndata.html#at-rules">at-rules</a>, they
4758 consist of everything up to the next block or semi-colon, whichever comes
4759 first.
4761 <p>The <a href="#fontfamilynamelist"><i title="font_family_name_list">font
4762 family list</i></a> is a comma-delimited list of <a
4763 href="#fontfamilyname"><i title="font_family_name">font family
4764 names</i></a> that match the definition of <a
4765 href="#family-name-value"><var><family-name></var></a> for the <a
4766 href="#propdef-font-family" title="font-family!!property">‘<code
4767 class=property>font-family</code>’</a> property. This means that only
4768 named font families are allowed, rules that include generic or system
4769 fonts in the list of font families are syntax errors. However, if a user
4770 agent defines a generic font to be a specific named font (e.g. Helvetica),
4771 the settings associated with that family name will be used. If syntax
4772 errors occur within the font family list, the entire rule must be ignored.
4774 <p>Within <a href="#featurevalueblock"><i
4775 title="feature_value_block">feature value blocks</i></a>, the <a
4776 href="#featuretype"><i title="feature_type">feature type</i></a> is
4777 ‘<code class=css>@</code>’ followed by the name of one of the <a
4778 href="#font-specific"><em>font specific</em></a> property values of ‘<a
4779 href="#propdef-font-variant-alternates"><code
4780 class=property>font-variant-alternates</code></a>’ (e.g. <a
4781 href="#swash"><code>@swash</code></a>). The identifiers used within
4782 feature value definitions follow the rules of CSS user identifiers and are
4783 case-sensitive. They are unique only for a given set of font families and
4784 <a href="#featuretype"><i title="feature_type">feature type</i></a>. The
4785 same identifier used with a different <a href="#featuretype"><i
4786 title="feature_type">feature type</i></a> is treated as a separate and
4787 distinct value. If the same identifier is defined mulitple times for a
4788 given <a href="#featuretype"><i title="feature_type">feature type</i></a>
4789 and font family, the last defined value is used. Values associated with a
4790 given identifier are limited to integer values 0 or greater.
4792 <p>When syntax errors occur within a <a href="#featurevaluedefinition"><i
4793 title="feature_value_definition">feature value definition</i></a>, such as
4794 invalid identifiers or values, the entire <a
4795 href="#featurevaluedefinition"><i title="feature_value_definition">feature
4796 value definition</i></a> must be omitted, just as syntax errors in style
4797 declarations are handled. When the <a href="#featuretype"><i
4798 title="feature_type">feature type</i></a> is invalid, the entire
4799 associated <a href="#featurevalueblock"><i
4800 title="feature_value_block">feature value block</i></a> must be ignored.
4802 <div class=example>
4803 <p>Rules that are equivalent given syntax error handling:</p>
4805 <pre>@font-feature-values Bongo {
4806 @swash { ornate: 1; }
4807 annotation { boxed: 4; } /* should be @annotation! */
4808 @swash { double-loops: 1; flowing: -1; } /* negative value */
4809 @ornaments ; /* incomplete definition */
4810 @styleset { double-W: 14; sharp-terminals: 16 1 } /* missing ; */
4811 <a href="http://www.angryalien.com/0504/shiningbunnies.html" style="text-decoration: none; border: none;">redrum</a> /* random editing mistake */
4812 }</pre>
4814 <p>The example above is equivalent to:</p>
4816 <pre>@font-feature-values Bongo {
4817 @swash { ornate: 1; }
4818 @swash { double-loops: 1; }
4819 @styleset { double-W: 14; sharp-terminals: 16 1; }
4820 }</pre>
4821 </div>
4823 <p>If multiple <a
4824 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
4825 rules are defined for a given family, the resulting values definitions are
4826 the union of the definitions contained within these rules. This allows a
4827 set of named values to be defined for a given font family globally for a
4828 site and specific additions made per-page.
4830 <div class=example>
4831 <p>Using both site-wide and per-page feature values:</p>
4833 <pre>
4834 site.css:
4836 @font-feature-values Mercury Serif {
4837 @styleset {
4838 stacked-g: 3; /* "two-storey" versions of g, a */
4839 stacked-a: 4;
4840 }
4841 }
4843 page.css:
4845 @font-feature-values Mercury Serif {
4846 @styleset {
4847 geometric-m: 7; /* alternate version of m */
4848 }
4849 }
4851 body {
4852 font-family: Mercury Serif, serif;
4854 /* enable both the use of stacked g and alternate m */
4855 font-variant-alternates: styleset(stacked-g, geometric-m);
4856 }</pre>
4857 </div>
4859 <div class=example>
4860 <p>Using a commonly named value allows authors to use a single style rule
4861 to cover a set of fonts for which the underlying selector is different
4862 for each font. If either font in the example below is found, a circled
4863 number glyph will be used:</p>
4865 <pre>@font-feature-values Taisho Gothic {
4866 @annotation { boxed: 1; circled: 4; }
4867 }
4869 @font-feature-values Otaru Kisa {
4870 @annotation { circled: 1; black-boxed: 3; }
4871 }
4873 h3.title {
4874 /* circled form defined for both fonts */
4875 font-family: Taisho Gothic, Otaru Kisa;
4876 font-variant: annotation(circled);
4877 }</pre>
4878 </div>
4880 <h4 id=multi-valued-feature-value-definitions><span class=secno>6.9.2
4881 </span>Multi-valued feature value definitions</h4>
4883 <p>Most <a href="#font-specific"><em>font specific</em></a> ‘<a
4884 href="#propdef-font-variant-alternates"><code
4885 class=property>font-variant-alternates</code></a>’ property values take
4886 a single value (e.g. ‘<a href="#swash"><code
4887 class=property>swash</code></a>’). The ‘<a
4888 href="#character-variant"><code
4889 class=property>character-variant</code></a>’ property value allows two
4890 values and ‘<a href="#styleset"><code
4891 class=property>styleset</code></a>’ allows an unlimited number.
4893 <p>For the styleset property value, multiple values indicate the style sets
4894 to be enabled. Values between 1 and 99 enable OpenType features <span
4895 class=tag>ss01</span> through <span class=tag>ss99</span>. However, the
4896 OpenType standard only officially defines <span class=tag>ss01</span>
4897 through <span class=tag>ss20</span>. For OpenType fonts, values greater
4898 than 99 or equal to 0 do not generate a syntax error when parsed but
4899 enable no OpenType features.
4901 <pre>@font-feature-values Mars Serif {
4902 @styleset {
4903 alt-g: 1; /* implies ss01 = 1 */
4904 curly-quotes: 3; /* implies ss03 = 1 */
4905 code: 4 5; /* implies ss04 = 1, ss05 = 1 */
4906 }
4908 @styleset {
4909 dumb: 125; /* >99, ignored */
4910 }
4912 @swash {
4913 swishy: 3 5; /* more than 1 value for swash, syntax error */
4914 }
4915 }
4917 p.codeblock {
4918 /* implies ss03 = 1, ss04 = 1, ss05 = 1 */
4919 font-variant-alternates: styleset(curly-quotes, code);
4920 }</pre>
4922 <p>For character-variant, a single value between 1 and 99 indicates the
4923 enabling of OpenType feature <span class=tag>cv01</span> through <span
4924 class=tag>cv99</span>. For OpenType fonts, values greater than 99 or equal
4925 to 0 are ignored but do not generate a syntax error when parsed but enable
4926 no OpenType features. When two values are listed, the first value
4927 indicates the feature used and the second the value passed for that
4928 feature. If more than two values are assigned to a given name, a syntax
4929 error occurs and the entire <a href="#featurevaluedefinition"><i
4930 title="feature_value_definition">feature value definition</i></a> is
4931 ignored.
4933 <pre>@font-feature-values MM Greek {
4934 @character-variant { alpha-2: 1 2; } /* implies cv01 = 2 */
4935 @character-variant { beta-3: 2 3; } /* implies cv02 = 3 */
4936 @character-variant { epsilon: 5 3 6; } /* more than 2 values, syntax error, definition ignored */
4937 @character-variant { gamma: 12; } /* implies cv12 = 1 */
4938 @character-variant { zeta: 20 3; } /* implies cv20 = 3 */
4939 @character-variant { zeta-2: 20 2; } /* implies cv20 = 2 */
4940 @character-variant { silly: 105; } /* >99, ignored */
4941 @character-variant { dumb: 323 3; } /* >99, ignored */
4942 }
4944 #title {
4945 /* use the third alternate beta, first alternate gamma */
4946 font-variant-alternates: character-variant(beta-3, gamma);
4947 }
4949 p {
4950 /* zeta-2 follows zeta, implies cv20 = 2 */
4951 font-variant-alternates: character-variant(zeta, zeta-2);
4952 }
4954 .special {
4955 /* zeta follows zeta-2, implies cv20 = 3 */
4956 font-variant-alternates: character-variant(zeta-2, zeta);
4957 }</pre>
4959 <div class=figure><img alt="Matching text on Byzantine seals using
4960 character variants" src=byzantineseal.png>
4961 <p class=caption>Byzantine seal text displayed with character variants
4962 </div>
4964 <div class=example>
4965 <p>In the figure above, the text in red is rendered using a font
4966 containing character variants that mimic the character forms found on a
4967 Byzantine seal from the 8th century A.D. Two lines below is the same text
4968 displayed in a font without variants. Note the two variants for U and N
4969 used on the seal.</p>
4971 <pre>@font-feature-values Athena Ruby {
4972 @character-variant {
4973 leo-B: 2 1;
4974 leo-M: 13 3;
4975 leo-alt-N: 14 1;
4976 leo-N: 14 2;
4977 leo-T: 20 1;
4978 leo-U: 21 2;
4979 leo-alt-U: 21 4;
4980 }
4981 }
4983 p {
4984 font-variant: discretionary-ligatures,
4985 character-variant(leo-B, leo-M, leo-N, leo-T, leo-U);
4986 }
4988 span.alt-N {
4989 font-variant-alternates: character-variant(leo-alt-N);
4990 }
4992 span.alt-U {
4993 font-variant-alternates: character-variant(leo-alt-U);
4994 }
4996 <p>ENO....UP͞RSTU<span class="alt-U">U</span>͞<span class="alt-U">U</span>ΚΑΙTỤẠG̣IUPNS</p>
4998 <p>LEON|ΚΑΙCONSTA|NTI<span class="alt-N">N</span>OS..|STOIBAṢ.|LIṢROM|AIO<span class="alt-N">N</span></p>
4999 </pre>
5000 </div>
5002 <h3 id=font-variant-east-asian-prop><span class=secno>6.10 </span>East
5003 Asian text rendering: the <a
5004 href="#propdef-font-variant-east-asian">font-variant-east-asian</a>
5005 property</h3>
5007 <table class=propdef id=namefont-variant-east-asianvaluenormal-l>
5008 <tbody>
5009 <tr>
5010 <td>Name:
5012 <td><dfn
5013 id=propdef-font-variant-east-asian>font-variant-east-asian</dfn>
5015 <tr>
5016 <td>Value:
5018 <td><a href="#font-variant-east-asian-normal-value"
5019 title="normal!!font-variant-east-asian">normal</a> | [ <a
5020 href="#east-asian-variant-values"><var><east-asian-variant-values></var></a>
5021 || <a
5022 href="#east-asian-width-values"><var><east-asian-width-values></var></a>
5023 || <a href="#ruby">ruby</a> ]
5025 <tr>
5026 <td>Initial:
5028 <td>normal
5030 <tr>
5031 <td>Applies to:
5033 <td>all elements
5035 <tr>
5036 <td>Inherited:
5038 <td>yes
5040 <tr>
5041 <td>Percentages:
5043 <td>N/A
5045 <tr>
5046 <td>Media:
5048 <td>visual
5050 <tr>
5051 <td>Computed value:
5053 <td>as specified
5055 <tr>
5056 <td>Animatable:
5058 <td>no
5059 </table>
5061 <p>Allows control of glyph substitution and sizing in East Asian text.
5063 <pre
5064 class=prod><dfn id=east-asian-variant-values><var><east-asian-variant-values></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>
5066 <pre
5067 class=prod><dfn id=east-asian-width-values><var><east-asian-width-values></var></dfn> = [ <a href="#full-width">full-width</a> | <a href="#proportional-width">proportional-width</a> ]</pre>
5069 <p>Individual values have the following meanings:
5071 <dl>
5072 <dt><dfn id=font-variant-east-asian-normal-value
5073 title="normal!!font-variant-east-asian">normal</dfn>
5075 <dd>None of the features listed below are enabled.
5077 <dt><dfn id=jis78>jis78</dfn>
5079 <dd>Enables rendering of JIS78 forms (OpenType feature: <span
5080 class=tag>jp78</span>).
5081 </dl>
5083 <div class=featex><img alt="JIS78 form example" src=jp78.png></div>
5085 <dl>
5086 <dt><dfn id=jis83>jis83</dfn>
5088 <dd>Enables rendering of JIS83 forms (OpenType feature: <span
5089 class=tag>jp83</span>).
5091 <dt><dfn id=jis90>jis90</dfn>
5093 <dd>Enables rendering of JIS90 forms (OpenType feature: <span
5094 class=tag>jp90</span>).
5096 <dt><dfn id=jis04>jis04</dfn>
5098 <dd>Enables rendering of JIS2004 forms (OpenType feature: <span
5099 class=tag>jp04</span>).
5100 <p>The various JIS variants reflect the glyph forms defined in different
5101 Japanese national standards. Fonts generally include glyphs defined by
5102 the most recent national standard but it's sometimes necessary to use
5103 older variants, to match signage for example.</p>
5105 <dt><dfn id=simplified>simplified</dfn>
5107 <dd>Enables rendering of simplified forms (OpenType feature: <span
5108 class=tag>smpl</span>).
5110 <dt><dfn id=traditional>traditional</dfn>
5112 <dd>Enables rendering of traditional forms (OpenType feature: <span
5113 class=tag>trad</span>).
5114 </dl>
5116 <p>The ‘<a href="#simplified"><code
5117 class=property>simplified</code></a>’ and ‘<a
5118 href="#traditional"><code class=property>traditional</code></a>’ values
5119 allow control over the glyph forms for characters which have been
5120 simplified over time but for which the older, traditional form is still
5121 used in some contexts. The exact set of characters and glyph forms will
5122 vary to some degree by context for which a given font was designed.
5124 <div class=featex><img alt="tradtional form example" src=trad.png></div>
5126 <dl>
5127 <dt><dfn id=full-width>full-width</dfn>
5129 <dd>Enables rendering of full-width variants (OpenType feature: <span
5130 class=tag>fwid</span>).
5132 <dt><dfn id=proportional-width>proportional-width</dfn>
5134 <dd>Enables rendering of proportionally-spaced variants (OpenType feature:
5135 <span class=tag>pwid</span>).
5136 </dl>
5138 <div class=featex><img alt="proportionally spaced Japanese example"
5139 src=pwid.png></div>
5141 <dl>
5142 <dt><dfn id=ruby>ruby</dfn>
5144 <dd>Enables display of ruby variant glyphs (OpenType feature: <span
5145 class=tag>ruby</span>). Since ruby text is generally smaller than the
5146 associated body text, font designers can design special glyphs for use
5147 with ruby that are more readable than scaled down versions of the default
5148 glyphs. Only glyph selection is affected, there is no associated font
5149 scaling or other change that affects line layout. The red ruby text below
5150 is shown with default glyphs (top) and with ruby variant glyphs (bottom).
5151 Note the slight difference in stroke thickness.
5152 </dl>
5154 <div class=featex><img alt="ruby variant example" src=rubyshinkansen.png></div>
5156 <h3 id=font-variant-prop><span class=secno>6.11 </span>Overall shorthand
5157 for font rendering: the <a href="#propdef-font-variant">font-variant</a>
5158 property</h3>
5160 <table class=propdef id=namefont-variantvaluenormal-none-ltcommo>
5161 <tbody>
5162 <tr>
5163 <td>Name:
5165 <td><dfn id=propdef-font-variant
5166 title="font-variant!!property">font-variant</dfn>
5168 <tr>
5169 <td>Value:
5171 <td><a href="#font-variant-normal-value"
5172 title="normal!!font-variant">normal</a> | <a
5173 href="#font-variant-none-value" title="none!!font-variant">none</a> | [
5174 <a href="#common-lig-values"><var><common-lig-values></var></a>
5175 || <a
5176 href="#discretionary-lig-values"><var><discretionary-lig-values></var></a>
5177 || <a
5178 href="#historical-lig-values"><var><historical-lig-values></var></a>
5179 || <a
5180 href="#contextual-alt-values"><var><contextual-alt-values></var></a>
5181 || <a href="#stylistic"><var
5182 title=stylistic>stylistic(<feature-value-name>)</var></a> || <a
5183 href="#historical-forms"><var>historical-forms</var></a> || <a
5184 href="#styleset"><var
5185 title=styleset>styleset(<feature-value-name> #)</var></a> || <a
5186 href="#character-variant"><var
5187 title=character-variant>character-variant(<feature-value-name>
5188 #)</var></a> || <a href="#swash"><var
5189 title=swash>swash(<feature-value-name>)</var></a> || <a
5190 href="#ornaments"><var
5191 title=ornaments>ornaments(<feature-value-name>)</var></a> || <a
5192 href="#annotation"><var
5193 title=annotation>annotation(<feature-value-name>)</var></a> || [
5194 <a href="#small-caps"><i>small-caps</i></a> | <a
5195 href="#all-small-caps"><i>all-small-caps</i></a> | <a
5196 href="#petite-caps"><i>petite-caps</i></a> | <a
5197 href="#all-petite-caps"><i>all-petite-caps</i></a> | <a
5198 href="#unicase"><i>unicase</i></a> | <a
5199 href="#titling-caps"><i>titling-caps</i></a> ] || <a
5200 href="#numeric-figure-values"><var><numeric-figure-values></var></a>
5201 || <a
5202 href="#numeric-spacing-values"><var><numeric-spacing-values></var></a>
5203 || <a
5204 href="#numeric-fraction-values"><var><numeric-fraction-values></var></a>
5205 || <a href="#ordinal"><i>ordinal</i></a> || <a
5206 href="#slashed-zero"><i>slashed-zero</i></a> || <a
5207 href="#east-asian-variant-values"><var><east-asian-variant-values></var></a>
5208 || <a
5209 href="#east-asian-width-values"><var><east-asian-width-values></var></a>
5210 || <a href="#ruby"><i>ruby</i></a> ]
5212 <tr>
5213 <td>Initial:
5215 <td>normal
5217 <tr>
5218 <td>Applies to:
5220 <td>all elements
5222 <tr>
5223 <td>Inherited:
5225 <td>yes
5227 <tr>
5228 <td>Percentages:
5230 <td>see individual properties
5232 <tr>
5233 <td>Media:
5235 <td>visual
5237 <tr>
5238 <td>Computed value:
5240 <td>see individual properties
5242 <tr>
5243 <td>Animatable:
5245 <td>see individual properties
5246 </table>
5248 <p>The <a href="#propdef-font-variant"
5249 title="font-variant!!property">‘<code
5250 class=property>font-variant</code>’</a> property is a shorthand for all
5251 font-variant subproperties. The value <dfn id=font-variant-normal-value
5252 title="normal!!font-variant">‘<code
5253 class=property>normal</code>’</dfn> resets all subproperties of <a
5254 href="#propdef-font-variant" title="font-variant!!property">‘<code
5255 class=property>font-variant</code>’</a> to their inital value. The <dfn
5256 id=font-variant-none-value title="none!!font-variant">‘<code
5257 class=property>none</code>’</dfn> value sets ‘<a
5258 href="#propdef-font-variant-ligatures"><code
5259 class=property>font-variant-ligatures</code></a>’ to ‘<code
5260 class=property>none</code>’ and resets all other font feature properties
5261 to their initial value. Like other shorthands, using <a
5262 href="#propdef-font-variant" title="font-variant!!property">‘<code
5263 class=property>font-variant</code>’</a> resets unspecified <a
5264 href="#propdef-font-variant" title="font-variant!!property">‘<code
5265 class=property>font-variant</code>’</a> subproperties to their initial
5266 values. It does not reset the values of either ‘<a
5267 href="#propdef-font-language-override"><code
5268 class=property>font-language-override</code></a>’ or <a
5269 href="#propdef-font-feature-settings"
5270 title="font-feature-settings!!property">‘<code
5271 class=property>font-feature-settings</code>’</a>.
5273 <h3 id=font-feature-settings-prop><span class=secno>6.12 </span>Low-level
5274 font feature settings control: the <a
5275 href="#propdef-font-feature-settings">font-feature-settings</a> property</h3>
5277 <table class=propdef id=namefont-feature-settingsvaluenormal-ltf>
5278 <tbody>
5279 <tr>
5280 <td>Name:
5282 <td><dfn id=propdef-font-feature-settings
5283 title="font-feature-settings!!property">font-feature-settings</dfn>
5285 <tr>
5286 <td>Value:
5288 <td><a href="#font-feature-settings-normal-value"
5289 title="normal!!font-feature-settings">normal</a> | <a
5290 href="#feature-tag-value"><var><feature-tag-value></var></a> #
5292 <tr>
5293 <td>Initial:
5295 <td>normal
5297 <tr>
5298 <td>Applies to:
5300 <td>all elements
5302 <tr>
5303 <td>Inherited:
5305 <td>yes
5307 <tr>
5308 <td>Percentages:
5310 <td>N/A
5312 <tr>
5313 <td>Media:
5315 <td>visual
5317 <tr>
5318 <td>Computed value:
5320 <td>as specified
5322 <tr>
5323 <td>Animatable:
5325 <td>no
5326 </table>
5328 <p>This property provides low-level control over OpenType font features. It
5329 is intended as a way of providing access to font features that are not
5330 widely used but are needed for a particular use case.
5332 <p>Authors should generally use <a href="#propdef-font-variant"
5333 title="font-variant!!property">‘<code
5334 class=property>font-variant</code>’</a> and its related subproperties
5335 whenever possible and only use this property for special cases where its
5336 use is the only way of accessing a particular infrequently used font
5337 feature.
5339 <pre>/* enable small caps and use second swash alternate */
5340 font-feature-settings: "smcp", "swsh" 2;</pre>
5342 <p>A value of <dfn id=font-feature-settings-normal-value
5343 title="normal!!font-feature-settings">‘<code
5344 class=property>normal</code>’</dfn> means that no change in glyph
5345 selection or positioning occurs due to this property.
5347 <p>Feature tag values have the following syntax:
5349 <pre
5350 class=prod><dfn id=feature-tag-value><var><feature-tag-value></var></dfn> = <string> [ <integer> | on | off ]?</pre>
5352 <p>The <string> is a case-sensitive OpenType feature tag. As
5353 specified in the OpenType specification, feature tags contain four ASCII
5354 characters. Tag strings longer or shorter than four characters, or
5355 containing characters outside the U+20–7E codepoint range are invalid.
5356 Feature tags need only match a feature tag defined in the font, so they
5357 are not limited to explicitly registered OpenType features. Fonts defining
5358 custom feature tags should follow the <a
5359 href="http://www.microsoft.com/typography/otspec/featuretags.htm">tag name
5360 rules</a> defined in the OpenType specification <a
5361 href="#OPENTYPE-FEATURES"
5362 rel=biblioentry>[OPENTYPE-FEATURES]<!--{{!OPENTYPE-FEATURES}}--></a>.
5364 <p>Feature tags not present in the font are ignored; a user agent must not
5365 attempt to synthesize fallback behavior based on these feature tags. The
5366 one exception is that user agents may synthetically support the <span
5367 class=tag>kern</span> feature with fonts that contain kerning data in the
5368 form of a ‘<code class=property>kern</code>’ table but lack <span
5369 class=tag>kern</span> feature support in the ‘<code
5370 class=property>GPOS</code>’ table.
5372 <p class=note>In general, authors should use the ‘<a
5373 href="#propdef-font-kerning"><code
5374 class=property>font-kerning</code></a>’ property to explicitly enable or
5375 disable kerning since this property always affects fonts with either type
5376 of kerning data.
5378 <p>If present, a value indicates an index used for glyph selection. An
5379 <integer> value must be 0 or greater. A value of 0 indicates that
5380 the feature is disabled. For boolean features, a value of 1 enables the
5381 feature. For non-boolean features, a value of 1 or greater enables the
5382 feature and indicates the feature selection index. A value of ‘<code
5383 class=property>on</code>’ is synonymous with 1 and ‘<code
5384 class=property>off</code>’ is synonymous with 0. If the value is
5385 omitted, a value of 1 is assumed.
5387 <pre>
5388 font-feature-settings: "dlig" 1; /* dlig=1 enable discretionary ligatures */
5389 font-feature-settings: "smcp" on; /* smcp=1 enable small caps */
5390 font-feature-settings: 'c2sc'; /* c2sc=1 enable caps to small caps */
5391 font-feature-settings: "liga" off; /* liga=0 no common ligatures */
5392 font-feature-settings: "tnum", 'hist'; /* tnum=1, hist=1 enable tabular numbers and historical forms */
5393 font-feature-settings: "tnum" "hist"; /* invalid, need a comma-delimited list */
5394 font-feature-settings: "silly" off; /* invalid, tag too long */
5395 font-feature-settings: "PKRN"; /* PKRN=1 enable custom feature */
5396 font-feature-settings: dlig; /* invalid, tag must be a string */
5397 </pre>
5399 <p>When values greater than the range supported by the font are specified,
5400 the behavior is explicitly undefined. For boolean features, in general
5401 these will enable the feature. For non-boolean features, out of range
5402 values will in general be equivalent to a 0 value. However, in both cases
5403 the exact behavior will depend upon the way the font is designed
5404 (specifically, which type of lookup is used to define the feature).
5406 <p>Although specifically defined for OpenType feature tags, feature tags
5407 for other modern font formats that support font features may be added in
5408 the future. Where possible, features defined for other font formats should
5409 attempt to follow the pattern of registered OpenType tags.
5411 <div class=example>
5412 <p>The Japanese text below will be rendered with half-width kana
5413 characters:</p>
5415 <pre lang=ja>
5416 body { font-feature-settings: "hwid"; /* Half-width OpenType feature */ }
5418 <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</p>
5419 </pre>
5420 </div>
5422 <h3 id=font-language-override-prop><span class=secno>6.13 </span>Font
5423 language override: the <a
5424 href="#propdef-font-language-override">font-language-override</a> property</h3>
5426 <table class=propdef id=namefont-language-overridevaluenormal-lt>
5427 <tbody>
5428 <tr>
5429 <td>Name:
5431 <td><dfn id=propdef-font-language-override>font-language-override</dfn>
5433 <tr>
5434 <td>Value:
5436 <td><a href="#font-language-override-normal-value"
5437 title="normal!!font-language-override">normal</a> | <a
5438 href="#font-language-override-string-value"><var><string></var></a>
5440 <tr>
5441 <td>Initial:
5443 <td><a href="#font-language-override-normal-value"
5444 title="normal!!font-language-override">normal</a>
5446 <tr>
5447 <td>Applies to:
5449 <td>all elements
5451 <tr>
5452 <td>Inherited:
5454 <td>yes
5456 <tr>
5457 <td>Percentages:
5459 <td>N/A
5461 <tr>
5462 <td>Media:
5464 <td>visual
5466 <tr>
5467 <td>Computed value:
5469 <td>as specified
5471 <tr>
5472 <td>Animatable:
5474 <td>no
5475 </table>
5477 <p>Normally, authors can control the use of language-specific glyph
5478 substitutions and positioning by setting the content language of an
5479 element, as <a href="#language-specific-support">described above</a>:
5481 <pre><!-- Display text using S'gaw Karen specific features -->
5482 <p lang="ksw">...</p></pre>
5484 <p>In some cases, authors may need to specify a language system that
5485 differs from the content language, for example due to the need to mimic
5486 another language's typographic traditions. The ‘<a
5487 href="#propdef-font-language-override"><code
5488 class=property>font-language-override</code></a>’ property allows
5489 authors to explicitly specify the language system of the font, overriding
5490 the language system implied by the content language.
5492 <p>Values have the following meanings:
5494 <dl>
5495 <dt><dfn id=font-language-override-normal-value
5496 title="normal!!font-language-override">normal</dfn>
5498 <dd>specifies that when rendering with OpenType fonts, the content
5499 language of the element is used to infer the OpenType language system
5501 <dt><dfn
5502 id=font-language-override-string-value><var><string></var></dfn>
5504 <dd>single three-letter case-sensitive OpenType <a
5505 href="http://www.microsoft.com/typography/otspec/languagetags.htm">language
5506 system tag</a>, specifies the OpenType language system to be used instead
5507 of the language system implied by the language of the element
5508 </dl>
5509 <!-- For this level, string represents a single language code, there's no concept of "fallback"
5510 http://www.w3.org/2013/06/07-css-minutes.html#item04 -->
5512 <p>Use of invalid OpenType language system tags must not generate a parse
5513 error but must be ignored when doing glyph selection and placement.
5515 <div class=example>
5516 <p>The <a href="http://www.un.org/en/documents/udhr/index.shtml">Universal
5517 Declaration of Human Rights</a> has been translated into a wide variety
5518 of languages. In Turkish, Article 9 of this document might be marked up
5519 as below:</p>
5521 <pre lang=tr><body lang="tr">
5523 <h4>Madde 9</h4>
5524 <p>Hiç kimse keyfi olarak tutuklanamaz, alıkonulanamaz veya sürülemez.</p>
5525 </pre>
5527 <p>Here the user agent uses the value of the ‘<code
5528 class=property>lang</code>’ attribute when rendering text and
5529 appropriately renders this text without ‘<code
5530 class=property>fi</code>’ ligatures. There is no need to use the ‘<a
5531 href="#propdef-font-language-override"><code
5532 class=property>font-language-override</code></a>’ property.</p>
5534 <p>However, a given font may lack support for a specific language. In this
5535 situation authors may need to use the typographic conventions of a
5536 related language that are supported by that font:</p>
5538 <pre lang=mk><body lang="mk"> <!-- Macedonian lang code -->
5540 body { font-language-override: "SRB"; /* Serbian OpenType language tag */ }
5542 <h4>Члeн 9</h4>
5543 <p>Никoj чoвeк нeмa дa бидe пoдлoжeн нa прoизвoлнo aпсeњe, притвoр или прoгoнувaњe.</p>
5545 </pre>
5547 <p>The Macedonian text here will be rendered using Serbian typographic
5548 conventions, with the assumption that the font specified supports
5549 Serbian.</p>
5550 </div>
5552 <p><a id=rendering-considerations></a>
5554 <h2 id=font-feature-resolution><span class=secno>7 </span>Font Feature
5555 Resolution</h2>
5557 <p>As described in the previous section, font features can be enabled in a
5558 variety of ways, either via the use of <a href="#propdef-font-variant"
5559 title="font-variant!!property">‘<code
5560 class=property>font-variant</code>’</a> or <a
5561 href="#propdef-font-feature-settings"
5562 title="font-feature-settings!!property">‘<code
5563 class=property>font-feature-settings</code>’</a> in a style rule or
5564 within an <a href="#at-font-face-rule"><code>@font-face</code></a> rule.
5565 The resolution order for the union of these settings is defined below.
5566 Features defined via CSS properties are applied on top of layout engine
5567 default features.
5569 <h3 id=default-features><span class=secno>7.1 </span>Default features</h3>
5571 <p>For OpenType fonts, user agents must enable the default features defined
5572 in the OpenType documentation for a given script and writing mode.
5573 Required ligatures, common ligatures and contextual forms must be enabled
5574 by default (OpenType features: <span class=tag>rlig, liga, clig,
5575 calt</span>), along with localized forms (OpenType feature: <span
5576 class=tag>locl</span>), and features required for proper display of
5577 composed characters and marks (OpenType features: <span class=tag>ccmp,
5578 mark, mkmk</span>). These features must always be enabled, even when the
5579 value of the <a href="#propdef-font-variant"
5580 title="font-variant!!property">‘<code
5581 class=property>font-variant</code>’</a> and <a
5582 href="#propdef-font-feature-settings"
5583 title="font-feature-settings!!property">‘<code
5584 class=property>font-feature-settings</code>’</a> properties is <span
5585 title="normal value">‘<code class=property>normal</code>’</span>.
5586 Individual features are only disabled when explicitly overridden by the
5587 author, as when ‘<a href="#propdef-font-variant-ligatures"><code
5588 class=property>font-variant-ligatures</code></a>’ is set to ‘<a
5589 href="#no-common-ligatures"><code
5590 class=property>no-common-ligatures</code></a>’. For handling complex
5591 scripts such as <a
5592 href="http://www.microsoft.com/typography/otfntdev/arabicot/features.aspx">Arabic</a>,
5593 <a
5594 href="http://www.microsoft.com/typography/otfntdev/mongolot/features.htm">Mongolian</a>
5595 or <a
5596 href="http://www.microsoft.com/typography/otfntdev/devanot/features.aspx">Devanagari</a>
5597 additional features are required. For upright text within vertical text
5598 runs, vertical alternates (OpenType feature: <span class=tag>vert</span>)
5599 must be enabled.
5601 <h3 id=feature-precedence><span class=secno>7.2 </span>Feature precedence</h3>
5603 <p>General and <a href="#font-specific"><em>font specific</em></a> font
5604 feature property settings are resolved in the order below, in ascending
5605 order of precedence. This ordering is used to construct a combined list of
5606 font features that affect a given text run.
5608 <ol>
5609 <li>Font features enabled by default, including features required for a
5610 given script.
5612 <li>If the font is defined via an <a
5613 href="#at-font-face-rule"><code>@font-face</code></a> rule, the font
5614 features implied by the font-variant descriptor in the <a
5615 href="#at-font-face-rule"><code>@font-face</code></a> rule.
5617 <li>If the font is defined via an <a
5618 href="#at-font-face-rule"><code>@font-face</code></a> rule, the font
5619 features implied by the font-feature-settings descriptor in the <a
5620 href="#at-font-face-rule"><code>@font-face</code></a> rule.
5622 <li>Font features implied by the value of the <a
5623 href="#propdef-font-variant" title="font-variant!!property">‘<code
5624 class=property>font-variant</code>’</a> property, the related <a
5625 href="#propdef-font-variant" title="font-variant!!property">‘<code
5626 class=property>font-variant</code>’</a> subproperties and any other CSS
5627 property that uses OpenType features (e.g. the ‘<a
5628 href="#propdef-font-kerning"><code
5629 class=property>font-kerning</code></a>’ property).</li>
5630 <!-- other CSS props override 'font-variant' but not 'font-feature-settings' -->
5631 <!-- http://lists.w3.org/Archives/Public/www-style/2013Aug/0110.html -->
5633 <li>Feature settings determined by properties other than <a
5634 href="#propdef-font-variant" title="font-variant!!property">‘<code
5635 class=property>font-variant</code>’</a> or <a
5636 href="#propdef-font-feature-settings"
5637 title="font-feature-settings!!property">‘<code
5638 class=property>font-feature-settings</code>’</a>. For example, setting
5639 a non-default value for the ‘<code
5640 class=property>letter-spacing</code>’ property disables common
5641 ligatures.
5643 <li>Font features implied by the value of <a
5644 href="#propdef-font-feature-settings"
5645 title="font-feature-settings!!property">‘<code
5646 class=property>font-feature-settings</code>’</a> property.
5647 </ol>
5649 <p>This ordering allows authors to set up a general set of defaults for
5650 fonts within their <a
5651 href="#at-font-face-rule"><code>@font-face</code></a> rules, then override
5652 them with property settings for specific elements. General property
5653 settings override the settings in <a
5654 href="#at-font-face-rule"><code>@font-face</code></a> rules and low-level
5655 font feature settings override <a href="#propdef-font-variant"
5656 title="font-variant!!property">‘<code
5657 class=property>font-variant</code>’</a> property settings.
5659 <p>For situations where the combined list of font feature settings contains
5660 more than one value for the same feature, the last value is used. When a
5661 font lacks support for a given underlying font feature, text is simply
5662 rendered as if that font feature was not enabled; font fallback does not
5663 occur and no attempt is made to synthesize the feature except where
5664 explicitly defined for specific properties.
5666 <h3 id=feature-precedence-examples><span class=secno>7.3 </span>Feature
5667 precedence examples</h3>
5669 <div class=example>
5670 <p>With the styles below, numbers are rendered proportionally when used
5671 within a paragraph but are shown in tabular form within tables of prices:</p>
5673 <pre>body {
5674 font-variant-numeric: proportional-nums;
5675 }
5677 table.prices td {
5678 font-variant-numeric: tabular-nums;
5679 }
5680 </pre>
5681 </div>
5683 <div class=example>
5684 <p>When the <a href="#descdef-font-variant"
5685 title="font-variant!!descriptor">font-variant</a> descriptor is used
5686 within an <a href="#at-font-face-rule"><code>@font-face</code></a> rule,
5687 it only applies to the font defined by that rule.</p>
5689 <pre>@font-face {
5690 font-family: MainText;
5691 src: url(http://example.com/font.woff);
5692 font-variant: oldstyle-nums proportional-nums styleset(1,3);
5693 }
5695 body {
5696 font-family: MainText, Helvetica;
5697 }
5699 table.prices td {
5700 font-variant-numeric: tabular-nums;
5701 }
5702 </pre>
5704 <p>In this case, old-style numerals will be used throughout but only where
5705 the font "MainText" is used. Just as in the previous example, tabular
5706 values will be used in price tables since ‘<a
5707 href="#tabular-nums"><code class=property>tabular-nums</code></a>’
5708 appears in a general style rule and its use is mutually exclusive with
5709 ‘<a href="#proportional-nums"><code
5710 class=property>proportional-nums</code></a>’. Stylistic alternate sets
5711 will only be used where MainText is used.</p>
5712 </div>
5714 <div class=example>
5715 <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule can
5716 also be used to access font features in locally available fonts via the
5717 use of <code>local()</code> in the ‘<a href="#descdef-src"><code
5718 class=property>src</code></a>’ descriptor of the <a
5719 href="#at-font-face-rule"><code>@font-face</code></a> definition:</p>
5721 <pre>@font-face {
5722 font-family: BodyText;
5723 src: local("HiraMaruPro-W4");
5724 font-variant: proportional-width;
5725 font-feature-settings: "ital"; /* Latin italics within CJK text feature */
5726 }
5728 body { font-family: BodyText, serif; }
5729 </pre>
5731 <p>If available, a Japanese font "Hiragino Maru Gothic" will be used. When
5732 text rendering occurs, Japanese kana will be proportionally spaced and
5733 Latin text will be italicised. Text rendered with the fallback serif font
5734 will use default rendering properties.</p>
5735 </div>
5737 <div class=example>
5738 <p>In the example below, discretionary ligatures are enabled only for a
5739 downloadable font but are disabled within spans of class "special":</p>
5741 <pre>@font-face {
5742 font-family: main;
5743 src: url(fonts/ffmeta.woff) format("woff");
5744 font-variant: discretionary-ligatures;
5745 }
5747 body { font-family: main, Helvetica; }
5748 span.special { font-variant-ligatures: no-discretionary-ligatures; }
5749 </pre>
5751 <p>Suppose one adds a rule using ‘<code
5752 class=property>font-feature-settings</code>’ to enable discretionary
5753 ligatures:</p>
5755 <pre>body { font-family: main, Helvetica; }
5756 span { font-feature-settings: "dlig"; }
5757 span.special { font-variant-ligatures: no-discretionary-ligatures; }
5758 </pre>
5760 <p>In this case, discretionary ligatures <em>will</em> be rendered within
5761 spans of class "special". This is because both the <a
5762 href="#propdef-font-feature-settings"
5763 title="font-feature-settings!!property">‘<code
5764 class=property>font-feature-settings</code>’</a> and ‘<a
5765 href="#propdef-font-variant-ligatures"><code
5766 class=property>font-variant-ligatures</code></a>’ properties apply to
5767 these spans. Although the ‘<code class=css>no-discretionary
5768 ligatures</code>’ setting of ‘<a
5769 href="#propdef-font-variant-ligatures"><code
5770 class=property>font-variant-ligatures</code></a>’ effectively disables
5771 the OpenType <span class=tag>dlig</span> feature, because the <a
5772 href="#propdef-font-feature-settings"
5773 title="font-feature-settings!!property">‘<code
5774 class=property>font-feature-settings</code>’</a> is resolved after
5775 that, the ‘<code class=property>dlig</code>’ value reenables
5776 discretionary ligatures.</p>
5777 </div>
5779 <h2 id=object-model><span class=secno>8 </span>Object Model</h2>
5781 <p>The contents of <a href="#at-font-face-rule"><code>@font-face</code></a>
5782 and <a
5783 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
5784 rules can be accessed via the following extensions to the CSS Object
5785 Model.
5787 <h3 id=om-fontface><span class=secno>8.1 </span>The <a
5788 href="#cssfontfacerule"><code>CSSFontFaceRule</code></a> interface</h3>
5790 <p>The <dfn id=cssfontfacerule>CSSFontFaceRule</dfn> interface represents a
5791 <a href="#at-font-face-rule"><code>@font-face</code></a> rule.
5793 <pre class=idl>
5794 interface CSSFontFaceRule : CSSRule {
5795 attribute DOMString family;
5796 attribute DOMString src;
5797 attribute DOMString style;
5798 attribute DOMString weight;
5799 attribute DOMString stretch;
5800 attribute DOMString unicodeRange;
5801 attribute DOMString variant;
5802 attribute DOMString featureSettings;
5803 }</pre>
5805 <p>The DOM Level 2 Style specification <a href="#DOM-LEVEL-2-STYLE"
5806 rel=biblioentry>[DOM-LEVEL-2-STYLE]<!--{{DOM-LEVEL-2-STYLE}}--></a>
5807 defined a different variant of this rule. This definition supercedes that
5808 one.
5810 <h3 id=om-fontfeaturevalues><span class=secno>8.2 </span>The <a
5811 href="#cssfontfeaturevaluesrule"><code>CSSFontFeatureValuesRule</code></a>
5812 interface</h3>
5814 <p>The <code>CSSRule</code> interface is extended as follows:
5816 <pre class=idl>partial interface CSSRule {
5817 const unsigned short FONT_FEATURE_VALUES_RULE = 14;
5818 }</pre>
5820 <p>The <dfn id=cssfontfeaturevaluesrule>CSSFontFeatureValuesRule</dfn>
5821 interface represents a <a
5822 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
5823 rule.
5825 <pre class=idl>interface CSSFontFeatureValuesRule : CSSRule {
5826 attribute DOMString fontFamily;
5827 readonly attribute CSSFontFeatureValuesMap annotation;
5828 readonly attribute CSSFontFeatureValuesMap ornaments;
5829 readonly attribute CSSFontFeatureValuesMap stylistic;
5830 readonly attribute CSSFontFeatureValuesMap swash;
5831 readonly attribute CSSFontFeatureValuesMap characterVariant;
5832 readonly attribute CSSFontFeatureValuesMap styleset;
5833 }
5835 [MapClass(DOMString, sequence<unsigned long>)]
5836 interface CSSFontFeatureValuesMap {
5837 void set(DOMString featureValueName,
5838 (unsigned long or sequence<unsigned long>) values);
5839 }</pre>
5841 <dl class=idl-attributes>
5842 <dt><var>fontFamily</var> of type <code>DOMString</code>
5844 <dd>The list of one or more font families for which a given set of feature
5845 values is defined.
5847 <dt>value maps of type <code>CSSFontFeatureValuesMap</code>, readonly
5849 <dd>Maps of feature values associated with feature value names for a given
5850 ‘<a href="#propdef-font-variant-alternates"><code
5851 class=property>font-variant-alternates</code></a>’ value type
5852 </dl>
5854 <p>Each value map attribute of <a
5855 href="#cssfontfeaturevaluesrule"><code>CSSFontFeatureValuesRule</code></a>
5856 reflects the values defined via a corresponding <a
5857 href="#featurevalueblock"><i title="feature_value_block">feature value
5858 block</i></a>. Thus, the <var title="annotation
5859 attribute">annotation</var> attribute contains the values contained within
5860 a <code title="@annotation">@annotation</code> <a
5861 href="#featurevalueblock"><i title="feature_value_block">feature value
5862 block</i></a>, the <var title="ornaments attribute">ornaments</var>
5863 attribute contains the values contained with a <code
5864 title="@ornaments">@ornaments</code> <a href="#featurevalueblock"><i
5865 title="feature_value_block">feature value block</i></a> and so forth.
5867 <p>The <code>CSSFontFeatureValuesMap</code> interface uses the <a
5868 href="http://dev.w3.org/2006/webapi/WebIDL/#es-map-members">default map
5869 class methods</a> but the <code>set</code> method has different behavior.
5870 It takes a sequence of unsigned integers and associates it with a given
5871 <code>featureValueName</code>. The method behaves the same as the default
5872 map class method except that a single unsigned long value is treated as a
5873 sequence of a single value. The method throws an exception if an invalid
5874 number of values is passed in. If the associated <a
5875 href="#featurevalueblock"><i title="feature_value_block">feature value
5876 block</i></a> only allows a limited number of values, the <code>set</code>
5877 method throws an <code>InvalidAccessError</code> exception when the input
5878 sequence to <code>set</code> contains more than the limited number of
5879 values. See the description of <a
5880 href="#multi-valued-feature-value-definitions">multi-valued feature value
5881 definitions</a> for details on the maximum number of values allowed for a
5882 given type of <a href="#featurevalueblock"><i
5883 title="feature_value_block">feature value block</i></a>. The
5884 <code>get</code> method always returns a sequence of values, even if the
5885 sequence only contains a single value.
5887 <h2 class=no-num id=platform-props-to-css>Appendix A: Mapping platform font
5888 properties to CSS properties</h2>
5890 <p><em>This appendix is included as background for some of the problems and
5891 situations that are described in other sections. It should be viewed as
5892 informative only.</em>
5894 <p>Font properties in CSS are designed to be independent of the underlying
5895 font formats used; they can be used to specify bitmap fonts, Type1 fonts,
5896 SVG fonts in addition to the common TrueType and OpenType fonts. But there
5897 are facets of the TrueType and OpenType formats that often cause confusion
5898 for authors and present challenges to implementers on different platforms.
5900 <p>Originally developed at Apple, TrueType was designed as an outline font
5901 format for both screen and print. Microsoft joined Apple in developing the
5902 TrueType format and both platforms have supported TrueType fonts since
5903 then. Font data in the TrueType format consists of a set of tables
5904 distinguished with common four-letter tag names, each containing a
5905 specific type of data. For example, naming information, including
5906 copyright and license information, is stored in the ‘<code
5907 class=property>name</code>’ table. The <a
5908 href="#character-map"><em>character map</em></a> (‘<code
5909 class=property>cmap</code>’) table contains a mapping of character
5910 encodings to glyphs. Apple later added additional tables for supporting
5911 enhanced typographic functionality; these are now called Apple Advanced
5912 Typography, or AAT, fonts. Microsoft and Adobe developed a separate set of
5913 tables for advanced typography and called their format OpenType <a
5914 href="#OPENTYPE" rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a>.
5916 <p>In many cases the font data used under Microsoft Windows or Linux is
5917 slightly different from the data used under Apple's Mac OS X because the
5918 TrueType format allowed for explicit variation across platforms. This
5919 includes font metrics, names and <a href="#character-map"><em>character
5920 map</em></a> data.
5922 <p>Specifically, font family name data is handled differently across
5923 platforms. For TrueType and OpenType fonts these names are contained in
5924 the ‘<code class=property>name</code>’ table, in name records with
5925 name ID 1. Mulitple names can be stored for different locales, but
5926 Microsoft recommends fonts always include at least a US English version of
5927 the name. On Windows, Microsoft made the decision for backwards
5928 compatibility to limit this family name to a maximum of four faces; for
5929 larger groupings the "preferred family" (name ID 16) or "WWS family" (name
5930 ID 21) can be used. Other platforms such as OSX don't have this
5931 limitation, so the family name is used to define all possible groupings.
5933 <p>Other name table data provides names used to uniquely identify a
5934 specific face within a family. The full font name (name ID 4) and the
5935 Postscript name (name ID 6) describe a single face uniquely. For example,
5936 the bold face of the Gill Sans family has a fullname of "Gill Sans Bold"
5937 and a Postscript name of "GillSans-Bold". There can be multiple localized
5938 versions of the fullname for a given face, but the Postscript name is
5939 always a unique name made from a limited set of ASCII characters.
5941 <p>On various platforms, different names are used to search for a font. For
5942 example, with the Windows GDI CreateIndirectFont API, either a family or
5943 fullname can be used to lookup a face, while on Mac OS X the
5944 CTFontCreateWithName API call is used to lookup a given face using the
5945 fullname and Postscript name. Under Linux, the fontconfig API allows fonts
5946 to be searched using any of these names. In situations where platform
5947 API's automatically substitute other font choices, it may be necessary to
5948 verify a returned font matches a given name.
5950 <p>The weight of a given face can be determined via the usWeightClass field
5951 of the OS/2 table or inferred from the style name (name ID 2). Likewise,
5952 the width can be determined via the usWidthClass of the OS/2 table or
5953 inferred from the style name. For historical reasons related to synthetic
5954 bolding at weights 200 or lower with the Windows GDI API, font designers
5955 have sometimes skewed values in the OS/2 table to avoid these weights.
5957 <p>Rendering complex scripts that use contextual shaping such as Thai,
5958 Arabic and Devanagari requires features present only in OpenType or AAT
5959 fonts. Currently, complex script rendering is supported on Windows and
5960 Linux using OpenType font features while both OpenType and AAT font
5961 features are used under Mac OS X.
5963 <h2 class=no-num id=ch-ch-ch-changes>Changes</h2>
5965 <h3 class=no-num id=recent-changes> Changes from the <a
5966 href="http://www.w3.org/TR/2013/WD-css-fonts-3-20130711/">July 2013 CSS3
5967 Fonts Last Call Working Draft</a></h3>
5969 <ul>
5970 <li>reorder feature precedence such that features implied by other CSS
5971 properties override ‘<code class=property>font-variant</code>’
5972 settings
5974 <li>switched examples to use .woff files
5976 <li>revised wording of font fetching algorithm
5978 <li>drop ‘<code class=property>auto</code>’ value for ‘<a
5979 href="#propdef-font-size-adjust"><code
5980 class=property>font-size-adjust</code></a>’
5982 <li>clarify effect of ‘<a href="#propdef-font-size-adjust"><code
5983 class=property>font-size-adjust</code></a>’ on <a class=property
5984 href="http://www.w3.org/TR/CSS2/visudet.html#propdef-line-height">‘<code
5985 class=property>line-height</code>’</a>
5987 <li>allow user agents to synthesize OpenType <span class=tag>kern</span>
5988 feature
5990 <li>add example of ordinals and associated markup
5992 <li>minor editorial cleanups
5993 </ul>
5995 <h2 class=no-num id=acknowledgments>Acknowledgments</h2>
5997 <p>I'd like to thank Tal Leming, Jonathan Kew and Christopher Slye for all
5998 their help and feedback. John Hudson was kind enough to take the time to
5999 explain the subtleties of OpenType language tags and provided the example
6000 of character variant usage for displaying text on Byzantine seals. Ken
6001 Lunde and Eric Muller provided valuable feedback on CJK OpenType features
6002 and Unicode variation selectors. The idea for supporting font features by
6003 using <a href="#propdef-font-variant"
6004 title="font-variant!!property">‘<code
6005 class=property>font-variant</code>’</a> subproperties originated with
6006 Håkon Wium Lie, Adam Twardoch and Tal Leming. Elika Etemad supplied some
6007 of the initial design ideas for the <a
6008 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
6009 rule. Thanks also to House Industries for allowing the use of Ed Interlock
6010 in the discretionary ligatures example.
6012 <p>A special thanks to Robert Bringhurst for the sublime mind expansion
6013 that is <em>The Elements of Typographic Style</em>.
6015 <h2 class=no-num id=conformance> Conformance</h2>
6017 <h3 class=no-num id=conventions> Document Conventions</h3>
6019 <p>Conformance requirements are expressed with a combination of descriptive
6020 assertions and RFC 2119 terminology. The key words “MUST”, “MUST
6021 NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”,
6022 “SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL” in the
6023 normative parts of this document are to be interpreted as described in RFC
6024 2119. However, for readability, these words do not appear in all uppercase
6025 letters in this specification.
6027 <p>All of the text of this specification is normative except sections
6028 explicitly marked as non-normative, examples, and notes. <a
6029 href="#RFC2119" rel=biblioentry>[RFC2119]<!--{{!RFC2119}}--></a>
6031 <p>Examples in this specification are introduced with the words “for
6032 example” or are set apart from the normative text with
6033 <code>class="example"</code>, like this:
6035 <div class=example>
6036 <p>This is an example of an informative example.
6037 </div>
6039 <p>Informative notes begin with the word “Note” and are set apart from
6040 the normative text with <code>class="note"</code>, like this:
6042 <p class=note>Note, this is an informative note.
6044 <h3 class=no-num id=conformance-classes> Conformance Classes</h3>
6046 <p>Conformance to CSS Fonts Level 3 Module is defined for three conformance
6047 classes:
6049 <dl>
6050 <dt><dfn id=style-sheet title="style sheet!!as conformance class">style
6051 sheet</dfn>
6053 <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#style-sheet">CSS
6054 style sheet</a>.
6056 <dt><dfn id=renderer>renderer</dfn>
6058 <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
6059 that interprets the semantics of a style sheet and renders documents that
6060 use them.
6062 <dt><dfn id=authoring-tool>authoring tool</dfn>
6064 <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
6065 that writes a style sheet.
6066 </dl>
6068 <p>A style sheet is conformant to CSS Fonts Level 3 Module if all of its
6069 declarations that use properties defined in this module have values that
6070 are valid according to the generic CSS grammar and the individual grammars
6071 of each property as given in this module.
6073 <p>A renderer is conformant to CSS Fonts Level 3 Module if, in addition to
6074 interpreting the style sheet as defined by the appropriate specifications,
6075 it supports all the features defined by CSS Fonts Level 3 Module by
6076 parsing them correctly and rendering the document accordingly. However,
6077 the inability of a UA to correctly render a document due to limitations of
6078 the device does not make the UA non-conformant. (For example, a UA is not
6079 required to render color on a monochrome monitor.)
6081 <p>An authoring tool is conformant to CSS Fonts Level 3 Module if it writes
6082 style sheets that are syntactically correct according to the generic CSS
6083 grammar and the individual grammars of each feature in this module, and
6084 meet all other conformance requirements of style sheets as described in
6085 this module.
6087 <h3 class=no-num id=partial> Partial Implementations</h3>
6089 <p>So that authors can exploit the forward-compatible parsing rules to
6090 assign fallback values, CSS renderers <strong>must</strong> treat as
6091 invalid (and <a
6092 href="http://www.w3.org/TR/CSS21/conform.html#ignore">ignore as
6093 appropriate</a>) any at-rules, properties, property values, keywords, and
6094 other syntactic constructs for which they have no usable level of support.
6095 In particular, user agents <strong>must not</strong> selectively ignore
6096 unsupported component values and honor supported values in a single
6097 multi-value property declaration: if any value is considered invalid (as
6098 unsupported values must be), CSS requires that the entire declaration be
6099 ignored.
6101 <h3 class=no-num id=experimental> Experimental Implementations</h3>
6103 <p>To avoid clashes with future CSS features, the CSS2.1 specification
6104 reserves a <a
6105 href="http://www.w3.org/TR/CSS21/syndata.html#vendor-keywords">prefixed
6106 syntax</a> for proprietary and experimental extensions to CSS.
6108 <p>Prior to a specification reaching the Candidate Recommendation stage in
6109 the W3C process, all implementations of a CSS feature are considered
6110 experimental. The CSS Working Group recommends that implementations use a
6111 vendor-prefixed syntax for such features, including those in W3C Working
6112 Drafts. This avoids incompatibilities with future changes in the draft.
6114 <h3 class=no-num id=testing> Non-Experimental Implementations</h3>
6116 <p>Once a specification reaches the Candidate Recommendation stage,
6117 non-experimental implementations are possible, and implementors should
6118 release an unprefixed implementation of any CR-level feature they can
6119 demonstrate to be correctly implemented according to spec.
6121 <p>To establish and maintain the interoperability of CSS across
6122 implementations, the CSS Working Group requests that non-experimental CSS
6123 renderers submit an implementation report (and, if necessary, the
6124 testcases used for that implementation report) to the W3C before releasing
6125 an unprefixed implementation of any CSS features. Testcases submitted to
6126 W3C are subject to review and correction by the CSS Working Group.
6128 <p>Further information on submitting testcases and implementation reports
6129 can be found from on the CSS Working Group's website at <a
6130 href="http://www.w3.org/Style/CSS/Test/">http://www.w3.org/Style/CSS/Test/</a>.
6131 Questions should be directed to the <a
6132 href="http://lists.w3.org/Archives/Public/public-css-testsuite">public-css-testsuite@w3.org</a>
6133 mailing list.
6135 <h2 class=no-num id=references>References</h2>
6137 <h3 class=no-num id=normative-references>Normative References</h3>
6138 <!--begin-normative-->
6139 <!-- Sorted by label -->
6141 <dl class=bibliography>
6142 <dd style="display: none"><!-- keeps the doc valid if the DL is empty -->
6143 <!---->
6145 <dt id=CHARMOD>[CHARMOD]
6147 <dd>Martin J. Dürst; et al. <a
6148 href="http://www.w3.org/TR/2005/REC-charmod-20050215/"><cite>Character
6149 Model for the World Wide Web 1.0: Fundamentals.</cite></a> 15 February
6150 2005. W3C Recommendation. URL: <a
6151 href="http://www.w3.org/TR/2005/REC-charmod-20050215/">http://www.w3.org/TR/2005/REC-charmod-20050215/</a>
6152 </dd>
6153 <!---->
6155 <dt id=CORS>[CORS]
6157 <dd>Anne van Kesteren. <a
6158 href="http://www.w3.org/TR/2013/CR-cors-20130129/"><cite>Cross-Origin
6159 Resource Sharing.</cite></a> 29 January 2013. W3C Candidate
6160 Recommendation. (Work in progress.) URL: <a
6161 href="http://www.w3.org/TR/2013/CR-cors-20130129/">http://www.w3.org/TR/2013/CR-cors-20130129/</a>
6162 </dd>
6163 <!---->
6165 <dt id=CSS21>[CSS21]
6167 <dd>Bert Bos; et al. <a
6168 href="http://www.w3.org/TR/2011/REC-CSS2-20110607/"><cite>Cascading Style
6169 Sheets Level 2 Revision 1 (CSS 2.1) Specification.</cite></a> 7 June
6170 2011. W3C Recommendation. URL: <a
6171 href="http://www.w3.org/TR/2011/REC-CSS2-20110607/">http://www.w3.org/TR/2011/REC-CSS2-20110607/</a>
6172 </dd>
6173 <!---->
6175 <dt id=CSS3VAL>[CSS3VAL]
6177 <dd>Håkon Wium Lie; Tab Atkins; Elika J. Etemad. <a
6178 href="http://www.w3.org/TR/2013/CR-css3-values-20130730/"><cite>CSS
6179 Values and Units Module Level 3.</cite></a> 30 July 2013. W3C Candidate
6180 Recommendation. (Work in progress.) URL: <a
6181 href="http://www.w3.org/TR/2013/CR-css3-values-20130730/">http://www.w3.org/TR/2013/CR-css3-values-20130730/</a>
6182 </dd>
6183 <!---->
6185 <dt id=HTML5>[HTML5]
6187 <dd>Robin Berjon; et al. <a
6188 href="http://www.w3.org/TR/2013/CR-html5-20130806/"><cite>HTML5.</cite></a>
6189 6 August 2013. W3C Candidate Recommendation. (Work in progress.) URL: <a
6190 href="http://www.w3.org/TR/2013/CR-html5-20130806/">http://www.w3.org/TR/2013/CR-html5-20130806/</a>
6191 </dd>
6192 <!---->
6194 <dt id=OPEN-FONT-FORMAT>[OPEN-FONT-FORMAT]
6196 <dd><a
6197 href="http://standards.iso.org/ittf/PubliclyAvailableStandards/c052136_ISO_IEC_14496-22_2009%28E%29.zip"><cite>Information
6198 technology — Coding of audio-visual objects — Part 22: Open Font
6199 Format.</cite></a> International Organization for Standardization.
6200 ISO/IEC 14496-22:2009. URL: <a
6201 href="http://standards.iso.org/ittf/PubliclyAvailableStandards/c052136_ISO_IEC_14496-22_2009%28E%29.zip">http://standards.iso.org/ittf/PubliclyAvailableStandards/c052136_ISO_IEC_14496-22_2009%28E%29.zip</a>
6202 </dd>
6203 <!---->
6205 <dt id=OPENTYPE>[OPENTYPE]
6207 <dd><a
6208 href="http://www.microsoft.com/typography/otspec/default.htm"><cite>OpenType
6209 specification.</cite></a> Microsoft. URL: <a
6210 href="http://www.microsoft.com/typography/otspec/default.htm">http://www.microsoft.com/typography/otspec/default.htm</a>
6211 </dd>
6212 <!---->
6214 <dt id=OPENTYPE-FEATURES>[OPENTYPE-FEATURES]
6216 <dd><a
6217 href="http://www.microsoft.com/typography/otspec/featurelist.htm"><cite>OpenType
6218 feature registry.</cite></a> Microsoft. URL: <a
6219 href="http://www.microsoft.com/typography/otspec/featurelist.htm">http://www.microsoft.com/typography/otspec/featurelist.htm</a>
6220 </dd>
6221 <!---->
6223 <dt id=RFC2119>[RFC2119]
6225 <dd>S. Bradner. <a href="http://www.ietf.org/rfc/rfc2119.txt"><cite>Key
6226 words for use in RFCs to Indicate Requirement Levels.</cite></a> Internet
6227 RFC 2119. URL: <a
6228 href="http://www.ietf.org/rfc/rfc2119.txt">http://www.ietf.org/rfc/rfc2119.txt</a>
6229 </dd>
6230 <!---->
6232 <dt id=UAX15>[UAX15]
6234 <dd>Mark Davis; Ken Whistler. <a
6235 href="http://www.unicode.org/reports/tr15/"><cite>Unicode Normalization
6236 Forms.</cite></a> 31 August 2012. Unicode Standard Annex #15. URL: <a
6237 href="http://www.unicode.org/reports/tr15/">http://www.unicode.org/reports/tr15/</a>
6238 </dd>
6239 <!---->
6241 <dt id=UAX29>[UAX29]
6243 <dd>Mark Davis. <a
6244 href="http://www.unicode.org/reports/tr29/"><cite>Unicode Text
6245 Segmentation.</cite></a> 12 September 2012. Unicode Standard Annex #29.
6246 URL: <a
6247 href="http://www.unicode.org/reports/tr29/">http://www.unicode.org/reports/tr29/</a>
6248 </dd>
6249 <!---->
6251 <dt id=UNICODE>[UNICODE]
6253 <dd>The Unicode Consortium. <a
6254 href="http://www.unicode.org/standard/versions/enumeratedversions.html"><cite>The
6255 Unicode Standard.</cite></a> 2012. Defined by: The Unicode Standard,
6256 Version 6.2.0 (Mountain View, CA: The Unicode Consortium, 2012. ISBN
6257 978-1-936213-07-8), as updated from time to time by the publication of
6258 new versions URL: <a
6259 href="http://www.unicode.org/standard/versions/enumeratedversions.html">http://www.unicode.org/standard/versions/enumeratedversions.html</a>
6260 </dd>
6261 <!---->
6262 </dl>
6263 <!--end-normative-->
6264 <!--{{!CSS21}}-->
6265 <!--{{!CSS3VAL}}-->
6266 <!--{{!OPENTYPE}}-->
6267 <!--{{!OPENTYPE-FEATURES}}-->
6268 <!--{{!OPEN-FONT-FORMAT}}-->
6269 <!--{{!UNICODE}}-->
6270 <!--{{!UAX15}}-->
6271 <!--{{!UAX29}}-->
6272 <!--{{!CORS}}-->
6273 <!--{{!HTML5}}-->
6274 <!--{{!CHARMOD}}-->
6276 <h3 class=no-num id=other-references>Other References</h3>
6277 <!--begin-informative-->
6278 <!-- Sorted by label -->
6280 <dl class=bibliography>
6281 <dd style="display: none"><!-- keeps the doc valid if the DL is empty -->
6282 <!---->
6284 <dt id=AAT-FEATURES>[AAT-FEATURES]
6286 <dd><a href="http://developer.apple.com/fonts/registry/"><cite>Apple
6287 Advanced Typography font feature registry.</cite></a> Apple. URL: <a
6288 href="http://developer.apple.com/fonts/registry/">http://developer.apple.com/fonts/registry/</a>
6289 </dd>
6290 <!---->
6292 <dt id=ARABIC-TYPO>[ARABIC-TYPO]
6294 <dd>Huda Smitshuijzen AbiFares. <cite>Arabic Typography: A Comprehensive
6295 Sourcebook.</cite> Saqi Books. 2001. ISBN 0-86356-347-3.</dd>
6296 <!---->
6298 <dt id=CHARMOD-NORM>[CHARMOD-NORM]
6300 <dd>François Yergeau; et al. <a
6301 href="http://www.w3.org/TR/2012/WD-charmod-norm-20120501/"><cite>Character
6302 Model for the World Wide Web 1.0: Normalization.</cite></a> 1 May 2012.
6303 W3C Working Draft. (Work in progress.) URL: <a
6304 href="http://www.w3.org/TR/2012/WD-charmod-norm-20120501/">http://www.w3.org/TR/2012/WD-charmod-norm-20120501/</a>
6305 </dd>
6306 <!---->
6308 <dt id=CJKV-INFO-PROCESSING>[CJKV-INFO-PROCESSING]
6310 <dd>Ken Lunde. <cite>CJKV Information Processing, Second Edition.</cite>
6311 O'Reilly Media, Inc. 2009. ISBN 0-596-51447-1.</dd>
6312 <!---->
6314 <dt id=CSS3-CONDITIONAL>[CSS3-CONDITIONAL]
6316 <dd>L. David Baron. <a
6317 href="http://www.w3.org/TR/2013/CR-css3-conditional-20130404/"><cite>CSS
6318 Conditional Rules Module Level 3.</cite></a> 4 April 2013. W3C Candidate
6319 Recommendation. (Work in progress.) URL: <a
6320 href="http://www.w3.org/TR/2013/CR-css3-conditional-20130404/">http://www.w3.org/TR/2013/CR-css3-conditional-20130404/</a>
6321 </dd>
6322 <!---->
6324 <dt id=CSS3TEXT>[CSS3TEXT]
6326 <dd>Elika J. Etemad; Koji Ishii. <a
6327 href="http://www.w3.org/TR/2012/WD-css3-text-20121113/"><cite>CSS Text
6328 Module Level 3.</cite></a> 13 November 2012. W3C Working Draft. (Work in
6329 progress.) URL: <a
6330 href="http://www.w3.org/TR/2012/WD-css3-text-20121113/">http://www.w3.org/TR/2012/WD-css3-text-20121113/</a>
6331 </dd>
6332 <!---->
6334 <dt id=DIGITAL-TYPOGRAPHY>[DIGITAL-TYPOGRAPHY]
6336 <dd>Richard Rubinstein. <cite>Digital Typography, An Introduction to Type
6337 and Composition for Computer System Design.</cite> Addison-Wesley. 1988.
6338 ISBN 0-201-17633-5.</dd>
6339 <!---->
6341 <dt id=DOM-LEVEL-2-STYLE>[DOM-LEVEL-2-STYLE]
6343 <dd>Chris Wilson; Philippe Le Hégaret; Vidur Apparao. <a
6344 href="http://www.w3.org/TR/2000/REC-DOM-Level-2-Style-20001113/"><cite>Document
6345 Object Model (DOM) Level 2 Style Specification.</cite></a> 13 November
6346 2000. W3C Recommendation. URL: <a
6347 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>
6348 </dd>
6349 <!---->
6351 <dt id=ELEMTYPO>[ELEMTYPO]
6353 <dd>Robert Bringhurst. <cite>The Elements of Typographic Style, Version
6354 4.</cite> Hartley & Marks. 2013. ISBN 0-88179-212-8.</dd>
6355 <!---->
6357 <dt id=LANGCULTTYPE>[LANGCULTTYPE]
6359 <dd>John D. Berry, Ed. <cite>Language Culture Type.</cite> Graphis. 2001.
6360 ISBN 1-932026-01-0.</dd>
6361 <!---->
6363 <dt id=OPENTYPE-FONT-GUIDE>[OPENTYPE-FONT-GUIDE]
6365 <dd><a
6366 href="https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf"><cite>OpenType
6367 User Guide.</cite></a> FontShop International. URL: <a
6368 href="https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf">https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf</a>
6369 </dd>
6370 <!---->
6372 <dt id=RASTER-TRAGEDY>[RASTER-TRAGEDY]
6374 <dd>Beat Stamm. <a href="http://www.rastertragedy.com/"><cite>The Raster
6375 Tragedy at Low-Resolution Revisited.</cite></a> 7 December 2011. URL: <a
6376 href="http://www.rastertragedy.com/">http://www.rastertragedy.com/</a></dd>
6377 <!---->
6379 <dt id=WINDOWS-GLYPH-PROC>[WINDOWS-GLYPH-PROC]
6381 <dd>John Hudson. <a
6382 href="http://www.microsoft.com/typography/developers/opentype/default.htm"><cite>Windows
6383 Glyph Processing.</cite></a> Microsoft Typogrraphy. URL: <a
6384 href="http://www.microsoft.com/typography/developers/opentype/default.htm">http://www.microsoft.com/typography/developers/opentype/default.htm</a>
6385 </dd>
6386 <!---->
6387 </dl>
6388 <!--end-informative-->
6389 <!--{{ARABIC-TYPO}}-->
6390 <!--{{CJKV-INFO-PROCESSING}}-->
6391 <!--{{DIGITAL-TYPOGRAPHY}}-->
6392 <!--{{DOM-LEVEL-2-STYLE}}-->
6393 <!--{{ELEMTYPO}}-->
6394 <!--{{LANGCULTTYPE}}-->
6395 <!--{{OPENTYPE-FONT-GUIDE}}-->
6396 <!--{{RASTER-TRAGEDY}}-->
6397 <!--{{WINDOWS-GLYPH-PROC}}-->
6398 <!--{{CHARMOD-NORM}}-->
6399 <!--{{AAT-FEATURES}}-->
6400 <!--{{CSS3-CONDITIONAL}}-->
6401 <!--{{CSS3TEXT}}-->
6403 <h2 class=no-num id=index>Index</h2>
6404 <!--begin-index-->
6406 <ul class=indexlist>
6407 <li>100...900 weight values, <a href="#font-weight-numeric-values"
6408 title="100...900 weight values"><strong>3.2</strong></a>
6410 <li><var><absolute-size></var>, <a href="#absolute-size-value"
6411 title="<absolute-size>"><strong>3.5</strong></a>
6413 <li><var><common-lig-values></var>, <a href="#common-lig-values"
6414 title="<common-lig-values>"><strong>6.4</strong></a>
6416 <li><var><contextual-alt-values></var>, <a
6417 href="#contextual-alt-values"
6418 title="<contextual-alt-values>"><strong>6.4</strong></a>
6420 <li><var><discretionary-lig-values></var>, <a
6421 href="#discretionary-lig-values"
6422 title="<discretionary-lig-values>"><strong>6.4</strong></a>
6424 <li><var><east-asian-variant-values></var>, <a
6425 href="#east-asian-variant-values"
6426 title="<east-asian-variant-values>"><strong>6.10</strong></a>
6428 <li><var><east-asian-width-values></var>, <a
6429 href="#east-asian-width-values"
6430 title="<east-asian-width-values>"><strong>6.10</strong></a>
6432 <li><var><family-name></var>, <a href="#family-name-value"
6433 title="<family-name>"><strong>3.1</strong></a>
6435 <li><var><feature-tag-value></var>, <a href="#feature-tag-value"
6436 title="<feature-tag-value>"><strong>6.12</strong></a>
6438 <li><var><font-face-name></var>, <a href="#font-face-name-value"
6439 title="<font-face-name>"><strong>4.3</strong></a>
6441 <li><var><font-variant-css21></var>, <a
6442 href="#font-variant-css21-values"
6443 title="<font-variant-css21>"><strong>3.7</strong></a>
6445 <li><var><generic-family></var>, <a href="#generic-family-value"
6446 title="<generic-family>"><strong>3.1</strong></a>
6448 <li><var><historical-lig-values></var>, <a
6449 href="#historical-lig-values"
6450 title="<historical-lig-values>"><strong>6.4</strong></a>
6452 <li><var><length></var>, <a href="#length-size-value"
6453 title="<length>"><strong>3.5</strong></a>
6455 <li><var><number></var>, <a href="#aspect-ratio-value"
6456 title="<number>"><strong>3.6</strong></a>
6458 <li><var><numeric-figure-values></var>, <a
6459 href="#numeric-figure-values"
6460 title="<numeric-figure-values>"><strong>6.7</strong></a>
6462 <li><var><numeric-fraction-values></var>, <a
6463 href="#numeric-fraction-values"
6464 title="<numeric-fraction-values>"><strong>6.7</strong></a>
6466 <li><var><numeric-spacing-values></var>, <a
6467 href="#numeric-spacing-values"
6468 title="<numeric-spacing-values>"><strong>6.7</strong></a>
6470 <li><var><percentage></var>, <a href="#percentage-size-value"
6471 title="<percentage>"><strong>3.5</strong></a>
6473 <li><var><relative-size></var>, <a href="#relative-size-value"
6474 title="<relative-size>"><strong>3.5</strong></a>
6476 <li><var><string></var>, <a
6477 href="#font-language-override-string-value"
6478 title="<string>"><strong>6.13</strong></a>
6480 <li><var><urange></var>, <a href="#urange-value"
6481 title="<urange>"><strong>4.5</strong></a>
6483 <li><code>@font-face</code>, <a href="#at-font-face-rule"
6484 title="@font-face"><strong>4.1</strong></a>
6486 <li><code>@font-feature-values</code>, <a
6487 href="#at-font-feature-values-rule"
6488 title="@font-feature-values"><strong>6.9</strong></a>
6490 <li>all-petite-caps, <a href="#all-petite-caps"
6491 title=all-petite-caps><strong>6.6</strong></a>
6493 <li>all-small-caps, <a href="#all-small-caps"
6494 title=all-small-caps><strong>6.6</strong></a>
6496 <li>annotation, <a href="#annotation"
6497 title=annotation><strong>6.8</strong></a>
6499 <li>aspect value, <a href="#aspect-value0" title="aspect
6500 value"><strong>3.6</strong></a>
6502 <li>authoring tool, <a href="#authoring-tool" title="authoring
6503 tool"><strong>#</strong></a>
6505 <li>auto
6506 <ul>
6507 <li>font-kerning, <a href="#font-kerning-auto-value" title="auto,
6508 font-kerning"><strong>6.3</strong></a>
6509 </ul>
6511 <li>bold, <a href="#bold" title=bold><strong>3.2</strong></a>
6513 <li>bolder, <a href="#bolder" title=bolder><strong>3.2</strong></a>
6515 <li>character map, <a href="#character-map" title="character
6516 map"><strong>5.2</strong></a>
6518 <li>character-variant, <a href="#character-variant"
6519 title=character-variant><strong>6.8</strong></a>
6521 <li>common-ligatures, <a href="#common-ligatures"
6522 title=common-ligatures><strong>6.4</strong></a>
6524 <li>composite face, <a href="#composite-face" title="composite
6525 face"><strong>5.2</strong></a>
6527 <li>condensed, <a href="#condensed"
6528 title=condensed><strong>3.3</strong></a>
6530 <li>contextual, <a href="#contextual"
6531 title=contextual><strong>6.4</strong></a>
6533 <li>CSSFontFaceRule, <a href="#cssfontfacerule"
6534 title=CSSFontFaceRule><strong>8.1</strong></a>
6536 <li>CSSFontFeatureValuesRule, <a href="#cssfontfeaturevaluesrule"
6537 title=CSSFontFeatureValuesRule><strong>8.2</strong></a>
6539 <li>cursive, definition of, <a href="#cursive0" title="cursive, definition
6540 of"><strong>#</strong></a>
6542 <li>default face, <a href="#default-face" title="default
6543 face"><strong>5.2</strong></a>
6545 <li>descriptor_declaration, <a href="#descriptordeclaration"
6546 title="descriptor_declaration"><strong>4.1</strong></a>
6548 <li>diagonal-fractions, <a href="#diagonal-fractions"
6549 title=diagonal-fractions><strong>6.7</strong></a>
6551 <li>discretionary-ligatures, <a href="#discretionary-ligatures"
6552 title=discretionary-ligatures><strong>6.4</strong></a>
6554 <li>effective character map, <a href="#effective-character-map"
6555 title="effective character map"><strong>4.5</strong></a>
6557 <li>expanded, <a href="#expanded" title=expanded><strong>3.3</strong></a>
6559 <li>extra-condensed, <a href="#extra-condensed"
6560 title=extra-condensed><strong>3.3</strong></a>
6562 <li>extra-expanded, <a href="#extra-expanded"
6563 title=extra-expanded><strong>3.3</strong></a>
6565 <li>fantasy, definition of, <a href="#fantasy0" title="fantasy, definition
6566 of"><strong>#</strong></a>
6568 <li>feature_type, <a href="#featuretype"
6569 title="feature_type"><strong>6.9.1</strong></a>
6571 <li>feature_value_block, <a href="#featurevalueblock"
6572 title="feature_value_block"><strong>6.9.1</strong></a>
6574 <li>feature_value_definition, <a href="#featurevaluedefinition"
6575 title="feature_value_definition"><strong>6.9.1</strong></a>
6577 <li>first available font, <a href="#first-available-font" title="first
6578 available font"><strong>5.2</strong></a>
6580 <li>font, <a href="#propdef-font" title=font><strong>3.7</strong></a>
6582 <li>font specific, <a href="#font-specific" title="font
6583 specific"><strong>6.8</strong></a>
6585 <li>font-family
6586 <ul>
6587 <li>descriptor, <a href="#descdef-font-family" title="font-family,
6588 descriptor"><strong>4.2</strong></a>
6590 <li>property, <a href="#propdef-font-family" title="font-family,
6591 property"><strong>3.1</strong></a>
6592 </ul>
6594 <li>font-feature-settings
6595 <ul>
6596 <li>descriptor, <a href="#descdef-font-feature-settings"
6597 title="font-feature-settings, descriptor"><strong>4.7</strong></a>
6599 <li>property, <a href="#propdef-font-feature-settings"
6600 title="font-feature-settings, property"><strong>6.12</strong></a>
6601 </ul>
6603 <li>font-kerning, <a href="#propdef-font-kerning"
6604 title=font-kerning><strong>6.3</strong></a>
6606 <li>font-language-override, <a href="#propdef-font-language-override"
6607 title=font-language-override><strong>6.13</strong></a>
6609 <li>font-size, <a href="#propdef-font-size"
6610 title=font-size><strong>3.5</strong></a>
6612 <li>font-size-adjust, <a href="#propdef-font-size-adjust"
6613 title=font-size-adjust><strong>3.6</strong></a>
6615 <li>font-stretch
6616 <ul>
6617 <li>descriptor, <a href="#descdef-font-stretch" title="font-stretch,
6618 descriptor"><strong>4.4</strong></a>
6620 <li>property, <a href="#propdef-font-stretch" title="font-stretch,
6621 property"><strong>3.3</strong></a>
6622 </ul>
6624 <li>font-style
6625 <ul>
6626 <li>descriptor, <a href="#descdef-font-style" title="font-style,
6627 descriptor"><strong>4.4</strong></a>
6629 <li>property, <a href="#propdef-font-style" title="font-style,
6630 property"><strong>3.4</strong></a>
6631 </ul>
6633 <li>font-synthesis, <a href="#propdef-font-synthesis"
6634 title=font-synthesis><strong>3.8</strong></a>
6636 <li>font-variant
6637 <ul>
6638 <li>descriptor, <a href="#descdef-font-variant" title="font-variant,
6639 descriptor"><strong>4.7</strong></a>
6641 <li>property, <a href="#propdef-font-variant" title="font-variant,
6642 property"><strong>6.11</strong></a>
6643 </ul>
6645 <li>font-variant-alternates, <a href="#propdef-font-variant-alternates"
6646 title=font-variant-alternates><strong>6.8</strong></a>
6648 <li>font-variant-caps, <a href="#propdef-font-variant-caps"
6649 title=font-variant-caps><strong>6.6</strong></a>
6651 <li>font-variant-east-asian, <a href="#propdef-font-variant-east-asian"
6652 title=font-variant-east-asian><strong>6.10</strong></a>
6654 <li>font-variant-ligatures, <a href="#propdef-font-variant-ligatures"
6655 title=font-variant-ligatures><strong>6.4</strong></a>
6657 <li>font-variant-numeric, <a href="#propdef-font-variant-numeric"
6658 title=font-variant-numeric><strong>6.7</strong></a>
6660 <li>font-variant-position, <a href="#propdef-font-variant-position"
6661 title=font-variant-position><strong>6.5</strong></a>
6663 <li>font-weight
6664 <ul>
6665 <li>descriptor, <a href="#descdef-font-weight" title="font-weight,
6666 descriptor"><strong>4.4</strong></a>
6668 <li>property, <a href="#propdef-font-weight" title="font-weight,
6669 property"><strong>3.2</strong></a>
6670 </ul>
6672 <li>font_face_rule, <a href="#fontfacerule"
6673 title="font_face_rule"><strong>4.1</strong></a>
6675 <li>FONT_FACE_SYM, <a href="#fontfacesym"
6676 title="FONT_FACE_SYM"><strong>4.1</strong></a>
6678 <li>font_family_name, <a href="#fontfamilyname"
6679 title="font_family_name"><strong>6.9.1</strong></a>
6681 <li>font_family_name_list, <a href="#fontfamilynamelist"
6682 title="font_family_name_list"><strong>6.9.1</strong></a>
6684 <li>font_feature_values_rule, <a href="#fontfeaturevaluesrule"
6685 title="font_feature_values_rule"><strong>6.9.1</strong></a>
6687 <li>FONT_FEATURE_VALUES_SYM, <a href="#fontfeaturevaluessym"
6688 title="FONT_FEATURE_VALUES_SYM"><strong>6.9.1</strong></a>
6690 <li>full-width, <a href="#full-width"
6691 title=full-width><strong>6.10</strong></a>
6693 <li>historical-forms, <a href="#historical-forms"
6694 title=historical-forms><strong>6.8</strong></a>
6696 <li>historical-ligatures, <a href="#historical-ligatures"
6697 title=historical-ligatures><strong>6.4</strong></a>
6699 <li>italic, <a href="#italic" title=italic><strong>3.4</strong></a>
6701 <li>jis04, <a href="#jis04" title=jis04><strong>6.10</strong></a>
6703 <li>jis78, <a href="#jis78" title=jis78><strong>6.10</strong></a>
6705 <li>jis83, <a href="#jis83" title=jis83><strong>6.10</strong></a>
6707 <li>jis90, <a href="#jis90" title=jis90><strong>6.10</strong></a>
6709 <li>lighter, <a href="#lighter" title=lighter><strong>3.2</strong></a>
6711 <li>lining-nums, <a href="#lining-nums"
6712 title=lining-nums><strong>6.7</strong></a>
6714 <li>monospace, definition of, <a href="#monospace0" title="monospace,
6715 definition of"><strong>#</strong></a>
6717 <li>no-common-ligatures, <a href="#no-common-ligatures"
6718 title=no-common-ligatures><strong>6.4</strong></a>
6720 <li>no-contextual, <a href="#no-contextual"
6721 title=no-contextual><strong>6.4</strong></a>
6723 <li>no-discretionary-ligatures, <a href="#no-discretionary-ligatures"
6724 title=no-discretionary-ligatures><strong>6.4</strong></a>
6726 <li>no-historical-ligatures, <a href="#no-historical-ligatures"
6727 title=no-historical-ligatures><strong>6.4</strong></a>
6729 <li>none
6730 <ul>
6731 <li>font-kerning, <a href="#font-kerning-none-value" title="none,
6732 font-kerning"><strong>6.3</strong></a>
6734 <li>font-size-adjust, <a href="#font-size-adjust-none-value"
6735 title="none, font-size-adjust"><strong>3.6</strong></a>
6737 <li>font-variant, <a href="#font-variant-none-value" title="none,
6738 font-variant"><strong>6.11</strong></a>
6740 <li>font-variant-ligatures, <a href="#font-variant-ligatures-none-value"
6741 title="none, font-variant-ligatures"><strong>6.4</strong></a>
6742 </ul>
6744 <li>normal
6745 <ul>
6746 <li>font-feature-settings, <a href="#font-feature-settings-normal-value"
6747 title="normal, font-feature-settings"><strong>6.12</strong></a>
6749 <li>font-kerning, <a href="#font-kerning-normal-value" title="normal,
6750 font-kerning"><strong>6.3</strong></a>
6752 <li>font-language-override, <a
6753 href="#font-language-override-normal-value" title="normal,
6754 font-language-override"><strong>6.13</strong></a>
6756 <li>font-stretch, <a href="#font-stretch-normal-value" title="normal,
6757 font-stretch"><strong>3.3</strong></a>
6759 <li>font-style, <a href="#font-style-normal-value" title="normal,
6760 font-style"><strong>3.4</strong></a>
6762 <li>font-variant, <a href="#font-variant-normal-value" title="normal,
6763 font-variant"><strong>6.11</strong></a>
6765 <li>font-variant-alternates, <a
6766 href="#font-variant-alternates-normal-value" title="normal,
6767 font-variant-alternates"><strong>6.8</strong></a>
6769 <li>font-variant-caps, <a href="#font-variant-caps-normal-value"
6770 title="normal, font-variant-caps"><strong>6.6</strong></a>
6772 <li>font-variant-east-asian, <a
6773 href="#font-variant-east-asian-normal-value" title="normal,
6774 font-variant-east-asian"><strong>6.10</strong></a>
6776 <li>font-variant-ligatures, <a
6777 href="#font-variant-ligatures-normal-value" title="normal,
6778 font-variant-ligatures"><strong>6.4</strong></a>
6780 <li>font-variant-numeric, <a href="#font-variant-numeric-normal-value"
6781 title="normal, font-variant-numeric"><strong>6.7</strong></a>
6783 <li>font-variant-position, <a href="#font-variant-position-normal-value"
6784 title="normal, font-variant-position"><strong>6.5</strong></a>
6786 <li>font-weight, <a href="#font-weight-normal-value" title="normal,
6787 font-weight"><strong>3.2</strong></a>
6788 </ul>
6790 <li>oblique, <a href="#oblique" title=oblique><strong>3.4</strong></a>
6792 <li>oldstyle-nums, <a href="#oldstyle-nums"
6793 title=oldstyle-nums><strong>6.7</strong></a>
6795 <li>ordinal, <a href="#ordinal" title=ordinal><strong>6.7</strong></a>
6797 <li>ornaments, <a href="#ornaments"
6798 title=ornaments><strong>6.8</strong></a>
6800 <li>petite-caps, <a href="#petite-caps"
6801 title=petite-caps><strong>6.6</strong></a>
6803 <li>proportional-nums, <a href="#proportional-nums"
6804 title=proportional-nums><strong>6.7</strong></a>
6806 <li>proportional-width, <a href="#proportional-width"
6807 title=proportional-width><strong>6.10</strong></a>
6809 <li>renderer, <a href="#renderer" title=renderer><strong>#</strong></a>
6811 <li>ruby, <a href="#ruby" title=ruby><strong>6.10</strong></a>
6813 <li>sans-serif, definition of, <a href="#sans-serif0" title="sans-serif,
6814 definition of"><strong>#</strong></a>
6816 <li>semi-condensed, <a href="#semi-condensed-"
6817 title=semi-condensed><strong>3.3</strong></a>
6819 <li>semi-expanded, <a href="#semi-expanded"
6820 title=semi-expanded><strong>3.3</strong></a>
6822 <li>serif, definition of, <a href="#serif0" title="serif, definition
6823 of"><strong>#</strong></a>
6825 <li>simplified, <a href="#simplified"
6826 title=simplified><strong>6.10</strong></a>
6828 <li>slashed-zero, <a href="#slashed-zero"
6829 title=slashed-zero><strong>6.7</strong></a>
6831 <li>small-caps, <a href="#small-caps"
6832 title=small-caps><strong>6.6</strong></a>
6834 <li>src, <a href="#descdef-src" title=src><strong>4.3</strong></a>
6836 <li>stacked-fractions, <a href="#stacked-fractions"
6837 title=stacked-fractions><strong>6.7</strong></a>
6839 <li>style sheet
6840 <ul>
6841 <li>as conformance class, <a href="#style-sheet" title="style sheet, as
6842 conformance class"><strong>#</strong></a>
6843 </ul>
6845 <li>styleset, <a href="#styleset" title=styleset><strong>6.8</strong></a>
6847 <li>stylistic, <a href="#stylistic"
6848 title=stylistic><strong>6.8</strong></a>
6850 <li>sub, <a href="#sub" title=sub><strong>6.5</strong></a>
6852 <li>super, <a href="#super" title=super><strong>6.5</strong></a>
6854 <li>support, <a href="#support" title=support><strong>5.2</strong></a>
6856 <li>swash, <a href="#swash" title=swash><strong>6.8</strong></a>
6858 <li>system font fallback, <a href="#system-font-fallback" title="system
6859 font fallback"><strong>5.2</strong></a>
6861 <li>tabular-nums, <a href="#tabular-nums"
6862 title=tabular-nums><strong>6.7</strong></a>
6864 <li>titling-caps, <a href="#titling-caps"
6865 title=titling-caps><strong>6.6</strong></a>
6867 <li>traditional, <a href="#traditional"
6868 title=traditional><strong>6.10</strong></a>
6870 <li>ultra-condensed, <a href="#ultra-condensed"
6871 title=ultra-condensed><strong>3.3</strong></a>
6873 <li>ultra-expanded, <a href="#ultra-expanded"
6874 title=ultra-expanded><strong>3.3</strong></a>
6876 <li>unicase, <a href="#unicase" title=unicase><strong>6.6</strong></a>
6878 <li>unicode-range, <a href="#descdef-unicode-range"
6879 title=unicode-range><strong>4.5</strong></a>
6881 <li>weight, <a href="#weight" title=weight><strong>2</strong></a>
6883 <li>width, <a href="#width" title=width><strong>2</strong></a>
6884 </ul>
6885 <!--end-index-->
6887 <h2 class=no-num id=property-index>Property index</h2>
6888 <!--begin-properties-->
6890 <table class=proptable>
6891 <thead>
6892 <tr>
6893 <th>Property
6895 <th>Values
6897 <th>Initial
6899 <th>Applies to
6901 <th>Inh.
6903 <th>Percentages
6905 <th>Media
6907 <tbody>
6908 <tr>
6909 <th><a class=property href="#propdef-font">font</a>
6911 <td>[ [ <‘font-style’> || <font-variant-css21> ||
6912 <‘font-weight’> || <‘font-stretch’ ]?
6913 <‘font-size’> [ / <‘line-height’> ]?
6914 <‘font-family’> ] | caption | icon | menu | message-box |
6915 small-caption | status-bar
6917 <td>see individual properties
6919 <td>all elements
6921 <td>yes
6923 <td>see individual properties
6925 <td>visual
6927 <tr>
6928 <th><span class=property>font-family</span>
6930 <td>[ <family-name> | <generic-family> ] #
6932 <td>depends on user agent
6934 <td>all elements
6936 <td>yes
6938 <td>N/A
6940 <td>visual
6942 <tr>
6943 <th><span class=property>font-feature-settings</span>
6945 <td>normal | <feature-tag-value> #
6947 <td>normal
6949 <td>all elements
6951 <td>yes
6953 <td>N/A
6955 <td>visual
6957 <tr>
6958 <th><a class=property href="#propdef-font-kerning">font-kerning</a>
6960 <td>auto | normal | none
6962 <td>auto
6964 <td>all elements
6966 <td>yes
6968 <td>N/A
6970 <td>visual
6972 <tr>
6973 <th><a class=property
6974 href="#propdef-font-language-override">font-language-override</a>
6976 <td>normal | <string>
6978 <td>normal
6980 <td>all elements
6982 <td>yes
6984 <td>N/A
6986 <td>visual
6988 <tr>
6989 <th><a class=property href="#propdef-font-size">font-size</a>
6991 <td><absolute-size> | <relative-size> | <length> |
6992 <percentage>
6994 <td>medium
6996 <td>all elements
6998 <td>yes
7000 <td>refer to parent element's font size
7002 <td>visual
7004 <tr>
7005 <th><a class=property
7006 href="#propdef-font-size-adjust">font-size-adjust</a>
7008 <td>none | <number>
7010 <td>none
7012 <td>all elements
7014 <td>yes
7016 <td>N/A
7018 <td>visual
7020 <tr>
7021 <th><span class=property>font-stretch</span>
7023 <td>normal | ultra-condensed | extra-condensed | condensed |
7024 semi-condensed | semi-expanded | expanded | extra-expanded |
7025 ultra-expanded
7027 <td>normal
7029 <td>all elements
7031 <td>yes
7033 <td>N/A
7035 <td>visual
7037 <tr>
7038 <th><span class=property>font-style</span>
7040 <td>normal | italic | oblique
7042 <td>normal
7044 <td>all elements
7046 <td>yes
7048 <td>N/A
7050 <td>visual
7052 <tr>
7053 <th><a class=property href="#propdef-font-synthesis">font-synthesis</a>
7055 <td>none | [ weight || style ]
7057 <td>weight style
7059 <td>all elements
7061 <td>yes
7063 <td>N/A
7065 <td>visual
7067 <tr>
7068 <th><span class=property>font-variant</span>
7070 <td>normal | none | [ <common-lig-values> ||
7071 <discretionary-lig-values> || <historical-lig-values> ||
7072 <contextual-alt-values> || stylistic(<feature-value-name>)
7073 || historical-forms || styleset(<feature-value-name> #) ||
7074 character-variant(<feature-value-name> #) ||
7075 swash(<feature-value-name>) ||
7076 ornaments(<feature-value-name>) ||
7077 annotation(<feature-value-name>) || [ small-caps | all-small-caps
7078 | petite-caps | all-petite-caps | unicase | titling-caps ] ||
7079 <numeric-figure-values> || <numeric-spacing-values> ||
7080 <numeric-fraction-values> || ordinal || slashed-zero ||
7081 <east-asian-variant-values> || <east-asian-width-values> ||
7082 ruby ]
7084 <td>normal
7086 <td>all elements
7088 <td>yes
7090 <td>see individual properties
7092 <td>visual
7094 <tr>
7095 <th><a class=property
7096 href="#propdef-font-variant-alternates">font-variant-alternates</a>
7098 <td>normal | [ stylistic(<feature-value-name>) || historical-forms
7099 || styleset(<feature-value-name> #) ||
7100 character-variant(<feature-value-name> #) ||
7101 swash(<feature-value-name>) ||
7102 ornaments(<feature-value-name>) ||
7103 annotation(<feature-value-name>) ]
7105 <td>normal
7107 <td>all elements
7109 <td>yes
7111 <td>N/A
7113 <td>visual
7115 <tr>
7116 <th><a class=property
7117 href="#propdef-font-variant-caps">font-variant-caps</a>
7119 <td>normal | small-caps | all-small-caps | petite-caps | all-petite-caps
7120 | unicase | titling-caps
7122 <td>normal
7124 <td>all elements
7126 <td>yes
7128 <td>N/A
7130 <td>visual
7132 <tr>
7133 <th><a class=property
7134 href="#propdef-font-variant-east-asian">font-variant-east-asian</a>
7136 <td>normal | [ <east-asian-variant-values> ||
7137 <east-asian-width-values> || ruby ]
7139 <td>normal
7141 <td>all elements
7143 <td>yes
7145 <td>N/A
7147 <td>visual
7149 <tr>
7150 <th><a class=property
7151 href="#propdef-font-variant-ligatures">font-variant-ligatures</a>
7153 <td>normal | none | [ <common-lig-values> ||
7154 <discretionary-lig-values> || <historical-lig-values> ||
7155 <contextual-alt-values> ]
7157 <td>normal
7159 <td>all elements
7161 <td>yes
7163 <td>N/A
7165 <td>visual
7167 <tr>
7168 <th><a class=property
7169 href="#propdef-font-variant-numeric">font-variant-numeric</a>
7171 <td>normal | [ <numeric-figure-values> ||
7172 <numeric-spacing-values> || <numeric-fraction-values> ||
7173 ordinal || slashed-zero ]
7175 <td>normal
7177 <td>all elements
7179 <td>yes
7181 <td>N/A
7183 <td>visual
7185 <tr>
7186 <th><a class=property
7187 href="#propdef-font-variant-position">font-variant-position</a>
7189 <td>normal | sub | super
7191 <td>normal
7193 <td>all elements
7195 <td>yes
7197 <td>N/A
7199 <td>visual
7201 <tr>
7202 <th><span class=property>font-weight</span>
7204 <td>normal | bold | bolder | lighter | 100 | 200 | 300 | 400 | 500 | 600
7205 | 700 | 800 | 900
7207 <td>normal
7209 <td>all elements
7211 <td>yes
7213 <td>N/A
7215 <td>visual
7216 </table>
7217 <!--end-properties-->
7218 <!--begin-descriptors-->
7220 <table class=proptable>
7221 <thead>
7222 <tr>
7223 <th>Descriptor
7225 <th>Value
7227 <th>Initial
7229 <th>Percentages
7231 <th>Media
7233 <tbody>
7234 <tr>
7235 <th><span class=property>font-family</span>
7237 <td><family-name>
7239 <td>N/A
7241 <tr>
7242 <th><span class=property>font-feature-settings</span>
7244 <td>normal | <feature-tag-value> #
7246 <td>normal
7248 <tr>
7249 <th><span class=property>font-stretch</span>
7251 <td>normal | ultra-condensed | extra-condensed | condensed |
7252 semi-condensed | semi-expanded | expanded | extra-expanded |
7253 ultra-expanded
7255 <td>normal
7257 <tr>
7258 <th><span class=property>font-style</span>
7260 <td>normal | italic | oblique
7262 <td>normal
7264 <tr>
7265 <th><span class=property>font-variant</span>
7267 <td>normal | none | [ <common-lig-values> ||
7268 <discretionary-lig-values> || <historical-lig-values> ||
7269 <contextual-alt-values> || stylistic(<feature-value-name>)
7270 || historical-forms || styleset(<feature-value-name> #) ||
7271 character-variant(<feature-value-name> #) ||
7272 swash(<feature-value-name>) ||
7273 ornaments(<feature-value-name>) ||
7274 annotation(<feature-value-name>) || [ small-caps | all-small-caps
7275 | petite-caps | all-petite-caps | unicase | titling-caps ] ||
7276 <numeric-figure-values> || <numeric-spacing-values> ||
7277 <numeric-fraction-values> || ordinal || slashed-zero ||
7278 <east-asian-variant-values> || <east-asian-width-values> ||
7279 ruby ]
7281 <td>normal
7283 <tr>
7284 <th><span class=property>font-weight</span>
7286 <td>normal | bold | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900
7288 <td>normal
7290 <tr>
7291 <th><a class=property href="#descdef-src">src</a>
7293 <td>[ <url> [format(<string> #)]? | <font-face-name> ] #
7295 <td>N/A
7297 <tr>
7298 <th><a class=property href="#descdef-unicode-range">unicode-range</a>
7300 <td><urange> #
7302 <td>U+0-10FFFF
7303 </table>
7304 <!--end-descriptors-->
7305 <script type="text/javascript">
7306 window.onload = function () {
7307 if (!("devicePixelRatio" in window && window.devicePixelRatio > 1)) return;
7308 var i, hiresElements = document.getElementsByClassName("hires");
7309 for (i = 0; i < hiresElements.length; i++) {
7310 var h = hiresElements[i];
7311 if (h.tagName != "IMG") continue;
7312 var src = h.getAttribute("src");
7313 var src2x = src.replace(/\.\w+$/, function(m) { return "@2x" + m; });
7314 h.src = src2x;
7315 }
7316 }
7317 </script>
7318 </html>
7319 <!-- Keep this comment at the end of the file
7320 Local variables:
7321 mode: sgml
7322 sgml-declaration:"~/SGML/HTML4.decl"
7323 sgml-default-doctype-name:"html"
7324 sgml-minimize-attributes:t
7325 sgml-nofill-elements:("pre" "style" "br")
7326 sgml-live-element-indicator:t
7327 sgml-omittag:nil
7328 sgml-shorttag:nil
7329 sgml-namecase-general:t
7330 sgml-general-insert-case:lower
7331 sgml-always-quote-attributes:t
7332 sgml-indent-step:nil
7333 sgml-indent-data:t
7334 sgml-parent-document:nil
7335 sgml-exposed-tags:nil
7336 sgml-local-catalogs:nil
7337 sgml-local-ecat-files:nil
7338 End:
7339 -->
7340 <!--
7342 to do:
7344 - wording of OpenType family name handling
7345 - handling combining sequences in the font matching algorithm
7346 - fix-up fi ligature example
7348 -->