Mon, 10 Jun 2013 17:47:39 +0900
[css3-fonts] editorial fixes in cluster matching section
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5 <head><meta content="text/html;charset=utf-8" http-equiv=Content-Type>
7 <title>CSS Fonts Module Level 3</title>
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9 FIXME when publishing: copy the current default.css and link to
10 "default.css" rather than "../default.css"
11 -->
12 <link href="../default.css" rel=stylesheet type="text/css">
13 <link href="../csslogo.ico" rel="shortcut icon" type="image/x-icon">
14 <!-- I'm just experimenting here, don't get your bee in a bonnet -->
15 <script src="http://use.typekit.com/xon2bky.js"
16 type="text/javascript"></script>
17 <script type="text/javascript">try{Typekit.load();}catch(e){}</script>
19 <style type="text/css">
21 body, th, td, h1, h2, h3, h4, h5, h6 {
22 font-family: "myriad-pro", sans-serif !important;
23 }
25 body {
26 padding: 2em 70px 2em 70px;
27 }
29 p + p, p.mtb {
30 margin-top: 0.8em;
31 text-indent: 0px;
32 }
34 #bolderlighter {
35 width: 40%;
36 }
38 #bolderlighter th {
39 text-align: center;
40 }
42 #fontformats td, #eventhandlers td, #fontformats th, #eventhandlers th {
43 padding-right: 2em;
44 text-align: left;
45 }
47 dd {
48 margin-bottom: 1em;
49 }
51 #authors dd {
52 margin-bottom: 0;
53 }
55 #fontstylematchingalg {
56 list-style-type: lower-alpha;
57 }
59 #fontmatchingalg ul, #fontmatchingalg ol {
60 margin-top: 0.8em;
61 }
63 #fontmatchingalg li + li {
64 margin-top: 0.8em;
65 }
67 div.example {
68 padding: 1em;
69 margin-top: 1em;
70 }
72 div.example + div.example {
73 margin-top: 2em;
74 }
76 div.figure {
77 page-break-inside: avoid;
78 }
80 pre.prod { white-space: pre-wrap; margin: 1em 0 1em 2em }
82 div.featex {
83 width: 700px;
84 }
86 div.featex img {
87 margin: auto;
88 display: block;
89 }
91 span.tag {
92 font-family: monospace;
93 font-size: 120%;
94 }
96 ol ol {
97 list-style-type: lower-alpha;
98 }
100 .idl-code {
101 font-weight: bold;
102 color: #c50;
103 }
104 </style>
105 <link href="http://www.w3.org/StyleSheets/TR/W3C-ED.css" rel=stylesheet
106 type="text/css">
107 <script defer=defer
108 src="http://test.csswg.org/harness/annotate.js#CSS3-FONTS_DEV"
109 type="text/javascript"></script>
111 <body>
112 <div class=head> <!--begin-logo-->
113 <p><a href="http://www.w3.org/"><img alt=W3C height=48
114 src="http://www.w3.org/Icons/w3c_home" width=72></a> <!--end-logo-->
116 <h1>CSS Fonts Module Level 3</h1>
118 <h2 class="no-num no-toc" id=editors-draft-10-june-2013>Editor's Draft 10
119 June 2013</h2>
121 <dl id=authors>
122 <dt>This version:
124 <dd><a
125 href="http://dev.w3.org/csswg/css-fonts/">http://dev.w3.org/csswg/css-fonts/</a>
126 <!-- <dd><a href="http://www.w3.org/TR/2013/ED-css3-fonts-20130610/">http://www.w3.org/TR/2013/ED-css3-fonts-20130610/</a> -->
129 <dt>Latest version:
131 <dd><a
132 href="http://www.w3.org/TR/css3-fonts/">http://www.w3.org/TR/css3-fonts/</a>
134 <dt>Latest editor's draft:
136 <dd><a
137 href="http://dev.w3.org/csswg/css-fonts/">http://dev.w3.org/csswg/css-fonts/</a>
138 (<a
139 href="https://dvcs.w3.org/hg/csswg/log/tip/css-fonts/Fonts.html">change
140 log</a>)
142 <dt>Previous version:
144 <dd><a
145 href="http://www.w3.org/TR/2013/WD-css3-fonts-20130212/">http://www.w3.org/TR/2013/WD-css3-fonts-20130212/</a>
147 <dt>Issues List:
149 <dd><a href="http://www.w3.org/Style/CSS/Tracker/products/18">CSS3 Fonts
150 issues in Tracker</a>
152 <dd><a
153 href="https://www.w3.org/Bugs/Public/buglist.cgi?query_format=advanced&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>Editor:
167 <dd><a href="mailto:jdaggett@mozilla.com">John Daggett (Mozilla)</a>
168 </dl>
169 <!--begin-copyright-->
170 <p class=copyright><a
171 href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright"
172 rel=license>Copyright</a> © 2013 <a href="http://www.w3.org/"><abbr
173 title="World Wide Web Consortium">W3C</abbr></a><sup>®</sup> (<a
174 href="http://www.csail.mit.edu/"><abbr title="Massachusetts Institute of
175 Technology">MIT</abbr></a>, <a href="http://www.ercim.eu/"><abbr
176 title="European Research Consortium for Informatics and
177 Mathematics">ERCIM</abbr></a>, <a href="http://www.keio.ac.jp/">Keio</a>,
178 <a href="http://ev.buaa.edu.cn/">Beihang</a>), All Rights Reserved. W3C
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180 href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>,
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184 href="http://www.w3.org/Consortium/Legal/copyright-documents">document
185 use</a> rules apply.</p>
186 <!--end-copyright-->
187 <hr title="Separator for header">
188 </div>
190 <h2 class="no-num no-toc" id=abstract>Abstract</h2>
192 <p>This CSS3 module describes how font properties are specified and how
193 font resources are loaded dynamically. The contents of this specification
194 are a consolidation of content previously divided into <a
195 href="http://www.w3.org/TR/2002/WD-css3-fonts-20020802/">CSS3 Fonts</a>
196 and <a href="http://www.w3.org/TR/2002/WD-css3-webfonts-20020802/">CSS3
197 Web Fonts</a> modules. The description of font load events was moved into
198 the <a href="http://dev.w3.org/csswg/css3-font-load-events/">CSS3 Font
199 Load Events</a> module.
201 <h2 class="no-num no-toc" id=status>Status of this document</h2>
202 <!--begin-status-->
204 <p>This is a public copy of the editors' draft. It is provided for
205 discussion only and may change at any moment. Its publication here does
206 not imply endorsement of its contents by W3C. Don't cite this document
207 other than as work in progress.
209 <p>The (<a
210 href="http://lists.w3.org/Archives/Public/www-style/">archived</a>) public
211 mailing list <a
212 href="mailto:www-style@w3.org?Subject=%5Bcss3-fonts%5D%20PUT%20SUBJECT%20HERE">
213 www-style@w3.org</a> (see <a
214 href="http://www.w3.org/Mail/Request">instructions</a>) is preferred for
215 discussion of this specification. When sending e-mail, please put the text
216 “css3-fonts” in the subject, preferably like this:
217 “[<!---->css3-fonts<!---->] <em>…summary of comment…</em>”
219 <p>This document was produced by the <a
220 href="http://www.w3.org/Style/CSS/members">CSS Working Group</a> (part of
221 the <a href="http://www.w3.org/Style/">Style Activity</a>).
223 <p>This document was produced by a group operating under the <a
224 href="http://www.w3.org/Consortium/Patent-Policy-20040205/">5 February
225 2004 W3C Patent Policy</a>. W3C maintains a <a
226 href="http://www.w3.org/2004/01/pp-impl/32061/status"
227 rel=disclosure>public list of any patent disclosures</a> made in
228 connection with the deliverables of the group; that page also includes
229 instructions for disclosing a patent. An individual who has actual
230 knowledge of a patent which the individual believes contains <a
231 href="http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">Essential
232 Claim(s)</a> must disclose the information in accordance with <a
233 href="http://www.w3.org/Consortium/Patent-Policy-20040205/#sec-Disclosure">section
234 6 of the W3C Patent Policy</a>.</p>
235 <!--end-status-->
237 <h3 class="no-num no-toc" id=atrisk>Features at risk</h3>
239 <p>The following features are at risk and may be removed when exiting CR:
241 <ul>
242 <li>fallback handling for text decoration in superscript/subscript variant
243 glyphs (‘<a href="#propdef-font-variant-position"><code
244 class=property>font-variant-position</code></a>’)
246 <li>‘<a href="#propdef-font-language-override"><code
247 class=property>font-language-override</code></a>’ property
248 </ul>
250 <p>This draft is a <strong>Last Call Working Draft</strong>. Please send
251 comments to the <a
252 href="http://lists.w3.org/Archives/Public/www-style/">www-style mailing
253 list</a> as described above. The <strong>deadline for comments</strong> is
254 six weeks after the date of publication in the header.
256 <h2 class="no-num no-toc" id=contents>Table of contents</h2>
257 <!--begin-toc-->
259 <ul class=toc>
260 <li><a href="#introduction"><span class=secno>1 </span>Introduction</a>
262 <li><a href="#typography-background"><span class=secno>2 </span>Typography
263 Background</a>
265 <li><a href="#basic-font-props"><span class=secno>3 </span>Basic Font
266 Properties</a>
267 <ul class=toc>
268 <li><a href="#font-family-prop"><span class=secno>3.1 </span>Font
269 family: the font-family property</a>
270 <ul class=toc>
271 <li><a href="#generic-font-families"><span class=secno>3.1.1
272 </span>Generic font families</a>
273 </ul>
275 <li><a href="#font-weight-prop"><span class=secno>3.2 </span>Font
276 weight: the font-weight property</a>
278 <li><a href="#font-stretch-prop"><span class=secno>3.3 </span>Font
279 width: the font-stretch property</a>
281 <li><a href="#font-style-prop"><span class=secno>3.4 </span>Font style:
282 the font-style property</a>
284 <li><a href="#font-size-prop"><span class=secno>3.5 </span>Font size:
285 the font-size property</a>
287 <li><a href="#font-size-adjust-prop"><span class=secno>3.6
288 </span>Relative sizing: the font-size-adjust property</a>
290 <li><a href="#font-prop"><span class=secno>3.7 </span>Shorthand font
291 property: the font property</a>
293 <li><a href="#font-synthesis-prop"><span class=secno>3.8
294 </span>Controlling synthetic faces: the font-synthesis property</a>
295 </ul>
297 <li><a href="#font-resources"><span class=secno>4 </span>Font
298 Resources</a>
299 <ul class=toc>
300 <li><a href="#font-face-rule"><span class=secno>4.1 </span>The
301 <code>@font-face</code> rule</a>
303 <li><a href="#font-family-desc"><span class=secno>4.2 </span>Font
304 family: the font-family descriptor</a>
306 <li><a href="#src-desc"><span class=secno>4.3 </span>Font reference: the
307 src descriptor</a>
309 <li><a href="#font-prop-desc"><span class=secno>4.4 </span>Font property
310 descriptors: the font-style, font-weight, font-stretch descriptors</a>
312 <li><a href="#unicode-range-desc"><span class=secno>4.5 </span>Character
313 range: the unicode-range descriptor</a>
315 <li><a href="#composite-fonts"><span class=secno>4.6 </span>Using
316 character ranges to define composite fonts</a>
318 <li><a href="#font-rend-desc"><span class=secno>4.7 </span>Font
319 features: the font-variant and font-feature-settings descriptors</a>
321 <li><a href="#font-face-loading"><span class=secno>4.8 </span>Font
322 loading guidelines</a>
324 <li><a href="#same-origin-restriction"><span class=secno>4.9
325 </span>Same-origin restriction for fonts</a>
326 <ul class=toc>
327 <li><a href="#default-same-origin-restriction"><span class=secno>4.9.1
328 </span>Default same-origin restriction</a>
330 <li><a href="#allowing-cross-origin-font-loading"><span
331 class=secno>4.9.2 </span>Allowing cross-origin font loading</a>
332 </ul>
333 </ul>
335 <li><a href="#font-matching-algorithm"><span class=secno>5 </span>Font
336 Matching Algorithm</a>
337 <ul class=toc>
338 <li><a href="#font-family-casing"><span class=secno>5.1 </span>Case
339 sensitivity of font family names</a>
341 <li><a href="#font-style-matching"><span class=secno>5.2 </span>Matching
342 font styles</a>
344 <li><a href="#cluster-matching"><span class=secno>5.3 </span>Cluster
345 matching</a>
347 <li><a href="#char-handling-issues"><span class=secno>5.4
348 </span>Character handling issues</a>
350 <li><a href="#font-matching-changes"><span class=secno>5.5 </span>Font
351 matching changes since CSS 2.1</a>
353 <li><a href="#font-matching-examples"><span class=secno>5.6 </span>Font
354 matching examples</a>
355 </ul>
357 <li><a href="#font-rend-props"><span class=secno>6 </span>Font Feature
358 Properties</a>
359 <ul class=toc>
360 <li><a href="#glyph-selection-positioning"><span class=secno>6.1
361 </span>Glyph selection and positioning</a>
363 <li><a href="#language-specific-support"><span class=secno>6.2
364 </span>Language-specific display</a>
366 <li><a href="#font-kerning-prop"><span class=secno>6.3 </span>Kerning:
367 the font-kerning property</a>
369 <li><a href="#font-variant-ligatures-prop"><span class=secno>6.4
370 </span>Ligatures: the font-variant-ligatures property</a>
372 <li><a href="#font-variant-position-prop"><span class=secno>6.5
373 </span>Subscript and superscript forms: the font-variant-position
374 property</a>
376 <li><a href="#font-variant-caps-prop"><span class=secno>6.6
377 </span>Capitalization: the font-variant-caps property</a>
379 <li><a href="#font-variant-numeric-prop"><span class=secno>6.7
380 </span>Numerical formatting: the font-variant-numeric property</a>
382 <li><a href="#font-variant-alternates-prop"><span class=secno>6.8
383 </span>Alternates and swashes: the font-variant-alternates property</a>
386 <li><a href="#font-feature-values"><span class=secno>6.9 </span>Defining
387 font specific alternates: the <code>@font-feature-values</code>
388 rule</a>
389 <ul class=toc>
390 <li><a href="#basic-syntax"><span class=secno>6.9.1 </span>Basic
391 syntax</a>
393 <li><a href="#multi-valued-feature-value-definitions"><span
394 class=secno>6.9.2 </span>Multi-valued feature value definitions</a>
395 </ul>
397 <li><a href="#font-variant-east-asian-prop"><span class=secno>6.10
398 </span>East Asian text rendering: the font-variant-east-asian
399 property</a>
401 <li><a href="#font-variant-prop"><span class=secno>6.11 </span>Overall
402 shorthand for font rendering: the font-variant property</a>
404 <li><a href="#font-feature-settings-prop"><span class=secno>6.12
405 </span>Low-level font feature settings control: the
406 font-feature-settings property</a>
408 <li><a href="#font-language-override-prop"><span class=secno>6.13
409 </span>Font language override: the font-language-override property</a>
410 </ul>
412 <li><a href="#font-feature-resolution"><span class=secno>7 </span>Font
413 Feature Resolution </a>
414 <ul class=toc>
415 <li><a href="#default-features"><span class=secno>7.1 </span>Default
416 features</a>
418 <li><a href="#feature-precedence"><span class=secno>7.2 </span>Feature
419 precedence</a>
421 <li><a href="#feature-precedence-examples"><span class=secno>7.3
422 </span>Feature precedence examples</a>
423 </ul>
425 <li><a href="#object-model"><span class=secno>8 </span>Object Model</a>
426 <ul class=toc>
427 <li><a href="#om-fontface"><span class=secno>8.1 </span>The
428 <code>CSSFontFaceRule</code> interface</a>
430 <li><a href="#om-fontfeaturevalues"><span class=secno>8.2 </span>The
431 <code>CSSFontFeatureValuesRule</code> interface</a>
432 </ul>
434 <li class=no-num><a href="#platform-props-to-css">Appendix A: Mapping
435 platform font properties to CSS properties</a>
437 <li class=no-num><a href="#ch-ch-ch-changes">Changes</a>
438 <ul class=toc>
439 <li class=no-num><a href="#recent-changes"> Changes from the February
440 2013 CSS3 Fonts Working Draft</a>
441 </ul>
443 <li class=no-num><a href="#acknowledgments">Acknowledgments</a>
445 <li class=no-num><a href="#conformance"> Conformance</a>
446 <ul class=toc>
447 <li class=no-num><a href="#conventions"> Document Conventions</a>
449 <li class=no-num><a href="#conformance-classes"> Conformance Classes</a>
452 <li class=no-num><a href="#partial"> Partial Implementations</a>
454 <li class=no-num><a href="#experimental"> Experimental
455 Implementations</a>
457 <li class=no-num><a href="#testing"> Non-Experimental
458 Implementations</a>
459 </ul>
461 <li class=no-num><a href="#references">References</a>
462 <ul class=toc>
463 <li class=no-num><a href="#normative-references">Normative
464 References</a>
466 <li class=no-num><a href="#other-references">Other References</a>
467 </ul>
469 <li class=no-num><a href="#index">Index</a>
471 <li class=no-num><a href="#property-index">Property index</a>
472 </ul>
473 <!--end-toc-->
475 <h2 id=introduction><span class=secno>1 </span>Introduction</h2>
477 <p>A font provides a resource containing the visual representation of
478 characters. At the simplest level it contains information that maps
479 character codes to shapes (called glyphs) that represent these characters.
480 Fonts sharing a common design style are commonly grouped into font
481 families classified by a set of standard font properties. Within a family,
482 the shape displayed for a given character can vary by stroke weight, slant
483 or relative width, among others. An individual font face is described by a
484 unique combination of these properties. For a given range of text, CSS
485 font properties are used to select a font family and a specific font face
486 within that family to be used when rendering that text. As a simple
487 example, to use the bold form of Helvetica one could use:
489 <pre>body {
490 font-family: Helvetica;
491 font-weight: bold;
492 }</pre>
494 <p>Font resources may be installed locally on the system on which a user
495 agent is running or downloadable. For local font resources descriptive
496 information can be obtained directly from the font resource. For
497 downloadable font resources (sometimes referred to as web fonts), the
498 descriptive information is included with the reference to the font
499 resource.
501 <p>Families of fonts typically don't contain a single face for each
502 possible variation of font properties. The CSS font selection mechanism
503 describes how to match a given set of CSS font properties to a single font
504 face.
506 <h2 id=typography-background><span class=secno>2 </span>Typography
507 Background</h2>
509 <p><em>This section is non-normative.</em>
511 <p> Typographic traditions vary across the globe, so there is no unique way
512 to classify all fonts across languages and cultures. For even common Latin
513 letters, wide variations are possible:
515 <div class=figure><img alt="variations in glyphs for a single character"
516 src=aaaaaa.png>
517 <p class=caption>One character, many glyph variations
518 </div>
520 <p>Differences in the anatomy of letterforms is one way to distinguish
521 fonts. For Latin fonts, flourishes at the ends of a character's main
522 strokes, or serifs, can distinguish a font from those without. Similar
523 comparisons exist in non-Latin fonts between fonts with tapered strokes
524 and those using primarily uniform strokes:
526 <div class=figure><img alt="serif vs. non-serifs" src=serifvssansserif.png>
527 <p class=caption>Letterforms with and without serifs
528 </div>
530 <div class=figure><img alt="serif vs. non-serifs for japanese"
531 src=minchovsgothic.png>
532 <p class=caption>Similar groupings for Japanese typefaces
533 </div>
535 <p>Fonts contain letterforms and the data needed to map characters to these
536 letterforms. Often this may be a simple one-to-one mapping, but more
537 complex mappings are also possible. The use of combining diacritic marks
538 creates many variations for an underlying letterform:
540 <div class=figure><img alt="diacritic marks" src=aaaaaa-diacritics.png>
541 <p class=caption>Variations with diacritic marks
542 </div>
544 <p>A sequence of characters can be represented by a single glyph known as a
545 ligature:
547 <div class=figure><img alt="example of a fi ligature"
548 src=final-ligature.png>
549 <p class=caption>Ligature example
550 </div>
552 <p>Visual transformations based on textual context are often stylistic
553 option in European languages. They are required to correctly render
554 languages like Arabic, the lam and alef characters below <em>must</em> be
555 combined when they exist in sequence:
557 <div class=figure><img alt="lam alef ligature" src=lamaleflig.png>
558 <p class=caption>Required Arabic ligature
559 </div>
561 <p>The relative complexity of these shaping transformations requires
562 additional data within the font.
564 <p>Sets of font faces with various stylistic variations are often grouped
565 together into font families. In the simplest case a regular face is
566 supplemented with bold and italic faces, but much more extensive groupings
567 are possible. Variations in the thickness of letterform strokes, the <dfn
568 id=weight>weight</dfn>, and the overall proportions of the letterform, the
569 <dfn id=width>width</dfn>, are most common. In the example below, each
570 letter uses a different font face within the Univers font family. The
571 width used increases from top to bottom and the weight increases from left
572 to right:
574 <div class=figure><img alt="various width and weight variations within a
575 single family" src=weightwidthvariations.png>
576 <p class=caption>Weight and width variations within a single font family
577 </div>
579 <p>Creating fonts that support multiple scripts is a difficult task;
580 designers need to understand the cultural traditions surrounding the use
581 of type in different scripts and come up with letterforms that somehow
582 share a common theme. Many languages often share a common script and each
583 of these languages may have noticeable stylistic differences. For example,
584 the Arabic script is shared by Persian and Urdu and Cyrillic is used with
585 many languages, not just Russian.
587 <p>The <a href="#character-map"><em>character map</em></a> of a font
588 defines the mapping of characters to glyphs for that font. If a document
589 contains characters not supported by the <a href="#character-map"><em
590 title="character map">character maps</em></a> of the fonts contained in a
591 font family list, a user agent may use a <a
592 href="#system-font-fallback"><em>system font fallback</em></a> procedure
593 to locate an appropriate font that does. If no appropriate font can be
594 found, some form of "missing glyph" character will be rendered by the user
595 agent. System fallback can occur when the specified list of font families
596 does not include a font that supports a given character.
598 <p>Although the <a href="#character-map"><em>character map</em></a> of a
599 font maps a given character to a glyph for that character, modern font
600 technologies such as OpenType and AAT (Apple Advanced Typography) provide
601 ways of mapping a character to different glyphs based upon feature
602 settings. Fonts in these formats allow these features to be embedded in
603 the font itself and controlled by applications. Common typographic
604 features which can be specified this way include ligatures, swashes,
605 contextual alternates, proportional and tabular figures, and automatic
606 fractions, to list just a few. For a visual overview of OpenType features,
607 see the <a href="#OPENTYPE-FONT-GUIDE"
608 rel=biblioentry>[OPENTYPE-FONT-GUIDE]<!--{{OPENTYPE-FONT-GUIDE}}--></a>.
610 <h2 id=basic-font-props><span class=secno>3 </span>Basic Font Properties</h2>
612 <p>The particular font face used to render a character is determined by the
613 font family and other font properties that apply to a given element. This
614 structure allows settings to be varied independent of each other.</p>
615 <!-- prop: font-family -->
617 <h3 id=font-family-prop><span class=secno>3.1 </span>Font family: the <a
618 href="#propdef-font-family">font-family</a> property</h3>
620 <table class=propdef id=namefont-familyvalue-ltfamily-namegt-ltg>
621 <tbody>
622 <tr>
623 <td>Name:
625 <td><dfn id=propdef-font-family
626 title="font-family!!property">font-family</dfn>
628 <tr>
629 <td>Value:
631 <td>[ <a href="#family-name-value"><var><family-name></var></a> |
632 <a href="#generic-family-value"><var><generic-family></var></a> ]
633 #
635 <tr>
636 <td>Initial:
638 <td>depends on user agent
640 <tr>
641 <td>Applies to:
643 <td>all elements
645 <tr>
646 <td>Inherited:
648 <td>yes
650 <tr>
651 <td>Percentages:
653 <td>N/A
655 <tr>
656 <td>Media:
658 <td>visual
660 <tr>
661 <td>Computed value:
663 <td>as specified
665 <tr>
666 <td>Animatable:
668 <td>no
669 </table>
671 <p>This property specifies a prioritized list of font family names or
672 generic family names. A font family defines a set of faces that vary in
673 weight, width or slope. CSS uses the combination of a family name with
674 other style attributes to select an individual face. Using this selection
675 mechanism, rather than selecting a face via the style name as is often
676 done in design applications, allows some degree of regularity in textual
677 display when fallback occurs.
679 <p class=note>Designers should note that the CSS definition of font
680 attributes used for selection are explicitly not intended to define a font
681 taxonomy. A type designer's idea of a family may often extend to a set of
682 faces that vary along axes other than just the standard axes of weight,
683 width and slope. A family may extend to include both a set of serif faces
684 and a set of sans-serif faces or vary along axes that are unique to that
685 family. The CSS font selection mechanism merely provides a way to
686 determine the “closest” substitute when substitution is necessary.
688 <p>Unlike other CSS properties, component values are a comma-separated list
689 indicating alternatives. A user agent iterates through the list of family
690 names until it matches an available font that contains a glyph for the
691 character to be rendered. This allows for differences in available fonts
692 across platforms and for differences in the range of characters supported
693 by individual fonts.
695 <p>A font family name only specifies a name given to a set of font faces,
696 it does not specify an individual face. For example, given the
697 availability of the fonts below, Futura would match but Futura Medium
698 would not:
700 <div class=figure><img alt="family and face names"
701 src=familyvsfacename.png>
702 <p class=caption>Family and individual face names
703 </div>
705 <p>Consider the example below:
707 <div class=example>
708 <pre>body {
709 font-family: Helvetica, Verdana, sans-serif;
710 }</pre>
712 <p>If Helvetica is available it will be used when rendering. If neither
713 Helvetica nor Verdana is present, then the user-agent-defined sans serif
714 font will be used.</p>
715 </div>
717 <p>There are two types of font family names:
719 <dl>
720 <dt><dfn id=family-name-value><var><family-name></var></dfn>
722 <dd>The name of a font family of choice such as Helvetica or Verdana in
723 the previous example.
725 <dt><dfn id=generic-family-value><var><generic-family></var></dfn>
727 <dd> The following generic family keywords are defined: ‘<a
728 href="#serif"><code class=property>serif</code></a>’, ‘<a
729 href="#sans-serif"><code class=property>sans-serif</code></a>’, ‘<a
730 href="#cursive"><code class=property>cursive</code></a>’, ‘<a
731 href="#fantasy"><code class=property>fantasy</code></a>’, and ‘<a
732 href="#monospace"><code class=property>monospace</code></a>’. These
733 keywords can be used as a general fallback mechanism when an author's
734 desired font choices are not available. As keywords, they must not be
735 quoted. Authors are encouraged to append a generic font family as a last
736 alternative for improved robustness.
737 </dl>
739 <p>Font family names other than generic families must either be given
740 quoted as <a
741 href="//www.w3.org/TR/CSS21/syndata.html#strings">strings,</a> or unquoted
742 as a sequence of one or more <a
743 href="//www.w3.org/TR/CSS21/syndata.html#value-def-identifier">identifiers.</a>
744 This means most punctuation characters and digits at the start of each
745 token must be escaped in unquoted font family names.
747 <p>To illustrate this, the following declarations are invalid:
749 <pre>
750 font-family: Red/Black, sans-serif;
751 font-family: "Lucida" Grande, sans-serif;
752 font-family: Ahem!, sans-serif;
753 font-family: test@foo, sans-serif;
754 font-family: #POUND, sans-serif;
755 font-family: Hawaii 5-0, sans-serif;
756 </pre>
758 <p>If a sequence of identifiers is given as a font family name, the
759 computed value is the name converted to a string by joining all the
760 identifiers in the sequence by single spaces.
762 <p>To avoid mistakes in escaping, it is recommended to quote font family
763 names that contain white space, digits, or punctuation characters other
764 than hyphens:
766 <pre>
767 body { font-family: "New Century Schoolbook", serif }
769 <BODY STYLE="font-family: '21st Century', fantasy">
770 </pre>
772 <p>Font family <em>names</em> that happen to be the same as a keyword value
773 (‘<code class=property>inherit</code>’, ‘<a href="#serif"><code
774 class=property>serif</code></a>’, ‘<a href="#sans-serif"><code
775 class=property>sans-serif</code></a>’, ‘<a href="#monospace"><code
776 class=property>monospace</code></a>’, ‘<a href="#fantasy"><code
777 class=property>fantasy</code></a>’, and ‘<a href="#cursive"><code
778 class=property>cursive</code></a>’) must be quoted to prevent confusion
779 with the keywords with the same names. The keywords ‘<code
780 class=property>initial</code>’ and ‘<code
781 class=property>default</code>’ are reserved for future use and must also
782 be quoted when used as font names. UAs must not consider these keywords as
783 matching the <a
784 href="#family-name-value"><var><family-name></var></a> type.
786 <p>The precise way a set of fonts are grouped into font families varies
787 depending upon the platform font management API's. The Windows GDI API
788 only allows four faces to be grouped into a family while the DirectWrite
789 API and API's on OSX and other platforms support font families with a
790 variety of weights, widths and slopes (see <a
791 href="#platform-props-to-css">Appendix A</a> for more details).
793 <p>Some font formats allow fonts to carry multiple localizations of the
794 family name. User agents must recognize and correctly match all of these
795 names independent of the underlying platform localization, system API used
796 or document encoding:
798 <div class=figure><img alt="examples of localized family names"
799 src=localizedfamilynames.png>
800 <p class=caption>Localized family names
801 </div>
803 <h4 id=generic-font-families><span class=secno>3.1.1 </span>Generic font
804 families</h4>
806 <p>All five generic font families are defined to exist in all CSS
807 implementations (they need not necessarily map to five distinct actual
808 fonts). User agents should provide reasonable default choices for the
809 generic font families, which express the characteristics of each family as
810 well as possible within the limits allowed by the underlying technology.
811 User agents are encouraged to allow users to select alternative choices
812 for the generic fonts.
814 <h5 class="no-num no-toc"> <span class=index-def id=serif0 title="serif,
815 definition of"><a name=serif-def><dfn id=serif>serif</dfn></a></span></h5>
817 <p>Serif fonts represent the formal text style for a script. This often
818 means but is not limited to glyphs that have finishing strokes, flared or
819 tapering ends, or have actual serifed endings (including slab serifs).
820 Serif fonts are typically proportionately-spaced. They often display a
821 greater variation between thick and thin strokes than fonts from the ‘<a
822 href="#sans-serif"><code class=property>sans-serif</code></a>’ generic
823 font family. CSS uses the term ‘<a href="#serif"><code
824 class=property>serif</code></a>’ to apply to a font for any script,
825 although other names may be more familiar for particular scripts, such as
826 Mincho (Japanese), Sung, Song or Kai (Chinese), Batang (Korean). For
827 Arabic, the Naskh style would correspond to ‘<a href="#serif"><code
828 class=property>serif</code></a>’ more due to its typographic role rather
829 than its actual design style. Any font that is so described may be used to
830 represent the generic ‘<a href="#serif"><code
831 class=property>serif</code></a>’ family.
833 <div class=figure><img alt="sample serif fonts" src=serifexamples.png>
834 <p class=caption>Sample serif fonts
835 </div>
837 <h5 class="no-num no-toc"> <span class=index-def id=sans-serif0
838 title="sans-serif, definition of"> <a name=sans-serif-def><dfn
839 id=sans-serif>sans-serif</dfn></a></span></h5>
841 <p>Glyphs in sans-serif fonts, as the term is used in CSS, are generally
842 low contrast (vertical and horizontal stems have the close to the same
843 thickness) and have stroke endings that are plain -- without any flaring,
844 cross stroke, or other ornamentation. Sans-serif fonts are typically
845 proportionately-spaced. They often have little variation between thick and
846 thin strokes, compared to fonts from the ‘<a href="#serif"><code
847 class=property>serif</code></a>’ family. CSS uses the term ‘<a
848 href="#sans-serif"><code class=property>sans-serif</code></a>’ to apply
849 to a font for any script, although other names may be more familiar for
850 particular scripts, such as Gothic (Japanese), Hei (Chinese), or Gulim
851 (Korean). Any font that is so described may be used to represent the
852 generic ‘<a href="#sans-serif"><code
853 class=property>sans-serif</code></a>’ family.
855 <div class=figure><img alt="sample sans-serif fonts"
856 src=sansserifexamples.png>
857 <p class=caption>Sample sans-serif fonts
858 </div>
860 <h5 class="no-num no-toc"> <span class=index-def id=cursive0
861 title="cursive, definition of"> <a name=cursive-def><dfn
862 id=cursive>cursive</dfn></a></span></h5>
864 <p>Glyphs in cursive fonts generally use a more informal script style, and
865 the result looks more like handwritten pen or brush writing than printed
866 letterwork. CSS uses the term ‘<a href="#cursive"><code
867 class=property>cursive</code></a>’ to apply to a font for any script,
868 although other names such as Chancery, Brush, Swing and Script are also
869 used in font names.
871 <div class=figure><img alt="sample cursive fonts" src=cursiveexamples.png>
872 <p class=caption>Sample cursive fonts
873 </div>
875 <h5 class="no-num no-toc"> <span class=index-def id=fantasy0
876 title="fantasy, definition of"> <a name=fantasy-def><dfn
877 id=fantasy>fantasy</dfn></a></span></h5>
879 <p>Fantasy fonts are primarily decorative or expressive fonts that contain
880 playful representations of characters. These do not include Pi or Picture
881 fonts which do not represent actual characters.
883 <div class=figure><img alt="sample fantasy fonts" src=fantasyexamples.png>
884 <p class=caption>Sample fantasy fonts
885 </div>
887 <h5 class="no-num no-toc"> <span class=index-def id=monospace0
888 title="monospace, definition of"> <a name=monospace-def><dfn
889 id=monospace>monospace</dfn></a></span></h5>
891 <p>The sole criterion of a monospace font is that all glyphs have the same
892 fixed width. This is often used to render samples of computer code.
894 <div class=figure><img alt="sample monospace fonts"
895 src=monospaceexamples.png>
896 <p class=caption>Sample monospace fonts
897 </div>
898 <!-- prop: font-weight -->
900 <h3 id=font-weight-prop><span class=secno>3.2 </span>Font weight: the <a
901 href="#propdef-font-weight">font-weight</a> property</h3>
903 <table class=propdef id=namefont-weightvaluenormal-bold-bolder-l>
904 <tbody>
905 <tr>
906 <td>Name:
908 <td><dfn id=propdef-font-weight
909 title="font-weight!!property">font-weight</dfn>
911 <tr>
912 <td>Value:
914 <td><a href="#font-weight-normal-value"
915 title="normal!!font-weight">normal</a> | <a href="#bold">bold</a> | <a
916 href="#bolder">bolder</a> | <a href="#lighter">lighter</a> | <a
917 href="#font-weight-numeric-values" title="100...900 weight
918 values">100</a> | <a href="#font-weight-numeric-values"
919 title="100...900 weight values">200</a> | <a
920 href="#font-weight-numeric-values" title="100...900 weight
921 values">300</a> | <a href="#font-weight-numeric-values"
922 title="100...900 weight values">400</a> | <a
923 href="#font-weight-numeric-values" title="100...900 weight
924 values">500</a> | <a href="#font-weight-numeric-values"
925 title="100...900 weight values">600</a> | <a
926 href="#font-weight-numeric-values" title="100...900 weight
927 values">700</a> | <a href="#font-weight-numeric-values"
928 title="100...900 weight values">800</a> | <a
929 href="#font-weight-numeric-values" title="100...900 weight
930 values">900</a>
932 <tr>
933 <td>Initial:
935 <td>normal
937 <tr>
938 <td>Applies to:
940 <td>all elements
942 <tr>
943 <td>Inherited:
945 <td>yes
947 <tr>
948 <td>Percentages:
950 <td>N/A
952 <tr>
953 <td>Media:
955 <td>visual
957 <tr>
958 <td>Computed value:
960 <td>numeric weight value (see description)
962 <tr>
963 <td>Animatable:
965 <td>as <a
966 href="http://dev.w3.org/csswg/css3-transitions/#animtype-font-weight">font
967 weight</a>
968 </table>
970 <p>The <a href="#propdef-font-weight"
971 title="font-weight!!property">‘<code
972 class=property>font-weight</code>’</a> property specifies the weight of
973 glyphs in the font, their degree of blackness or stroke thickness.
975 <p>Values have the following meanings:
977 <dl>
978 <dt><dfn id=font-weight-numeric-values title="100...900 weight values">100
979 to 900</dfn>
981 <dd>These values form an ordered sequence, where each number indicates a
982 weight that is at least as dark as its predecessor. These roughly
983 correspond to the commonly used weight names below:
984 </dl>
986 <ul>
987 <li>100 - Thin
989 <li>200 - Extra Light (Ultra Light)
991 <li>300 - Light
993 <li>400 - Normal
995 <li>500 - Medium
997 <li>600 - Semi Bold (Demi Bold)
999 <li>700 - Bold
1001 <li>800 - Extra Bold (Ultra Bold)
1003 <li>900 - Black (Heavy)
1004 </ul>
1006 <dl>
1007 <dt><dfn id=font-weight-normal-value
1008 title="normal!!font-weight">normal</dfn>
1010 <dd>Same as ‘<code class=css>400</code>’.
1012 <dt><dfn id=bold>bold</dfn>
1014 <dd>Same as ‘<code class=css>700</code>’.
1016 <dt><dfn id=bolder>bolder</dfn>
1018 <dd>Specifies a bolder weight than the inherited value.
1020 <dt><dfn id=lighter>lighter</dfn>
1022 <dd>Specifies a lighter weight than the inherited value.
1023 </dl>
1025 <p>Font formats that use a scale other than a nine-step scale should map
1026 their scale onto the CSS scale so that 400 roughly corresponds with a face
1027 that would be labeled as Regular, Book, Roman and 700 roughly matches a
1028 face that would be labeled as Bold. Or weights may be inferred from the
1029 style names, ones that correspond roughly with the scale above. The scale
1030 is relative, so a face with a larger weight value must never appear
1031 lighter. If style names are used to infer weights, care should be taken to
1032 handle variations in style names across locales.
1034 <p>Quite often there are only a few weights available for a particular font
1035 family. When a weight is specified for which no face exists, a face with a
1036 nearby weight is used. In general, bold weights map to faces with heavier
1037 weights and light weights map to faces with lighter weights (see the <a
1038 href="#font-matching-algorithm">font matching section below</a> for a
1039 precise definition). The examples here illustrate which face is used for
1040 different weights, grey indicates a face for that weight does not exist so
1041 a face with a nearby weight is used:
1043 <div class=figure><img alt="weight mappings for a family with 400, 700 and
1044 900 weights" src=optimaweights.png>
1045 <p class=caption>Weight mappings for a font family with 400, 700 and 900
1046 weight faces
1047 </div>
1049 <div class=figure><img alt="weight mappings for a family with 300, 600
1050 weights" src=hiraginoweights.png>
1051 <p class=caption>Weight mappings for a font family with 300 and 600 weight
1052 faces
1053 </div>
1055 <p>Although the practice is not well-loved by typographers, bold faces are
1056 often synthesized by user agents for faces that lack actual bold faces.
1057 For the purposes of style matching, these faces must be treated as if they
1058 exist within the family. Authors can explicitly avoid this behavior by
1059 using the ‘<a href="#propdef-font-synthesis"><code
1060 class=property>font-synthesis</code></a>’ property.
1062 <p>Specified values of ‘<a href="#bolder"><code
1063 class=property>bolder</code></a>’ and ‘<a href="#lighter"><code
1064 class=property>lighter</code></a>’ indicate weights relative to the
1065 weight of the parent element. The computed weight is calculated based on
1066 the inherited <a href="#propdef-font-weight"
1067 title="font-weight!!property">‘<code
1068 class=property>font-weight</code>’</a> value using the chart below.
1070 <table class=data id=bolderlighter summary="Bolder/lighter mappings">
1071 <thead>
1072 <tr>
1073 <th>Inherited value
1075 <th>bolder
1077 <th>lighter
1079 <tbody>
1080 <tr>
1081 <th>100
1083 <td>400
1085 <td>100
1087 <tr>
1088 <th>200
1090 <td>400
1092 <td>100
1094 <tr>
1095 <th>300
1097 <td>400
1099 <td>100
1101 <tr>
1102 <th>400
1104 <td>700
1106 <td>100
1108 <tr>
1109 <th>500
1111 <td>700
1113 <td>100
1115 <tr>
1116 <th>600
1118 <td>900
1120 <td>400
1122 <tr>
1123 <th>700
1125 <td>900
1127 <td>400
1129 <tr>
1130 <th>800
1132 <td>900
1134 <td>700
1136 <tr>
1137 <th>900
1139 <td>900
1141 <td>700
1142 </table>
1144 <p>The table above is equivalent to selecting the next relative bolder or
1145 lighter face, given a font family containing normal and bold faces along
1146 with a thin and a heavy face. Authors who desire finer control over the
1147 exact weight values used for a given element may use numerical values
1148 instead of relative weights.</p>
1149 <!-- prop: font-stretch -->
1151 <h3 id=font-stretch-prop><span class=secno>3.3 </span>Font width: the <a
1152 href="#propdef-font-stretch">font-stretch</a> property</h3>
1154 <table class=propdef id=namefont-stretchvalue-normal-ultra-conde>
1155 <tbody>
1156 <tr>
1157 <td>Name:
1159 <td><dfn id=propdef-font-stretch
1160 title="font-stretch!!property">font-stretch</dfn>
1162 <tr>
1163 <td>Value:
1165 <td> <a href="#font-stretch-normal-value"
1166 title="normal!!font-stretch">normal</a> | <a
1167 href="#ultra-condensed">ultra-condensed</a> | <a
1168 href="#extra-condensed">extra-condensed</a> | <a
1169 href="#condensed">condensed</a> | <a
1170 href="#semi-condensed-">semi-condensed</a> | <a
1171 href="#semi-expanded">semi-expanded</a> | <a
1172 href="#expanded">expanded</a> | <a
1173 href="#extra-expanded">extra-expanded</a> | <a
1174 href="#ultra-expanded">ultra-expanded</a>
1176 <tr>
1177 <td>Initial:
1179 <td>normal
1181 <tr>
1182 <td>Applies to:
1184 <td>all elements
1186 <tr>
1187 <td>Inherited:
1189 <td>yes
1191 <tr>
1192 <td>Percentages:
1194 <td>N/A
1196 <tr>
1197 <td>Media:
1199 <td>visual
1201 <tr>
1202 <td>Computed value:
1204 <td>as specified
1206 <tr>
1207 <td>Animatable:
1209 <td>as <a href="#font-stretch-animation">font stretch</a>
1210 </table>
1212 <p>The <a href="#propdef-font-stretch"
1213 title="font-stretch!!property">‘<code
1214 class=property>font-stretch</code>’</a> property selects a normal,
1215 condensed, or expanded face from a font family. Absolute keyword values
1216 have the following ordering, from narrowest to widest:
1218 <ul>
1219 <li><dfn id=ultra-condensed>ultra-condensed</dfn>
1221 <li><dfn id=extra-condensed>extra-condensed</dfn>
1223 <li><dfn id=condensed>condensed</dfn>
1225 <li><dfn id=semi-condensed->semi-condensed </dfn>
1227 <li><dfn id=font-stretch-normal-value
1228 title="normal!!font-stretch">normal</dfn>
1230 <li><dfn id=semi-expanded>semi-expanded</dfn>
1232 <li><dfn id=expanded>expanded</dfn>
1234 <li><dfn id=extra-expanded>extra-expanded</dfn>
1236 <li><dfn id=ultra-expanded>ultra-expanded</dfn>
1237 </ul>
1239 <p>When a face does not exist for a given width, normal or condensed values
1240 map to a narrower face, otherwise a wider face. Conversely, expanded
1241 values map to a wider face, otherwise a narrower face. The figure below
1242 shows how the nine font-stretch property settings affect font selection
1243 for font family containing a variety of widths, grey indicates a width for
1244 which no face exists and a different width is substituted:
1246 <div class=figure><img alt="width mappings for a family with condensed,
1247 normal and expanded faces" src=universwidths.png>
1248 <p class=caption>Width mappings for a font family with condensed, normal
1249 and expanded width faces
1250 </div>
1252 <p id=font-stretch-animation>Animation of font stretch: Font stretch is
1253 interpolated in discrete steps. The interpolation happens as though the
1254 ordered values are equally spaced real numbers. The interpolation result
1255 is rounded to the nearest value, with values exactly halfway between two
1256 values rounded towards the later value in the list above.</p>
1257 <!-- prop: font-style -->
1259 <h3 id=font-style-prop><span class=secno>3.4 </span>Font style: the <a
1260 href="#propdef-font-style">font-style</a> property</h3>
1262 <table class=propdef id=namefont-stylevaluenormal-italic-oblique>
1263 <tbody>
1264 <tr>
1265 <td>Name:
1267 <td><dfn id=propdef-font-style
1268 title="font-style!!property">font-style</dfn>
1270 <tr>
1271 <td>Value:
1273 <td><a href="#font-style-normal-value"
1274 title="normal!!font-style">normal</a> | <a href="#italic">italic</a> |
1275 <a href="#oblique">oblique</a>
1277 <tr>
1278 <td>Initial:
1280 <td>normal
1282 <tr>
1283 <td>Applies to:
1285 <td>all elements
1287 <tr>
1288 <td>Inherited:
1290 <td>yes
1292 <tr>
1293 <td>Percentages:
1295 <td>N/A
1297 <tr>
1298 <td>Media:
1300 <td>visual
1302 <tr>
1303 <td>Computed value:
1305 <td>as specified
1307 <tr>
1308 <td>Animatable:
1310 <td>no
1311 </table>
1313 <p>The <a href="#propdef-font-style" title="font-style!!property">‘<code
1314 class=property>font-style</code>’</a> property allows italic or oblique
1315 faces to be selected. Italic forms are generally cursive in nature while
1316 oblique faces are typically sloped versions of the regular face. Oblique
1317 faces can be simulated by artificially sloping the glyphs of the regular
1318 face. Compare the artificially sloped renderings of Palatino ‘<code
1319 class=property>a</code>’ and Baskerville ‘<code
1320 class=property>N</code>’ in grey with the actual italic versions:
1322 <div class=figure><img alt="artificial sloping vs. real italics"
1323 src=realvsfakeitalics.png>
1324 <p class=caption>Artificial sloping versus real italics
1325 </div>
1327 <p>Values have the following meanings:
1329 <dl>
1330 <dt><dfn id=font-style-normal-value
1331 title="normal!!font-style">normal</dfn>
1333 <dd>selects a face that is classified as a normal face, one that is
1334 neither italic or obliqued
1336 <dt><dfn id=italic>italic</dfn>
1338 <dd>selects a font that is labeled as an italic face, or an oblique face
1339 if one is not
1341 <dt><dfn id=oblique>oblique</dfn>
1343 <dd>selects a font that is labeled as an oblique face, or an italic face
1344 if one is not
1345 </dl>
1347 <p>If no italic or oblique face is available, oblique faces can be
1348 synthesized by rendering non-obliqued faces with an artificial obliquing
1349 operation. The use of these artificially obliqued faces can be disabled
1350 using the ‘<a href="#propdef-font-synthesis"><code
1351 class=property>font-synthesis</code></a>’ property. The details of the
1352 obliquing operation are not explicitly defined.</p>
1353 <!-- resolution on the "undefined" nature of synthetics: http://www.w3.org/2013/06/06-css-minutes.html#item03 -->
1355 <p>Many scripts lack the tradition of mixing a cursive form within text
1356 rendered with a normal face. Chinese, Japanese and Korean fonts almost
1357 always lack italic or oblique faces. Fonts that support a mixture of
1358 scripts will sometimes omit specific scripts such as Arabic from the set
1359 of glyphs supported in the italic face. User agents should be careful
1360 about making <a href="#character-map"><em>character map</em></a>
1361 assumptions across faces when implementing support for <a
1362 href="#system-font-fallback"><em>system font fallback</em></a>.</p>
1363 <!-- prop: font-size -->
1365 <h3 id=font-size-prop><span class=secno>3.5 </span>Font size: the <a
1366 href="#propdef-font-size">font-size</a> property</h3>
1368 <table class=propdef id=namefont-sizevalueltabsolute-sizegt-ltre>
1369 <tbody>
1370 <tr>
1371 <td>Name:
1373 <td><dfn id=propdef-font-size>font-size</dfn>
1375 <tr>
1376 <td>Value:
1378 <td><a href="#absolute-size-value"><var><absolute-size></var></a>
1379 | <a href="#relative-size-value"><var><relative-size></var></a> |
1380 <a href="#length-size-value"><var><length></var></a> | <a
1381 href="#percentage-size-value"><var><percentage></var></a>
1383 <tr>
1384 <td>Initial:
1386 <td>medium
1388 <tr>
1389 <td>Applies to:
1391 <td>all elements
1393 <tr>
1394 <td>Inherited:
1396 <td>yes
1398 <tr>
1399 <td>Percentages:
1401 <td>refer to parent element's font size
1403 <tr>
1404 <td>Media:
1406 <td>visual
1408 <tr>
1409 <td>Computed value:
1411 <td>absolute length
1413 <tr>
1414 <td>Animatable:
1416 <td>as <a
1417 href="http://dev.w3.org/csswg/css3-transitions/#animtype-length">length</a>
1418 </table>
1420 <p>This property indicates the desired height of glyphs from the font. For
1421 scalable fonts, the font-size is a scale factor applied to the EM unit of
1422 the font. (Note that certain glyphs may bleed outside their EM box.) For
1423 non-scalable fonts, the font-size is converted into absolute units and
1424 matched against the declared font-size of the font, using the same
1425 absolute coordinate space for both of the matched values. Values have the
1426 following meanings:
1428 <dl>
1429 <dt><dfn id=absolute-size-value><var><absolute-size></var></dfn>
1431 <dd> An <a
1432 href="#absolute-size-value"><var><absolute-size></var></a> keyword
1433 refers to an entry in a table of font sizes computed and kept by the user
1434 agent. Possible values are:
1435 <p> [ xx-small | x-small | small | medium | large | x-large | xx-large ]</p>
1437 <dt><dfn id=relative-size-value><var><relative-size></var></dfn>
1439 <dd> A <a href="#relative-size-value"><var><relative-size></var></a>
1440 keyword is interpreted relative to the table of font sizes and the
1441 computed ‘<a href="#propdef-font-size"><code
1442 class=property>font-size</code></a>’ of the parent element. Possible
1443 values are:
1444 <p> [ larger | smaller ]
1446 <p> For example, if the parent element has a font size of ‘<code
1447 class=property>medium</code>’, a value of ‘<code
1448 class=property>larger</code>’ will make the font size of the current
1449 element be ‘<code class=property>large</code>’. If the parent
1450 element's size is not close to a table entry, the user agent is free to
1451 interpolate between table entries or round off to the closest one. The
1452 user agent may have to extrapolate table values if the numerical value
1453 goes beyond the keywords.
1455 <dt><dfn id=length-size-value><var><length></var></dfn>
1457 <dd>A length value specifies an absolute font size (independent of the
1458 user agent's font table). Negative lengths are illegal.
1460 <dt><dfn id=percentage-size-value><var><percentage></var></dfn>
1462 <dd>A percentage value specifies an absolute font size relative to the
1463 parent element's font size. Use of percentage values, or values in
1464 ‘<code class=property>em</code>’s, leads to more robust and
1465 cascadable style sheets.
1466 </dl>
1468 <p>The following table provides user agent guidelines for the absolute-size
1469 scaling factor and their mapping to HTML heading and absolute font-sizes.
1470 The ‘<code class=property>medium</code>’ value is used as the
1471 reference middle value. The user agent may fine-tune these values for
1472 different fonts or different types of display devices.
1474 <table class=data>
1475 <thead>
1476 <tr>
1477 <th>CSS absolute-size values
1479 <th>xx-small
1481 <th>x-small
1483 <th>small
1485 <th>medium
1487 <th>large
1489 <th>x-large
1491 <th>xx-large
1493 <th>
1495 <tbody>
1496 <tr>
1497 <th>scaling factor
1499 <td>3/5
1501 <td>3/4
1503 <td>8/9
1505 <td>1
1507 <td>6/5
1509 <td>3/2
1511 <td>2/1
1513 <td>3/1
1515 <tr>
1516 <th>HTML headings
1518 <td>h6
1520 <td>
1522 <td>h5
1524 <td>h4
1526 <td>h3
1528 <td>h2
1530 <td>h1
1532 <td>
1534 <tr>
1535 <th>HTML font sizes
1537 <td>1
1539 <td>
1541 <td>2
1543 <td>3
1545 <td>4
1547 <td>5
1549 <td>6
1551 <td>7
1552 </table>
1554 <p class=note><em><strong>Note 1.</strong> To preserve readability, an UA
1555 applying these guidelines should nevertheless avoid creating font-size
1556 resulting in less than 9 device pixels per EM unit on a computer
1557 display.</em>
1559 <p class=note><em><strong>Note 2.</strong> In CSS1, the suggested scaling
1560 factor between adjacent indexes was 1.5 which user experience proved to be
1561 too large. In CSS2, the suggested scaling factor for computer screen
1562 between adjacent indexes was 1.2 which still created issues for the small
1563 sizes. The new scaling factor varies between each index to provide a
1564 better readability.</em>
1566 <p>The actual value of this property may differ from the computed value due
1567 a numerical value on ‘<a href="#propdef-font-size-adjust"><code
1568 class=property>font-size-adjust</code></a>’ and the unavailability of
1569 certain font sizes.
1571 <p>Child elements inherit the computed <a class=noxref
1572 href="#font-size-prop"> <span class=property>‘<code
1573 class=property>font-size</code>’</span></a> value (otherwise, the effect
1574 of <a class=noxref href="#font-size-adjust-prop"><span
1575 class=property>‘<code
1576 class=property>font-size-adjust</code>’</span></a> would compound).
1578 <div class=example>
1579 <p style="display:none">Example(s):
1581 <p>
1583 <pre>p { font-size: 12pt; }
1584 blockquote { font-size: larger }
1585 em { font-size: 150% }
1586 em { font-size: 1.5em }
1587 </pre>
1588 </div>
1589 <!-- prop: font-size-adjust -->
1591 <h3 id=font-size-adjust-prop><span class=secno>3.6 </span>Relative sizing:
1592 the <a href="#propdef-font-size-adjust">font-size-adjust</a> property</h3>
1594 <table class=propdef id=namefont-size-adjustvaluenone-auto-ltnum>
1595 <tbody>
1596 <tr>
1597 <td>Name:
1599 <td><dfn id=propdef-font-size-adjust>font-size-adjust</dfn>
1601 <tr>
1602 <td>Value:
1604 <td><a href="#font-size-adjust-none-value"
1605 title="none!!font-size-adjust">none</a> | <a
1606 href="#font-size-adjust-auto-value"
1607 title="auto!!font-size-adjust">auto</a> | <a
1608 href="#aspect-ratio-value"><var><number></var></a>
1610 <tr>
1611 <td>Initial:
1613 <td>none
1615 <tr>
1616 <td>Applies to:
1618 <td>all elements
1620 <tr>
1621 <td>Inherited:
1623 <td>yes
1625 <tr>
1626 <td>Percentages:
1628 <td>N/A
1630 <tr>
1631 <td>Media:
1633 <td>visual
1635 <tr>
1636 <td>Computed value:
1638 <td>as specified
1640 <tr>
1641 <td>Animatable:
1643 <td>as <a
1644 href="http://dev.w3.org/csswg/css3-transitions/#animtype-number">number</a>
1645 </table>
1647 <p>For any given font size, the apparent size and legibility of text varies
1648 across fonts. For scripts such as Latin or Cyrillic that distinguish
1649 between upper and lowercase letters, the relative height of lowercase
1650 letters compared to their uppercase counterparts is a determining factor
1651 of legibility. This is commonly referred to as the <a class=index-def
1652 href="#aspect-value" id=aspect-value0 title="aspect value"><dfn
1653 id=aspect-value>aspect value</dfn></a>. Precisely defined, it is equal to
1654 the x-height of a font divided by the font size.
1656 <p>In situations where font fallback occurs, fallback fonts may not share
1657 the same aspect ratio as the desired font family and will thus appear less
1658 readable. The font-size-adjust property is a way to preserve the
1659 readability of text when font fallback occurs. It does this by adjusting
1660 the font-size so that the x-height is the same regardless of the font
1661 used.
1663 <div class=example>
1664 <p>The style defined below defines Verdana as the desired font family, but
1665 if Verdana is not available Futura or Times will be used.</p>
1667 <pre>p {
1668 font-family: Verdana, Futura, Times;
1669 }
1671 <p>Lorem ipsum dolor sit amet, ...</p>
1672 </pre>
1674 <p>Verdana has a relatively high aspect ratio, lowercase letters are
1675 relatively tall compared to uppercase letters, so at small sizes text
1676 appears legible. Times has a lower aspect ratio and so if fallback
1677 occurs, the text will be less legible at small sizes than Verdana.</p>
1678 </div>
1680 <p>How text rendered in each of these fonts compares is shown below, the
1681 columns show text rendered in Verdana, Futura and Times. The same
1682 font-size value is used across cells within each row and red lines are
1683 included to show the differences in x-height. In the upper half each row
1684 is rendered in the same font-size value. The same is true for the lower
1685 half but in this half the font-size-adjust property is also set so that
1686 the actual font size is adjusted to preserve the x-height across each row.
1687 Note how small text remains relatively legible across each row in the
1688 lower half.
1690 <div class=figure><img alt="text with and without font-size-adjust"
1691 src=fontsizeadjust.png>
1692 <p class=caption>Text with and without the use of font-size-adjust
1693 </div>
1695 <p>This property allows authors to specify an aspect value for an element
1696 that will effectively preserve the x-height of the first choice font,
1697 whether it is substituted or not. Values have the following meanings:
1699 <dl>
1700 <dt><dfn id=font-size-adjust-none-value
1701 title="none!!font-size-adjust">none</dfn>
1703 <dd>Do not preserve the font's x-height.
1705 <dt><dfn id=font-size-adjust-auto-value
1706 title="auto!!font-size-adjust">auto</dfn>
1708 <dd>Behaves just like <number>, except the number used is the aspect
1709 value calculated by user agents for the first font in the list of fonts
1710 defined for the initial value of the <a href="#propdef-font-family"
1711 title="font-family!!property">‘<code
1712 class=property>font-family</code>’</a> property. Effectively this is
1713 the default font used when <a href="#propdef-font-family"
1714 title="font-family!!property">‘<code
1715 class=property>font-family</code>’</a> is not otherwise specified.
1716 <p>Authors can use this value to specify that font size should be
1717 normalized across fonts based on the x-height without the need to
1718 specify the aspect ratio explicitly.</p>
1720 <dt><dfn id=aspect-ratio-value><var><number></var></dfn>
1722 <dd>Specifies the aspect value used in the calculation below to calculate
1723 the adjusted font size:
1724 <pre>c = ( a / a' ) s
1725 </pre>
1727 <p>where:</p>
1729 <pre>s = font-size value
1730 a = aspect value as specified by the font-size-adjust property
1731 a' = aspect value of actual font
1732 c = adjusted font-size to use
1733 </pre>
1735 <p>This value applies to any font that is selected but in typical usage
1736 it should be based on the aspect value of the first font in the
1737 font-family list. If this is specified accurately, the <tt>(a/a')</tt>
1738 term in the formula above is effectively 1 for the first font and no
1739 adjustment occurs. If the value is specified inaccurately, text rendered
1740 using the first font in the family list will display differently in
1741 older user agents that don't support font-size-adjust.</p>
1742 </dl>
1744 <p>Authors can calculate the aspect value for a given font by comparing
1745 spans with the same content but different font-size-adjust properties. If
1746 the same font-size is used, the spans will match when the font-size-adjust
1747 value is accurate for the given font.
1749 <div class=example>
1750 <p>Two spans with borders are used to determine the aspect value of a
1751 font. The font-size is the same for both spans but the font-size-adjust
1752 property is specified only for the right span. Starting with a value of
1753 0.5, the aspect value can be adjusted until the borders around the two
1754 letters line up.</p>
1756 <pre>p {
1757 font-family: Futura;
1758 font-size: 500px;
1759 }
1761 span {
1762 border: solid 1px red;
1763 }
1765 .adjust {
1766 font-size-adjust: 0.5;
1767 }
1769 <p><span>b</span><span class="adjust">b</span></p>
1770 </pre>
1772 <div class=figure><img alt="Futura with an aspect value of 0.5"
1773 src=beforefontsizeadjust.png>
1774 <p class=caption>Futura with an aspect value of 0.5
1775 </div>
1777 <p>The box on the right is a bit bigger than the one on the left, so the
1778 aspect value of this font is something less than 0.5. Adjust the value
1779 until the boxes align.</p>
1780 </div>
1781 <!-- prop: font -->
1783 <h3 id=font-prop><span class=secno>3.7 </span>Shorthand font property: the
1784 <a href="#propdef-font">font</a> property</h3>
1786 <table class=propdef id=namefontvalue-ltlsquofont-stylersquogt-l>
1787 <tbody>
1788 <tr>
1789 <td>Name:
1791 <td><dfn id=propdef-font>font</dfn>
1793 <tr>
1794 <td>Value:
1796 <td>[ [ <var><<a href="#propdef-font-style"
1797 title="font-style!!property">‘<code
1798 class=property>font-style</code>’</a>></var> || <a
1799 href="#font-variant-css21-values"><var><font-variant-css21></var></a>
1800 || <var><<a href="#propdef-font-weight"
1801 title="font-weight!!property">‘<code
1802 class=property>font-weight</code>’</a>></var> || <var><<a
1803 href="#propdef-font-stretch" title="font-stretch!!property">‘<code
1804 class=property>font-stretch</code>’</a></var> ]? <var><‘<a
1805 href="#propdef-font-size"><code
1806 class=property>font-size</code></a>’></var> [ / <var><‘<code
1807 class=property>line-height</code>’></var> ]? <var><<a
1808 href="#propdef-font-family" title="font-family!!property">‘<code
1809 class=property>font-family</code>’</a>></var> ] | caption | icon |
1810 menu | message-box | small-caption | status-bar
1812 <tr>
1813 <td>Initial:
1815 <td>see individual properties
1817 <tr>
1818 <td>Applies to:
1820 <td>all elements
1822 <tr>
1823 <td>Inherited:
1825 <td>yes
1827 <tr>
1828 <td>Percentages:
1830 <td>see individual properties
1832 <tr>
1833 <td>Media:
1835 <td>visual
1837 <tr>
1838 <td>Computed value:
1840 <td>see individual properties
1842 <tr>
1843 <td>Animatable:
1845 <td>see individual properties
1846 </table>
1848 <p>The <span class=property>‘<a href="#propdef-font"><code
1849 class=property>font</code></a>’</span> property is, except as described
1850 below, a shorthand property for setting <a href="#propdef-font-style"
1851 title="font-style!!property">‘<code
1852 class=property>font-style</code>’</a>, <a href="#propdef-font-variant"
1853 title="font-variant!!property">‘<code
1854 class=property>font-variant</code>’</a>, <a href="#propdef-font-weight"
1855 title="font-weight!!property">‘<code
1856 class=property>font-weight</code>’</a>, <a href="#propdef-font-stretch"
1857 title="font-stretch!!property">‘<code
1858 class=property>font-stretch</code>’</a>, <span class=property>‘<a
1859 href="#propdef-font-size"><code
1860 class=property>font-size</code></a>’</span>, <a class=property
1861 href="http://www.w3.org/TR/CSS2/visudet.html#propdef-line-height">‘<code
1862 class=property>line-height</code>’</a>, <a href="#propdef-font-family"
1863 title="font-family!!property">‘<code
1864 class=property>font-family</code>’</a> at the same place in the
1865 stylesheet. Values for the <a href="#propdef-font-variant"
1866 title="font-variant!!property">‘<code
1867 class=property>font-variant</code>’</a> property may also be included
1868 but only those supported in CSS 2.1, none of the <a
1869 href="#propdef-font-variant" title="font-variant!!property">‘<code
1870 class=property>font-variant</code>’</a> values added in this
1871 specification can be used in the <span class=property>‘<a
1872 href="#propdef-font"><code class=property>font</code></a>’</span>
1873 shorthand:
1875 <pre
1876 class=prod><dfn id=font-variant-css21-values><var><font-variant-css21></var></dfn> = [normal | small-caps]</pre>
1878 <p>The syntax of this property is based on a traditional typographical
1879 shorthand notation to set multiple properties related to fonts.
1881 <p>All subproperties of the ‘<a href="#propdef-font"><code
1882 class=property>font</code></a>’ property are first reset to their
1883 initial values, including those listed above plus <span
1884 class=property>‘<a href="#propdef-font-size-adjust"><code
1885 class=property>font-size-adjust</code></a>’</span>, <span
1886 class=property>‘<a href="#propdef-font-kerning"><code
1887 class=property>font-kerning</code></a>’</span>, subproperties of <a
1888 href="#propdef-font-variant" title="font-variant!!property">‘<code
1889 class=property>font-variant</code>’</a> and and <span>‘<a
1890 href="#propdef-font-language-override"><code
1891 class=property>font-language-override</code></a>’</span>. Then, those
1892 properties that are given explicit values in the <span
1893 class=property>‘<a href="#propdef-font"><code
1894 class=property>font</code></a>’</span> shorthand are set to those
1895 values. For a definition of allowed and initial values, see the previously
1896 defined properties. For reasons of backwards compatibility, it is not
1897 possible to set <span class=property>‘<a
1898 href="#propdef-font-size-adjust"><code
1899 class=property>font-size-adjust</code></a>’</span> to anything other
1900 than its initial value using the <span class=property>‘<a
1901 href="#propdef-font"><code class=property>font</code></a>’</span>
1902 shorthand property; instead, use the individual property.
1904 <div class=example>
1905 <p style="display:none">Example(s):
1907 <p>
1909 <pre>p { font: 12pt/14pt sans-serif }
1910 p { font: 80% sans-serif }
1911 p { font: x-large/110% "new century schoolbook", serif }
1912 p { font: bold italic large Palatino, serif }
1913 p { font: normal small-caps 120%/120% fantasy }
1914 p { font: condensed oblique 12pt "Helvetica Neue", serif; }
1915 </pre>
1917 <p> In the second rule, the font size percentage value (‘<code
1918 class=css>80%</code>’) refers to the computed ‘<a
1919 href="#propdef-font-size"><code class=property>font-size</code></a>’ of
1920 the parent element. In the third rule, the line height percentage
1921 (‘<code class=css>110%</code>’) refers to the font size of the
1922 element itself.
1924 <p>The first three rules do not specify the <a
1925 href="#propdef-font-variant" title="font-variant!!property">‘<code
1926 class=property>font-variant</code>’</a> and <a
1927 href="#propdef-font-weight" title="font-weight!!property">‘<code
1928 class=property>font-weight</code>’</a> explicitly, so these properties
1929 receive their initial values (<span title="normal value">‘<code
1930 class=property>normal</code>’</span>). Notice that the font family name
1931 "new century schoolbook", which contains spaces, is enclosed in quotes.
1932 The fourth rule sets the <a href="#propdef-font-weight"
1933 title="font-weight!!property">‘<code
1934 class=property>font-weight</code>’</a> to ‘<a href="#bold"><code
1935 class=property>bold</code></a>’, the <a href="#propdef-font-style"
1936 title="font-style!!property">‘<code
1937 class=property>font-style</code>’</a> to ‘<a href="#italic"><code
1938 class=property>italic</code></a>’, and implicitly sets <a
1939 href="#propdef-font-variant" title="font-variant!!property">‘<code
1940 class=property>font-variant</code>’</a> to <a
1941 href="#font-variant-normal-value" title="normal!!font-variant">‘<code
1942 class=property>normal</code>’</a>.
1944 <p> The fifth rule sets the <a href="#propdef-font-variant"
1945 title="font-variant!!property">‘<code
1946 class=property>font-variant</code>’</a> (‘<a href="#small-caps"><code
1947 class=property>small-caps</code></a>’), the <span class=property>‘<a
1948 href="#propdef-font-size"><code
1949 class=property>font-size</code></a>’</span> (120% of the parent's font
1950 size), the <a class=property
1951 href="http://www.w3.org/TR/CSS2/visudet.html#propdef-line-height">‘<code
1952 class=property>line-height</code>’</a> (120% of the font size) and the
1953 <a href="#propdef-font-family" title="font-family!!property">‘<code
1954 class=property>font-family</code>’</a> (‘<a href="#fantasy"><code
1955 class=property>fantasy</code></a>’). It follows that the keyword <span
1956 title="normal value">‘<code class=property>normal</code>’</span>
1957 applies to the two remaining properties: <a href="#propdef-font-style"
1958 title="font-style!!property">‘<code
1959 class=property>font-style</code>’</a> and <a
1960 href="#propdef-font-weight" title="font-weight!!property">‘<code
1961 class=property>font-weight</code>’</a>.
1963 <p>The sixth rule sets the <a href="#propdef-font-style"
1964 title="font-style!!property">‘<code
1965 class=property>font-style</code>’</a>, <a href="#propdef-font-stretch"
1966 title="font-stretch!!property">‘<code
1967 class=property>font-stretch</code>’</a>, <span class=property>‘<a
1968 href="#propdef-font-size"><code
1969 class=property>font-size</code></a>’</span>, and <a
1970 href="#propdef-font-family" title="font-family!!property">‘<code
1971 class=property>font-family</code>’</a>, the other font properties being
1972 set to their initial values.
1973 </div>
1975 <p>Since the <a href="#propdef-font-stretch"
1976 title="font-stretch!!property">‘<code
1977 class=property>font-stretch</code>’</a> property was not defined in CSS
1978 2.1, when using <a href="#propdef-font-stretch"
1979 title="font-stretch!!property">‘<code
1980 class=property>font-stretch</code>’</a> values within ‘<a
1981 href="#propdef-font"><code class=property>font</code></a>’ rules,
1982 authors should include a extra version compatible with older user agents:
1984 <pre>p {
1985 font: 80% sans-serif; /* for older user agents */
1986 font: condensed 80% sans-serif;
1987 }</pre>
1989 <p>The following values refer to system fonts:
1991 <dl>
1992 <dt><strong>caption</strong>
1994 <dd>The font used for captioned controls (e.g., buttons, drop-downs,
1995 etc.).
1997 <dt><strong>icon</strong>
1999 <dd>The font used to label icons.
2001 <dt><strong>menu</strong>
2003 <dd>The font used in menus (e.g., dropdown menus and menu lists).
2005 <dt><strong>message-box</strong>
2007 <dd>The font used in dialog boxes.
2009 <dt><strong>small-caption</strong>
2011 <dd>The font used for labeling small controls.
2013 <dt><strong>status-bar</strong>
2015 <dd>The font used in window status bars.
2016 </dl>
2018 <p>System fonts may only be set as a whole; that is, the font family, size,
2019 weight, style, etc. are all set at the same time. These values may then be
2020 altered individually if desired. If no font with the indicated
2021 characteristics exists on a given platform, the user agent should either
2022 intelligently substitute (e.g., a smaller version of the ‘<code
2023 class=property>caption</code>’ font might be used for the ‘<code
2024 class=property>small-caption</code>’ font), or substitute a user agent
2025 default font. As for regular fonts, if, for a system font, any of the
2026 individual properties are not part of the operating system's available
2027 user preferences, those properties should be set to their initial values.
2029 <p>That is why this property is "almost" a shorthand property: system fonts
2030 can only be specified with this property, not with <a
2031 href="#propdef-font-family" title="font-family!!property">‘<code
2032 class=property>font-family</code>’</a> itself, so <span
2033 class=property>‘<a href="#propdef-font"><code
2034 class=property>font</code></a>’</span> allows authors to do more than
2035 the sum of its subproperties. However, the individual properties such as
2036 <a href="#propdef-font-weight" title="font-weight!!property">‘<code
2037 class=property>font-weight</code>’</a> are still given values taken from
2038 the system font, which can be independently varied.
2040 <p>Note that the keywords used for the system fonts listed above are only
2041 treated as keywords when they occur in the initial position, in other
2042 positions the same string is treated as part of the font family name:
2044 <pre> font: menu; /* use the font settings for system menus */
2045 font: large menu; /* use a font family named "menu" */</pre>
2047 <div class=example>
2048 <p style="display:none">Example(s):
2050 <p>
2052 <pre>button { font: 300 italic 1.3em/1.7em "FB Armada", sans-serif }
2053 button p { font: menu }
2054 button p em { font-weight: bolder }
2055 </pre>
2057 <p>If the font used for dropdown menus on a particular system happened to
2058 be, for example, 9-point Charcoal, with a weight of 600, then P elements
2059 that were descendants of BUTTON would be displayed as if this rule were
2060 in effect:
2062 <pre>button p { font: 600 9pt Charcoal }
2063 </pre>
2065 <p>Because the <span class=property>‘<a href="#propdef-font"><code
2066 class=property>font</code></a>’</span> shorthand resets to its initial
2067 value any property not explicitly given a value, this has the same effect
2068 as this declaration:
2070 <pre>button p {
2071 font-style: normal;
2072 font-variant: normal;
2073 font-weight: 600;
2074 font-size: 9pt;
2075 line-height: normal;
2076 font-family: Charcoal
2077 }
2078 </pre>
2079 </div>
2080 <!-- prop: font-synthesis -->
2082 <h3 id=font-synthesis-prop><span class=secno>3.8 </span>Controlling
2083 synthetic faces: the <a href="#propdef-font-synthesis">font-synthesis</a>
2084 property</h3>
2086 <table class=propdef id=namefont-synthesisvaluenone-weight-style>
2087 <tbody>
2088 <tr>
2089 <td>Name:
2091 <td><dfn id=propdef-font-synthesis>font-synthesis</dfn>
2093 <tr>
2094 <td>Value:
2096 <td>none | [ weight || style ]
2098 <tr>
2099 <td>Initial:
2101 <td>weight style
2103 <tr>
2104 <td>Applies to:
2106 <td>all elements
2108 <tr>
2109 <td>Inherited:
2111 <td>yes
2113 <tr>
2114 <td>Percentages:
2116 <td>N/A
2118 <tr>
2119 <td>Media:
2121 <td>visual
2123 <tr>
2124 <td>Computed value:
2126 <td>as specified
2128 <tr>
2129 <td>Animatable:
2131 <td>no
2132 </table>
2134 <p>This property controls whether user agents are allowed to synthesize
2135 bold or oblique font faces when a font family lacks bold or italic faces.
2136 If ‘<a href="#weight"><code class=property>weight</code></a>’ is not
2137 specified, user agents must not synthesize bold faces and if ‘<code
2138 class=property>style</code>’ is not specified user agents must not
2139 synthesize italic faces. A value of ‘<code class=property>none</code>’
2140 disallows all synthetic faces.
2142 <div class=example>
2143 <p>The style rule below disables the use of synthetically obliqued Arabic:</p>
2145 <pre>*:lang(ar) { font-synthesis: none; }
2146 </pre>
2147 </div>
2149 <h2 id=font-resources><span class=secno>4 </span>Font Resources</h2>
2151 <h3 id=font-face-rule><span class=secno>4.1 </span>The <dfn
2152 id=at-font-face-rule style="font-weight: inherit; font-style:
2153 inherit"><code>@font-face</code></dfn> rule</h3>
2155 <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule allows
2156 for linking to fonts that are automatically fetched and activated when
2157 needed. This allows authors to select a font that closely matches the
2158 design goals for a given page rather than limiting the font choice to a
2159 set of fonts available on all platforms. A set of font descriptors define
2160 the location of a font resource, either locally or externally, along with
2161 the style characteristics of an individual face. Multiple <a
2162 href="#at-font-face-rule"><code>@font-face</code></a> rules can be used to
2163 construct font families with a variety of faces. Using CSS font matching
2164 rules, a user agent can selectively download only those faces that are
2165 needed for a given piece of text.
2167 <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule
2168 consists of the <a href="#at-font-face-rule"><code>@font-face</code></a>
2169 at-keyword followed by a block of descriptor declarations. In terms of the
2170 grammar, this specification defines the following productions:
2172 <pre><dfn id=fontfacerule>font_face_rule</dfn>
2173 : <a href="#fontfacesym"><i>FONT_FACE_SYM</i></a> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* '{' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="#descriptordeclaration"><i>descriptor_declaration</i></a>? [ ';' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="#descriptordeclaration"><i>descriptor_declaration</i></a>? ]* '}' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>*
2174 ;
2176 <dfn id=descriptordeclaration>descriptor_declaration</dfn>
2177 : <a href="http://www.w3.org/TR/CSS21/grammar.html#grammar"><i>property</i></a> ':' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="http://www.w3.org/TR/CSS21/grammar.html#grammar"><i>expr</i></a>
2178 ;</pre>
2180 <p>The following new definitions are introduced:
2182 <pre>- -|\\0{0,4}2d(\r\n|[ \t\r\n\f])?
2183 F f|\\0{0,4}(46|66)(\r\n|[ \t\r\n\f])?</pre>
2185 <p>The following new token is introduced:
2187 <pre>@{F}{O}{N}{T}{-}{F}{A}{C}{E} {return <dfn id=fontfacesym>FONT_FACE_SYM</dfn>;}</pre>
2189 <p>Each <a href="#at-font-face-rule"><code>@font-face</code></a> rule
2190 specifies a value for every font descriptor, either implicitly or
2191 explicitly. Those not given explicit values in the rule take the initial
2192 value listed with each descriptor in this specification. These descriptors
2193 apply solely within the context of the <a
2194 href="#at-font-face-rule"><code>@font-face</code></a> rule in which they
2195 are defined, and do not apply to document language elements. There is no
2196 notion of which elements the descriptors apply to or whether the values
2197 are inherited by child elements. When a given descriptor occurs multiple
2198 times in a given <a href="#at-font-face-rule"><code>@font-face</code></a>
2199 rule, only the last descriptor declaration is used and all prior
2200 declarations for that descriptor are ignored.
2202 <div class=example>
2203 <p>To use a downloadable font called Gentium:</p>
2205 <pre>
2206 @font-face {
2207 font-family: Gentium;
2208 src: url(http://example.com/fonts/Gentium.ttf);
2209 }
2211 p { font-family: Gentium, serif; }
2212 </pre>
2214 <p>The user agent will download Gentium and use it when rendering text
2215 within paragraph elements. If for some reason the site serving the font
2216 is unavailable, the default serif font will be used.</p>
2217 </div>
2219 <p>A given set of <a href="#at-font-face-rule"><code>@font-face</code></a>
2220 rules define a set of fonts available for use within the documents that
2221 contain these rules. When font matching is done, fonts defined using these
2222 rules are considered before other available fonts on a system.
2224 <p>Downloaded fonts are only available to documents that reference them.
2225 The process of activating these fonts must not make them available to
2226 other applications or to documents that don't directly link to the same
2227 font. User agent implementers might consider it convenient to use
2228 downloaded fonts when rendering characters in other documents for which no
2229 other available font exists as part of the <a
2230 href="#system-font-fallback"><em>system font fallback</em></a> procedure.
2231 However, this would cause a security leak since the contents of one page
2232 would be able to affect other pages, something an attacker could use as an
2233 attack vector. These restrictions do not affect caching behavior, fonts
2234 are cached the same way other web resources are cached.
2236 <p>This at-rule follows the forward-compatible parsing rules of CSS. Like
2237 properties in a declaration block, declarations of any descriptors that
2238 are not supported by the user agent must be ignored. <a
2239 href="#at-font-face-rule"><code>@font-face</code></a> rules require a
2240 font-family and src descriptor; if either of these are missing, the <a
2241 href="#at-font-face-rule"><code>@font-face</code></a> rule is invalid and
2242 must be ignored entirely.
2244 <p>In cases where user agents have limited platform resources or implement
2245 the ability to disable downloadable font resources, <a
2246 href="#at-font-face-rule"><code>@font-face</code></a> rules must simply be
2247 ignored; the behavior of individual descriptors as defined in this
2248 specification should not be altered.
2250 <h3 id=font-family-desc><span class=secno>4.2 </span>Font family: the <a
2251 href="#descdef-font-family">font-family</a> descriptor</h3>
2253 <table class=descdef>
2254 <tbody>
2255 <tr>
2256 <td>Name:
2258 <td><dfn id=descdef-font-family
2259 title="font-family!!descriptor">font-family</dfn>
2261 <tr>
2262 <td>Value:
2264 <td><a href="#family-name-value"><var><family-name></var></a>
2266 <tr>
2267 <td><em>Initial:</em>
2269 <td>N/A
2270 </table>
2272 <p>This descriptor defines the font family name that will be used in all
2273 CSS font family name matching. It is required for the <a
2274 href="#at-font-face-rule"><code>@font-face</code></a> rule to be valid. It
2275 overrides the font family names contained in the underlying font data. If
2276 the font family name is the same as a font family available in a given
2277 user's environment, it effectively hides the underlying font for documents
2278 that use the stylesheet. This permits a web author to freely choose
2279 font-family names without worrying about conflicts with font family names
2280 present in a given user's environment. Likewise, platform substitutions
2281 for a given font family name must not be used.
2283 <h3 id=src-desc><span class=secno>4.3 </span>Font reference: the <a
2284 href="#descdef-src">src</a> descriptor</h3>
2286 <table class=descdef>
2287 <tbody>
2288 <tr>
2289 <td>Name:
2291 <td><dfn id=descdef-src>src</dfn>
2293 <tr>
2294 <td>Value:
2296 <td>[ <url> [format(<string> #)]? | <a
2297 href="#font-face-name-value"><var><font-face-name></var></a> ] #
2299 <tr>
2300 <td><em>Initial:</em>
2302 <td>N/A
2303 </table>
2305 <p>This descriptor specifies the resource containing font data. It is
2306 required for the <a href="#at-font-face-rule"><code>@font-face</code></a>
2307 rule to be valid. Its value is a prioritized, comma-separated list of
2308 external references or locally-installed font face names. When a font is
2309 needed the user agent iterates over the set of references listed, using
2310 the first one it can successfully activate. Fonts containing invalid data
2311 or local font faces that are not found are ignored and the user agent
2312 loads the next font in the list.
2314 <p>As with other URLs in CSS, the URL may be relative, in which case it is
2315 resolved relative to the location of the style sheet containing the <a
2316 href="#at-font-face-rule"><code>@font-face</code></a> rule. In the case of
2317 SVG fonts, the URL points to an element within a document containing SVG
2318 font definitions. If the element reference is omitted, a reference to the
2319 first defined font is implied. Similarly, font container formats that can
2320 contain more than one font must load one and only one of the fonts for a
2321 given <a href="#at-font-face-rule"><code>@font-face</code></a> rule.
2322 Fragment identifiers are used to indicate which font to load. If a
2323 container format lacks a defined fragment identifier scheme,
2324 implementations should use a simple 1-based indexing scheme (e.g.
2325 "font-collection#1" for the first font, "font-collection#2" for the second
2326 font).
2328 <pre>
2329 src: url(fonts/simple.ttf); /* load simple.ttf relative to stylesheet location */
2330 src: url(/fonts/simple.ttf); /* load simple.ttf from absolute location */
2331 src: url(fonts.svg#simple); /* load SVG font with id 'simple' */
2332 </pre>
2334 <p>External references consist of a URL, followed by an optional hint
2335 describing the format of the font resource referenced by that URL. The
2336 format hint contains a comma-separated list of format strings that denote
2337 well-known font formats. Conformant user agents must skip downloading a
2338 font resource if the format hints indicate only unsupported or unknown
2339 font formats. If no format hints are supplied, the user agent should
2340 download the font resource.
2342 <pre>
2343 /* load WOFF font if possible, otherwise use OpenType font */
2344 @font-face {
2345 font-family: bodytext;
2346 src: url(ideal-sans-serif.woff) format("woff"),
2347 url(basic-sans-serif.ttf) format("opentype");
2348 }
2349 </pre>
2351 <p>Format strings defined by this specification:
2353 <table class=data id=fontformats>
2354 <thead>
2355 <tr>
2356 <th>String
2358 <th>Font Format
2360 <th>Common extensions
2362 <tbody>
2363 <tr>
2364 <th>"woff"
2366 <td><a href="http://www.w3.org/TR/WOFF/">WOFF (Web Open Font Format)</a>
2368 <td>.woff
2370 <tr>
2371 <th>"truetype"
2373 <td><a
2374 href="http://www.microsoft.com/typography/otspec/default.htm">TrueType</a>
2376 <td>.ttf
2378 <tr>
2379 <th>"opentype"
2381 <td><a
2382 href="http://www.microsoft.com/typography/otspec/default.htm">OpenType</a>
2384 <td>.ttf, .otf
2386 <tr>
2387 <th>"embedded-opentype"
2389 <td><a
2390 href="http://www.w3.org/Submission/2008/SUBM-EOT-20080305/">Embedded
2391 OpenType</a>
2393 <td>.eot
2395 <tr>
2396 <th>"svg"
2398 <td><a href="http://www.w3.org/TR/SVG/fonts.html">SVG Font</a>
2400 <td>.svg, .svgz
2401 </table>
2403 <p>Given the overlap in common usage between TrueType and OpenType, the
2404 format hints "truetype" and "opentype" must be considered as synonymous; a
2405 format hint of "opentype" does not imply that the font contains Postscript
2406 CFF style glyph data or that it contains OpenType layout information (see
2407 <a href="#platform-props-to-css">Appendix A</a> for more background on
2408 this).
2410 <p>When authors would prefer to use a locally available copy of a given
2411 font and download it if it's not, <code>local()</code> can be used. The
2412 locally-installed <dfn
2413 id=font-face-name-value><var><font-face-name></var></dfn> argument
2414 to <code>local()</code> is a format-specific string that uniquely
2415 identifies a single font face within a larger family. The syntax for a <a
2416 href="#font-face-name-value"><var><font-face-name></var></a> is a
2417 unique font face name enclosed by "local(" and ")". The name can
2418 optionally be enclosed in quotes. If unquoted, the unquoted font family
2419 name processing conventions apply; the name must be a sequence of
2420 identifiers separated by whitespace which is converted to a string by
2421 joining the identifiers together separated by a single space.
2423 <pre>
2424 /* regular face of Gentium */
2425 @font-face {
2426 font-family: MyGentium;
2427 src: local(Gentium), /* use locally available Gentium */
2428 url(Gentium.ttf); /* otherwise, download it */
2429 }
2430 </pre>
2432 <p>For OpenType and TrueType fonts, this string is used to match only the
2433 Postscript name or the full font name in the name table of locally
2434 available fonts. Which type of name is used varies by platform and font,
2435 so authors should include both of these names to assure proper matching
2436 across platforms. Platform substitutions for a given font name must not be
2437 used.
2439 <pre>
2440 /* bold face of Gentium */
2441 @font-face {
2442 font-family: MyGentium;
2443 src: local(Gentium Bold), /* full font name */
2444 local(Gentium-Bold), /* Postscript name */
2445 url(GentiumBold.ttf); /* otherwise, download it */
2446 font-weight: bold;
2447 }
2448 </pre>
2450 <p>Just as a <a href="#at-font-face-rule"><code>@font-face</code></a> rule
2451 specifies the characteristics of a single font within a family, the unique
2452 name used with <code>local()</code> specifies a single font, not an entire
2453 font family. Defined in terms of OpenType font data, the Postscript name
2454 is found in the font's <a
2455 href="http://www.microsoft.com/typography/otspec/name.htm">name table</a>,
2456 in the name record with nameID = 6 (see <a href="#OPENTYPE"
2457 rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a> for more details). The
2458 Postscript name is the commonly used key for all fonts on OSX and for
2459 Postscript CFF fonts under Windows. The full font name (nameID = 4) is
2460 used as a unique key for fonts with TrueType glyphs on Windows.
2462 <p>For OpenType fonts with multiple localizations of the full font name,
2463 the US English version is used (language ID = 0x409 for Windows and
2464 language ID = 0 for Macintosh) or the first localization when a US English
2465 full font name is not available (the OpenType specification recommends
2466 that <a href="http://www.microsoft.com/typography/otspec/recom.htm">all
2467 fonts minimally include US English names</a>). User agents that also match
2468 other full font names, e.g. matching the Dutch name when the current
2469 system locale is set to Dutch, are considered non-conformant. This is done
2470 not to prefer English but to avoid matching inconsistencies across font
2471 versions and OS localizations, since font style names (e.g. "Bold") are
2472 frequently localized into many languages and the set of localizations
2473 available varies widely across platform and font version. User agents that
2474 match a concatenation of family name (nameID = 1) with style name (nameID
2475 = 2) are considered non-conformant.
2477 <p>This also allows for referencing faces that belong to larger families
2478 that cannot otherwise be referenced.
2480 <div class=example>
2481 <p>Use a local font or reference an SVG font in another document:</p>
2483 <pre>
2484 @font-face {
2485 font-family: Headline;
2486 src: local(Futura-Medium),
2487 url(fonts.svg#MyGeometricModern) format("svg");
2488 }
2489 </pre>
2491 <p>Create an alias for local Japanese fonts on different platforms:</p>
2493 <pre>
2494 @font-face {
2495 font-family: jpgothic;
2496 src: local(HiraKakuPro-W3), local(Meiryo), local(IPAPGothic);
2497 }
2498 </pre>
2500 <p>Reference a font face that cannot be matched within a larger family:</p>
2502 <pre>
2503 @font-face {
2504 font-family: Hoefler Text Ornaments;
2505 /* has the same font properties as Hoefler Text Regular */
2506 src: local(HoeflerText-Ornaments);
2507 }
2508 </pre>
2510 <p>Since localized fullnames never match, a document with the header style
2511 rules below would always render using the default serif font, regardless
2512 whether a particular system locale parameter is set to Finnish or not:</p>
2514 <pre>
2515 @font-face {
2516 font-family: SectionHeader;
2517 src: local("Arial Lihavoitu"); /* Finnish fullname for Arial Bold, should fail */
2518 font-weight: bold;
2519 }
2521 h2 { font-family: SectionHeader, serif; }
2522 </pre>
2524 <p>A conformant user agent would never load the font ‘<code
2525 class=css>gentium.eot</code>’ in the example below, since it is
2526 included in the first definition of the ‘<a href="#descdef-src"><code
2527 class=property>src</code></a>’ descriptor which is overridden by the
2528 second definition in the same <a
2529 href="#at-font-face-rule"><code>@font-face</code></a> rule:</p>
2531 <pre>
2532 @font-face {
2533 font-family: MainText;
2534 src: url(gentium.eot); /* for use with older non-conformant user agents */
2535 src: local("Gentium"), url(gentium.ttf); /* Overrides src definition */
2536 }
2537 </pre>
2538 </div>
2540 <h3 id=font-prop-desc><span class=secno>4.4 </span>Font property
2541 descriptors: the <a href="#descdef-font-style">font-style</a>, <a
2542 href="#descdef-font-weight">font-weight</a>, <a
2543 href="#descdef-font-stretch">font-stretch</a> descriptors</h3>
2545 <table class=descdef>
2546 <tbody>
2547 <tr>
2548 <td>Name:
2550 <td><dfn id=descdef-font-style
2551 title="font-style!!descriptor">font-style</dfn>
2553 <tr>
2554 <td>Value:
2556 <td>normal | italic | oblique
2558 <tr>
2559 <td><em>Initial:</em>
2561 <td>normal
2562 </table>
2564 <table class=descdef>
2565 <tbody>
2566 <tr>
2567 <td>Name:
2569 <td><dfn id=descdef-font-weight
2570 title="font-weight!!descriptor">font-weight</dfn>
2572 <tr>
2573 <td>Value:
2575 <td>normal | bold | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900
2577 <tr>
2578 <td><em>Initial:</em>
2580 <td>normal
2581 </table>
2583 <table class=descdef>
2584 <tbody>
2585 <tr>
2586 <td>Name:
2588 <td><dfn id=descdef-font-stretch
2589 title="font-stretch!!descriptor">font-stretch</dfn>
2591 <tr>
2592 <td>Value:
2594 <td>normal | ultra-condensed | extra-condensed | condensed |
2595 semi-condensed | semi-expanded | expanded | extra-expanded |
2596 ultra-expanded
2598 <tr>
2599 <td><em>Initial:</em>
2601 <td>normal
2602 </table>
2604 <p>These descriptors define the characteristics of a font face and are used
2605 in the process of matching styles to specific faces. For a font family
2606 defined with several <a
2607 href="#at-font-face-rule"><code>@font-face</code></a> rules, user agents
2608 can either download all faces in the family or use these descriptors to
2609 selectively download font faces that match actual styles used in document.
2610 The values for these descriptors are the same as those for the
2611 corresponding font properties except that relative keywords are not
2612 allowed, ‘<a href="#bolder"><code class=property>bolder</code></a>’
2613 and ‘<a href="#lighter"><code class=property>lighter</code></a>’. If
2614 these descriptors are omitted, initial values are assumed.
2616 <p>The value for these font face style attributes is used in place of the
2617 style implied by the underlying font data. This allows authors to combine
2618 faces in flexible combinations, even in situations where the original font
2619 data was arranged differently. User agents that implement synthetic
2620 bolding and obliquing must only apply synthetic styling in cases where the
2621 font descriptors imply this is needed, rather than based on the style
2622 attributes implied by the font data.
2624 <h3 id=unicode-range-desc><span class=secno>4.5 </span>Character range: the
2625 <a href="#descdef-unicode-range">unicode-range</a> descriptor</h3>
2627 <table class=descdef>
2628 <tbody>
2629 <tr>
2630 <td>Name:
2632 <td><dfn id=descdef-unicode-range>unicode-range</dfn>
2634 <tr>
2635 <td>Value:
2637 <td><a href="#urange-value"><var><urange></var></a> #
2639 <tr>
2640 <td><em>Initial:</em>
2642 <td>U+0-10FFFF
2643 </table>
2645 <p>This descriptor defines the set of Unicode codepoints that may be
2646 supported by the font face for which it is declared. The descriptor value
2647 is a comma-delimited list of Unicode range (<a
2648 href="#urange-value"><var><urange></var></a>) values. The union of
2649 these ranges defines the set of codepoints that serves as a hint for user
2650 agents when deciding whether or not to download a font resource for a
2651 given text run.
2653 <p>Each <dfn id=urange-value><var><urange></var></dfn> value is a <a
2654 href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><code
2655 title="UNICODE-RANGE token">UNICODE-RANGE</code></a> token made up of a
2656 "U+" or "u+" prefix followed by a codepoint range in one of the three
2657 forms listed below. Ranges that do not fit one of the these forms are
2658 invalid and cause the declaration to be ignored.
2660 <dl>
2661 <dt>single codepoint (e.g. U+416)
2663 <dd>a valid Unicode codepoint, represented as one to six hexadecimal
2664 digits
2666 <dt>interval range (e.g. U+400-4ff)
2668 <dd>represented as two hyphen-separated valid Unicode codepoints
2669 indicating the inclusive start and end codepoints of a range
2671 <dt>wildcard range (e.g. U+4??)
2673 <dd>defined by the set of codepoints implied when trailing ‘<code
2674 class=css>?</code>’ characters signify any hexadeximal digit
2675 </dl>
2677 <p>Individual codepoints are written using hexadecimal values that
2678 correspond to <a href="http://www.unicode.org/charts/">Unicode character
2679 codepoints</a>. Valid Unicode codepoint values vary between 0 and 10FFFF
2680 inclusive. Digit values of codepoints are ASCII case-insensitive. For
2681 interval ranges, the start and end codepoints are valid Unicode values and
2682 the end codepoint is greater than or equal to the start codepoint.
2684 <p>Wildcard ranges specified with ‘?’ that lack an initial digit (e.g.
2685 "U+???") are valid and equivalent to a wildcard range with an initial zero
2686 digit (e.g. "U+0???" = "U+0000-0FFF"). Wildcard ranges that extend beyond
2687 the range of valid Unicode codepoints are invalid. Because of this, the
2688 maximum number of trailing ‘<code class=css>?</code>’ wildcard
2689 characters is five, even though the <a
2690 href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><code
2691 title="UNICODE-RANGE token">UNICODE-RANGE</code></a> token accepts six.
2693 <p>Within the comma-delimited list of Unicode ranges in a ‘<a
2694 href="#descdef-unicode-range"><code
2695 class=property>unicode-range</code></a>’ descriptor declaration, ranges
2696 may overlap. The union of these ranges defines the set of codepoints for
2697 which the corresponding font may be used. User agents must not download or
2698 use the font for codepoints outside this set. User agents may normalize
2699 the list of ranges into a list that is different but represents the same
2700 set of codepoints.
2702 <p>The associated font might not contain glyphs for the entire set of
2703 codepoints defined by the ‘<a href="#descdef-unicode-range"><code
2704 class=property>unicode-range</code></a>’ descriptor. When the font is
2705 used, the <dfn id=effective-character-map>effective character map</dfn> is
2706 the intersection of the codepoints defined by ‘<a
2707 href="#descdef-unicode-range"><code
2708 class=property>unicode-range</code></a>’ with the font's <a
2709 href="#character-map"><em>character map</em></a>. This allows authors to
2710 define supported ranges in terms of broad ranges without worrying about
2711 the precise codepoint ranges supported by the underlying font.
2713 <h3 id=composite-fonts><span class=secno>4.6 </span>Using character ranges
2714 to define composite fonts</h3>
2716 <p>Multiple <a href="#at-font-face-rule"><code>@font-face</code></a> rules
2717 with different unicode ranges for the same family and style descriptor
2718 values can be used to create composite fonts that mix the glyphs from
2719 different fonts for different scripts. This can be used to combine fonts
2720 that only contain glyphs for a single script (e.g. Latin, Greek, Cyrillic)
2721 or it can be used by authors as a way of segmenting a font into fonts for
2722 commonly used characters and less frequently used characters. Since the
2723 user agent will only pull down the fonts it needs this helps reduce page
2724 bandwidth.
2726 <p>If the unicode ranges overlap for a set of <a
2727 href="#at-font-face-rule"><code>@font-face</code></a> rules with the same
2728 family and style descriptor values, the rules are ordered in the reverse
2729 order they were defined; the last rule defined is the first to be checked
2730 for a given character.
2732 <p>Example ranges for specific languages or characters:
2734 <dl>
2735 <dt>unicode-range: U+A5;
2737 <dd>a single code point, the yen/yuan symbol
2739 <dt>unicode-range: U+0-7F;
2741 <dd>code range for basic ASCII characters
2743 <dt>unicode-range: U+590-5ff;
2745 <dd>code range for Hebrew characters
2747 <dt>unicode-range: U+A5, U+4E00-9FFF, U+30??, U+FF00-FF9F;
2749 <dd>code range for Japanese kanji, hiragana and katakana characters plus
2750 yen/yuan symbol
2751 </dl>
2753 <div class=example>
2754 <p>The BBC provides news services in a wide variety of languages, many
2755 that are not well supported across all platforms. Using an <a
2756 href="#at-font-face-rule"><code>@font-face</code></a> rule, the BBC could
2757 provide a font for any of these languages, as it already does via a
2758 manual font download.</p>
2760 <pre>
2761 @font-face {
2762 font-family: BBCBengali;
2763 src: url(fonts/BBCBengali.ttf) format("opentype");
2764 unicode-range: U+00-FF, U+980-9FF;
2765 }
2766 </pre>
2767 </div>
2769 <div class=example>
2770 <p>Technical documents often require a wide range of symbols. The STIX
2771 Fonts project is one project aimed at providing fonts to support a wide
2772 range of technical typesetting in a standardized way. The example below
2773 shows the use of a font that provides glyphs for many of the mathematical
2774 and technical symbol ranges within Unicode:</p>
2776 <pre>
2777 @font-face {
2778 font-family: STIXGeneral;
2779 src: local(STIXGeneral), url(/stixfonts/STIXGeneral.otf);
2780 unicode-range: U+000-49F, U+2000-27FF, U+2900-2BFF, U+1D400-1D7FF;
2781 }
2782 </pre>
2783 </div>
2785 <div class=example>
2786 <p>This example shows how an author can override the glyphs used for Latin
2787 characters in a Japanese font with glyphs from a different font. The
2788 first rule specifies no range so it defaults to the entire range. The
2789 range specified in the second rule overlaps but takes precedence because
2790 it is defined later.</p>
2792 <pre>
2793 @font-face {
2794 font-family: JapaneseWithGentium;
2795 src: local(MSMincho);
2796 /* no range specified, defaults to entire range */
2797 }
2799 @font-face {
2800 font-family: JapaneseWithGentium;
2801 src: url(../fonts/Gentium.ttf);
2802 unicode-range: U+0-2FF;
2803 }
2804 </pre>
2805 </div>
2807 <div class=example>
2808 <p>Consider a family constructed to optimize bandwidth by separating out
2809 Latin, Japanese and other characters into different font files:</p>
2811 <pre>
2812 /* fallback font - size: 4.5MB */
2813 @font-face {
2814 font-family: DroidSans;
2815 src: url(DroidSansFallback.ttf);
2816 /* no range specified, defaults to entire range */
2817 }
2819 /* Japanese glyphs - size: 1.2MB */
2820 @font-face {
2821 font-family: DroidSans;
2822 src: url(DroidSansJapanese.ttf);
2823 unicode-range: U+3000-9FFF, U+ff??;
2824 }
2826 /* Latin, Greek, Cyrillic along with some
2827 punctuation and symbols - size: 190KB */
2828 @font-face {
2829 font-family: DroidSans;
2830 src: url(DroidSans.ttf);
2831 unicode-range: U+000-5FF, U+1e00-1fff, U+2000-2300;
2832 }
2833 </pre>
2835 <p>For simple Latin text, only the font for Latin characters is
2836 downloaded:</p>
2838 <pre>
2839 body { font-family: DroidSans; }
2841 <p>This is that</p>
2842 </pre>
2844 <p>In this case the user agent first checks the unicode-range for the font
2845 containing Latin characters (DroidSans.ttf). Since all the characters
2846 above are in the range U+0-5FF, the user agent downloads the font and
2847 renders the text with that font.</p>
2849 <p>Next, consider text that makes use of an arrow character (⇨):</p>
2851 <pre>
2852 <p>This &#x21e8; that<p>
2853 </pre>
2855 <p>The user agent again first checks the unicode-range of the font
2856 containing Latin characters. Since U+2000-2300 includes the arrow code
2857 point (U+21E8), the user agent downloads the font. For this character
2858 however the Latin font does not have a matching glyph, so the effective
2859 unicode-range used for font matching excludes this code point. Next, the
2860 user agent evaluates the Japanese font. The unicode-range for the
2861 Japanese font, U+3000-9FFF and U+ff??, does not include U+21E8, so the
2862 user agent does not download the Japanese font. Next the fallback font is
2863 considered. The <a href="#at-font-face-rule"><code>@font-face</code></a>
2864 rule for the fallback font does not define unicode-range so its value
2865 defaults to the range of all Unicode code points. The fallback font is
2866 downloaded and used to render the arrow character.</p>
2867 </div>
2869 <h3 id=font-rend-desc><span class=secno>4.7 </span>Font features: the <a
2870 href="#descdef-font-variant">font-variant</a> and <a
2871 href="#descdef-font-feature-settings">font-feature-settings</a>
2872 descriptors</h3>
2874 <table class=descdef>
2875 <tbody>
2876 <tr>
2877 <td>Name:
2879 <td><dfn id=descdef-font-variant
2880 title="font-variant!!descriptor">font-variant</dfn>
2882 <tr>
2883 <td>Value:
2885 <td><a href="#font-variant-normal-value"
2886 title="normal!!font-variant">normal</a> | <a
2887 href="#font-variant-none-value" title="none!!font-variant">none</a> | [
2888 <a href="#common-lig-values"><var><common-lig-values></var></a>
2889 || <a
2890 href="#discretionary-lig-values"><var><discretionary-lig-values></var></a>
2891 || <a
2892 href="#historical-lig-values"><var><historical-lig-values></var></a>
2893 || <a
2894 href="#contextual-alt-values"><var><contextual-alt-values></var></a>
2895 || <a href="#stylistic"><var
2896 title=stylistic>stylistic(<feature-value-name>)</var></a> || <a
2897 href="#historical-forms"><var>historical-forms</var></a> || <a
2898 href="#styleset"><var
2899 title=styleset>styleset(<feature-value-name> #)</var></a> || <a
2900 href="#character-variant"><var
2901 title=character-variant>character-variant(<feature-value-name>
2902 #)</var></a> || <a href="#swash"><var
2903 title=swash>swash(<feature-value-name>)</var></a> || <a
2904 href="#ornaments"><var
2905 title=ornaments>ornaments(<feature-value-name>)</var></a> || <a
2906 href="#annotation"><var
2907 title=annotation>annotation(<feature-value-name>)</var></a> || [
2908 <a href="#small-caps"><i>small-caps</i></a> | <a
2909 href="#all-small-caps"><i>all-small-caps</i></a> | <a
2910 href="#petite-caps"><i>petite-caps</i></a> | <a
2911 href="#all-petite-caps"><i>all-petite-caps</i></a> | <a
2912 href="#unicase"><i>unicase</i></a> | <a
2913 href="#titling-caps"><i>titling-caps</i></a> ] || <a
2914 href="#numeric-figure-values"><var><numeric-figure-values></var></a>
2915 || <a
2916 href="#numeric-spacing-values"><var><numeric-spacing-values></var></a>
2917 || <a
2918 href="#numeric-fraction-values"><var><numeric-fraction-values></var></a>
2919 || <a href="#ordinal"><i>ordinal</i></a> || <a
2920 href="#slashed-zero"><i>slashed-zero</i></a> || <a
2921 href="#east-asian-variant-values"><var><east-asian-variant-values></var></a>
2922 || <a
2923 href="#east-asian-width-values"><var><east-asian-width-values></var></a>
2924 || <a href="#ruby"><i>ruby</i></a> ]
2926 <tr>
2927 <td><em>Initial:</em>
2929 <td>normal
2930 </table>
2932 <table class=descdef>
2933 <tbody>
2934 <tr>
2935 <td>Name:
2937 <td><dfn id=descdef-font-feature-settings
2938 title="font-feature-settings!!descriptor">font-feature-settings</dfn>
2940 <tr>
2941 <td>Value:
2943 <td><a href="#font-feature-settings-normal-value"
2944 title="normal!!font-feature-settings">normal</a> | <a
2945 href="#feature-tag-value"><var><feature-tag-value></var></a> #
2947 <tr>
2948 <td><em>Initial:</em>
2950 <td>normal
2951 </table>
2953 <p>These descriptors define initial settings that apply when the font
2954 defined by an <a href="#at-font-face-rule"><code>@font-face</code></a>
2955 rule is rendered. They do not affect font selection. Values are identical
2956 to those defined for the corresponding <a href="#propdef-font-variant"
2957 title="font-variant!!property">‘<code
2958 class=property>font-variant</code>’</a> and <a
2959 href="#propdef-font-feature-settings"
2960 title="font-feature-settings!!property">‘<code
2961 class=property>font-feature-settings</code>’</a> properties defined
2962 below except that the value ‘<code class=property>inherit</code>’ is
2963 omitted. When multiple font feature descriptors or properties are used,
2964 the cumulative effect on text rendering is detailed in the section <a
2965 href="#font-feature-resolution">Font Feature Resolution</a> below. In
2966 cases where specific values define synthesized fallback for certain <a
2967 href="#propdef-font-variant" title="font-variant!!property">‘<code
2968 class=property>font-variant</code>’</a> subproperties, the same
2969 synthesized fallback applies when used within those values are used with
2970 the <a href="#descdef-font-style" title="font-style!!descriptor">‘<code
2971 class=property>font-variant</code>’</a> descriptor.
2973 <h3 id=font-face-loading><span class=secno>4.8 </span>Font loading
2974 guidelines</h3>
2976 <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule is
2977 designed to allow lazy loading of font resources that are only downloaded
2978 when used within a document. A stylesheet can include <a
2979 href="#at-font-face-rule"><code>@font-face</code></a> rules for a library
2980 of fonts of which only a select set are used; user agents must only
2981 download those fonts that are referred to within the style rules
2982 applicable to a given page. User agents that download all fonts defined in
2983 <a href="#at-font-face-rule"><code>@font-face</code></a> rules without
2984 considering whether those fonts are in fact used within a page are
2985 considered non-conformant. In cases where a font might be downloaded in
2986 character fallback cases, user agents may download a font if it's
2987 contained within the computed value of <a href="#propdef-font-family"
2988 title="font-family!!property">‘<code
2989 class=property>font-family</code>’</a> for a given text run.
2991 <pre>
2992 @font-face {
2993 font-family: GeometricModern;
2994 src: url(font.ttf);
2995 }
2997 p {
2998 /* font will be downloaded for pages with p elements */
2999 font-family: GeometricModern, sans-serif;
3000 }
3002 h2 {
3003 /* font may be downloaded for pages with h2 elements, even if Futura is available locally */
3004 font-family: Futura, GeometricModern, sans-serif;
3005 }
3006 </pre>
3008 <p>In cases where textual content is loaded before downloadable fonts are
3009 available, user agents may render text as it would be rendered if
3010 downloadable font resources are not available or they may render text
3011 transparently with fallback fonts to avoid a flash of text using a
3012 fallback font. In cases where the font download fails user agents must
3013 display text, simply leaving transparent text is considered non-conformant
3014 behavior. Authors are advised to use fallback fonts in their font lists
3015 that closely match the vertical metrics of the downloadable fonts to avoid
3016 large page reflows where possible.
3018 <h3 id=same-origin-restriction><span class=secno>4.9 </span>Same-origin
3019 restriction for fonts</h3>
3021 <h4 id=default-same-origin-restriction><span class=secno>4.9.1
3022 </span>Default same-origin restriction</h4>
3023 <!-- TPAC 2011 Resolution to require same-origin restriction for loading fonts:
3024 http://lists.w3.org/Archives/Public/www-style/2011Nov/0711.html
3025 http://www.w3.org/2011/10/31-webapps-minutes.html#item02
3026 -->
3028 <p>User agents must implement a same-origin restriction when loading fonts
3029 via the <a href="#at-font-face-rule"><code>@font-face</code></a>
3030 mechanism. This restriction limits the loading of fonts for a given
3031 document to fonts loaded from the same origin. Fonts can only be loaded
3032 via the same host, port, and method combination as the containing
3033 document, using the <a
3034 href="http://www.w3.org/TR/html5/browsers.html#origin">origin matching
3035 algorithm</a> described in the <a href="#HTML5"
3036 rel=biblioentry>[HTML5]<!--{{!HTML5}}--></a> specification. The origin of
3037 the stylesheet containing <a
3038 href="#at-font-face-rule"><code>@font-face</code></a> rules is not used
3039 when deciding whether a font is same origin or not, only the origin of the
3040 containing document is used. The restriction applies to all font types.
3042 <p>Given a document located at http://example.com/page.html, fonts defined
3043 with ‘<a href="#descdef-src"><code class=property>src</code></a>’
3044 definitions considered cross origin must not be loaded:
3046 <pre>
3047 /* same origin (i.e. domain, protocol, port match document) */
3048 src: url(fonts/simple.ttf);
3049 src: url(//fonts/simple.ttf);
3051 /* cross origin, different protocol */
3052 src: url(https://example.com/fonts/simple.ttf);
3054 /* cross origin, different domain */
3055 src: url(http://another.example.com/fonts/simple.ttf);
3056 </pre>
3058 <h4 id=allowing-cross-origin-font-loading><span class=secno>4.9.2
3059 </span>Allowing cross-origin font loading</h4>
3061 <p>User agents must also implement the ability to relax this restriction
3062 using cross-site origin controls <a href="#CORS"
3063 rel=biblioentry>[CORS]<!--{{!CORS}}--></a> for fonts loaded via HTTP.
3064 Sites can explicitly allow cross-site downloading of font data using the
3065 <code>Access-Control-Allow-Origin</code> HTTP header. For other protocols,
3066 no explicit relaxation mechanism is defined or required.
3068 <p>For font loads over HTTP, cross-origin requests must be made with the
3069 following parameter settings which are used in conjunction with the <a
3070 href="http://www.w3.org/TR/cors/#cross-origin-request-0"> <em>cross-origin
3071 request algorithm</em></a> <a href="#CORS"
3072 rel=biblioentry>[CORS]<!--{{!CORS}}--></a>:
3074 <ul>
3075 <li><em>request URL</em> — the URL of the font resource in the <a
3076 href="#descdef-src"><code>src</code></a> descriptor
3078 <li><em>request method</em> — GET
3080 <li><em>author request headers</em> — none
3082 <li><em>request entity body</em> — empty
3084 <li><em>source origin</em> — the origin of the page which linked to the
3085 stylesheet
3087 <li><em>manual redirect flag</em> — false
3089 <li><em>omit credentials flag</em> — true
3091 <li><em>force preflight flag</em> — false
3092 </ul>
3094 <h2 id=font-matching-algorithm><span class=secno>5 </span>Font Matching
3095 Algorithm</h2>
3097 <p>The algorithm below describes how fonts are associated with individual
3098 runs of text. For each character in the run a font family is chosen and a
3099 particular font face is selected containing a glyph for that character.
3101 <h3 id=font-family-casing><span class=secno>5.1 </span>Case sensitivity of
3102 font family names</h3>
3104 <p>As part of the font matching algorithm outlined below, user agents must
3105 match font family names used in style rules with actual font family names
3106 contained in fonts available in a given environment or with font family
3107 names defined in <a href="#at-font-face-rule"><code>@font-face</code></a>
3108 rules. User agents must match these names case insensitively, using the
3109 "Default Caseless Matching" algorithm outlined in the Unicode
3110 specification <a href="#UNICODE6"
3111 rel=biblioentry>[UNICODE6]<!--{{!UNICODE6}}--></a>. This algorithm is
3112 detailed in section 3.13 entitled "Default Case Algorithms". Specifically,
3113 the algorithm must be applied without normalizing the strings involved and
3114 without applying any language-specific tailorings. The case folding method
3115 specified by this algorithm uses the case mappings with status field
3116 ‘<code class=property>C</code>’ or ‘<code class=property>F</code>’
3117 in the CaseFolding.txt file of the Unicode Character Database.
3119 <p class=note> For authors this means that font family names are matched
3120 case insensitively, whether those names exist in a platform font or in the
3121 <a href="#at-font-face-rule"><code>@font-face</code></a> rules contained
3122 in a stylesheet. Authors should take care to ensure that names use a
3123 character sequence consistent with the actual font family name,
3124 particularly when using combining characters such as diacritical marks.
3125 For example, a family name that contains an uppercase A (U+0041) followed
3126 by a combining ring (U+030A) will <strong>not</strong> match a name that
3127 looks identical but which uses the precomposed lowercase a-ring character
3128 (U+00E5) instead of the combining sequence.
3130 <p class=note> Implementors should take care to verify that a given
3131 caseless string comparison implementation uses this precise algorithm and
3132 not assume that a given platform string matching routine follows it, as
3133 many of these have locale-specific behavior or use some level of string
3134 normalization.
3136 <h3 id=font-style-matching><span class=secno>5.2 </span>Matching font
3137 styles</h3>
3139 <p>The procedure for choosing a font for a given character in a run of text
3140 consists of iterating over the font families named by the <a
3141 href="#propdef-font-family" title="font-family!!property">‘<code
3142 class=property>font-family</code>’</a> property, selecting a font face
3143 with the appropriate style based on other font properties and then
3144 determining whether a glyph exists for the given character. This is done
3145 using the <dfn id=character-map>character map</dfn> of the font, data
3146 which maps characters to the default glyph for that character. A font is
3147 considered to <dfn id=support>support</dfn> a given character if (1) the
3148 character is contained in the font's <a
3149 href="#character-map"><em>character map</em></a> and (2) if required by
3150 the containing script, shaping information is available for that
3151 character.
3153 <p>Some legacy fonts may include a given character in the <a
3154 href="#character-map"><em>character map</em></a> but lack the shaping
3155 information (e.g. <a
3156 href="http://www.microsoft.com/typography/otspec/ttochap1.htm">OpenType
3157 layout tables</a> or <a
3158 href="http://scripts.sil.org/cms/scripts/page.php?site_id=projects&item_id=graphite_techAbout">Graphite
3159 tables</a>) necessary for correctly rendering text runs containing that
3160 character.
3162 <p>Codepoint sequences consisting of a base character followed by a
3163 sequence of combining characters are treated slightly differently, see the
3164 section on <a href="#cluster-matching">cluster matching</a> below.
3166 <p>For this procedure, the <dfn id=default-face>default face</dfn> for a
3167 given font family is defined to be the face that would be selected if all
3168 font style properties were set to their initial value.
3170 <ol id=fontmatchingalg>
3171 <li>Using the computed font property values for a given element, the user
3172 agent starts with the first family name specified by the <a
3173 href="#propdef-font-family" title="font-family!!property">‘<code
3174 class=property>font-family</code>’</a> property.
3176 <li>If the family name is a generic family keyword, the user agent looks
3177 up the appropriate font family name to be used. User agents may choose
3178 the generic font family to use based on the language of the containing
3179 element or the Unicode range of the character.
3181 <li>For other family names, the user agent attempts to find the family
3182 name among fonts defined via <a
3183 href="#at-font-face-rule"><code>@font-face</code></a> rules and then
3184 among available system fonts, matching names with a <a
3185 href="#font-family-casing">case-insensitive comparison</a> as outlined in
3186 the section above. On systems containing fonts with multiple localized
3187 font family names, user agents must match any of these names independent
3188 of the underlying system locale or platform API used. If the font
3189 resources defined for a given face in an <a
3190 href="#at-font-face-rule"><code>@font-face</code></a> rule are either not
3191 available or contain invalid font data, then the face should be treated
3192 as not present in the family. If no faces are present for a family
3193 defined via <a href="#at-font-face-rule"><code>@font-face</code></a>
3194 rules, the family should be treated as missing; matching a platform font
3195 with the same name must not occur in this case.
3197 <li>If a font family match occurs, the user agent assembles the set of
3198 font faces in that family and then narrows the set to a single face using
3199 other font properties in the order given below. A group of faces defined
3200 via <a href="#at-font-face-rule"><code>@font-face</code></a> rules with
3201 identical font descriptor values but differing ‘<a
3202 href="#descdef-unicode-range"><code
3203 class=property>unicode-range</code></a>’ values are considered to be a
3204 single <dfn id=composite-face>composite face</dfn> for this step:
3205 <ol id=fontstylematchingalg>
3206 <li><a href="#propdef-font-stretch"
3207 title="font-stretch!!property">‘<code
3208 class=property>font-stretch</code>’</a> is tried first. If the
3209 matching set contains faces with width values matching the <a
3210 href="#propdef-font-stretch" title="font-stretch!!property">‘<code
3211 class=property>font-stretch</code>’</a> value, faces with other width
3212 values are removed from the matching set. If there is no face that
3213 exactly matches the width value the nearest width is used instead. If
3214 the value of <a href="#propdef-font-stretch"
3215 title="font-stretch!!property">‘<code
3216 class=property>font-stretch</code>’</a> is <a
3217 href="#font-stretch-normal-value" title="normal!!font-stretch">‘<code
3218 class=property>normal</code>’</a> or one of the condensed values,
3219 narrower width values are checked first, then wider values. If the
3220 value of <a href="#propdef-font-stretch"
3221 title="font-stretch!!property">‘<code
3222 class=property>font-stretch</code>’</a> is one of the expanded
3223 values, wider values are checked first, followed by narrower values.
3224 Once the closest matching width has been determined by this process,
3225 faces with other widths are removed from the matching set.
3227 <li><a href="#propdef-font-style" title="font-style!!property">‘<code
3228 class=property>font-style</code>’</a> is tried next. If the value of
3229 <a href="#propdef-font-style" title="font-style!!property">‘<code
3230 class=property>font-style</code>’</a> is ‘<a href="#italic"><code
3231 class=property>italic</code></a>’, italic faces are checked first,
3232 then oblique, then normal faces. If the value is ‘<a
3233 href="#oblique"><code class=property>oblique</code></a>’, oblique
3234 faces are checked first, then italic faces and then normal faces. If
3235 the value is <a href="#font-style-normal-value"
3236 title="normal!!font-style">‘<code
3237 class=property>normal</code>’</a>, normal faces are checked first,
3238 then oblique faces, then italic faces. Faces with other style values
3239 are excluded from the matching set. User agents are permitted to
3240 distinguish between italic and oblique faces within platform font
3241 families but this is not required, so all italic or oblique faces may
3242 be treated as italic faces. However, within font families defined via
3243 <a href="#at-font-face-rule"><code>@font-face</code></a> rules, italic
3244 and oblique faces must be distinguished using the value of the <a
3245 href="#descdef-font-style" title="font-style!!descriptor">‘<code
3246 class=property>font-style</code>’</a> descriptor. For families that
3247 lack any italic or oblique faces, users agents may create artificial
3248 oblique faces, if this is permitted by the value of the ‘<a
3249 href="#propdef-font-synthesis"><code
3250 class=property>font-synthesis</code></a>’ property.
3252 <li><a href="#propdef-font-weight"
3253 title="font-weight!!property">‘<code
3254 class=property>font-weight</code>’</a> is matched next, so it will
3255 always reduce the matching set to a single font face. If bolder/lighter
3256 relative weights are used, the effective weight is calculated based on
3257 the inherited weight value, as described in the definition of the <a
3258 href="#propdef-font-weight" title="font-weight!!property">‘<code
3259 class=property>font-weight</code>’</a> property. Given the desired
3260 weight and the weights of faces in the matching set after the steps
3261 above, if the desired weight is available that face matches. Otherwise,
3262 a weight is chosen using the rules below:
3263 <ul>
3264 <li>If the desired weight is less than 400, weights below the desired
3265 weight are checked in descending order followed by weights above the
3266 desired weight in ascending order until a match is found.
3268 <li>If the desired weight is greater than 500, weights above the
3269 desired weight are checked in ascending order followed by weights
3270 below the desired weight in descending order until a match is found.
3272 <li>If the desired weight is 400, 500 is checked first and then the
3273 rule for desired weights less than 400 is used.
3275 <li>If the desired weight is 500, 400 is checked first and then the
3276 rule for desired weights less than 400 is used.
3277 </ul>
3279 <li><span class=property>‘<a href="#propdef-font-size"><code
3280 class=property>font-size</code></a>’</span> must be matched within a
3281 UA-dependent margin of tolerance. (Typically, sizes for scalable fonts
3282 are rounded to the nearest whole pixel, while the tolerance for
3283 bitmapped fonts could be as large as 20%.) Further computations, e.g.,
3284 by ‘<code class=property>em</code>’ values in other properties, are
3285 based on the <span class=property>‘<a href="#propdef-font-size"><code
3286 class=property>font-size</code></a>’</span> value that is used, not
3287 the one that is specified.
3288 </ol>
3290 <li>
3291 <p>If the matched face is defined via <a
3292 href="#at-font-face-rule"><code>@font-face</code></a> rules, user agents
3293 must use the procedure below to select a single font:
3295 <ol>
3296 <li>If the font resource has not been loaded and the range of characters
3297 defined by the ‘<a href="#descdef-unicode-range"><code
3298 class=property>unicode-range</code></a>’ descriptor value includes
3299 the character in question, load the font.
3301 <li>After downloading, if the <a
3302 href="#effective-character-map"><em>effective character map</em></a>
3303 supports the character in question, select that font.
3304 </ol>
3306 <p>When the matched face is a <a href="#composite-face"><em>composite
3307 face</em></a>, user agents must use the procedure above on each of the
3308 faces in the <a href="#composite-face"><em>composite face</em></a> in
3309 reverse order of <a
3310 href="#at-font-face-rule"><code>@font-face</code></a> rule definition.</p>
3312 <p>While the download occurs, user agents may either wait until the font
3313 is downloaded or render once with substituted font metrics and render
3314 again once the font is downloaded.</p>
3316 <li>
3317 <p>If no matching face exists or the matched face does not contain a
3318 glyph for the character to be rendered, the next family name is selected
3319 and the previous three steps repeated. Glyphs from other faces in the
3320 family are not considered. The only exception is that user agents may
3321 optionally substitute a synthetically obliqued version of the <a
3322 href="#default-face"><em>default face</em></a> if that face supports a
3323 given glyph and synthesis of these faces is permitted by the value of
3324 the ‘<a href="#propdef-font-synthesis"><code
3325 class=property>font-synthesis</code></a>’ property. For example, a
3326 synthetic italic version of the regular face may be used if the italic
3327 face doesn't support glyphs for Arabic.</p>
3328 <!-- resolution on the above: http://lists.w3.org/Archives/Public/www-style/2012Nov/0292.html -->
3331 <li>If there are no more font families to be evaluated and no matching
3332 face has been found, then the user agent performs a <dfn
3333 id=system-font-fallback>system font fallback</dfn> procedure to find the
3334 best match for the character to be rendered. The result of this procedure
3335 may vary across user agents.
3337 <li>If a particular character cannot be displayed using any font, the user
3338 agent should indicate by some means that a character is not being
3339 displayed, displaying either a symbolic representation of the missing
3340 glyph (e.g. using a <a
3341 href="http://en.wikipedia.org/wiki/Last_resort_font">Last Resort
3342 Font</a>) or using the missing character glyph from a default font.
3343 </ol>
3345 <h3 id=cluster-matching><span class=secno>5.3 </span>Cluster matching</h3>
3347 <p>When text contains characters such as combining marks, ideally the base
3348 character should be rendered using the same font as the mark, this assures
3349 proper placement of the mark. For this reason, the font matching algorithm
3350 for clusters is more specialized than the general case of matching a
3351 single character by itself. For sequences containing variation selectors,
3352 which indicate the precise glyph to be used for a given character, user
3353 agents always attempt <a href="#system-font-fallback"><em>system font
3354 fallback</em></a> to find the appropriate glyph before using the default
3355 glyph of the base character.
3357 <p>A sequence of codepoints containing combining mark or other modifiers is
3358 termed a grapheme cluster (see <a href="#CSS3TEXT"
3359 rel=biblioentry>[CSS3TEXT]<!--{{CSS3TEXT}}--></a> for a more complete
3360 description). For a given cluster containing a base character, <em>b</em>
3361 and a sequence of combining characters <em>c1, c2…</em>, the entire
3362 cluster is matched using these steps:
3364 <ol>
3365 <li>For each family in the font list, a face is chosen using the style
3366 selection rules defined in the previous section.
3367 <ol>
3368 <li>If all characters in the sequence <em>b + c1 + c2 …</em> are
3369 completely supported by the font, select this font for the sequence.
3371 <li>If a sequence of multiple codepoints is canonically equivalent to a
3372 single character and the font <a href="#support"><em
3373 title=support>supports</em></a> that character, select this font for
3374 the sequence.
3375 </ol>
3377 <li>If no font was found in the font list in step 1:
3378 <ol>
3379 <li>If <em>c1</em> is a variation selector, system fallback must be used
3380 to find a font that <a href="#support"><em
3381 title=support>supports</em></a> the full sequence of <em>b + c1</em>.
3382 If no font on the system <a href="#support"><em
3383 title=support>supports</em></a> the full sequence, match the single
3384 character <em>b</em> using the normal procedure for matching single
3385 characters and ignore the variation selector. Note: a sequence with
3386 more than one variation selector must be treated as an encoding error
3387 and the trailing selectors must be ignored. <a href="#UNICODE6"
3388 rel=biblioentry>[UNICODE6]<!--{{!UNICODE6}}--></a>
3390 <li>Otherwise, the user agent may optionally use system font fallback to
3391 match a font that <a href="#support"><em
3392 title=support>supports</em></a> the entire cluster.
3393 </ol>
3395 <li>If no font is found in step 2, use the matching sequence from step 1
3396 to determine the longest sequence that is completely <a
3397 href="#support"><em title=support>supported</em></a> by a font in the
3398 font list and attempt to match the remaining combining characters
3399 separately using the rules for single characters.
3400 </ol>
3402 <h3 id=char-handling-issues><span class=secno>5.4 </span>Character handling
3403 issues</h3>
3405 <p>The procedure above is always performed on text runs containing Unicode
3406 characters, documents using legacy encodings are assumed to have been
3407 transcoded before matching fonts. For fonts containing <a
3408 href="#character-map"><em title="character map">character maps</em></a>
3409 for both legacy encodings and Unicode, the contents of the legacy encoding
3410 <a href="#character-map"><em>character map</em></a> must have no effect on
3411 the results of the font matching process.
3413 <p>The font matching process does not assume that text runs are in either
3414 normalized or denormalized form (see <a href="#CHARMOD-NORM"
3415 rel=biblioentry>[CHARMOD-NORM]<!--{{CHARMOD-NORM}}--></a> for more
3416 details). Layout engines often convert base character plus combining
3417 character sequences into precomposed characters if they exist. The font
3418 matching algorithm outlined here supports both ways and fonts can
3419 generally support either but variations can occur. Authors should always
3420 tailor their choice of fonts to their content, including whether that
3421 content contains normalized or denormalized character streams.
3423 <p>If a given character is a Private-Use Area Unicode codepoint and none of
3424 the fonts in the fontlist contain a glyph for that codepoint, user agents
3425 must display some form of missing glyph symbol for that character rather
3426 than attempting <a href="#system-font-fallback"><em>system font
3427 fallback</em></a> for that codepoint. When matching the replacement
3428 character U+FFFD, user agents may skip the font matching process and
3429 immediately display some form of missing glyph symbol, they are not
3430 required to display the glyph from the font that would be selected by the
3431 font matching process.
3433 <p>In general, the fonts for a given family will all have the same or
3434 similar <a href="#character-map"><em title="character map">character
3435 maps</em></a>. The process outlined here is designed to handle even font
3436 families containing faces with widely variant <a href="#character-map"><em
3437 title="character map">character maps</em></a>. However, authors are
3438 cautioned that the use of such families can lead to unexpected results.
3440 <p>Optimizations of this process are allowed provided that an
3441 implementation behaves as if the algorithm had been followed exactly.
3442 Matching occurs in a well-defined order to insure that the results are as
3443 consistent as possible across user agents, given an identical set of
3444 available fonts and rendering technology.
3446 <h3 id=font-matching-changes><span class=secno>5.5 </span>Font matching
3447 changes since CSS 2.1</h3>
3449 <p>The algorithm above is different from CSS 2.1 in a number of key places.
3450 These changes were made to better reflect actual font matching behavior
3451 across user agent implementations.
3453 <p>Differences compared to the font matching algorithm in CSS 2.1:
3455 <ul>
3456 <li>The algorithm includes font-stretch matching.
3458 <li>All possible font-style matching scenarios are delineated.
3460 <li>Small-caps fonts are not matched as part of the font matching process,
3461 they are now handled via font features.
3463 <li>Unicode variation selector matching is required.
3465 <li>Cluster sequences are matched as a unit.
3466 </ul>
3468 <h3 id=font-matching-examples><span class=secno>5.6 </span>Font matching
3469 examples</h3>
3471 <div class=example>
3472 <p>It's useful to note that the CSS selector syntax may be used to create
3473 language-sensitive typography. For example, some Chinese and Japanese
3474 characters are unified to have the same Unicode code point, although the
3475 abstract glyphs are not the same in the two languages.
3477 <pre>*:lang(ja-jp) { font: 900 14pt/16pt "Heisei Mincho W9", serif; }
3478 *:lang(zh-tw) { font: 800 14pt/16.5pt "Li Sung", serif; }
3479 </pre>
3481 <p>This selects any element that has the given language - Japanese or
3482 Traditional Chinese - and uses the appropriate font.
3483 </div>
3485 <h2 id=font-rend-props><span class=secno>6 </span>Font Feature Properties</h2>
3487 <p>Modern font technologies support a variety of advanced typographic and
3488 language-specific font features. Using these features, a single font can
3489 provide glyphs for a wide range of ligatures, contextual and stylistic
3490 alternates, tabular and old-style figures, small capitals, automatic
3491 fractions, swashes, and alternates specific to a given language. To allow
3492 authors control over these font capabilities, the ‘<code
3493 class=property>font-variant</code>’ property has been expanded for CSS3.
3494 It now functions as a shorthand for a set of properties that provide
3495 control over stylistic font features.
3497 <h3 id=glyph-selection-positioning><span class=secno>6.1 </span>Glyph
3498 selection and positioning</h3>
3500 <p>Simple fonts used for displaying Latin text use a very basic processing
3501 model. Fonts contain a <a href="#character-map"><em>character map</em></a>
3502 which maps each character to a glyph for that character. Glyphs for
3503 subsequent characters are simply placed one after the other along a run of
3504 text. Modern font formats such as OpenType and AAT (Apple Advanced
3505 Typography) use a richer processing model. The glyph for a given character
3506 can be chosen and positioned not just based on the codepoint of the
3507 character itself, but also on adjacent characters as well as the language,
3508 script, and features enabled for the text. Font features may be required
3509 for specific scripts, or recommended as enabled by default or they might
3510 be stylistic features meant to be used under author control.
3512 <p>For a good visual overview of these features, see the <a
3513 href="#OPENTYPE-FONT-GUIDE"
3514 rel=biblioentry>[OPENTYPE-FONT-GUIDE]<!--{{OPENTYPE-FONT-GUIDE}}--></a>.
3515 For a detailed description of glyph processing for OpenType fonts, see <a
3516 href="#WINDOWS-GLYPH-PROC"
3517 rel=biblioentry>[WINDOWS-GLYPH-PROC]<!--{{WINDOWS-GLYPH-PROC}}--></a>.
3519 <p>Stylistic font features can be classified into two broad categories:
3520 ones that affect the harmonization of glyph shapes with the surrounding
3521 context, such as kerning and ligature features, and ones such as the
3522 small-caps, subscript/superscript and alternate features that affect shape
3523 selection.
3525 <p>The subproperties of <a href="#propdef-font-variant"
3526 title="font-variant!!property">‘<code
3527 class=property>font-variant</code>’</a> listed below are used to control
3528 these stylistic font features. They do not control features that are
3529 required for displaying certain scripts, such as the OpenType features
3530 used when displaying Arabic or Indic language text. They affect glyph
3531 selection and positioning, but do not affect font selection as described
3532 in the font matching section (except in cases required for compatibility
3533 with CSS 2.1).
3535 <p>To assure consistent behavior across user agents, the equivalent
3536 OpenType property settings are listed for individual properties and are
3537 normative. When using other font formats these should be used as a
3538 guideline to map CSS font feature property values to specific font
3539 features.
3541 <h3 id=language-specific-support><span class=secno>6.2
3542 </span>Language-specific display</h3>
3544 <p>OpenType also supports language-specific glyph selection and
3545 positioning, so that text can be displayed correctly in cases where the
3546 language dictates a specific display behavior. Many languages share a
3547 common script, but the shape of certain letters can vary across those
3548 languages. For example, certain Cyrillic letters have different shapes in
3549 Russian text than in Bulgarian. In Latin text, it's common to render "fi"
3550 with an explicit fi-ligature that lacks a dot on the "i". However, in
3551 languages such as Turkish which uses both a dotted-i and a dotless-i, it's
3552 important to not use this ligature or use a specialized version that
3553 contains a dot over the "i". The example below shows language-specific
3554 variations based on stylistic traditions found in Spanish, Italian and
3555 French orthography:
3557 <div class=featex><img alt="language specific forms, spanish"
3558 src=locl-1.png></div>
3560 <div class=featex><img alt="language specific forms, italian"
3561 src=locl-2.png></div>
3563 <div class=featex><img alt="language specific forms, french"
3564 src=locl-3.png></div>
3566 <p>If the content language of the element is known according to the rules
3567 of the <a
3568 href="http://www.w3.org/TR/CSS21/conform.html#doclanguage">document
3569 language</a>, user agents are required to infer the OpenType language
3570 system from the content language and use that when selecting and
3571 positioning glyphs using an OpenType font.
3573 <p>For OpenType fonts, in some cases it may be necessary to explicitly
3574 declare the OpenType language to be used, for example when displaying text
3575 in a given language that uses the typographic conventions of another
3576 language or when the font does not explicitly support a given language but
3577 supports a language that shares common typographic conventions. The ‘<a
3578 href="#propdef-font-language-override"><code
3579 class=property>font-language-override</code></a>’ property is used for
3580 this purpose.</p>
3581 <!-- prop: font-kerning -->
3583 <h3 id=font-kerning-prop><span class=secno>6.3 </span>Kerning: the <a
3584 href="#propdef-font-kerning">font-kerning</a> property</h3>
3586 <table class=propdef id=namefont-kerningvalueauto-normal-noneini>
3587 <tbody>
3588 <tr>
3589 <td>Name:
3591 <td><dfn id=propdef-font-kerning>font-kerning</dfn>
3593 <tr>
3594 <td>Value:
3596 <td><a href="#font-kerning-auto-value"
3597 title="auto!!font-kerning">auto</a> | <a
3598 href="#font-kerning-normal-value"
3599 title="normal!!font-kerning">normal</a> | <a
3600 href="#font-kerning-none-value" title="none!!font-kerning">none</a>
3602 <tr>
3603 <td>Initial:
3605 <td>auto
3607 <tr>
3608 <td>Applies to:
3610 <td>all elements
3612 <tr>
3613 <td>Inherited:
3615 <td>yes
3617 <tr>
3618 <td>Percentages:
3620 <td>N/A
3622 <tr>
3623 <td>Media:
3625 <td>visual
3627 <tr>
3628 <td>Computed value:
3630 <td>as specified
3632 <tr>
3633 <td>Animatable:
3635 <td>no
3636 </table>
3638 <p>Kerning is the contextual adjustment of inter-glyph spacing. This
3639 property controls metric kerning, kerning that utilizes adjustment data
3640 contained in the font.
3642 <dl>
3643 <dt><dfn id=font-kerning-auto-value title="auto!!font-kerning">auto</dfn>
3645 <dd>Specifies that kerning is applied at the discretion of the user agent
3647 <dt><dfn id=font-kerning-normal-value
3648 title="normal!!font-kerning">normal</dfn>
3650 <dd>Specifies that kerning is applied
3652 <dt><dfn id=font-kerning-none-value title="none!!font-kerning">none</dfn>
3654 <dd>Specifies that kerning is not applied
3655 </dl>
3657 <p>For fonts that do not include kerning data this property will have no
3658 visible effect. When rendering with OpenType fonts, the <a
3659 href="#OPENTYPE" rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a>
3660 specification suggests that kerning be enabled by default. When kerning is
3661 enabled, the OpenType <span class=tag>kern</span> feature is enabled (for
3662 vertical text runs the <span class=tag>vkrn</span> feature is enabled
3663 instead). User agents must also support fonts that only support kerning
3664 via data contained in a <span class=tag>kern</span> font table, as
3665 detailed in the OpenType specification. If the ‘<code
3666 class=property>letter-spacing</code>’ property is defined, kerning
3667 adjustments are considered part of the default spacing and letter spacing
3668 adjustments are made after kerning has been applied.
3670 <p>When set to ‘<code class=property>auto</code>’, user agents can
3671 determine whether to apply kerning or not based on a number of factors:
3672 text size, script, or other factors that influence text processing speed.
3673 Authors who want proper kerning should use <a
3674 href="#font-kerning-normal-value" title="normal!!font-kerning">‘<code
3675 class=property>normal</code>’</a> to explicitly enable kerning.
3676 Likewise, some authors may prefer to disable kerning in situations where
3677 performance is more important than precise appearance. However, in
3678 well-designed modern implementations the use of kerning generally does not
3679 have a large impact on text rendering speed.</p>
3680 <!-- prop: font-variant-ligatures -->
3682 <h3 id=font-variant-ligatures-prop><span class=secno>6.4 </span>Ligatures:
3683 the <a href="#propdef-font-variant-ligatures">font-variant-ligatures</a>
3684 property</h3>
3686 <table class=propdef id=namefont-variant-ligaturesvaluenormal-no>
3687 <tbody>
3688 <tr>
3689 <td>Name:
3691 <td><dfn id=propdef-font-variant-ligatures>font-variant-ligatures</dfn>
3693 <tr>
3694 <td>Value:
3696 <td><a href="#font-variant-ligatures-normal-value"
3697 title="normal!!font-variant-ligatures">normal</a> | <a
3698 href="#font-variant-ligatures-none-value"
3699 title="none!!font-variant-ligatures">none</a> | [ <a
3700 href="#common-lig-values"><var><common-lig-values></var></a> ||
3701 <a
3702 href="#discretionary-lig-values"><var><discretionary-lig-values></var></a>
3703 || <a
3704 href="#historical-lig-values"><var><historical-lig-values></var></a>
3705 || <a
3706 href="#contextual-alt-values"><var><contextual-alt-values></var></a>
3707 ]
3709 <tr>
3710 <td>Initial:
3712 <td>normal
3714 <tr>
3715 <td>Applies to:
3717 <td>all elements
3719 <tr>
3720 <td>Inherited:
3722 <td>yes
3724 <tr>
3725 <td>Percentages:
3727 <td>N/A
3729 <tr>
3730 <td>Media:
3732 <td>visual
3734 <tr>
3735 <td>Computed value:
3737 <td>as specified
3739 <tr>
3740 <td>Animatable:
3742 <td>no
3743 </table>
3745 <p>Ligatures and contextual forms are ways of combining glyphs to produce
3746 more harmonized forms.
3748 <pre
3749 class=prod><dfn id=common-lig-values><var><common-lig-values></var></dfn> = [ <a href="#common-ligatures">common-ligatures</a> | <a href="#no-common-ligatures">no-common-ligatures</a> ]</pre>
3751 <pre
3752 class=prod><dfn id=discretionary-lig-values><var><discretionary-lig-values></var></dfn> = [ <a href="#discretionary-ligatures">discretionary-ligatures</a> | <a href="#no-discretionary-ligatures">no-discretionary-ligatures</a> ]</pre>
3754 <pre
3755 class=prod><dfn id=historical-lig-values><var><historical-lig-values></var></dfn> = [ <a href="#historical-ligatures">historical-ligatures</a> | <a href="#no-historical-ligatures">no-historical-ligatures</a> ]</pre>
3757 <pre
3758 class=prod><dfn id=contextual-alt-values><var><contextual-alt-values></var></dfn> = [ <a href="#contextual">contextual</a> | <a href="#no-contextual">no-contextual</a> ]</pre>
3760 <p>Individual values have the following meanings:
3762 <dl>
3763 <dt><dfn id=font-variant-ligatures-normal-value
3764 title="normal!!font-variant-ligatures">normal</dfn>
3766 <dd>A value of <a href="#font-variant-ligatures-normal-value"
3767 title="normal!!font-variant-ligatures">‘<code
3768 class=property>normal</code>’</a> specifies that common default
3769 features are enabled, <a href="#font-feature-resolution">as described in
3770 detail in the next section</a>. For OpenType fonts, common ligatures and
3771 contextual forms are on by default, discretionary and historical
3772 ligatures are not.
3774 <dt><dfn id=font-variant-ligatures-none-value
3775 title="none!!font-variant-ligatures">none</dfn>
3777 <dd>Specifies that all types of ligatures and contextual forms covered by
3778 this property are explicitly disabled. In situations where ligatures are
3779 not considered necessary, this may improve the speed of text rendering.
3781 <dt><dfn id=common-ligatures>common-ligatures</dfn>
3783 <dd>Enables display of common ligatures (OpenType features: <span
3784 class=tag>liga, clig</span>). For OpenType fonts, common ligatures are
3785 enabled by default.
3786 </dl>
3788 <div class=featex><img alt="common ligature example" src=liga.png></div>
3790 <dl>
3791 <dt><dfn id=no-common-ligatures>no-common-ligatures</dfn>
3793 <dd>Disables display of common ligatures (OpenType features: <span
3794 class=tag>liga, clig</span>).
3796 <dt><dfn id=discretionary-ligatures>discretionary-ligatures</dfn>
3798 <dd>Enables display of discretionary ligatures (OpenType feature: <span
3799 class=tag>dlig</span>). Which ligatures are discretionary or optional is
3800 decided by the type designer, so authors will need to refer to the
3801 documentation of a given font to understand which ligatures are
3802 considered discretionary.
3803 </dl>
3805 <div class=featex><img alt="discretionary ligature example" src=dlig.png></div>
3807 <dl>
3808 <dt><dfn id=no-discretionary-ligatures>no-discretionary-ligatures</dfn>
3810 <dd>Disables display of discretionary ligatures (OpenType feature: <span
3811 class=tag>dlig</span>).
3813 <dt><dfn id=historical-ligatures>historical-ligatures</dfn>
3815 <dd>Enables display of historical ligatures (OpenType feature: <span
3816 class=tag>hlig</span>).
3817 </dl>
3819 <div class=featex><img alt="historical ligature example" src=hlig.png></div>
3821 <dl>
3822 <dt><dfn id=no-historical-ligatures>no-historical-ligatures</dfn>
3824 <dd>Disables display of historical ligatures (OpenType feature: <span
3825 class=tag>hlig</span>).
3827 <dt><dfn id=contextual>contextual</dfn>
3829 <dd>Enables display of contextual alternates (OpenType feature: <span
3830 class=tag>calt</span>). Although not strictly a ligature feature, like
3831 ligatures this feature is commonly used to harmonize the shapes of glyphs
3832 with the surrounding context. For OpenType fonts, this feature is on by
3833 default.
3834 </dl>
3836 <div class=featex><img alt="contextual alternate example" src=calt.png></div>
3838 <dl>
3839 <dt><dfn id=no-contextual>no-contextual</dfn>
3841 <dd>Disables display of contextual alternates (OpenType feature: <span
3842 class=tag>calt</span>).
3843 </dl>
3845 <p>Required ligatures, needed for correctly rendering complex scripts, are
3846 not affected by the settings above, including ‘<code
3847 class=property>none</code>’ (OpenType feature: <span
3848 class=tag>rlig</span>).</p>
3849 <!-- prop: font-variant-position -->
3851 <h3 id=font-variant-position-prop><span class=secno>6.5 </span>Subscript
3852 and superscript forms: the <a
3853 href="#propdef-font-variant-position">font-variant-position</a> property</h3>
3855 <table class=propdef id=namefont-variant-positionvaluenormal-sub>
3856 <tbody>
3857 <tr>
3858 <td>Name:
3860 <td><dfn id=propdef-font-variant-position>font-variant-position</dfn>
3862 <tr>
3863 <td>Value:
3865 <td><a href="#font-variant-position-normal-value"
3866 title="normal!!font-variant-position">normal</a> | <a
3867 href="#sub">sub</a> | <a href="#super">super</a>
3869 <tr>
3870 <td>Initial:
3872 <td>normal
3874 <tr>
3875 <td>Applies to:
3877 <td>all elements
3879 <tr>
3880 <td>Inherited:
3882 <td>yes
3884 <tr>
3885 <td>Percentages:
3887 <td>N/A
3889 <tr>
3890 <td>Media:
3892 <td>visual
3894 <tr>
3895 <td>Computed value:
3897 <td>as specified
3899 <tr>
3900 <td>Animatable:
3902 <td>no
3903 </table>
3905 <p>This property is used to enable typographic subscript and superscript
3906 glyphs. These are alternate glyphs designed within the same em-box as
3907 default glyphs and are intended to be laid out on the same baseline as the
3908 default glyphs, with no resizing or repositioning of the baseline. They
3909 are explicitly designed to match the surrounding text and to be more
3910 readable without affecting the line height.
3912 <div class=figure><img alt="comparison between real subscript glyphs and
3913 synthesized ones" src=realsubscripts.png>
3914 <p class=caption>Subscript glyphs (top) vs. typical synthesized subscripts
3915 (bottom)
3916 </div>
3918 <p>Individual values have the following meanings:
3920 <dl>
3921 <dt><dfn id=font-variant-position-normal-value
3922 title="normal!!font-variant-position">normal</dfn>
3924 <dd>None of the features listed below are enabled.
3926 <dt><dfn id=sub>sub</dfn>
3928 <dd>Enables display of subscript variants (OpenType feature: <span
3929 class=tag>subs</span>).
3931 <dt><dfn id=super>super</dfn>
3933 <dd>Enables display of superscript variants (OpenType feature: <span
3934 class=tag>sups</span>).
3935 </dl>
3937 <p>Because of the semantic nature of subscripts and superscripts, when the
3938 value is either ‘<a href="#sub"><code class=property>sub</code></a>’
3939 or ‘<a href="#super"><code class=property>super</code></a>’ for a
3940 given contiguous run of text, if a variant glyph is not available for all
3941 the characters in the run, simulated glyphs must be synthesized for all
3942 characters using reduced forms of the glyphs that would be used without
3943 this feature applied. This is done per run to avoid a mixture of variant
3944 glyphs and synthesized ones that would not align correctly. In the case of
3945 OpenType fonts that lack subscript or superscript glyphs for a given
3946 character, user agents must use the appropriate subscript and superscript
3947 metrics specified in the selected font's <a
3948 href="http://www.microsoft.com/typography/otspec/os2.htm#subxs">OS/2
3949 table</a> <a href="#OPENTYPE"
3950 rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a> to calculate the size
3951 and offset of the synthesized substitutes.
3953 <div class=figure><img alt="alternate superscripts vs. glyphs synthesized
3954 using superscript metrics" src=superscript-alt-synth.png>
3955 <p class=caption>Superscript alternate glyph (left), synthesized
3956 superscript glyphs (middle), and incorrect mixture of the two (right)
3957 </div>
3959 <p>In situations where text decorations are only applied to runs of text
3960 containing superscript or subscript glyphs, the synthesized glyphs must be
3961 used to avoid problems with the placement of decorations.
3963 <p>In the past, user agents have used font-size and vertical-align to
3964 simulate subscripts and superscripts for the <code title="HTML sub
3965 element">sub</code> and <code title="HTML sup element">sup</code>
3966 elements. To allow a backwards compatible way of defining subscripts and
3967 superscripts, it is recommended that authors use conditional rules <a
3968 href="#CSS3-CONDITIONAL"
3969 rel=biblioentry>[CSS3-CONDITIONAL]<!--{{CSS3-CONDITIONAL}}--></a> so that
3970 older user agents will still render subscripts and superscripts via the
3971 older mechanism.
3973 <p>Authors should note that fonts typically only provide subscript and
3974 superscript glyphs for a subset of all characters supported by the font.
3975 For example, while subscript and superscript glyphs are often available
3976 for Latin numbers, glyphs for punctuation and letter characters are less
3977 frequently provided. The synthetic fallback rules defined for this
3978 property assure that subscripts and superscripts will always appear but
3979 the appearance may not match author expectations if the font used does not
3980 provide the appropriate alternate glyph for all characters contained in a
3981 subscript or superscript.
3983 <p>This property is not cumulative. Applying it to elements within a
3984 subscript or superscript won't nest the placement of a subscript or
3985 superscript glyph. Images contained within text runs where the value of
3986 this property is ‘<a href="#sub"><code class=property>sub</code></a>’
3987 or ‘<a href="#super"><code class=property>super</code></a>’ will be
3988 drawn just as they would if the value was <a
3989 href="#font-variant-position-normal-value"
3990 title="normal!!font-variant-position">‘<code
3991 class=property>normal</code>’</a>.</p>
3992 <!-- due to lack of consensus, couldn't resolve on exact positioning of text decorations:
3993 http://www.w3.org/2013/06/06-css-minutes.html#item03 -->
3995 <p>Because of these limitations, ‘<a
3996 href="#propdef-font-variant-position"><code
3997 class=property>font-variant-position</code></a>’ is not recommended for
3998 use in user agent stylesheets. Authors should use it in cases where
3999 subscripts or superscripts will only contain the narrow range of
4000 characters supported by the fonts specified.
4002 <p class=note>The variant glyphs use the same baseline as the default
4003 glyphs would use. There is no shift in the placement along the baseline,
4004 so the use of variant glyphs doesn't affect the height of the inline box
4005 or alter the height of the linebox. This makes superscript and subscript
4006 variants ideal for situations where it's important that leading remain
4007 constant, such as in multi-column layout.
4009 <div class=example>
4010 <p>A typical user agent default style for the <a class=tag
4011 href="#sub">sub</a> element:</p>
4013 <pre>sub {
4014 vertical-align: sub;
4015 font-size: smaller;
4016 line-height: normal;
4017 }
4018 </pre>
4020 <p>Using font-variant-position to specify typographic subscripts in a way
4021 that will still show subscripts in older user agents:</p>
4023 <pre>@supports ( font-variant-position: sub ) {
4025 sub {
4026 vertical-align: baseline;
4027 font-size: 100%;
4028 line-height: inherit;
4029 font-variant-position: sub;
4030 }
4032 }
4033 </pre>
4035 <p>User agents that support the ‘<a
4036 href="#propdef-font-variant-position"><code
4037 class=property>font-variant-position</code></a>’ property will select a
4038 subscript variant glyph and render this without adjusting the baseline or
4039 font-size. Older user agents will ignore the ‘<a
4040 href="#propdef-font-variant-position"><code
4041 class=property>font-variant-position</code></a>’ property definition
4042 and use the standard defaults for subscripts.</p>
4043 </div>
4044 <!-- prop: font-variant-caps -->
4046 <h3 id=font-variant-caps-prop><span class=secno>6.6 </span>Capitalization:
4047 the <a href="#propdef-font-variant-caps">font-variant-caps</a> property</h3>
4049 <table class=propdef id=namefont-variant-capsvaluenormal-small-c>
4050 <tbody>
4051 <tr>
4052 <td>Name:
4054 <td><dfn id=propdef-font-variant-caps>font-variant-caps</dfn>
4056 <tr>
4057 <td>Value:
4059 <td><a href="#font-variant-caps-normal-value"
4060 title="normal!!font-variant-caps">normal</a> | <a
4061 href="#small-caps">small-caps</a> | <a
4062 href="#all-small-caps">all-small-caps</a> | <a
4063 href="#petite-caps">petite-caps</a> | <a
4064 href="#all-petite-caps">all-petite-caps</a> | <a
4065 href="#unicase">unicase</a> | <a href="#titling-caps">titling-caps</a>
4067 <tr>
4068 <td>Initial:
4070 <td>normal
4072 <tr>
4073 <td>Applies to:
4075 <td>all elements
4077 <tr>
4078 <td>Inherited:
4080 <td>yes
4082 <tr>
4083 <td>Percentages:
4085 <td>N/A
4087 <tr>
4088 <td>Media:
4090 <td>visual
4092 <tr>
4093 <td>Computed value:
4095 <td>as specified
4097 <tr>
4098 <td>Animatable:
4100 <td>no
4101 </table>
4103 <p>This property allows the selection of alternate glyphs used for small or
4104 petite capitals or for titling. These glyphs are specifically designed to
4105 blend well with the surrounding normal glyphs, to maintain the weight and
4106 readability which suffers when text is simply resized to fit this purpose.
4108 <p>Individual values have the following meanings:
4110 <dl>
4111 <dt><dfn id=font-variant-caps-normal-value
4112 title="normal!!font-variant-caps">normal</dfn>
4114 <dd>None of the features listed below are enabled.
4116 <dt><dfn id=small-caps>small-caps</dfn>
4118 <dd>Enables display of small capitals (OpenType feature: <span
4119 class=tag>smcp</span>). Small-caps glyphs typically use the form of
4120 uppercase letters but are reduced to the size of lowercase letters.
4121 </dl>
4123 <div class=featex><img alt="small-caps example" src=smcp.png></div>
4125 <dl>
4126 <dt><dfn id=all-small-caps>all-small-caps</dfn>
4128 <dd>Enables display of small capitals for both upper and lowercase letters
4129 (OpenType features: <span class=tag>c2sc, smcp</span>).
4131 <dt><dfn id=petite-caps>petite-caps</dfn>
4133 <dd>Enables display of petite capitals (OpenType feature: <span
4134 class=tag>pcap</span>).
4136 <dt><dfn id=all-petite-caps>all-petite-caps</dfn>
4138 <dd>Enables display of petite capitals for both upper and lowercase
4139 letters (OpenType features: <span class=tag>c2pc, pcap</span>).
4141 <dt><dfn id=unicase>unicase</dfn>
4143 <dd>Enables display of mixture of small capitals for uppercase letters
4144 with normal lowercase letters (OpenType feature: <span
4145 class=tag>unic</span>).
4147 <dt><dfn id=titling-caps>titling-caps</dfn>
4149 <dd>Enables display of titling capitals (OpenType feature: <span
4150 class=tag>titl</span>). Uppercase letter glyphs are often designed for
4151 use with lowercase letters. When used in all uppercase titling sequences
4152 they can appear too strong. Titling capitals are designed specifically
4153 for this situation.
4154 </dl>
4156 <p>The availability of these glyphs is based on whether a given feature is
4157 defined or not in the feature list of the font. User agents can optionally
4158 decide this on a per-script basis but should explicitly not decide this on
4159 a per-character basis.
4161 <p>Some fonts may only support a subset or none of the features described
4162 for this property. For backwards compatibility with CSS 2.1, if ‘<a
4163 href="#small-caps"><code class=property>small-caps</code></a>’ or ‘<a
4164 href="#all-small-caps"><code class=property>all-small-caps</code></a>’
4165 is specified but small-caps glyphs are not available for a given font,
4166 user agents should simulate a small-caps font, for example by taking a
4167 normal font and replacing the glyphs for lowercase letters with scaled
4168 versions of the glyphs for uppercase characters (replacing the glyphs for
4169 both upper and lowercase letters in the case of ‘<a
4170 href="#all-small-caps"><code class=property>all-small-caps</code></a>’).
4172 <div class=figure style="padding: 0; margin: auto;"><img alt="synthetic vs.
4173 real small-caps" class=hires src=synthetic-vs-real-small-caps.png
4174 width=512px>
4175 <p class=caption>Synthetic vs. real small-caps
4176 </div>
4178 <p>To match the surrounding text, a font may provide alternate glyphs for
4179 caseless characters when these features are enabled but when a user agent
4180 simulates small capitals, it must not attempt to simulate alternates for
4181 codepoints which are considered caseless.
4183 <div class=figure style="padding: 0; margin: auto;"><img alt="caseless
4184 characters with small-caps, all-small-caps enabled" class=hires
4185 src=small-capitals-variations.png width=418px>
4186 <p class=caption>Caseless characters with small-caps, all-small-caps
4187 enabled
4188 </div>
4190 <p>If either ‘<a href="#petite-caps"><code
4191 class=property>petite-caps</code></a>’ or ‘<a
4192 href="#all-petite-caps"><code class=property>all-petite-caps</code></a>’
4193 is specified for a font that doesn't support these features, the property
4194 behaves as if ‘<a href="#small-caps"><code
4195 class=property>small-caps</code></a>’ or ‘<a
4196 href="#all-small-caps"><code class=property>all-small-caps</code></a>’,
4197 respectively, had been specified. If ‘<a href="#unicase"><code
4198 class=property>unicase</code></a>’ is specified for a font that doesn't
4199 support that feature, the property behaves as if ‘<a
4200 href="#small-caps"><code class=property>small-caps</code></a>’ was
4201 applied only to lowercased uppercase letters. If ‘<a
4202 href="#titling-caps"><code class=property>titling-caps</code></a>’ is
4203 specified with a font that does not support this feature, this property
4204 has no visible effect. When simulated small capital glyphs are used, for
4205 scripts that lack uppercase and lowercase letters, ‘<a
4206 href="#small-caps"><code class=property>small-caps</code></a>’, ‘<a
4207 href="#all-small-caps"><code class=property>all-small-caps</code></a>’,
4208 ‘<a href="#petite-caps"><code class=property>petite-caps</code></a>’,
4209 ‘<a href="#all-petite-caps"><code
4210 class=property>all-petite-caps</code></a>’ and ‘<a
4211 href="#unicase"><code class=property>unicase</code></a>’ have no visible
4212 effect.
4214 <p>When casing transforms are used to simulate small capitals, the casing
4215 transformations must match those used for the <span
4216 class=property>‘<code class=property>text-transform</code>’</span>
4217 property.
4219 <p>As a last resort, unscaled uppercase letter glyphs in a normal font may
4220 replace glyphs in a small-caps font so that the text appears in all
4221 uppercase letters.
4223 <div class=figure style="padding: 0; margin: auto;"><img alt="using
4224 all-small-caps in acronym-laden text" class=hires
4225 src=acronym-laden-text.png width=596px>
4226 <p class=caption>Using small capitals to improve readability in
4227 acronym-laden text
4228 </div>
4230 <div class=example>
4231 <p>Quotes rendered italicised, with small-caps on the first line:</p>
4233 <pre>blockquote { font-style: italic; }
4234 blockquote:first-line { font-variant: small-caps; }
4236 <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>
4237 </pre>
4238 </div>
4239 <!-- prop: font-variant-numeric -->
4241 <h3 id=font-variant-numeric-prop><span class=secno>6.7 </span>Numerical
4242 formatting: the <a
4243 href="#propdef-font-variant-numeric">font-variant-numeric</a> property</h3>
4245 <table class=propdef id=namefont-variant-numericvaluenormal-ltnu>
4246 <tbody>
4247 <tr>
4248 <td>Name:
4250 <td><dfn id=propdef-font-variant-numeric>font-variant-numeric</dfn>
4252 <tr>
4253 <td>Value:
4255 <td><a href="#font-variant-numeric-normal-value"
4256 title="normal!!font-variant-numeric">normal</a> | [ <a
4257 href="#numeric-figure-values"><var><numeric-figure-values></var></a>
4258 || <a
4259 href="#numeric-spacing-values"><var><numeric-spacing-values></var></a>
4260 || <a
4261 href="#numeric-fraction-values"><var><numeric-fraction-values></var></a>
4262 || <a href="#ordinal">ordinal</a> || <a
4263 href="#slashed-zero">slashed-zero</a> ]
4265 <tr>
4266 <td>Initial:
4268 <td>normal
4270 <tr>
4271 <td>Applies to:
4273 <td>all elements
4275 <tr>
4276 <td>Inherited:
4278 <td>yes
4280 <tr>
4281 <td>Percentages:
4283 <td>N/A
4285 <tr>
4286 <td>Media:
4288 <td>visual
4290 <tr>
4291 <td>Computed value:
4293 <td>as specified
4295 <tr>
4296 <td>Animatable:
4298 <td>no
4299 </table>
4301 <p>Specifies control over numerical forms. The example below shows how some
4302 of these values can be combined to influence the rendering of tabular data
4303 with fonts that support these features. Within normal paragraph text,
4304 proportional numbers are used while tabular numbers are used so that
4305 columns of numbers line up properly:
4307 <div class=figure style="padding: 0; margin: auto;"><img alt="combining
4308 number styles" src=numberstyles.png>
4309 <p class=caption>Using number styles
4310 </div>
4312 <p>Possible combinations:
4314 <pre
4315 class=prod><dfn id=numeric-figure-values><var><numeric-figure-values></var></dfn> = [ <a href="#lining-nums">lining-nums</a> | <a href="#oldstyle-nums">oldstyle-nums</a> ]</pre>
4317 <pre
4318 class=prod><dfn id=numeric-spacing-values><var><numeric-spacing-values></var></dfn> = [ <a href="#proportional-nums">proportional-nums</a> | <a href="#tabular-nums">tabular-nums</a> ]</pre>
4320 <pre
4321 class=prod><dfn id=numeric-fraction-values><var><numeric-fraction-values></var></dfn> = [ <a href="#diagonal-fractions">diagonal-fractions</a> | <a href="#stacked-fractions">stacked-fractions</a> ]</pre>
4323 <p>Individual values have the following meanings:
4325 <dl>
4326 <dt><dfn id=font-variant-numeric-normal-value
4327 title="normal!!font-variant-numeric">normal</dfn>
4329 <dd>None of the features listed below are enabled.
4331 <dt><dfn id=lining-nums>lining-nums</dfn>
4333 <dd>Enables display of lining numerals (OpenType feature: <span
4334 class=tag>lnum</span>).
4336 <dt><dfn id=oldstyle-nums>oldstyle-nums</dfn>
4338 <dd>Enables display of old-style numerals (OpenType feature: <span
4339 class=tag>onum</span>).
4341 <dt><dfn id=proportional-nums>proportional-nums</dfn>
4343 <dd>Enables display of proportional numerals (OpenType feature: <span
4344 class=tag>pnum</span>).
4346 <dt><dfn id=tabular-nums>tabular-nums</dfn>
4348 <dd>Enables display of tabular numerals (OpenType feature: <span
4349 class=tag>tnum</span>).
4351 <dt><dfn id=diagonal-fractions>diagonal-fractions</dfn>
4353 <dd>Enables display of lining diagonal fractions (OpenType feature: <span
4354 class=tag>frac</span>).
4355 </dl>
4357 <div class=featex><img alt="diagonal fraction example" src=frac.png></div>
4359 <dl>
4360 <dt><dfn id=stacked-fractions>stacked-fractions</dfn>
4362 <dd>Enables display of lining stacked fractions (OpenType feature: <span
4363 class=tag>afrc</span>).
4364 </dl>
4366 <div class=featex><img alt="stacked fraction example" src=afrc.png></div>
4368 <dl>
4369 <dt><dfn id=ordinal>ordinal</dfn>
4371 <dd>Enables display of forms used with ordinal numbers (OpenType feature:
4372 <span class=tag>ordn</span>).
4374 <dt><dfn id=slashed-zero>slashed-zero</dfn>
4376 <dd>Enables display of slashed zeros (OpenType feature: <span
4377 class=tag>zero</span>).
4378 </dl>
4380 <div class=featex><img alt="slashed zero example" src=zero.png></div>
4382 <div class=example id=steak-marinade>
4383 <p>A simple flank steak marinade recipe, rendered with automatic fractions
4384 and old-style numerals:</p>
4386 <pre>.amount { font-variant-numeric: oldstyle-nums diagonal-fractions; }
4388 <h4>Steak marinade:</h4>
4389 <ul>
4390 <li><span class="amount">2</span> tbsp olive oil</li>
4391 <li><span class="amount">1</span> tbsp lemon juice</li>
4392 <li><span class="amount">1</span> tbsp soy sauce</li>
4393 <li><span class="amount">1 1/2</span> tbsp dry minced onion</li>
4394 <li><span class="amount">2 1/2</span> tsp italian seasoning</li>
4395 <li>Salt &amp; pepper</li>
4396 </ul>
4398 <p>Mix the meat with the marinade and let it sit covered in the refrigerator
4399 for a few hours or overnight.</p>
4400 </pre>
4402 <p>Note that the fraction feature is only applied to values not the entire
4403 paragraph. Fonts often implement this feature using contextual rules
4404 based on the use of the slash (‘<code class=css>/</code>’) character.
4405 As such, it's not suitable for use as a paragraph-level style.</p>
4406 </div>
4407 <!-- prop: font-variant-alternates -->
4409 <h3 id=font-variant-alternates-prop><span class=secno>6.8 </span>Alternates
4410 and swashes: the <a
4411 href="#propdef-font-variant-alternates">font-variant-alternates</a>
4412 property</h3>
4414 <table class=propdef id=namefont-variant-alternatesvaluenormal-s>
4415 <tbody>
4416 <tr>
4417 <td>Name:
4419 <td><dfn
4420 id=propdef-font-variant-alternates>font-variant-alternates</dfn>
4422 <tr>
4423 <td>Value:
4425 <td>normal | [ <a href="#stylistic"
4426 title=stylistic>stylistic(<feature-value-name>)</a> || <a
4427 href="#historical-forms">historical-forms</a> || <a href="#styleset"
4428 title=styleset>styleset(<feature-value-name> #)</a> || <a
4429 href="#character-variant"
4430 title=character-variant>character-variant(<feature-value-name>
4431 #)</a> || <a href="#swash"
4432 title=swash>swash(<feature-value-name>)</a> || <a
4433 href="#ornaments"
4434 title=ornaments>ornaments(<feature-value-name>)</a> || <a
4435 href="#annotation"
4436 title=annotation>annotation(<feature-value-name>)</a> ]
4438 <tr>
4439 <td>Initial:
4441 <td>normal
4443 <tr>
4444 <td>Applies to:
4446 <td>all elements
4448 <tr>
4449 <td>Inherited:
4451 <td>yes
4453 <tr>
4454 <td>Percentages:
4456 <td>N/A
4458 <tr>
4459 <td>Media:
4461 <td>visual
4463 <tr>
4464 <td>Computed value:
4466 <td>as specified
4468 <tr>
4469 <td>Animatable:
4471 <td>no
4472 </table>
4474 <p>For any given character, fonts can provide a variety of alternate glyphs
4475 in addition to the default glyph for that character. This property
4476 provides control over the selection of these alternate glyphs.
4478 <p>For many of the property values listed below, several different
4479 alternate glyphs are available. How many alternates are available and what
4480 they represent is font-specific, so these are each marked <dfn
4481 id=font-specific>font specific</dfn> in the value definitions below.
4482 Because the nature of these alternates is font-specific, the <a
4483 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
4484 rule is used to define values for a specific font family or set of
4485 families that associate a font-specific numeric
4486 <code><feature-index></code> with a custom
4487 <code><feature-value-name></code>, which is then used in this
4488 property to select specific alternates:
4490 <pre>@font-feature-values Noble Script { @swash { swishy: 1; flowing: 2; } }
4492 p {
4493 font-family: Noble Script;
4494 font-variant-alternates: swash(flowing); /* use swash alternate #2 */
4495 }</pre>
4497 <p>When a particular <code><feature-value-name></code> has not been
4498 defined for a given family or for a particular feature type, the computed
4499 value must be the same as if it had been defined. However, property values
4500 that contain these undefined <code><feature-value-name></code>
4501 identifiers must be ignored when choosing glyphs.
4503 <pre>/* these two style rules are effectively the same */
4504 p { font-variant-alternates: swash(unknown-value); } /* not a defined value, ignored */
4505 p { font-variant-alternates: normal; }
4506 </pre>
4508 <p>This allows values to be defined and used for a given set of font
4509 families but ignored if fallback occurs, since the font family name would
4510 be different. If a given value is outside the range supported by a given
4511 font, the value is ignored. These values never apply to generic font
4512 families.
4514 <p>Individual values have the following meanings:
4516 <dl>
4517 <dt><dfn id=font-variant-alternates-normal-value
4518 title="normal!!font-variant-alternates">normal</dfn>
4520 <dd>None of the features listed below are enabled.
4522 <dt><dfn id=historical-forms>historical-forms</dfn>
4524 <dd>Enables display of historical forms (OpenType feature: <span
4525 class=tag>hist</span>).
4526 </dl>
4528 <div class=featex><img alt="historical form example" src=hist.png></div>
4530 <dl>
4531 <dt><dfn id=stylistic
4532 title=stylistic>stylistic(<feature-value-name>)</dfn>
4534 <dd>Enables display of stylistic alternates (<a
4535 href="#font-specific"><em>font specific</em></a>, OpenType feature: <span
4536 class=tag>salt <feature-index></span>).
4537 </dl>
4539 <div class=featex><img alt="stylistic alternate example" src=salt.png></div>
4541 <dl>
4542 <dt><dfn id=styleset title=styleset>styleset(<feature-value-name>
4543 #)</dfn>
4545 <dd>Enables display with stylistic sets (<a href="#font-specific"><em>font
4546 specific</em></a>, OpenType feature: <span
4547 class=tag>ss<feature-index></span> OpenType currently defines <span
4548 class=tag>ss01</span> through <span class=tag>ss20</span>).
4549 </dl>
4551 <div class=featex><img alt="styleset example" src=ssnn.png></div>
4553 <dl>
4554 <dt><dfn id=character-variant
4555 title=character-variant>character-variant(<feature-value-name>
4556 #)</dfn>
4558 <dd>Enables display of specific character variants (<a
4559 href="#font-specific"><em>font specific</em></a>, OpenType feature: <span
4560 class=tag>cv<feature-index></span> OpenType currently defines <span
4561 class=tag>cv01</span> through <span class=tag>cv99</span>).
4563 <dt><dfn id=swash title=swash>swash(<feature-value-name>)</dfn>
4565 <dd>Enables display of swash glyphs (<a href="#font-specific"><em>font
4566 specific</em></a>, OpenType feature: <span class=tag>swsh
4567 <feature-index>, cswh <feature-index></span>).
4568 </dl>
4570 <div class=featex><img alt="swash example" src=swsh.png></div>
4572 <dl>
4573 <dt><dfn id=ornaments
4574 title=ornaments>ornaments(<feature-value-name>)</dfn>
4576 <dd>Enables replacement of default glyphs with ornaments, if provided in
4577 the font (<a href="#font-specific"><em>font specific</em></a>, OpenType
4578 feature: <span class=tag>ornm <feature-index></span>). Some fonts
4579 may offer ornament glyphs as alternates for a wide collection of
4580 characters; however, displaying arbitrary characters (e.g.,
4581 alphanumerics) as ornaments is poor practice as it distorts the semantics
4582 of the data. Font designers are encouraged to encode all ornaments
4583 (except those explicitly encoded in the Unicode Dingbats blocks, etc.) as
4584 alternates for the bullet character (U+2022) to allow authors to select
4585 the desired glyph using ‘<a href="#ornaments"><code
4586 class=property>ornaments</code></a>’.
4587 </dl>
4589 <div class=featex><img alt="ornaments example" src=ornm.png></div>
4591 <dl>
4592 <dt><dfn id=annotation
4593 title=annotation>annotation(<feature-value-name>)</dfn>
4595 <dd>Enables display of alternate annotation forms (<a
4596 href="#font-specific"><em>font specific</em></a>, OpenType feature: <span
4597 class=tag>nalt <feature-index></span>).
4598 </dl>
4600 <div class=featex><img alt="alternate annotation form example"
4601 src=nalt.png></div>
4603 <h3 id=font-feature-values><span class=secno>6.9 </span>Defining font
4604 specific alternates: the <dfn id=at-font-feature-values-rule
4605 style="font-weight: inherit; font-style:
4606 inherit"><code>@font-feature-values</code></dfn> rule</h3>
4608 <p>Several of the possible values of ‘<a
4609 href="#propdef-font-variant-alternates"><code
4610 class=property>font-variant-alternates</code></a>’ listed above are
4611 labeled as <a href="#font-specific"><em>font specific</em></a>. For these
4612 features fonts may define not just a single glyph but a set of alternate
4613 glyphs with an index to select a given alternate. Since these are font
4614 family specific, the <a
4615 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
4616 rule is used to define named values for these indices for a given family.
4618 <p class=note>See the <a href="#om-fontfeaturevalues">object model
4619 reference section</a> for a description of the interfaces used to modify
4620 these rules via the CSS Object Model.
4622 <div class=example>
4623 <p>In the case of the swash Q in the example shown above, the swash could
4624 be specified using these style rules:</p>
4626 <pre>
4628 @font-feature-values Jupiter Sans {
4629 @swash {
4630 delicate: 1;
4631 flowing: 2;
4632 }
4633 }
4635 h2 { font-family: Jupiter Sans, sans-serif; }
4637 /* show the second swash variant in h2 headings */
4638 h2:first-letter { font-variant-alternates: swash(flowing); }
4640 <h2>Quick</h2></pre>
4642 <p>When Jupiter Sans is present, the second alternate swash alternate will
4643 be displayed. When not present, no swash character will be shown, since
4644 the specific named value "flowing" is only defined for the Jupiter Sans
4645 family. The @-mark indicates the name of the property value for which a
4646 named value can be used. The name "flowing" is chosen by the author. The
4647 index that represents each alternate is defined within a given font's
4648 data.</p>
4649 </div>
4651 <h4 id=basic-syntax><span class=secno>6.9.1 </span>Basic syntax</h4>
4653 <p>An <a
4654 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
4655 rule is composed of a list of font families followed by a block containing
4656 individual <a href="#featurevalueblock"><i
4657 title="feature_value_block">feature value blocks</i></a> that take the
4658 form of @-rules. Each block defines a set of named values for a specific
4659 font feature when a given set of font families is used. Effectively, they
4660 define a mapping of ⟨family, feature, ident⟩ → ⟨values⟩ where
4661 ⟨values⟩ are the numeric indices used for specific features defined
4662 for a given font.
4664 <p>In terms of the grammar, this specification defines the following
4665 productions:
4667 <pre><dfn id=fontfeaturevaluesrule>font_feature_values_rule</dfn>
4668 : <a href="#fontfeaturevaluessym"><i>FONT_FEATURE_VALUES_SYM</i></a> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="#fontfamilynamelist"><i>font_family_name_list</i></a> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>*
4669 '{' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="#featurevalueblock"><i>feature_value_block</i></a>? [ <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="#featurevalueblock"><i>feature_value_block</i></a>? ]* '}' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>*
4670 ;
4672 <dfn id=fontfamilynamelist>font_family_name_list</dfn>
4673 : <a href="#fontfamilyname"><i>font_family_name</i></a> [ <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* ',' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="#fontfamilyname"><i>font_family_name</i></a> ]*
4674 ;
4676 <dfn id=fontfamilyname>font_family_name</dfn>
4677 : <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>STRING</i></a> | [ <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>IDENT</i></a> [ <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>IDENT</i></a> ]* ]
4678 ;
4680 <dfn id=featurevalueblock>feature_value_block</dfn>
4681 : <a href="#featuretype"><i>feature_type</i></a> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>*
4682 '{' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="#featurevaluedefinition"><i>feature_value_definition</i></a>? [ <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* ';' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="#featurevaluedefinition"><i>feature_value_definition</i></a>? ]* '}' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>*
4683 ;
4685 <dfn id=featuretype>feature_type</dfn>:
4686 <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>ATKEYWORD</i></a>
4687 ;
4689 <dfn id=featurevaluedefinition>feature_value_definition</dfn>
4690 : <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>IDENT</i></a> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* ':' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>NUMBER</i></a> [ <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>NUMBER</i></a> ]*
4691 ;
4692 </pre>
4694 <p>The following new token is introduced:
4696 <pre>@{F}{O}{N}{T}{-}{F}{E}{A}{T}{U}{R}{E}{-}{V}{A}{L}{U}{E}{S} {return <dfn id=fontfeaturevaluessym>FONT_FEATURE_VALUES_SYM</dfn>;}
4697 </pre>
4699 <p><a href="#featurevalueblock"><i title="feature_value_block">Feature
4700 value blocks</i></a> are handled as <a
4701 href="http://www.w3.org/TR/CSS2/syndata.html#at-rules">at-rules</a>, they
4702 consist of everything up to the next block or semi-colon, whichever comes
4703 first.
4705 <p>The <a href="#fontfamilynamelist"><i title="font_family_name_list">font
4706 family list</i></a> is a comma-delimited list of <a
4707 href="#fontfamilyname"><i title="font_family_name">font family
4708 names</i></a> that match the definition of <a
4709 href="#family-name-value"><var><family-name></var></a> for the <a
4710 href="#propdef-font-family" title="font-family!!property">‘<code
4711 class=property>font-family</code>’</a> property. This means that only
4712 named font families are allowed, rules that include generic or system
4713 fonts in the list of font families are syntax errors. However, if a user
4714 agent defines a generic font to be a specific named font (e.g. Helvetica),
4715 the settings associated with that family name will be used. If syntax
4716 errors occur within the font family list, the entire rule must be ignored.
4718 <p>Within <a href="#featurevalueblock"><i
4719 title="feature_value_block">feature value blocks</i></a>, the <a
4720 href="#featuretype"><i title="feature_type">feature type</i></a> is
4721 ‘<code class=css>@</code>’ followed by the name of one of the <a
4722 href="#font-specific"><em>font specific</em></a> property values of ‘<a
4723 href="#propdef-font-variant-alternates"><code
4724 class=property>font-variant-alternates</code></a>’ (e.g. <a
4725 href="#swash"><code>@swash</code></a>). The identifiers used within
4726 feature value definitions follow the rules of CSS user identifiers and are
4727 case-sensitive. They are unique only for a given set of font families and
4728 <a href="#featuretype"><i title="feature_type">feature type</i></a>. The
4729 same identifier used with a different <a href="#featuretype"><i
4730 title="feature_type">feature type</i></a> is treated as a separate and
4731 distinct value. If the same identifier is defined mulitple times for a
4732 given <a href="#featuretype"><i title="feature_type">feature type</i></a>
4733 and font family, the last defined value is used. Values associated with a
4734 given identifier are limited to integer values 0 or greater.
4736 <p>When syntax errors occur within a <a href="#featurevaluedefinition"><i
4737 title="feature_value_definition">feature value definition</i></a>, such as
4738 invalid identifiers or values, the entire <a
4739 href="#featurevaluedefinition"><i title="feature_value_definition">feature
4740 value definition</i></a> must be omitted, just as syntax errors in style
4741 declarations are handled. When the <a href="#featuretype"><i
4742 title="feature_type">feature type</i></a> is invalid, the entire
4743 associated <a href="#featurevalueblock"><i
4744 title="feature_value_block">feature value block</i></a> must be ignored.
4746 <div class=example>
4747 <p>Rules that are equivalent given syntax error handling:</p>
4749 <pre>@font-feature-values Bongo {
4750 @swash { ornate: 1; }
4751 annotation { boxed: 4; } /* should be @annotation! */
4752 @swash { double-loops: 1; flowing: -1; } /* negative value */
4753 @ornaments ; /* incomplete definition */
4754 @styleset { double-W: 14; sharp-terminals: 16 1 } /* missing ; */
4755 <a href="http://www.angryalien.com/0504/shiningbunnies.html" style="text-decoration: none; border: none;">redrum</a> /* random editing mistake */
4756 }</pre>
4758 <p>The example above is equivalent to:</p>
4760 <pre>@font-feature-values Bongo {
4761 @swash { ornate: 1; }
4762 @swash { double-loops: 1; }
4763 @styleset { double-W: 14; sharp-terminals: 16 1; }
4764 }</pre>
4765 </div>
4767 <p>If multiple <a
4768 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
4769 rules are defined for a given family, the resulting values definitions are
4770 the union of the definitions contained within these rules. This allows a
4771 set of named values to be defined for a given font family globally for a
4772 site and specific additions made per-page.
4774 <div class=example>
4775 <p>Using both site-wide and per-page feature values:</p>
4777 <pre>
4778 site.css:
4780 @font-feature-values Mercury Serif {
4781 @styleset {
4782 stacked-g: 3; /* "two-storey" versions of g, a */
4783 stacked-a: 4;
4784 }
4785 }
4787 page.css:
4789 @font-feature-values Mercury Serif {
4790 @styleset {
4791 geometric-m: 7; /* alternate version of m */
4792 }
4793 }
4795 body {
4796 font-family: Mercury Serif, serif;
4798 /* enable both the use of stacked g and alternate m */
4799 font-variant-alternates: styleset(stacked-g, geometric-m);
4800 }</pre>
4801 </div>
4803 <div class=example>
4804 <p>Using a commonly named value allows authors to use a single style rule
4805 to cover a set of fonts for which the underlying selector is different
4806 for each font. If either font in the example below is found, a circled
4807 number glyph will be used:</p>
4809 <pre>@font-feature-values Taisho Gothic {
4810 @annotation { boxed: 1; circled: 4; }
4811 }
4813 @font-feature-values Otaru Kisa {
4814 @annotation { circled: 1; black-boxed: 3; }
4815 }
4817 h3.title {
4818 /* circled form defined for both fonts */
4819 font-family: Taisho Gothic, Otaru Kisa;
4820 font-variant: annotation(circled);
4821 }</pre>
4822 </div>
4824 <h4 id=multi-valued-feature-value-definitions><span class=secno>6.9.2
4825 </span>Multi-valued feature value definitions</h4>
4827 <p>Most <a href="#font-specific"><em>font specific</em></a> ‘<a
4828 href="#propdef-font-variant-alternates"><code
4829 class=property>font-variant-alternates</code></a>’ property values take
4830 a single value (e.g. ‘<a href="#swash"><code
4831 class=property>swash</code></a>’). The ‘<a
4832 href="#character-variant"><code
4833 class=property>character-variant</code></a>’ property value allows two
4834 values and ‘<a href="#styleset"><code
4835 class=property>styleset</code></a>’ allows an unlimited number.
4837 <p>For the styleset property value, multiple values indicate the style sets
4838 to be enabled. Values between 1 and 99 enable OpenType features <span
4839 class=tag>ss01</span> through <span class=tag>ss99</span>. However, the
4840 OpenType standard only officially defines <span class=tag>ss01</span>
4841 through <span class=tag>ss20</span>. For OpenType fonts, values greater
4842 than 99 or equal to 0 do not generate a syntax error when parsed but
4843 enable no OpenType features.
4845 <pre>@font-feature-values Mars Serif {
4846 @styleset {
4847 alt-g: 1; /* implies ss01 = 1 */
4848 curly-quotes: 3; /* implies ss03 = 1 */
4849 code: 4 5; /* implies ss04 = 1, ss05 = 1 */
4850 }
4852 @styleset {
4853 dumb: 125; /* >99, ignored */
4854 }
4856 @swash {
4857 swishy: 3 5; /* more than 1 value for swash, syntax error */
4858 }
4859 }
4861 p.codeblock {
4862 /* implies ss03 = 1, ss04 = 1, ss05 = 1 */
4863 font-variant-alternates: styleset(curly-quotes, code);
4864 }</pre>
4866 <p>For character-variant, a single value between 1 and 99 indicates the
4867 enabling of OpenType feature <span class=tag>cv01</span> through <span
4868 class=tag>cv99</span>. For OpenType fonts, values greater than 99 or equal
4869 to 0 are ignored but do not generate a syntax error when parsed but enable
4870 no OpenType features. When two values are listed, the first value
4871 indicates the feature used and the second the value passed for that
4872 feature. If more than two values are assigned to a given name, a syntax
4873 error occurs and the entire <a href="#featurevaluedefinition"><i
4874 title="feature_value_definition">feature value definition</i></a> is
4875 ignored.
4877 <pre>@font-feature-values MM Greek {
4878 @character-variant { alpha-2: 1 2; } /* implies cv01 = 2 */
4879 @character-variant { beta-3: 2 3; } /* implies cv02 = 3 */
4880 @character-variant { epsilon: 5 3 6; } /* more than 2 values, syntax error, definition ignored */
4881 @character-variant { gamma: 12; } /* implies cv12 = 1 */
4882 @character-variant { zeta: 20 3; } /* implies cv20 = 3 */
4883 @character-variant { zeta-2: 20 2; } /* implies cv20 = 2 */
4884 @character-variant { silly: 105; } /* >99, ignored */
4885 @character-variant { dumb: 323 3; } /* >99, ignored */
4886 }
4888 #title {
4889 /* use the third alternate beta, first alternate gamma */
4890 font-variant-alternates: character-variant(beta-3, gamma);
4891 }
4893 p {
4894 /* zeta-2 follows zeta, implies cv20 = 2 */
4895 font-variant-alternates: character-variant(zeta, zeta-2);
4896 }
4898 .special {
4899 /* zeta follows zeta-2, implies cv20 = 3 */
4900 font-variant-alternates: character-variant(zeta-2, zeta);
4901 }</pre>
4903 <div class=figure><img alt="Matching text on Byzantine seals using
4904 character variants" src=byzantineseal.png>
4905 <p class=caption>Byzantine seal text displayed with character variants
4906 </div>
4908 <div class=example>
4909 <p>In the figure above, the text in red is rendered using a font
4910 containing character variants that mimic the character forms found on a
4911 Byzantine seal from the 8th century A.D. Two lines below is the same text
4912 displayed in a font without variants. Note the two variants for U and N
4913 used on the seal.</p>
4915 <pre>@font-feature-values Athena Ruby {
4916 @character-variant {
4917 leo-B: 2 1;
4918 leo-M: 13 3;
4919 leo-alt-N: 14 1;
4920 leo-N: 14 2;
4921 leo-T: 20 1;
4922 leo-U: 21 2;
4923 leo-alt-U: 21 4;
4924 }
4925 }
4927 p {
4928 font-variant: discretionary-ligatures,
4929 character-variant(leo-B, leo-M, leo-N, leo-T, leo-U);
4930 }
4932 span.alt-N {
4933 font-variant-alternates: character-variant(leo-alt-N);
4934 }
4936 span.alt-U {
4937 font-variant-alternates: character-variant(leo-alt-U);
4938 }
4940 <p>ENO....UP͞RSTU<span class="alt-U">U</span>͞<span class="alt-U">U</span>ΚΑΙTỤẠG̣IUPNS</p>
4942 <p>LEON|ΚΑΙCONSTA|NTI<span class="alt-N">N</span>OS..|STOIBAṢ.|LIṢROM|AIO<span class="alt-N">N</span></p>
4943 </pre>
4944 </div>
4946 <h3 id=font-variant-east-asian-prop><span class=secno>6.10 </span>East
4947 Asian text rendering: the <a
4948 href="#propdef-font-variant-east-asian">font-variant-east-asian</a>
4949 property</h3>
4951 <table class=propdef id=namefont-variant-east-asianvaluenormal-l>
4952 <tbody>
4953 <tr>
4954 <td>Name:
4956 <td><dfn
4957 id=propdef-font-variant-east-asian>font-variant-east-asian</dfn>
4959 <tr>
4960 <td>Value:
4962 <td><a href="#font-variant-east-asian-normal-value"
4963 title="normal!!font-variant-east-asian">normal</a> | [ <a
4964 href="#east-asian-variant-values"><var><east-asian-variant-values></var></a>
4965 || <a
4966 href="#east-asian-width-values"><var><east-asian-width-values></var></a>
4967 || <a href="#ruby">ruby</a> ]
4969 <tr>
4970 <td>Initial:
4972 <td>normal
4974 <tr>
4975 <td>Applies to:
4977 <td>all elements
4979 <tr>
4980 <td>Inherited:
4982 <td>yes
4984 <tr>
4985 <td>Percentages:
4987 <td>N/A
4989 <tr>
4990 <td>Media:
4992 <td>visual
4994 <tr>
4995 <td>Computed value:
4997 <td>as specified
4999 <tr>
5000 <td>Animatable:
5002 <td>no
5003 </table>
5005 <p>Allows control of glyph substitution and sizing in East Asian text.
5007 <pre
5008 class=prod><dfn id=east-asian-variant-values><var><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>
5010 <pre
5011 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>
5013 <p>Individual values have the following meanings:
5015 <dl>
5016 <dt><dfn id=font-variant-east-asian-normal-value
5017 title="normal!!font-variant-east-asian">normal</dfn>
5019 <dd>None of the features listed below are enabled.
5021 <dt><dfn id=jis78>jis78</dfn>
5023 <dd>Enables rendering of JIS78 forms (OpenType feature: <span
5024 class=tag>jp78</span>).
5025 </dl>
5027 <div class=featex><img alt="JIS78 form example" src=jp78.png></div>
5029 <dl>
5030 <dt><dfn id=jis83>jis83</dfn>
5032 <dd>Enables rendering of JIS83 forms (OpenType feature: <span
5033 class=tag>jp83</span>).
5035 <dt><dfn id=jis90>jis90</dfn>
5037 <dd>Enables rendering of JIS90 forms (OpenType feature: <span
5038 class=tag>jp90</span>).
5040 <dt><dfn id=jis04>jis04</dfn>
5042 <dd>Enables rendering of JIS2004 forms (OpenType feature: <span
5043 class=tag>jp04</span>).
5044 <p>The various JIS variants reflect the glyph forms defined in different
5045 Japanese national standards. Fonts generally include glyphs defined by
5046 the most recent national standard but it's sometimes necessary to use
5047 older variants, to match signage for example.</p>
5049 <dt><dfn id=simplified>simplified</dfn>
5051 <dd>Enables rendering of simplified forms (OpenType feature: <span
5052 class=tag>smpl</span>).
5054 <dt><dfn id=traditional>traditional</dfn>
5056 <dd>Enables rendering of traditional forms (OpenType feature: <span
5057 class=tag>trad</span>).
5058 </dl>
5060 <p>The ‘<a href="#simplified"><code
5061 class=property>simplified</code></a>’ and ‘<a
5062 href="#traditional"><code class=property>traditional</code></a>’ values
5063 allow control over the glyph forms for characters which have been
5064 simplified over time but for which the older, traditional form is still
5065 used in some contexts. The exact set of characters and glyph forms will
5066 vary to some degree by context for which a given font was designed.
5068 <div class=featex><img alt="tradtional form example" src=trad.png></div>
5070 <dl>
5071 <dt><dfn id=full-width>full-width</dfn>
5073 <dd>Enables rendering of full-width variants (OpenType feature: <span
5074 class=tag>fwid</span>).
5076 <dt><dfn id=proportional-width>proportional-width</dfn>
5078 <dd>Enables rendering of proportionally-spaced variants (OpenType feature:
5079 <span class=tag>pwid</span>).
5080 </dl>
5082 <div class=featex><img alt="proportionally spaced Japanese example"
5083 src=pwid.png></div>
5085 <dl>
5086 <dt><dfn id=ruby>ruby</dfn>
5088 <dd>Enables display of ruby variant glyphs (OpenType feature: <span
5089 class=tag>ruby</span>). Since ruby text is generally smaller than the
5090 associated body text, font designers can design special glyphs for use
5091 with ruby that are more readable than scaled down versions of the default
5092 glyphs. Only glyph selection is affected, there is no associated font
5093 scaling or other change that affects line layout. The red ruby text below
5094 is shown with default glyphs (top) and with ruby variant glyphs (bottom).
5095 Note the slight difference in stroke thickness.
5096 </dl>
5098 <div class=featex><img alt="ruby variant example" src=rubyshinkansen.png></div>
5100 <h3 id=font-variant-prop><span class=secno>6.11 </span>Overall shorthand
5101 for font rendering: the <a href="#propdef-font-variant">font-variant</a>
5102 property</h3>
5104 <table class=propdef id=namefont-variantvaluenormal-none-ltcommo>
5105 <tbody>
5106 <tr>
5107 <td>Name:
5109 <td><dfn id=propdef-font-variant
5110 title="font-variant!!property">font-variant</dfn>
5112 <tr>
5113 <td>Value:
5115 <td><a href="#font-variant-normal-value"
5116 title="normal!!font-variant">normal</a> | <a
5117 href="#font-variant-none-value" title="none!!font-variant">none</a> | [
5118 <a href="#common-lig-values"><var><common-lig-values></var></a>
5119 || <a
5120 href="#discretionary-lig-values"><var><discretionary-lig-values></var></a>
5121 || <a
5122 href="#historical-lig-values"><var><historical-lig-values></var></a>
5123 || <a
5124 href="#contextual-alt-values"><var><contextual-alt-values></var></a>
5125 || <a href="#stylistic"><var
5126 title=stylistic>stylistic(<feature-value-name>)</var></a> || <a
5127 href="#historical-forms"><var>historical-forms</var></a> || <a
5128 href="#styleset"><var
5129 title=styleset>styleset(<feature-value-name> #)</var></a> || <a
5130 href="#character-variant"><var
5131 title=character-variant>character-variant(<feature-value-name>
5132 #)</var></a> || <a href="#swash"><var
5133 title=swash>swash(<feature-value-name>)</var></a> || <a
5134 href="#ornaments"><var
5135 title=ornaments>ornaments(<feature-value-name>)</var></a> || <a
5136 href="#annotation"><var
5137 title=annotation>annotation(<feature-value-name>)</var></a> || [
5138 <a href="#small-caps"><i>small-caps</i></a> | <a
5139 href="#all-small-caps"><i>all-small-caps</i></a> | <a
5140 href="#petite-caps"><i>petite-caps</i></a> | <a
5141 href="#all-petite-caps"><i>all-petite-caps</i></a> | <a
5142 href="#unicase"><i>unicase</i></a> | <a
5143 href="#titling-caps"><i>titling-caps</i></a> ] || <a
5144 href="#numeric-figure-values"><var><numeric-figure-values></var></a>
5145 || <a
5146 href="#numeric-spacing-values"><var><numeric-spacing-values></var></a>
5147 || <a
5148 href="#numeric-fraction-values"><var><numeric-fraction-values></var></a>
5149 || <a href="#ordinal"><i>ordinal</i></a> || <a
5150 href="#slashed-zero"><i>slashed-zero</i></a> || <a
5151 href="#east-asian-variant-values"><var><east-asian-variant-values></var></a>
5152 || <a
5153 href="#east-asian-width-values"><var><east-asian-width-values></var></a>
5154 || <a href="#ruby"><i>ruby</i></a> ]
5156 <tr>
5157 <td>Initial:
5159 <td>normal
5161 <tr>
5162 <td>Applies to:
5164 <td>all elements
5166 <tr>
5167 <td>Inherited:
5169 <td>yes
5171 <tr>
5172 <td>Percentages:
5174 <td>see individual properties
5176 <tr>
5177 <td>Media:
5179 <td>visual
5181 <tr>
5182 <td>Computed value:
5184 <td>see individual properties
5186 <tr>
5187 <td>Animatable:
5189 <td>see individual properties
5190 </table>
5192 <p>The <a href="#propdef-font-variant"
5193 title="font-variant!!property">‘<code
5194 class=property>font-variant</code>’</a> property is a shorthand for all
5195 font-variant subproperties. The value <dfn id=font-variant-normal-value
5196 title="normal!!font-variant">‘<code
5197 class=property>normal</code>’</dfn> resets all subproperties of <a
5198 href="#propdef-font-variant" title="font-variant!!property">‘<code
5199 class=property>font-variant</code>’</a> to their inital value. The <dfn
5200 id=font-variant-none-value title="none!!font-variant">‘<code
5201 class=property>none</code>’</dfn> value sets ‘<a
5202 href="#propdef-font-variant-ligatures"><code
5203 class=property>font-variant-ligatures</code></a>’ to ‘<code
5204 class=property>none</code>’ and resets all other font feature properties
5205 to their initial value. Like other shorthands, using <a
5206 href="#propdef-font-variant" title="font-variant!!property">‘<code
5207 class=property>font-variant</code>’</a> resets unspecified <a
5208 href="#propdef-font-variant" title="font-variant!!property">‘<code
5209 class=property>font-variant</code>’</a> subproperties to their initial
5210 values. It does not reset the values of either ‘<a
5211 href="#propdef-font-language-override"><code
5212 class=property>font-language-override</code></a>’ or <a
5213 href="#propdef-font-feature-settings"
5214 title="font-feature-settings!!property">‘<code
5215 class=property>font-feature-settings</code>’</a>.
5217 <h3 id=font-feature-settings-prop><span class=secno>6.12 </span>Low-level
5218 font feature settings control: the <a
5219 href="#propdef-font-feature-settings">font-feature-settings</a> property</h3>
5221 <table class=propdef id=namefont-feature-settingsvaluenormal-ltf>
5222 <tbody>
5223 <tr>
5224 <td>Name:
5226 <td><dfn id=propdef-font-feature-settings
5227 title="font-feature-settings!!property">font-feature-settings</dfn>
5229 <tr>
5230 <td>Value:
5232 <td><a href="#font-feature-settings-normal-value"
5233 title="normal!!font-feature-settings">normal</a> | <a
5234 href="#feature-tag-value"><var><feature-tag-value></var></a> #
5236 <tr>
5237 <td>Initial:
5239 <td>normal
5241 <tr>
5242 <td>Applies to:
5244 <td>all elements
5246 <tr>
5247 <td>Inherited:
5249 <td>yes
5251 <tr>
5252 <td>Percentages:
5254 <td>N/A
5256 <tr>
5257 <td>Media:
5259 <td>visual
5261 <tr>
5262 <td>Computed value:
5264 <td>as specified
5266 <tr>
5267 <td>Animatable:
5269 <td>no
5270 </table>
5272 <p>This property provides low-level control over OpenType font features. It
5273 is intended as a way of providing access to font features that are not
5274 widely used but are needed for a particular use case.
5276 <p>Authors should generally use <a href="#propdef-font-variant"
5277 title="font-variant!!property">‘<code
5278 class=property>font-variant</code>’</a> and its related subproperties
5279 whenever possible and only use this property for special cases where its
5280 use is the only way of accessing a particular infrequently used font
5281 feature.
5283 <pre>/* enable small caps and use second swash alternate */
5284 font-feature-settings: "smcp", "swsh" 2;</pre>
5286 <p>A value of <dfn id=font-feature-settings-normal-value
5287 title="normal!!font-feature-settings">‘<code
5288 class=property>normal</code>’</dfn> means that no change in glyph
5289 selection or positioning occurs due to this property.
5291 <p>Feature tag values have the following syntax:
5293 <pre
5294 class=prod><dfn id=feature-tag-value><var><feature-tag-value></var></dfn> = <string> [ <integer> | on | off ]?</pre>
5296 <p>The <string> is a case-sensitive OpenType feature tag. As
5297 specified in the OpenType specification, feature tags contain four ASCII
5298 characters. Tag strings longer or shorter than four characters, or
5299 containing characters outside the U+20–7E codepoint range are invalid.
5300 Feature tags need only match a feature tag defined in the font, so they
5301 are not limited to explicitly registered OpenType features. Fonts defining
5302 custom feature tags should follow the <a
5303 href="http://www.microsoft.com/typography/otspec/featuretags.htm">tag name
5304 rules</a> defined in the OpenType specification <a
5305 href="#OPENTYPE-FEATURES"
5306 rel=biblioentry>[OPENTYPE-FEATURES]<!--{{!OPENTYPE-FEATURES}}--></a>.
5307 Feature tags not present in the font are ignored; a user agent must not
5308 attempt to synthesize fallback behavior based on these feature tags.
5310 <p>This means that explicitly disabling the <span class=tag>kern</span>
5311 feature will not affect the application of kerning data found in the
5312 ‘<code class=property>kern</code>’ table (as opposed to kerning data
5313 associated with the <span class=tag>kern</span> feature in the ‘<code
5314 class=property>GPOS</code>’ table). Authors should use the ‘<a
5315 href="#propdef-font-kerning"><code
5316 class=property>font-kerning</code></a>’ property to explictly enable or
5317 disable kerning since this property affects both types of kerning.
5319 <p>If present, a value indicates an index used for glyph selection. An
5320 <integer> value must be 0 or greater. A value of 0 indicates that
5321 the feature is disabled. For boolean features, a value of 1 enables the
5322 feature. For non-boolean features, a value of 1 or greater enables the
5323 feature and indicates the feature selection index. A value of ‘<code
5324 class=property>on</code>’ is synonymous with 1 and ‘<code
5325 class=property>off</code>’ is synonymous with 0. If the value is
5326 omitted, a value of 1 is assumed.
5328 <pre>
5329 font-feature-settings: "dlig" 1; /* dlig=1 enable discretionary ligatures */
5330 font-feature-settings: "smcp" on; /* smcp=1 enable small caps */
5331 font-feature-settings: 'c2sc'; /* c2sc=1 enable caps to small caps */
5332 font-feature-settings: "liga" off; /* liga=0 no common ligatures */
5333 font-feature-settings: "tnum", 'hist'; /* tnum=1, hist=1 enable tabular numbers and historical forms */
5334 font-feature-settings: "tnum" "hist"; /* invalid, need a comma-delimited list */
5335 font-feature-settings: "palin" off; /* good idea but invalid tagname */
5336 font-feature-settings: "PKRN"; /* PKRN=1 enable custom feature */
5337 font-feature-settings: dlig; /* invalid, tag must be a string */
5338 </pre>
5340 <p>When values greater than the range supported by the font are specified,
5341 the behavior is explicitly undefined. For boolean features, in general
5342 these will enable the feature. For non-boolean features, out of range
5343 values will in general be equivalent to a 0 value. However, in both cases
5344 the exact behavior will depend upon the way the font is designed
5345 (specifically, which type of lookup is used to define the feature).
5347 <p>Although specifically defined for OpenType feature tags, feature tags
5348 for other modern font formats that support font features may be added in
5349 the future. Where possible, features defined for other font formats should
5350 attempt to follow the pattern of registered OpenType tags.
5352 <div class=example>
5353 <p>The Japanese text below will be rendered with half-width kana
5354 characters:</p>
5356 <pre lang=ja>
5357 body { font-feature-settings: "hwid"; /* Half-width OpenType feature */ }
5359 <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>
5360 </pre>
5361 </div>
5363 <h3 id=font-language-override-prop><span class=secno>6.13 </span>Font
5364 language override: the <a
5365 href="#propdef-font-language-override">font-language-override</a> property</h3>
5367 <table class=propdef id=namefont-language-overridevaluenormal-lt>
5368 <tbody>
5369 <tr>
5370 <td>Name:
5372 <td><dfn id=propdef-font-language-override>font-language-override</dfn>
5374 <tr>
5375 <td>Value:
5377 <td><a href="#font-language-override-normal-value"
5378 title="normal!!font-language-override">normal</a> | <a
5379 href="#font-language-override-string-value"><var><string></var></a>
5381 <tr>
5382 <td>Initial:
5384 <td><a href="#font-language-override-normal-value"
5385 title="normal!!font-language-override">normal</a>
5387 <tr>
5388 <td>Applies to:
5390 <td>all elements
5392 <tr>
5393 <td>Inherited:
5395 <td>yes
5397 <tr>
5398 <td>Percentages:
5400 <td>N/A
5402 <tr>
5403 <td>Media:
5405 <td>visual
5407 <tr>
5408 <td>Computed value:
5410 <td>as specified
5412 <tr>
5413 <td>Animatable:
5415 <td>no
5416 </table>
5418 <p>Normally, authors can control the use of language-specific glyph
5419 substitutions and positioning by setting the content language of an
5420 element, as <a href="#language-specific-support">described above</a>:
5422 <pre><!-- Display text using S'gaw Karen specific features -->
5423 <p lang="ksw">...</p></pre>
5425 <p>In some cases, authors may need to specify a language system that
5426 differs from the content language, for example due to the need to mimic
5427 another language's typographic traditions. The ‘<a
5428 href="#propdef-font-language-override"><code
5429 class=property>font-language-override</code></a>’ property allows
5430 authors to explicitly specify the language system of the font, overriding
5431 the language system implied by the content language.
5433 <p>Values have the following meanings:
5435 <dl>
5436 <dt><dfn id=font-language-override-normal-value
5437 title="normal!!font-language-override">normal</dfn>
5439 <dd>specifies that when rendering with OpenType fonts, the content
5440 language of the element is used to infer the OpenType language system
5442 <dt><dfn
5443 id=font-language-override-string-value><var><string></var></dfn>
5445 <dd>single three-letter case-sensitive OpenType <a
5446 href="http://www.microsoft.com/typography/otspec/languagetags.htm">language
5447 system tag</a>, specifies the OpenType language system to be used instead
5448 of the language system implied by the language of the element
5449 </dl>
5450 <!-- For this level, string represents a single language code, there's no concept of "fallback"
5451 http://www.w3.org/2013/06/07-css-minutes.html#item04 -->
5453 <p>Use of invalid OpenType language system tags must not generate a parse
5454 error but must be ignored when doing glyph selection and placement.
5456 <div class=example>
5457 <p>The <a href="http://www.un.org/en/documents/udhr/index.shtml">Universal
5458 Declaration of Human Rights</a> has been translated into a wide variety
5459 of languages. In Turkish, Article 9 of this document might be marked up
5460 as below:</p>
5462 <pre lang=tr><body lang="tr">
5464 <h4>Madde 9</h4>
5465 <p>Hiç kimse keyfi olarak tutuklanamaz, alıkonulanamaz veya sürülemez.</p>
5466 </pre>
5468 <p>Here the user agent uses the value of the ‘<code
5469 class=property>lang</code>’ attribute when rendering text and
5470 appropriately renders this text without ‘<code
5471 class=property>fi</code>’ ligatures. There is no need to use the ‘<a
5472 href="#propdef-font-language-override"><code
5473 class=property>font-language-override</code></a>’ property.</p>
5475 <p>However, a given font may lack support for a specific language. In this
5476 situation authors may need to use the typographic conventions of a
5477 related language that are supported by that font:</p>
5479 <pre lang=mk><body lang="mk"> <!-- Macedonian lang code -->
5481 body { font-language-override: "SRB"; /* Serbian OpenType language tag */ }
5483 <h4>Члeн 9</h4>
5484 <p>Никoj чoвeк нeмa дa бидe пoдлoжeн нa прoизвoлнo aпсeњe, притвoр или прoгoнувaњe.</p>
5486 </pre>
5488 <p>The Macedonian text here will be rendered using Serbian typographic
5489 conventions, with the assumption that the font specified supports
5490 Serbian.</p>
5491 </div>
5493 <p><a id=rendering-considerations></a>
5495 <h2 id=font-feature-resolution><span class=secno>7 </span>Font Feature
5496 Resolution</h2>
5498 <p>As described in the previous section, font features can be enabled in a
5499 variety of ways, either via the use of <a href="#propdef-font-variant"
5500 title="font-variant!!property">‘<code
5501 class=property>font-variant</code>’</a> or <a
5502 href="#propdef-font-feature-settings"
5503 title="font-feature-settings!!property">‘<code
5504 class=property>font-feature-settings</code>’</a> in a style rule or
5505 within an <a href="#at-font-face-rule"><code>@font-face</code></a> rule.
5506 The resolution order for the union of these settings is defined below.
5507 Features defined via CSS properties are applied on top of layout engine
5508 default features.
5510 <h3 id=default-features><span class=secno>7.1 </span>Default features</h3>
5512 <p>For OpenType fonts, user agents must enable the default features defined
5513 in the OpenType documentation for a given script and writing mode.
5514 Required ligatures, common ligatures and contextual forms must be enabled
5515 by default (OpenType features: <span class=tag>rlig, liga, clig,
5516 calt</span>), along with localized forms (OpenType feature: <span
5517 class=tag>locl</span>), and features required for proper display of
5518 composed characters and marks (OpenType features: <span class=tag>ccmp,
5519 mark, mkmk</span>). These features must always be enabled, even when the
5520 value of the <a href="#propdef-font-variant"
5521 title="font-variant!!property">‘<code
5522 class=property>font-variant</code>’</a> and <a
5523 href="#propdef-font-feature-settings"
5524 title="font-feature-settings!!property">‘<code
5525 class=property>font-feature-settings</code>’</a> properties is <span
5526 title="normal value">‘<code class=property>normal</code>’</span>.
5527 Individual features are only disabled when explicitly overridden by the
5528 author, as when ‘<a href="#propdef-font-variant-ligatures"><code
5529 class=property>font-variant-ligatures</code></a>’ is set to ‘<a
5530 href="#no-common-ligatures"><code
5531 class=property>no-common-ligatures</code></a>’. For handling complex
5532 scripts such as <a
5533 href="http://www.microsoft.com/typography/otfntdev/arabicot/features.aspx">Arabic</a>,
5534 <a
5535 href="http://www.microsoft.com/typography/otfntdev/mongolot/features.htm">Mongolian</a>
5536 or <a
5537 href="http://www.microsoft.com/typography/otfntdev/devanot/features.aspx">Devanagari</a>
5538 additional features are required. For upright text within vertical text
5539 runs, vertical alternates (OpenType feature: <span class=tag>vert</span>)
5540 must be enabled.
5542 <h3 id=feature-precedence><span class=secno>7.2 </span>Feature precedence</h3>
5544 <p>General and <a href="#font-specific"><em>font specific</em></a> font
5545 feature property settings are resolved in the order below, in ascending
5546 order of precedence. This ordering is used to construct a combined list of
5547 font features that affect a given text run.
5549 <ol>
5550 <li>Font features enabled by default, including features required for a
5551 given script.
5553 <li>If the font is defined via an <a
5554 href="#at-font-face-rule"><code>@font-face</code></a> rule, the font
5555 features implied by the font-variant descriptor in the <a
5556 href="#at-font-face-rule"><code>@font-face</code></a> rule.
5558 <li>If the font is defined via an <a
5559 href="#at-font-face-rule"><code>@font-face</code></a> rule, the font
5560 features implied by the font-feature-settings descriptor in the <a
5561 href="#at-font-face-rule"><code>@font-face</code></a> rule.
5563 <li>Feature settings determined by properties other than <a
5564 href="#propdef-font-variant" title="font-variant!!property">‘<code
5565 class=property>font-variant</code>’</a> or <a
5566 href="#propdef-font-feature-settings"
5567 title="font-feature-settings!!property">‘<code
5568 class=property>font-feature-settings</code>’</a>. For example, setting
5569 a non-default value for the ‘<code
5570 class=property>letter-spacing</code>’ property disables common
5571 ligatures.
5573 <li>Font features implied by the value of the <a
5574 href="#propdef-font-variant" title="font-variant!!property">‘<code
5575 class=property>font-variant</code>’</a> property, the related <a
5576 href="#propdef-font-variant" title="font-variant!!property">‘<code
5577 class=property>font-variant</code>’</a> subproperties and any other CSS
5578 property that uses OpenType features (e.g. the ‘<a
5579 href="#propdef-font-kerning"><code
5580 class=property>font-kerning</code></a>’ property).
5582 <li>Font features implied by the value of <a
5583 href="#propdef-font-feature-settings"
5584 title="font-feature-settings!!property">‘<code
5585 class=property>font-feature-settings</code>’</a> property.
5586 </ol>
5588 <p>This ordering allows authors to set up a general set of defaults for
5589 fonts within their <a
5590 href="#at-font-face-rule"><code>@font-face</code></a> rules, then override
5591 them with property settings for specific elements. General property
5592 settings override the settings in <a
5593 href="#at-font-face-rule"><code>@font-face</code></a> rules and low-level
5594 font feature settings override <a href="#propdef-font-variant"
5595 title="font-variant!!property">‘<code
5596 class=property>font-variant</code>’</a> property settings.
5598 <p>For situations where the combined list of font feature settings contains
5599 more than one value for the same feature, the last value is used. When a
5600 font lacks support for a given underlying font feature, text is simply
5601 rendered as if that font feature was not enabled; font fallback does not
5602 occur and no attempt is made to synthesize the feature except where
5603 explicitly defined for specific properties.
5605 <h3 id=feature-precedence-examples><span class=secno>7.3 </span>Feature
5606 precedence examples</h3>
5608 <div class=example>
5609 <p>With the styles below, numbers are rendered proportionally when used
5610 within a paragraph but are shown in tabular form within tables of prices:</p>
5612 <pre>body {
5613 font-variant-numeric: proportional-nums;
5614 }
5616 table.prices td {
5617 font-variant-numeric: tabular-nums;
5618 }
5619 </pre>
5620 </div>
5622 <div class=example>
5623 <p>When the <a href="#descdef-font-variant"
5624 title="font-variant!!descriptor">font-variant</a> descriptor is used
5625 within an <a href="#at-font-face-rule"><code>@font-face</code></a> rule,
5626 it only applies to the font defined by that rule.</p>
5628 <pre>@font-face {
5629 font-family: MainText;
5630 src: url(http://example.com/font.ttf);
5631 font-variant: oldstyle-nums proportional-nums styleset(1,3);
5632 }
5634 body {
5635 font-family: MainText, Helvetica;
5636 }
5638 table.prices td {
5639 font-variant-numeric: tabular-nums;
5640 }
5641 </pre>
5643 <p>In this case, old-style numerals will be used throughout but only where
5644 the font "MainText" is used. Just as in the previous example, tabular
5645 values will be used in price tables since ‘<a
5646 href="#tabular-nums"><code class=property>tabular-nums</code></a>’
5647 appears in a general style rule and its use is mutually exclusive with
5648 ‘<a href="#proportional-nums"><code
5649 class=property>proportional-nums</code></a>’. Stylistic alternate sets
5650 will only be used where MainText is used.</p>
5651 </div>
5653 <div class=example>
5654 <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule can
5655 also be used to access font features in locally available fonts via the
5656 use of <code>local()</code> in the ‘<a href="#descdef-src"><code
5657 class=property>src</code></a>’ descriptor of the <a
5658 href="#at-font-face-rule"><code>@font-face</code></a> definition:</p>
5660 <pre>@font-face {
5661 font-family: BodyText;
5662 src: local("HiraMaruPro-W4");
5663 font-variant: proportional-width;
5664 font-feature-settings: "ital"; /* Latin italics within CJK text feature */
5665 }
5667 body { font-family: BodyText, serif; }
5668 </pre>
5670 <p>If available, a Japanese font "Hiragino Maru Gothic" will be used. When
5671 text rendering occurs, Japanese kana will be proportionally spaced and
5672 Latin text will be italicised. Text rendered with the fallback serif font
5673 will use default rendering properties.</p>
5674 </div>
5676 <div class=example>
5677 <p>In the example below, discretionary ligatures are enabled only for a
5678 downloadable font but are disabled within spans of class "special":</p>
5680 <pre>@font-face {
5681 font-family: main;
5682 src: url(fonts/ffmeta.woff) format("woff");
5683 font-variant: discretionary-ligatures;
5684 }
5686 body { font-family: main, Helvetica; }
5687 span.special { font-variant-ligatures: no-discretionary-ligatures; }
5688 </pre>
5690 <p>Suppose one adds a rule using ‘<code
5691 class=property>font-feature-settings</code>’ to enable discretionary
5692 ligatures:</p>
5694 <pre>body { font-family: main, Helvetica; }
5695 span { font-feature-settings: "dlig"; }
5696 span.special { font-variant-ligatures: no-discretionary-ligatures; }
5697 </pre>
5699 <p>In this case, discretionary ligatures <em>will</em> be rendered within
5700 spans of class "special". This is because both the <a
5701 href="#propdef-font-feature-settings"
5702 title="font-feature-settings!!property">‘<code
5703 class=property>font-feature-settings</code>’</a> and ‘<a
5704 href="#propdef-font-variant-ligatures"><code
5705 class=property>font-variant-ligatures</code></a>’ properties apply to
5706 these spans. Although the ‘<code class=css>no-discretionary
5707 ligatures</code>’ setting of ‘<a
5708 href="#propdef-font-variant-ligatures"><code
5709 class=property>font-variant-ligatures</code></a>’ effectively disables
5710 the OpenType <span class=tag>dlig</span> feature, because the <a
5711 href="#propdef-font-feature-settings"
5712 title="font-feature-settings!!property">‘<code
5713 class=property>font-feature-settings</code>’</a> is resolved after
5714 that, the ‘<code class=property>dlig</code>’ value reenables
5715 discretionary ligatures.</p>
5716 </div>
5718 <h2 id=object-model><span class=secno>8 </span>Object Model</h2>
5720 <p>The contents of <a href="#at-font-face-rule"><code>@font-face</code></a>
5721 and <a
5722 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
5723 rules can be accessed via the following extensions to the CSS Object
5724 Model.
5726 <h3 id=om-fontface><span class=secno>8.1 </span>The <a
5727 href="#cssfontfacerule"><code>CSSFontFaceRule</code></a> interface</h3>
5729 <p>The <dfn id=cssfontfacerule>CSSFontFaceRule</dfn> interface represents a
5730 <a href="#at-font-face-rule"><code>@font-face</code></a> rule.
5732 <pre class=idl>
5733 interface CSSFontFaceRule : CSSRule {
5734 attribute DOMString family;
5735 attribute DOMString src;
5736 attribute DOMString style;
5737 attribute DOMString weight;
5738 attribute DOMString stretch;
5739 attribute DOMString unicodeRange;
5740 attribute DOMString variant;
5741 attribute DOMString featureSettings;
5742 }</pre>
5744 <p>The DOM Level 2 Style specification <a href="#DOM-LEVEL-2-STYLE"
5745 rel=biblioentry>[DOM-LEVEL-2-STYLE]<!--{{DOM-LEVEL-2-STYLE}}--></a>
5746 defined a different variant of this rule. This definition supercedes that
5747 one.
5749 <h3 id=om-fontfeaturevalues><span class=secno>8.2 </span>The <a
5750 href="#cssfontfeaturevaluesrule"><code>CSSFontFeatureValuesRule</code></a>
5751 interface</h3>
5753 <p>The <code>CSSRule</code> interface is extended as follows:
5755 <pre class=idl>partial interface CSSRule {
5756 const unsigned short FONT_FEATURE_VALUES_RULE = 14;
5757 }</pre>
5759 <p>The <dfn id=cssfontfeaturevaluesrule>CSSFontFeatureValuesRule</dfn>
5760 interface represents a <a
5761 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
5762 rule.
5764 <pre class=idl>interface CSSFontFeatureValuesRule : CSSRule {
5765 readonly attribute DOMString familyList;
5766 readonly attribute DOMString valueText;
5767 };</pre>
5769 <dl class=idl-attributes>
5770 <dt><var>familyList</var> of type <code>DOMString</code>, readonly
5772 <dd>The list of one or more font families for which a given set of feature
5773 values is defined.
5775 <dt><var>valueText</var> of type <code>DOMString</code>, readonly
5777 <dd>Serialized set of feature values.
5778 </dl>
5780 <p class=issue>This needs to be reworked along the lines of <a
5781 href="http://lists.w3.org/Archives/Public/www-style/2013May/0781.html">Tab's
5782 proposal</a> for a rule containing a family list and map objects for each
5783 of the feature types.
5785 <h2 class=no-num id=platform-props-to-css>Appendix A: Mapping platform font
5786 properties to CSS properties</h2>
5788 <p><em>This appendix is included as background for some of the problems and
5789 situations that are described in other sections. It should be viewed as
5790 informative only.</em>
5792 <p>Font properties in CSS are designed to be independent of the underlying
5793 font formats used; they can be used to specify bitmap fonts, Type1 fonts,
5794 SVG fonts in addition to the common TrueType and OpenType fonts. But there
5795 are facets of the TrueType and OpenType formats that often cause confusion
5796 for authors and present challenges to implementers on different platforms.
5798 <p>Originally developed at Apple, TrueType was designed as an outline font
5799 format for both screen and print. Microsoft joined Apple in developing the
5800 TrueType format and both platforms have supported TrueType fonts since
5801 then. Font data in the TrueType format consists of a set of tables
5802 distinguished with common four-letter tag names, each containing a
5803 specific type of data. For example, naming information, including
5804 copyright and license information, is stored in the ‘<code
5805 class=property>name</code>’ table. The <a
5806 href="#character-map"><em>character map</em></a> (‘<code
5807 class=property>cmap</code>’) table contains a mapping of character
5808 encodings to glyphs. Apple later added additional tables for supporting
5809 enhanced typographic functionality; these are now called Apple Advanced
5810 Typography, or AAT, fonts. Microsoft and Adobe developed a separate set of
5811 tables for advanced typography and called their format OpenType <a
5812 href="#OPENTYPE" rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a>.
5814 <p>In many cases the font data used under Microsoft Windows or Linux is
5815 slightly different from the data used under Apple's Mac OS X because the
5816 TrueType format allowed for explicit variation across platforms. This
5817 includes font metrics, names and <a href="#character-map"><em>character
5818 map</em></a> data.
5820 <p>Specifically, font family name data is handled differently across
5821 platforms. For TrueType and OpenType fonts these names are contained in
5822 the ‘<code class=property>name</code>’ table, in name records with
5823 name ID 1. Mulitple names can be stored for different locales, but
5824 Microsoft recommends fonts always include at least a US English version of
5825 the name. On Windows, Microsoft made the decision for backwards
5826 compatibility to limit this family name to a maximum of four faces; for
5827 larger groupings the "preferred family" (name ID 16) or "WWS family" (name
5828 ID 21) can be used. Other platforms such as OSX don't have this
5829 limitation, so the family name is used to define all possible groupings.
5831 <p>Other name table data provides names used to uniquely identify a
5832 specific face within a family. The full font name (name ID 4) and the
5833 Postscript name (name ID 6) describe a single face uniquely. For example,
5834 the bold face of the Gill Sans family has a fullname of "Gill Sans Bold"
5835 and a Postscript name of "GillSans-Bold". There can be multiple localized
5836 versions of the fullname for a given face, but the Postscript name is
5837 always a unique name made from a limited set of ASCII characters.
5839 <p>On various platforms, different names are used to search for a font. For
5840 example, with the Windows GDI CreateIndirectFont API, either a family or
5841 fullname can be used to lookup a face, while on Mac OS X the
5842 CTFontCreateWithName API call is used to lookup a given face using the
5843 fullname and Postscript name. Under Linux, the fontconfig API allows fonts
5844 to be searched using any of these names. In situations where platform
5845 API's automatically substitute other font choices, it may be necessary to
5846 verify a returned font matches a given name.
5848 <p>The weight of a given face can be determined via the usWeightClass field
5849 of the OS/2 table or inferred from the style name (name ID 2). Likewise,
5850 the width can be determined via the usWidthClass of the OS/2 table or
5851 inferred from the style name. For historical reasons related to synthetic
5852 bolding at weights 200 or lower with the Windows GDI API, font designers
5853 have sometimes skewed values in the OS/2 table to avoid these weights.
5855 <p>Rendering complex scripts that use contextual shaping such as Thai,
5856 Arabic and Devanagari requires features present only in OpenType or AAT
5857 fonts. Currently, complex script rendering is supported on Windows and
5858 Linux using OpenType font features while both OpenType and AAT font
5859 features are used under Mac OS X.
5861 <h2 class=no-num id=ch-ch-ch-changes>Changes</h2>
5863 <h3 class=no-num id=recent-changes> Changes from the <a
5864 href="http://www.w3.org/TR/2013/WD-css3-fonts-20130212/">February 2013
5865 CSS3 Fonts Working Draft</a></h3>
5867 <p>Major changes include:
5869 <ul>
5870 <li>Moved font load events into a separate <a
5871 href="http://dev.w3.org/csswg/css3-font-load-events/">spec</a>
5873 <li>Tightened syntax rules for <a
5874 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
5875 rules
5877 <li>Added grammar productions for <a
5878 href="#at-font-face-rule"><code>@font-face</code></a> and <a
5879 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
5880 rules
5882 <li>Tightened definition of synthetic oblique
5884 <li>Revised definition of ‘<a href="#descdef-unicode-range"><code
5885 class=property>unicode-range</code></a>’ descriptor
5887 <li>Detailed font matching of composite faces
5888 </ul>
5890 <h2 class=no-num id=acknowledgments>Acknowledgments</h2>
5892 <p>I'd like to thank Tal Leming, Jonathan Kew and Christopher Slye for all
5893 their help and feedback. John Hudson was kind enough to take the time to
5894 explain the subtleties of OpenType language tags and provided the example
5895 of character variant usage for displaying text on Byzantine seals. Ken
5896 Lunde and Eric Muller provided valuable feedback on CJK OpenType features
5897 and Unicode variation selectors. The idea for supporting font features by
5898 using <a href="#propdef-font-variant"
5899 title="font-variant!!property">‘<code
5900 class=property>font-variant</code>’</a> subproperties originated with
5901 Håkon Wium Lie, Adam Twardoch and Tal Leming. Elika Etemad supplied some
5902 of the initial design ideas for the <a
5903 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
5904 rule. Thanks also to House Industries for allowing the use of Ed Interlock
5905 in the discretionary ligatures example.
5907 <p>A special thanks to Robert Bringhurst for the sublime mind expansion
5908 that is <em>The Elements of Typographic Style</em>.
5910 <h2 class=no-num id=conformance> Conformance</h2>
5912 <h3 class=no-num id=conventions> Document Conventions</h3>
5914 <p>Conformance requirements are expressed with a combination of descriptive
5915 assertions and RFC 2119 terminology. The key words “MUST”, “MUST
5916 NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”,
5917 “SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL” in the
5918 normative parts of this document are to be interpreted as described in RFC
5919 2119. However, for readability, these words do not appear in all uppercase
5920 letters in this specification.
5922 <p>All of the text of this specification is normative except sections
5923 explicitly marked as non-normative, examples, and notes. <a
5924 href="#RFC2119" rel=biblioentry>[RFC2119]<!--{{!RFC2119}}--></a>
5926 <p>Examples in this specification are introduced with the words “for
5927 example” or are set apart from the normative text with
5928 <code>class="example"</code>, like this:
5930 <div class=example>
5931 <p>This is an example of an informative example.
5932 </div>
5934 <p>Informative notes begin with the word “Note” and are set apart from
5935 the normative text with <code>class="note"</code>, like this:
5937 <p class=note>Note, this is an informative note.
5939 <h3 class=no-num id=conformance-classes> Conformance Classes</h3>
5941 <p>Conformance to CSS Fonts Level 3 Module is defined for three conformance
5942 classes:
5944 <dl>
5945 <dt><dfn id=style-sheet title="style sheet!!as conformance class">style
5946 sheet</dfn>
5948 <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#style-sheet">CSS
5949 style sheet</a>.
5951 <dt><dfn id=renderer>renderer</dfn>
5953 <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
5954 that interprets the semantics of a style sheet and renders documents that
5955 use them.
5957 <dt><dfn id=authoring-tool>authoring tool</dfn>
5959 <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
5960 that writes a style sheet.
5961 </dl>
5963 <p>A style sheet is conformant to CSS Fonts Level 3 Module if all of its
5964 declarations that use properties defined in this module have values that
5965 are valid according to the generic CSS grammar and the individual grammars
5966 of each property as given in this module.
5968 <p>A renderer is conformant to CSS Fonts Level 3 Module if, in addition to
5969 interpreting the style sheet as defined by the appropriate specifications,
5970 it supports all the features defined by CSS Fonts Level 3 Module by
5971 parsing them correctly and rendering the document accordingly. However,
5972 the inability of a UA to correctly render a document due to limitations of
5973 the device does not make the UA non-conformant. (For example, a UA is not
5974 required to render color on a monochrome monitor.)
5976 <p>An authoring tool is conformant to CSS Fonts Level 3 Module if it writes
5977 style sheets that are syntactically correct according to the generic CSS
5978 grammar and the individual grammars of each feature in this module, and
5979 meet all other conformance requirements of style sheets as described in
5980 this module.
5982 <h3 class=no-num id=partial> Partial Implementations</h3>
5984 <p>So that authors can exploit the forward-compatible parsing rules to
5985 assign fallback values, CSS renderers <strong>must</strong> treat as
5986 invalid (and <a
5987 href="http://www.w3.org/TR/CSS21/conform.html#ignore">ignore as
5988 appropriate</a>) any at-rules, properties, property values, keywords, and
5989 other syntactic constructs for which they have no usable level of support.
5990 In particular, user agents <strong>must not</strong> selectively ignore
5991 unsupported component values and honor supported values in a single
5992 multi-value property declaration: if any value is considered invalid (as
5993 unsupported values must be), CSS requires that the entire declaration be
5994 ignored.
5996 <h3 class=no-num id=experimental> Experimental Implementations</h3>
5998 <p>To avoid clashes with future CSS features, the CSS2.1 specification
5999 reserves a <a
6000 href="http://www.w3.org/TR/CSS21/syndata.html#vendor-keywords">prefixed
6001 syntax</a> for proprietary and experimental extensions to CSS.
6003 <p>Prior to a specification reaching the Candidate Recommendation stage in
6004 the W3C process, all implementations of a CSS feature are considered
6005 experimental. The CSS Working Group recommends that implementations use a
6006 vendor-prefixed syntax for such features, including those in W3C Working
6007 Drafts. This avoids incompatibilities with future changes in the draft.
6009 <h3 class=no-num id=testing> Non-Experimental Implementations</h3>
6011 <p>Once a specification reaches the Candidate Recommendation stage,
6012 non-experimental implementations are possible, and implementors should
6013 release an unprefixed implementation of any CR-level feature they can
6014 demonstrate to be correctly implemented according to spec.
6016 <p>To establish and maintain the interoperability of CSS across
6017 implementations, the CSS Working Group requests that non-experimental CSS
6018 renderers submit an implementation report (and, if necessary, the
6019 testcases used for that implementation report) to the W3C before releasing
6020 an unprefixed implementation of any CSS features. Testcases submitted to
6021 W3C are subject to review and correction by the CSS Working Group.
6023 <p>Further information on submitting testcases and implementation reports
6024 can be found from on the CSS Working Group's website at <a
6025 href="http://www.w3.org/Style/CSS/Test/">http://www.w3.org/Style/CSS/Test/</a>.
6026 Questions should be directed to the <a
6027 href="http://lists.w3.org/Archives/Public/public-css-testsuite">public-css-testsuite@w3.org</a>
6028 mailing list.
6030 <h2 class=no-num id=references>References</h2>
6032 <h3 class=no-num id=normative-references>Normative References</h3>
6033 <!--begin-normative-->
6034 <!-- Sorted by label -->
6036 <dl class=bibliography>
6037 <dd style="display: none"><!-- keeps the doc valid if the DL is empty -->
6038 <!---->
6040 <dt id=CHARMOD>[CHARMOD]
6042 <dd>Martin J. Dürst; et al. <a
6043 href="http://www.w3.org/TR/2005/REC-charmod-20050215/"><cite>Character
6044 Model for the World Wide Web 1.0: Fundamentals.</cite></a> 15 February
6045 2005. W3C Recommendation. URL: <a
6046 href="http://www.w3.org/TR/2005/REC-charmod-20050215/">http://www.w3.org/TR/2005/REC-charmod-20050215/</a>
6047 </dd>
6048 <!---->
6050 <dt id=CORS>[CORS]
6052 <dd>Anne van Kesteren. <a
6053 href="http://www.w3.org/TR/2013/CR-cors-20130129/"><cite>Cross-Origin
6054 Resource Sharing.</cite></a> 29 January 2013. W3C Candidate
6055 Recommendation. (Work in progress.) URL: <a
6056 href="http://www.w3.org/TR/2013/CR-cors-20130129/">http://www.w3.org/TR/2013/CR-cors-20130129/</a>
6057 </dd>
6058 <!---->
6060 <dt id=CSS21>[CSS21]
6062 <dd>Bert Bos; et al. <a
6063 href="http://www.w3.org/TR/2011/REC-CSS2-20110607"><cite>Cascading Style
6064 Sheets Level 2 Revision 1 (CSS 2.1) Specification.</cite></a> 7 June
6065 2011. W3C Recommendation. URL: <a
6066 href="http://www.w3.org/TR/2011/REC-CSS2-20110607">http://www.w3.org/TR/2011/REC-CSS2-20110607</a>
6067 </dd>
6068 <!---->
6070 <dt id=CSS3VAL>[CSS3VAL]
6072 <dd>Håkon Wium Lie; Tab Atkins; Elika J. Etemad. <a
6073 href="http://www.w3.org/TR/2013/CR-css3-values-20130404/"><cite>CSS
6074 Values and Units Module Level 3.</cite></a> 4 April 2013. W3C Candidate
6075 Recommendation. (Work in progress.) URL: <a
6076 href="http://www.w3.org/TR/2013/CR-css3-values-20130404/">http://www.w3.org/TR/2013/CR-css3-values-20130404/</a>
6077 </dd>
6078 <!---->
6080 <dt id=HTML5>[HTML5]
6082 <dd>Ian Hickson. <a
6083 href="http://www.w3.org/TR/2012/CR-html5-20121217/"><cite>HTML5.</cite></a>
6084 17 December 2012. W3C Candidate Recommendation. (Work in progress.) URL:
6085 <a
6086 href="http://www.w3.org/TR/2012/CR-html5-20121217/">http://www.w3.org/TR/2012/CR-html5-20121217/</a>
6087 </dd>
6088 <!---->
6090 <dt id=OPEN-FONT-FORMAT>[OPEN-FONT-FORMAT]
6092 <dd><a
6093 href="http://standards.iso.org/ittf/PubliclyAvailableStandards/c052136_ISO_IEC_14496-22_2009(E).zip"><cite>Information
6094 technology — Coding of audio-visual objects — Part 22: Open Font
6095 Format.</cite></a> International Organization for Standardization.
6096 ISO/IEC 14496-22:2009. URL: <a
6097 href="http://standards.iso.org/ittf/PubliclyAvailableStandards/c052136_ISO_IEC_14496-22_2009(E).zip">http://standards.iso.org/ittf/PubliclyAvailableStandards/c052136_ISO_IEC_14496-22_2009(E).zip</a>
6098 </dd>
6099 <!---->
6101 <dt id=OPENTYPE>[OPENTYPE]
6103 <dd><a
6104 href="http://www.microsoft.com/typography/otspec/default.htm"><cite>OpenType
6105 specification.</cite></a> Microsoft. URL: <a
6106 href="http://www.microsoft.com/typography/otspec/default.htm">http://www.microsoft.com/typography/otspec/default.htm</a>
6107 </dd>
6108 <!---->
6110 <dt id=OPENTYPE-FEATURES>[OPENTYPE-FEATURES]
6112 <dd><a
6113 href="http://www.microsoft.com/typography/otspec/featurelist.htm"><cite>OpenType
6114 feature registry.</cite></a> Microsoft. URL: <a
6115 href="http://www.microsoft.com/typography/otspec/featurelist.htm">http://www.microsoft.com/typography/otspec/featurelist.htm</a>
6116 </dd>
6117 <!---->
6119 <dt id=RFC2119>[RFC2119]
6121 <dd>S. Bradner. <a href="http://www.ietf.org/rfc/rfc2119.txt"><cite>Key
6122 words for use in RFCs to Indicate Requirement Levels.</cite></a> Internet
6123 RFC 2119. URL: <a
6124 href="http://www.ietf.org/rfc/rfc2119.txt">http://www.ietf.org/rfc/rfc2119.txt</a>
6125 </dd>
6126 <!---->
6128 <dt id=UAX15>[UAX15]
6130 <dd>Mark Davis; Ken Whistler. <a
6131 href="http://www.unicode.org/reports/tr15/"><cite>Unicode Normalization
6132 Forms.</cite></a> 31 August 2012. Unicode Standard Annex #15. URL: <a
6133 href="http://www.unicode.org/reports/tr15/">http://www.unicode.org/reports/tr15/</a>
6134 </dd>
6135 <!---->
6137 <dt id=UAX29>[UAX29]
6139 <dd>Mark Davis. <a
6140 href="http://www.unicode.org/reports/tr29/"><cite>Unicode Text
6141 Segmentation.</cite></a> 12 September 2012. Unicode Standard Annex #29.
6142 URL: <a
6143 href="http://www.unicode.org/reports/tr29/">http://www.unicode.org/reports/tr29/</a>
6144 </dd>
6145 <!---->
6147 <dt id=UNICODE6>[UNICODE6]
6149 <dd>The Unicode Consortium. <a
6150 href="http://www.unicode.org/versions/Unicode6.2.0/"><cite>The Unicode
6151 Standard, Version 6.2.0.</cite></a> Defined by: The Unicode Standard,
6152 Version 6.2.0 URL: <a
6153 href="http://www.unicode.org/versions/Unicode6.2.0/">http://www.unicode.org/versions/Unicode6.2.0/</a>
6154 </dd>
6155 <!---->
6156 </dl>
6157 <!--end-normative-->
6158 <!--{{!CSS21}}-->
6159 <!--{{!CSS3VAL}}-->
6160 <!--{{!OPENTYPE}}-->
6161 <!--{{!OPENTYPE-FEATURES}}-->
6162 <!--{{!OPEN-FONT-FORMAT}}-->
6163 <!--{{!UNICODE6}}-->
6164 <!--{{!UAX15}}-->
6165 <!--{{!UAX29}}-->
6166 <!--{{!CORS}}-->
6167 <!--{{!HTML5}}-->
6168 <!--{{!CHARMOD}}-->
6170 <h3 class=no-num id=other-references>Other References</h3>
6171 <!--begin-informative-->
6172 <!-- Sorted by label -->
6174 <dl class=bibliography>
6175 <dd style="display: none"><!-- keeps the doc valid if the DL is empty -->
6176 <!---->
6178 <dt id=AAT-FEATURES>[AAT-FEATURES]
6180 <dd><a href="http://developer.apple.com/fonts/registry/"><cite>Apple
6181 Advanced Typography font feature registry.</cite></a> Apple. URL: <a
6182 href="http://developer.apple.com/fonts/registry/">http://developer.apple.com/fonts/registry/</a>
6183 </dd>
6184 <!---->
6186 <dt id=ARABIC-TYPO>[ARABIC-TYPO]
6188 <dd>Huda Smitshuijzen AbiFares. <cite>Arabic Typography: A Comprehensive
6189 Sourcebook.</cite> Saqi Books. 2001. ISBN 0-86356-347-3.</dd>
6190 <!---->
6192 <dt id=CHARMOD-NORM>[CHARMOD-NORM]
6194 <dd>François Yergeau; et al. <a
6195 href="http://www.w3.org/TR/2012/WD-charmod-norm-20120501/"><cite>Character
6196 Model for the World Wide Web 1.0: Normalization.</cite></a> 1 May 2012.
6197 W3C Working Draft. (Work in progress.) URL: <a
6198 href="http://www.w3.org/TR/2012/WD-charmod-norm-20120501/">http://www.w3.org/TR/2012/WD-charmod-norm-20120501/</a>
6199 </dd>
6200 <!---->
6202 <dt id=CJKV-INFO-PROCESSING>[CJKV-INFO-PROCESSING]
6204 <dd>Ken Lunde. <cite>CJKV Information Processing, Second Edition.</cite>
6205 O'Reilly Media, Inc. 2009. ISBN 0-596-51447-1.</dd>
6206 <!---->
6208 <dt id=CSS3-CONDITIONAL>[CSS3-CONDITIONAL]
6210 <dd>L. David Baron. <a
6211 href="http://www.w3.org/TR/2013/CR-css3-conditional-20130404/"><cite>CSS
6212 Conditional Rules Module Level 3.</cite></a> 4 April 2013. W3C Candidate
6213 Recommendation. (Work in progress.) URL: <a
6214 href="http://www.w3.org/TR/2013/CR-css3-conditional-20130404/">http://www.w3.org/TR/2013/CR-css3-conditional-20130404/</a>
6215 </dd>
6216 <!---->
6218 <dt id=CSS3TEXT>[CSS3TEXT]
6220 <dd>Elika J. Etemad; Koji Ishii. <a
6221 href="http://www.w3.org/TR/2012/WD-css3-text-20121113/"><cite>CSS Text
6222 Module Level 3.</cite></a> 13 November 2012. W3C Working Draft. (Work in
6223 progress.) URL: <a
6224 href="http://www.w3.org/TR/2012/WD-css3-text-20121113/">http://www.w3.org/TR/2012/WD-css3-text-20121113/</a>
6225 </dd>
6226 <!---->
6228 <dt id=DIGITAL-TYPOGRAPHY>[DIGITAL-TYPOGRAPHY]
6230 <dd>Richard Rubinstein. <cite>Digital Typography, An Introduction to Type
6231 and Composition for Computer System Design.</cite> Addison-Wesley. 1988.
6232 ISBN 0-201-17633-5.</dd>
6233 <!---->
6235 <dt id=DOM-LEVEL-2-STYLE>[DOM-LEVEL-2-STYLE]
6237 <dd>Chris Wilson; Philippe Le Hégaret; Vidur Apparao. <a
6238 href="http://www.w3.org/TR/2000/REC-DOM-Level-2-Style-20001113/"><cite>Document
6239 Object Model (DOM) Level 2 Style Specification.</cite></a> 13 November
6240 2000. W3C Recommendation. URL: <a
6241 href="http://www.w3.org/TR/2000/REC-DOM-Level-2-Style-20001113/">http://www.w3.org/TR/2000/REC-DOM-Level-2-Style-20001113/</a>
6242 </dd>
6243 <!---->
6245 <dt id=ELEMTYPO>[ELEMTYPO]
6247 <dd>Robert Bringhurst. <cite>The Elements of Typographic Style, Version
6248 4.</cite> Hartley & Marks. 2013. ISBN 0-88179-212-8.</dd>
6249 <!---->
6251 <dt id=LANGCULTTYPE>[LANGCULTTYPE]
6253 <dd>John D. Berry, Ed. <cite>Language Culture Type.</cite> Graphis. 2001.
6254 ISBN 1-932026-01-0.</dd>
6255 <!---->
6257 <dt id=OPENTYPE-FONT-GUIDE>[OPENTYPE-FONT-GUIDE]
6259 <dd><a
6260 href="https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf"><cite>OpenType
6261 User Guide.</cite></a> FontShop International. URL: <a
6262 href="https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf">https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf</a>
6263 </dd>
6264 <!---->
6266 <dt id=RASTER-TRAGEDY>[RASTER-TRAGEDY]
6268 <dd>Beat Stamm. <a href="http://www.rastertragedy.com/"><cite>The Raster
6269 Tragedy at Low-Resolution Revisited.</cite></a> 7 December 2011. URL: <a
6270 href="http://www.rastertragedy.com/">http://www.rastertragedy.com/</a></dd>
6271 <!---->
6273 <dt id=WINDOWS-GLYPH-PROC>[WINDOWS-GLYPH-PROC]
6275 <dd>John Hudson. <a
6276 href="http://www.microsoft.com/typography/developers/opentype/default.htm"><cite>Windows
6277 Glyph Processing.</cite></a> Microsoft Typogrraphy. URL: <a
6278 href="http://www.microsoft.com/typography/developers/opentype/default.htm">http://www.microsoft.com/typography/developers/opentype/default.htm</a>
6279 </dd>
6280 <!---->
6281 </dl>
6282 <!--end-informative-->
6283 <!--{{ARABIC-TYPO}}-->
6284 <!--{{CJKV-INFO-PROCESSING}}-->
6285 <!--{{DIGITAL-TYPOGRAPHY}}-->
6286 <!--{{DOM-LEVEL-2-STYLE}}-->
6287 <!--{{ELEMTYPO}}-->
6288 <!--{{LANGCULTTYPE}}-->
6289 <!--{{OPENTYPE-FONT-GUIDE}}-->
6290 <!--{{RASTER-TRAGEDY}}-->
6291 <!--{{WINDOWS-GLYPH-PROC}}-->
6292 <!--{{CHARMOD-NORM}}-->
6293 <!--{{AAT-FEATURES}}-->
6294 <!--{{CSS3-CONDITIONAL}}-->
6295 <!--{{CSS3TEXT}}-->
6297 <h2 class=no-num id=index>Index</h2>
6298 <!--begin-index-->
6300 <ul class=indexlist>
6301 <li>100...900 weight values, <a href="#font-weight-numeric-values"
6302 title="100...900 weight values"><strong>3.2</strong></a>
6304 <li><var><absolute-size></var>, <a href="#absolute-size-value"
6305 title="<absolute-size>"><strong>3.5</strong></a>
6307 <li><var><common-lig-values></var>, <a href="#common-lig-values"
6308 title="<common-lig-values>"><strong>6.4</strong></a>
6310 <li><var><contextual-alt-values></var>, <a
6311 href="#contextual-alt-values"
6312 title="<contextual-alt-values>"><strong>6.4</strong></a>
6314 <li><var><discretionary-lig-values></var>, <a
6315 href="#discretionary-lig-values"
6316 title="<discretionary-lig-values>"><strong>6.4</strong></a>
6318 <li><var><east-asian-variant-values></var>, <a
6319 href="#east-asian-variant-values"
6320 title="<east-asian-variant-values>"><strong>6.10</strong></a>
6322 <li><var><east-asian-width-values></var>, <a
6323 href="#east-asian-width-values"
6324 title="<east-asian-width-values>"><strong>6.10</strong></a>
6326 <li><var><family-name></var>, <a href="#family-name-value"
6327 title="<family-name>"><strong>3.1</strong></a>
6329 <li><var><feature-tag-value></var>, <a href="#feature-tag-value"
6330 title="<feature-tag-value>"><strong>6.12</strong></a>
6332 <li><var><font-face-name></var>, <a href="#font-face-name-value"
6333 title="<font-face-name>"><strong>4.3</strong></a>
6335 <li><var><font-variant-css21></var>, <a
6336 href="#font-variant-css21-values"
6337 title="<font-variant-css21>"><strong>3.7</strong></a>
6339 <li><var><generic-family></var>, <a href="#generic-family-value"
6340 title="<generic-family>"><strong>3.1</strong></a>
6342 <li><var><historical-lig-values></var>, <a
6343 href="#historical-lig-values"
6344 title="<historical-lig-values>"><strong>6.4</strong></a>
6346 <li><var><length></var>, <a href="#length-size-value"
6347 title="<length>"><strong>3.5</strong></a>
6349 <li><var><number></var>, <a href="#aspect-ratio-value"
6350 title="<number>"><strong>3.6</strong></a>
6352 <li><var><numeric-figure-values></var>, <a
6353 href="#numeric-figure-values"
6354 title="<numeric-figure-values>"><strong>6.7</strong></a>
6356 <li><var><numeric-fraction-values></var>, <a
6357 href="#numeric-fraction-values"
6358 title="<numeric-fraction-values>"><strong>6.7</strong></a>
6360 <li><var><numeric-spacing-values></var>, <a
6361 href="#numeric-spacing-values"
6362 title="<numeric-spacing-values>"><strong>6.7</strong></a>
6364 <li><var><percentage></var>, <a href="#percentage-size-value"
6365 title="<percentage>"><strong>3.5</strong></a>
6367 <li><var><relative-size></var>, <a href="#relative-size-value"
6368 title="<relative-size>"><strong>3.5</strong></a>
6370 <li><var><string></var>, <a
6371 href="#font-language-override-string-value"
6372 title="<string>"><strong>6.13</strong></a>
6374 <li><var><urange></var>, <a href="#urange-value"
6375 title="<urange>"><strong>4.5</strong></a>
6377 <li><code>@font-face</code>, <a href="#at-font-face-rule"
6378 title="@font-face"><strong>4.1</strong></a>
6380 <li><code>@font-feature-values</code>, <a
6381 href="#at-font-feature-values-rule"
6382 title="@font-feature-values"><strong>6.9</strong></a>
6384 <li>all-petite-caps, <a href="#all-petite-caps"
6385 title=all-petite-caps><strong>6.6</strong></a>
6387 <li>all-small-caps, <a href="#all-small-caps"
6388 title=all-small-caps><strong>6.6</strong></a>
6390 <li>annotation, <a href="#annotation"
6391 title=annotation><strong>6.8</strong></a>
6393 <li>aspect value, <a href="#aspect-value0" title="aspect
6394 value"><strong>3.6</strong></a>
6396 <li>authoring tool, <a href="#authoring-tool" title="authoring
6397 tool"><strong>#</strong></a>
6399 <li>auto
6400 <ul>
6401 <li>font-kerning, <a href="#font-kerning-auto-value" title="auto,
6402 font-kerning"><strong>6.3</strong></a>
6404 <li>font-size-adjust, <a href="#font-size-adjust-auto-value"
6405 title="auto, font-size-adjust"><strong>3.6</strong></a>
6406 </ul>
6408 <li>bold, <a href="#bold" title=bold><strong>3.2</strong></a>
6410 <li>bolder, <a href="#bolder" title=bolder><strong>3.2</strong></a>
6412 <li>character map, <a href="#character-map" title="character
6413 map"><strong>5.2</strong></a>
6415 <li>character-variant, <a href="#character-variant"
6416 title=character-variant><strong>6.8</strong></a>
6418 <li>common-ligatures, <a href="#common-ligatures"
6419 title=common-ligatures><strong>6.4</strong></a>
6421 <li>composite face, <a href="#composite-face" title="composite
6422 face"><strong>5.2</strong></a>
6424 <li>condensed, <a href="#condensed"
6425 title=condensed><strong>3.3</strong></a>
6427 <li>contextual, <a href="#contextual"
6428 title=contextual><strong>6.4</strong></a>
6430 <li>CSSFontFaceRule, <a href="#cssfontfacerule"
6431 title=CSSFontFaceRule><strong>8.1</strong></a>
6433 <li>CSSFontFeatureValuesRule, <a href="#cssfontfeaturevaluesrule"
6434 title=CSSFontFeatureValuesRule><strong>8.2</strong></a>
6436 <li>cursive, definition of, <a href="#cursive0" title="cursive, definition
6437 of"><strong>#</strong></a>
6439 <li>default face, <a href="#default-face" title="default
6440 face"><strong>5.2</strong></a>
6442 <li>descriptor_declaration, <a href="#descriptordeclaration"
6443 title="descriptor_declaration"><strong>4.1</strong></a>
6445 <li>diagonal-fractions, <a href="#diagonal-fractions"
6446 title=diagonal-fractions><strong>6.7</strong></a>
6448 <li>discretionary-ligatures, <a href="#discretionary-ligatures"
6449 title=discretionary-ligatures><strong>6.4</strong></a>
6451 <li>effective character map, <a href="#effective-character-map"
6452 title="effective character map"><strong>4.5</strong></a>
6454 <li>expanded, <a href="#expanded" title=expanded><strong>3.3</strong></a>
6456 <li>extra-condensed, <a href="#extra-condensed"
6457 title=extra-condensed><strong>3.3</strong></a>
6459 <li>extra-expanded, <a href="#extra-expanded"
6460 title=extra-expanded><strong>3.3</strong></a>
6462 <li>fantasy, definition of, <a href="#fantasy0" title="fantasy, definition
6463 of"><strong>#</strong></a>
6465 <li>feature_type, <a href="#featuretype"
6466 title="feature_type"><strong>6.9.1</strong></a>
6468 <li>feature_value_block, <a href="#featurevalueblock"
6469 title="feature_value_block"><strong>6.9.1</strong></a>
6471 <li>feature_value_definition, <a href="#featurevaluedefinition"
6472 title="feature_value_definition"><strong>6.9.1</strong></a>
6474 <li>font, <a href="#propdef-font" title=font><strong>3.7</strong></a>
6476 <li>font specific, <a href="#font-specific" title="font
6477 specific"><strong>6.8</strong></a>
6479 <li>font-family
6480 <ul>
6481 <li>descriptor, <a href="#descdef-font-family" title="font-family,
6482 descriptor"><strong>4.2</strong></a>
6484 <li>property, <a href="#propdef-font-family" title="font-family,
6485 property"><strong>3.1</strong></a>
6486 </ul>
6488 <li>font-feature-settings
6489 <ul>
6490 <li>descriptor, <a href="#descdef-font-feature-settings"
6491 title="font-feature-settings, descriptor"><strong>4.7</strong></a>
6493 <li>property, <a href="#propdef-font-feature-settings"
6494 title="font-feature-settings, property"><strong>6.12</strong></a>
6495 </ul>
6497 <li>font-kerning, <a href="#propdef-font-kerning"
6498 title=font-kerning><strong>6.3</strong></a>
6500 <li>font-language-override, <a href="#propdef-font-language-override"
6501 title=font-language-override><strong>6.13</strong></a>
6503 <li>font-size, <a href="#propdef-font-size"
6504 title=font-size><strong>3.5</strong></a>
6506 <li>font-size-adjust, <a href="#propdef-font-size-adjust"
6507 title=font-size-adjust><strong>3.6</strong></a>
6509 <li>font-stretch
6510 <ul>
6511 <li>descriptor, <a href="#descdef-font-stretch" title="font-stretch,
6512 descriptor"><strong>4.4</strong></a>
6514 <li>property, <a href="#propdef-font-stretch" title="font-stretch,
6515 property"><strong>3.3</strong></a>
6516 </ul>
6518 <li>font-style
6519 <ul>
6520 <li>descriptor, <a href="#descdef-font-style" title="font-style,
6521 descriptor"><strong>4.4</strong></a>
6523 <li>property, <a href="#propdef-font-style" title="font-style,
6524 property"><strong>3.4</strong></a>
6525 </ul>
6527 <li>font-synthesis, <a href="#propdef-font-synthesis"
6528 title=font-synthesis><strong>3.8</strong></a>
6530 <li>font-variant
6531 <ul>
6532 <li>descriptor, <a href="#descdef-font-variant" title="font-variant,
6533 descriptor"><strong>4.7</strong></a>
6535 <li>property, <a href="#propdef-font-variant" title="font-variant,
6536 property"><strong>6.11</strong></a>
6537 </ul>
6539 <li>font-variant-alternates, <a href="#propdef-font-variant-alternates"
6540 title=font-variant-alternates><strong>6.8</strong></a>
6542 <li>font-variant-caps, <a href="#propdef-font-variant-caps"
6543 title=font-variant-caps><strong>6.6</strong></a>
6545 <li>font-variant-east-asian, <a href="#propdef-font-variant-east-asian"
6546 title=font-variant-east-asian><strong>6.10</strong></a>
6548 <li>font-variant-ligatures, <a href="#propdef-font-variant-ligatures"
6549 title=font-variant-ligatures><strong>6.4</strong></a>
6551 <li>font-variant-numeric, <a href="#propdef-font-variant-numeric"
6552 title=font-variant-numeric><strong>6.7</strong></a>
6554 <li>font-variant-position, <a href="#propdef-font-variant-position"
6555 title=font-variant-position><strong>6.5</strong></a>
6557 <li>font-weight
6558 <ul>
6559 <li>descriptor, <a href="#descdef-font-weight" title="font-weight,
6560 descriptor"><strong>4.4</strong></a>
6562 <li>property, <a href="#propdef-font-weight" title="font-weight,
6563 property"><strong>3.2</strong></a>
6564 </ul>
6566 <li>font_face_rule, <a href="#fontfacerule"
6567 title="font_face_rule"><strong>4.1</strong></a>
6569 <li>FONT_FACE_SYM, <a href="#fontfacesym"
6570 title="FONT_FACE_SYM"><strong>4.1</strong></a>
6572 <li>font_family_name, <a href="#fontfamilyname"
6573 title="font_family_name"><strong>6.9.1</strong></a>
6575 <li>font_family_name_list, <a href="#fontfamilynamelist"
6576 title="font_family_name_list"><strong>6.9.1</strong></a>
6578 <li>font_feature_values_rule, <a href="#fontfeaturevaluesrule"
6579 title="font_feature_values_rule"><strong>6.9.1</strong></a>
6581 <li>FONT_FEATURE_VALUES_SYM, <a href="#fontfeaturevaluessym"
6582 title="FONT_FEATURE_VALUES_SYM"><strong>6.9.1</strong></a>
6584 <li>full-width, <a href="#full-width"
6585 title=full-width><strong>6.10</strong></a>
6587 <li>historical-forms, <a href="#historical-forms"
6588 title=historical-forms><strong>6.8</strong></a>
6590 <li>historical-ligatures, <a href="#historical-ligatures"
6591 title=historical-ligatures><strong>6.4</strong></a>
6593 <li>italic, <a href="#italic" title=italic><strong>3.4</strong></a>
6595 <li>jis04, <a href="#jis04" title=jis04><strong>6.10</strong></a>
6597 <li>jis78, <a href="#jis78" title=jis78><strong>6.10</strong></a>
6599 <li>jis83, <a href="#jis83" title=jis83><strong>6.10</strong></a>
6601 <li>jis90, <a href="#jis90" title=jis90><strong>6.10</strong></a>
6603 <li>lighter, <a href="#lighter" title=lighter><strong>3.2</strong></a>
6605 <li>lining-nums, <a href="#lining-nums"
6606 title=lining-nums><strong>6.7</strong></a>
6608 <li>monospace, definition of, <a href="#monospace0" title="monospace,
6609 definition of"><strong>#</strong></a>
6611 <li>no-common-ligatures, <a href="#no-common-ligatures"
6612 title=no-common-ligatures><strong>6.4</strong></a>
6614 <li>no-contextual, <a href="#no-contextual"
6615 title=no-contextual><strong>6.4</strong></a>
6617 <li>no-discretionary-ligatures, <a href="#no-discretionary-ligatures"
6618 title=no-discretionary-ligatures><strong>6.4</strong></a>
6620 <li>no-historical-ligatures, <a href="#no-historical-ligatures"
6621 title=no-historical-ligatures><strong>6.4</strong></a>
6623 <li>none
6624 <ul>
6625 <li>font-kerning, <a href="#font-kerning-none-value" title="none,
6626 font-kerning"><strong>6.3</strong></a>
6628 <li>font-size-adjust, <a href="#font-size-adjust-none-value"
6629 title="none, font-size-adjust"><strong>3.6</strong></a>
6631 <li>font-variant, <a href="#font-variant-none-value" title="none,
6632 font-variant"><strong>6.11</strong></a>
6634 <li>font-variant-ligatures, <a href="#font-variant-ligatures-none-value"
6635 title="none, font-variant-ligatures"><strong>6.4</strong></a>
6636 </ul>
6638 <li>normal
6639 <ul>
6640 <li>font-feature-settings, <a href="#font-feature-settings-normal-value"
6641 title="normal, font-feature-settings"><strong>6.12</strong></a>
6643 <li>font-kerning, <a href="#font-kerning-normal-value" title="normal,
6644 font-kerning"><strong>6.3</strong></a>
6646 <li>font-language-override, <a
6647 href="#font-language-override-normal-value" title="normal,
6648 font-language-override"><strong>6.13</strong></a>
6650 <li>font-stretch, <a href="#font-stretch-normal-value" title="normal,
6651 font-stretch"><strong>3.3</strong></a>
6653 <li>font-style, <a href="#font-style-normal-value" title="normal,
6654 font-style"><strong>3.4</strong></a>
6656 <li>font-variant, <a href="#font-variant-normal-value" title="normal,
6657 font-variant"><strong>6.11</strong></a>
6659 <li>font-variant-alternates, <a
6660 href="#font-variant-alternates-normal-value" title="normal,
6661 font-variant-alternates"><strong>6.8</strong></a>
6663 <li>font-variant-caps, <a href="#font-variant-caps-normal-value"
6664 title="normal, font-variant-caps"><strong>6.6</strong></a>
6666 <li>font-variant-east-asian, <a
6667 href="#font-variant-east-asian-normal-value" title="normal,
6668 font-variant-east-asian"><strong>6.10</strong></a>
6670 <li>font-variant-ligatures, <a
6671 href="#font-variant-ligatures-normal-value" title="normal,
6672 font-variant-ligatures"><strong>6.4</strong></a>
6674 <li>font-variant-numeric, <a href="#font-variant-numeric-normal-value"
6675 title="normal, font-variant-numeric"><strong>6.7</strong></a>
6677 <li>font-variant-position, <a href="#font-variant-position-normal-value"
6678 title="normal, font-variant-position"><strong>6.5</strong></a>
6680 <li>font-weight, <a href="#font-weight-normal-value" title="normal,
6681 font-weight"><strong>3.2</strong></a>
6682 </ul>
6684 <li>oblique, <a href="#oblique" title=oblique><strong>3.4</strong></a>
6686 <li>oldstyle-nums, <a href="#oldstyle-nums"
6687 title=oldstyle-nums><strong>6.7</strong></a>
6689 <li>ordinal, <a href="#ordinal" title=ordinal><strong>6.7</strong></a>
6691 <li>ornaments, <a href="#ornaments"
6692 title=ornaments><strong>6.8</strong></a>
6694 <li>petite-caps, <a href="#petite-caps"
6695 title=petite-caps><strong>6.6</strong></a>
6697 <li>proportional-nums, <a href="#proportional-nums"
6698 title=proportional-nums><strong>6.7</strong></a>
6700 <li>proportional-width, <a href="#proportional-width"
6701 title=proportional-width><strong>6.10</strong></a>
6703 <li>renderer, <a href="#renderer" title=renderer><strong>#</strong></a>
6705 <li>ruby, <a href="#ruby" title=ruby><strong>6.10</strong></a>
6707 <li>sans-serif, definition of, <a href="#sans-serif0" title="sans-serif,
6708 definition of"><strong>#</strong></a>
6710 <li>semi-condensed, <a href="#semi-condensed-"
6711 title=semi-condensed><strong>3.3</strong></a>
6713 <li>semi-expanded, <a href="#semi-expanded"
6714 title=semi-expanded><strong>3.3</strong></a>
6716 <li>serif, definition of, <a href="#serif0" title="serif, definition
6717 of"><strong>#</strong></a>
6719 <li>simplified, <a href="#simplified"
6720 title=simplified><strong>6.10</strong></a>
6722 <li>slashed-zero, <a href="#slashed-zero"
6723 title=slashed-zero><strong>6.7</strong></a>
6725 <li>small-caps, <a href="#small-caps"
6726 title=small-caps><strong>6.6</strong></a>
6728 <li>src, <a href="#descdef-src" title=src><strong>4.3</strong></a>
6730 <li>stacked-fractions, <a href="#stacked-fractions"
6731 title=stacked-fractions><strong>6.7</strong></a>
6733 <li>style sheet
6734 <ul>
6735 <li>as conformance class, <a href="#style-sheet" title="style sheet, as
6736 conformance class"><strong>#</strong></a>
6737 </ul>
6739 <li>styleset, <a href="#styleset" title=styleset><strong>6.8</strong></a>
6741 <li>stylistic, <a href="#stylistic"
6742 title=stylistic><strong>6.8</strong></a>
6744 <li>sub, <a href="#sub" title=sub><strong>6.5</strong></a>
6746 <li>super, <a href="#super" title=super><strong>6.5</strong></a>
6748 <li>support, <a href="#support" title=support><strong>5.2</strong></a>
6750 <li>swash, <a href="#swash" title=swash><strong>6.8</strong></a>
6752 <li>system font fallback, <a href="#system-font-fallback" title="system
6753 font fallback"><strong>5.2</strong></a>
6755 <li>tabular-nums, <a href="#tabular-nums"
6756 title=tabular-nums><strong>6.7</strong></a>
6758 <li>titling-caps, <a href="#titling-caps"
6759 title=titling-caps><strong>6.6</strong></a>
6761 <li>traditional, <a href="#traditional"
6762 title=traditional><strong>6.10</strong></a>
6764 <li>ultra-condensed, <a href="#ultra-condensed"
6765 title=ultra-condensed><strong>3.3</strong></a>
6767 <li>ultra-expanded, <a href="#ultra-expanded"
6768 title=ultra-expanded><strong>3.3</strong></a>
6770 <li>unicase, <a href="#unicase" title=unicase><strong>6.6</strong></a>
6772 <li>unicode-range, <a href="#descdef-unicode-range"
6773 title=unicode-range><strong>4.5</strong></a>
6775 <li>weight, <a href="#weight" title=weight><strong>2</strong></a>
6777 <li>width, <a href="#width" title=width><strong>2</strong></a>
6778 </ul>
6779 <!--end-index-->
6781 <h2 class=no-num id=property-index>Property index</h2>
6782 <!--begin-properties-->
6784 <table class=proptable>
6785 <thead>
6786 <tr>
6787 <th>Property
6789 <th>Values
6791 <th>Initial
6793 <th>Applies to
6795 <th>Inh.
6797 <th>Percentages
6799 <th>Media
6801 <tbody>
6802 <tr>
6803 <th><a class=property href="#propdef-font">font</a>
6805 <td>[ [ <‘font-style’> || <font-variant-css21> ||
6806 <‘font-weight’> || <‘font-stretch’ ]?
6807 <‘font-size’> [ / <‘line-height’> ]?
6808 <‘font-family’> ] | caption | icon | menu | message-box |
6809 small-caption | status-bar
6811 <td>see individual properties
6813 <td>all elements
6815 <td>yes
6817 <td>see individual properties
6819 <td>visual
6821 <tr>
6822 <th><span class=property>font-family</span>
6824 <td>[ <family-name> | <generic-family> ] #
6826 <td>depends on user agent
6828 <td>all elements
6830 <td>yes
6832 <td>N/A
6834 <td>visual
6836 <tr>
6837 <th><span class=property>font-feature-settings</span>
6839 <td>normal | <feature-tag-value> #
6841 <td>normal
6843 <td>all elements
6845 <td>yes
6847 <td>N/A
6849 <td>visual
6851 <tr>
6852 <th><a class=property href="#propdef-font-kerning">font-kerning</a>
6854 <td>auto | normal | none
6856 <td>auto
6858 <td>all elements
6860 <td>yes
6862 <td>N/A
6864 <td>visual
6866 <tr>
6867 <th><a class=property
6868 href="#propdef-font-language-override">font-language-override</a>
6870 <td>normal | <string>
6872 <td>normal
6874 <td>all elements
6876 <td>yes
6878 <td>N/A
6880 <td>visual
6882 <tr>
6883 <th><a class=property href="#propdef-font-size">font-size</a>
6885 <td><absolute-size> | <relative-size> | <length> |
6886 <percentage>
6888 <td>medium
6890 <td>all elements
6892 <td>yes
6894 <td>refer to parent element's font size
6896 <td>visual
6898 <tr>
6899 <th><a class=property
6900 href="#propdef-font-size-adjust">font-size-adjust</a>
6902 <td>none | auto | <number>
6904 <td>none
6906 <td>all elements
6908 <td>yes
6910 <td>N/A
6912 <td>visual
6914 <tr>
6915 <th><span class=property>font-stretch</span>
6917 <td>normal | ultra-condensed | extra-condensed | condensed |
6918 semi-condensed | semi-expanded | expanded | extra-expanded |
6919 ultra-expanded
6921 <td>normal
6923 <td>all elements
6925 <td>yes
6927 <td>N/A
6929 <td>visual
6931 <tr>
6932 <th><span class=property>font-style</span>
6934 <td>normal | italic | oblique
6936 <td>normal
6938 <td>all elements
6940 <td>yes
6942 <td>N/A
6944 <td>visual
6946 <tr>
6947 <th><a class=property href="#propdef-font-synthesis">font-synthesis</a>
6949 <td>none | [ weight || style ]
6951 <td>weight style
6953 <td>all elements
6955 <td>yes
6957 <td>N/A
6959 <td>visual
6961 <tr>
6962 <th><span class=property>font-variant</span>
6964 <td>normal | none | [ <common-lig-values> ||
6965 <discretionary-lig-values> || <historical-lig-values> ||
6966 <contextual-alt-values> || stylistic(<feature-value-name>)
6967 || historical-forms || styleset(<feature-value-name> #) ||
6968 character-variant(<feature-value-name> #) ||
6969 swash(<feature-value-name>) ||
6970 ornaments(<feature-value-name>) ||
6971 annotation(<feature-value-name>) || [ small-caps | all-small-caps
6972 | petite-caps | all-petite-caps | unicase | titling-caps ] ||
6973 <numeric-figure-values> || <numeric-spacing-values> ||
6974 <numeric-fraction-values> || ordinal || slashed-zero ||
6975 <east-asian-variant-values> || <east-asian-width-values> ||
6976 ruby ]
6978 <td>normal
6980 <td>all elements
6982 <td>yes
6984 <td>see individual properties
6986 <td>visual
6988 <tr>
6989 <th><a class=property
6990 href="#propdef-font-variant-alternates">font-variant-alternates</a>
6992 <td>normal | [ stylistic(<feature-value-name>) || historical-forms
6993 || styleset(<feature-value-name> #) ||
6994 character-variant(<feature-value-name> #) ||
6995 swash(<feature-value-name>) ||
6996 ornaments(<feature-value-name>) ||
6997 annotation(<feature-value-name>) ]
6999 <td>normal
7001 <td>all elements
7003 <td>yes
7005 <td>N/A
7007 <td>visual
7009 <tr>
7010 <th><a class=property
7011 href="#propdef-font-variant-caps">font-variant-caps</a>
7013 <td>normal | small-caps | all-small-caps | petite-caps | all-petite-caps
7014 | unicase | titling-caps
7016 <td>normal
7018 <td>all elements
7020 <td>yes
7022 <td>N/A
7024 <td>visual
7026 <tr>
7027 <th><a class=property
7028 href="#propdef-font-variant-east-asian">font-variant-east-asian</a>
7030 <td>normal | [ <east-asian-variant-values> ||
7031 <east-asian-width-values> || ruby ]
7033 <td>normal
7035 <td>all elements
7037 <td>yes
7039 <td>N/A
7041 <td>visual
7043 <tr>
7044 <th><a class=property
7045 href="#propdef-font-variant-ligatures">font-variant-ligatures</a>
7047 <td>normal | none | [ <common-lig-values> ||
7048 <discretionary-lig-values> || <historical-lig-values> ||
7049 <contextual-alt-values> ]
7051 <td>normal
7053 <td>all elements
7055 <td>yes
7057 <td>N/A
7059 <td>visual
7061 <tr>
7062 <th><a class=property
7063 href="#propdef-font-variant-numeric">font-variant-numeric</a>
7065 <td>normal | [ <numeric-figure-values> ||
7066 <numeric-spacing-values> || <numeric-fraction-values> ||
7067 ordinal || slashed-zero ]
7069 <td>normal
7071 <td>all elements
7073 <td>yes
7075 <td>N/A
7077 <td>visual
7079 <tr>
7080 <th><a class=property
7081 href="#propdef-font-variant-position">font-variant-position</a>
7083 <td>normal | sub | super
7085 <td>normal
7087 <td>all elements
7089 <td>yes
7091 <td>N/A
7093 <td>visual
7095 <tr>
7096 <th><span class=property>font-weight</span>
7098 <td>normal | bold | bolder | lighter | 100 | 200 | 300 | 400 | 500 | 600
7099 | 700 | 800 | 900
7101 <td>normal
7103 <td>all elements
7105 <td>yes
7107 <td>N/A
7109 <td>visual
7110 </table>
7111 <!--end-properties-->
7112 <!--begin-descriptors-->
7114 <table class=proptable>
7115 <thead>
7116 <tr>
7117 <th>Descriptor
7119 <th>Value
7121 <th>Initial
7123 <th>Percentages
7125 <th>Media
7127 <tbody>
7128 <tr>
7129 <th><span class=property>font-family</span>
7131 <td><family-name>
7133 <td>N/A
7135 <tr>
7136 <th><span class=property>font-feature-settings</span>
7138 <td>normal | <feature-tag-value> #
7140 <td>normal
7142 <tr>
7143 <th><span class=property>font-stretch</span>
7145 <td>normal | ultra-condensed | extra-condensed | condensed |
7146 semi-condensed | semi-expanded | expanded | extra-expanded |
7147 ultra-expanded
7149 <td>normal
7151 <tr>
7152 <th><span class=property>font-style</span>
7154 <td>normal | italic | oblique
7156 <td>normal
7158 <tr>
7159 <th><span class=property>font-variant</span>
7161 <td>normal | none | [ <common-lig-values> ||
7162 <discretionary-lig-values> || <historical-lig-values> ||
7163 <contextual-alt-values> || stylistic(<feature-value-name>)
7164 || historical-forms || styleset(<feature-value-name> #) ||
7165 character-variant(<feature-value-name> #) ||
7166 swash(<feature-value-name>) ||
7167 ornaments(<feature-value-name>) ||
7168 annotation(<feature-value-name>) || [ small-caps | all-small-caps
7169 | petite-caps | all-petite-caps | unicase | titling-caps ] ||
7170 <numeric-figure-values> || <numeric-spacing-values> ||
7171 <numeric-fraction-values> || ordinal || slashed-zero ||
7172 <east-asian-variant-values> || <east-asian-width-values> ||
7173 ruby ]
7175 <td>normal
7177 <tr>
7178 <th><span class=property>font-weight</span>
7180 <td>normal | bold | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900
7182 <td>normal
7184 <tr>
7185 <th><a class=property href="#descdef-src">src</a>
7187 <td>[ <url> [format(<string> #)]? | <font-face-name> ] #
7189 <td>N/A
7191 <tr>
7192 <th><a class=property href="#descdef-unicode-range">unicode-range</a>
7194 <td><urange> #
7196 <td>U+0-10FFFF
7197 </table>
7198 <!--end-descriptors-->
7199 <script type="text/javascript">
7200 window.onload = function () {
7201 if (!("devicePixelRatio" in window && window.devicePixelRatio > 1)) return;
7202 var i, hiresElements = document.getElementsByClassName("hires");
7203 for (i = 0; i < hiresElements.length; i++) {
7204 var h = hiresElements[i];
7205 if (h.tagName != "IMG") continue;
7206 var src = h.getAttribute("src");
7207 var src2x = src.replace(/\.\w+$/, function(m) { return "@2x" + m; });
7208 h.src = src2x;
7209 }
7210 }
7211 </script>
7212 </html>
7213 <!-- Keep this comment at the end of the file
7214 Local variables:
7215 mode: sgml
7216 sgml-declaration:"~/SGML/HTML4.decl"
7217 sgml-default-doctype-name:"html"
7218 sgml-minimize-attributes:t
7219 sgml-nofill-elements:("pre" "style" "br")
7220 sgml-live-element-indicator:t
7221 sgml-omittag:nil
7222 sgml-shorttag:nil
7223 sgml-namecase-general:t
7224 sgml-general-insert-case:lower
7225 sgml-always-quote-attributes:t
7226 sgml-indent-step:nil
7227 sgml-indent-data:t
7228 sgml-parent-document:nil
7229 sgml-exposed-tags:nil
7230 sgml-local-catalogs:nil
7231 sgml-local-ecat-files:nil
7232 End:
7233 -->
7234 <!--
7236 to do:
7238 - wording of OpenType family name handling
7239 - handling combining sequences in the font matching algorithm
7240 - fix-up fi ligature example
7242 -->