Tue, 11 Jun 2013 16:52:35 +0900
[css3-fonts] define first available font
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4 <html lang=en>
5 <head><meta content="text/html;charset=utf-8" http-equiv=Content-Type>
7 <title>CSS Fonts Module Level 3</title>
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9 FIXME when publishing: copy the current default.css and link to
10 "default.css" rather than "../default.css"
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12 <link href="../default.css" rel=stylesheet type="text/css">
13 <link href="../csslogo.ico" rel="shortcut icon" type="image/x-icon">
14 <!-- I'm just experimenting here, don't get your bee in a bonnet -->
15 <script src="http://use.typekit.com/xon2bky.js"
16 type="text/javascript"></script>
17 <script type="text/javascript">try{Typekit.load();}catch(e){}</script>
19 <style type="text/css">
21 body, th, td, h1, h2, h3, h4, h5, h6 {
22 font-family: "myriad-pro", sans-serif !important;
23 }
25 body {
26 padding: 2em 70px 2em 70px;
27 }
29 p + p, p.mtb {
30 margin-top: 0.8em;
31 text-indent: 0px;
32 }
34 #bolderlighter {
35 width: 40%;
36 }
38 #bolderlighter th {
39 text-align: center;
40 }
42 #fontformats td, #eventhandlers td, #fontformats th, #eventhandlers th {
43 padding-right: 2em;
44 text-align: left;
45 }
47 dd {
48 margin-bottom: 1em;
49 }
51 #authors dd {
52 margin-bottom: 0;
53 }
55 #fontstylematchingalg {
56 list-style-type: lower-alpha;
57 }
59 #fontmatchingalg ul, #fontmatchingalg ol {
60 margin-top: 0.8em;
61 }
63 #fontmatchingalg li + li {
64 margin-top: 0.8em;
65 }
67 div.example {
68 padding: 1em;
69 margin-top: 1em;
70 }
72 div.example + div.example {
73 margin-top: 2em;
74 }
76 div.figure {
77 page-break-inside: avoid;
78 }
80 pre.prod { white-space: pre-wrap; margin: 1em 0 1em 2em }
82 div.featex {
83 width: 700px;
84 }
86 div.featex img {
87 margin: auto;
88 display: block;
89 }
91 span.tag {
92 font-family: monospace;
93 font-size: 120%;
94 }
96 ol ol {
97 list-style-type: lower-alpha;
98 }
100 .idl-code {
101 font-weight: bold;
102 color: #c50;
103 }
104 </style>
105 <link href="http://www.w3.org/StyleSheets/TR/W3C-ED.css" rel=stylesheet
106 type="text/css">
107 <script defer=defer
108 src="http://test.csswg.org/harness/annotate.js#CSS3-FONTS_DEV"
109 type="text/javascript"></script>
111 <body>
112 <div class=head> <!--begin-logo-->
113 <p><a href="http://www.w3.org/"><img alt=W3C height=48
114 src="http://www.w3.org/Icons/w3c_home" width=72></a> <!--end-logo-->
116 <h1>CSS Fonts Module Level 3</h1>
118 <h2 class="no-num no-toc" id=editors-draft-11-june-2013>Editor's Draft 11
119 June 2013</h2>
121 <dl id=authors>
122 <dt>This version:
124 <dd><a
125 href="http://dev.w3.org/csswg/css-fonts/">http://dev.w3.org/csswg/css-fonts/</a>
126 <!-- <dd><a href="http://www.w3.org/TR/2013/ED-css3-fonts-20130611/">http://www.w3.org/TR/2013/ED-css3-fonts-20130611/</a> -->
129 <dt>Latest version:
131 <dd><a
132 href="http://www.w3.org/TR/css3-fonts/">http://www.w3.org/TR/css3-fonts/</a>
134 <dt>Latest editor's draft:
136 <dd><a
137 href="http://dev.w3.org/csswg/css-fonts/">http://dev.w3.org/csswg/css-fonts/</a>
138 (<a
139 href="https://dvcs.w3.org/hg/csswg/log/tip/css-fonts/Fonts.html">change
140 log</a>)
142 <dt>Previous version:
144 <dd><a
145 href="http://www.w3.org/TR/2013/WD-css3-fonts-20130212/">http://www.w3.org/TR/2013/WD-css3-fonts-20130212/</a>
147 <dt>Issues List:
149 <dd><a href="http://www.w3.org/Style/CSS/Tracker/products/18">CSS3 Fonts
150 issues in Tracker</a>
152 <dd><a
153 href="https://www.w3.org/Bugs/Public/buglist.cgi?query_format=advanced&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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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 class=issue>How does the use of ‘<a
1657 href="#propdef-font-size-adjust"><code
1658 class=property>font-size-adjust</code></a>’ affect <a
1659 href="http://www.w3.org/TR/css3-values/#font-relative-lengths"><em>font-relative</em></a>
1660 unit sizes? Are all units affected the same way, i.e. including the
1661 definition of ‘<code class=property>em</code>’?
1663 <p>In situations where font fallback occurs, fallback fonts may not share
1664 the same aspect ratio as the desired font family and will thus appear less
1665 readable. The font-size-adjust property is a way to preserve the
1666 readability of text when font fallback occurs. It does this by adjusting
1667 the font-size so that the x-height is the same regardless of the font
1668 used.
1670 <div class=example>
1671 <p>The style defined below defines Verdana as the desired font family, but
1672 if Verdana is not available Futura or Times will be used.</p>
1674 <pre>p {
1675 font-family: Verdana, Futura, Times;
1676 }
1678 <p>Lorem ipsum dolor sit amet, ...</p>
1679 </pre>
1681 <p>Verdana has a relatively high aspect ratio, lowercase letters are
1682 relatively tall compared to uppercase letters, so at small sizes text
1683 appears legible. Times has a lower aspect ratio and so if fallback
1684 occurs, the text will be less legible at small sizes than Verdana.</p>
1685 </div>
1687 <p>How text rendered in each of these fonts compares is shown below, the
1688 columns show text rendered in Verdana, Futura and Times. The same
1689 font-size value is used across cells within each row and red lines are
1690 included to show the differences in x-height. In the upper half each row
1691 is rendered in the same font-size value. The same is true for the lower
1692 half but in this half the font-size-adjust property is also set so that
1693 the actual font size is adjusted to preserve the x-height across each row.
1694 Note how small text remains relatively legible across each row in the
1695 lower half.
1697 <div class=figure><img alt="text with and without font-size-adjust"
1698 src=fontsizeadjust.png>
1699 <p class=caption>Text with and without the use of font-size-adjust
1700 </div>
1702 <p>This property allows authors to specify an aspect value for an element
1703 that will effectively preserve the x-height of the first choice font,
1704 whether it is substituted or not. Values have the following meanings:
1706 <dl>
1707 <dt><dfn id=font-size-adjust-none-value
1708 title="none!!font-size-adjust">none</dfn>
1710 <dd>Do not preserve the font's x-height.
1712 <dt><dfn id=font-size-adjust-auto-value
1713 title="auto!!font-size-adjust">auto</dfn>
1715 <dd>Behaves just like <number>, except the number used is the aspect
1716 value calculated by user agents for the first font in the list of fonts
1717 defined for the initial value of the <a href="#propdef-font-family"
1718 title="font-family!!property">‘<code
1719 class=property>font-family</code>’</a> property. Effectively this is
1720 the default font used when <a href="#propdef-font-family"
1721 title="font-family!!property">‘<code
1722 class=property>font-family</code>’</a> is not otherwise specified.
1723 <p>Authors can use this value to specify that font size should be
1724 normalized across fonts based on the x-height without the need to
1725 specify the aspect ratio explicitly.</p>
1727 <dt><dfn id=aspect-ratio-value><var><number></var></dfn>
1729 <dd>Specifies the aspect value used in the calculation below to calculate
1730 the adjusted font size:
1731 <pre>c = ( a / a' ) s
1732 </pre>
1734 <p>where:</p>
1736 <pre>s = font-size value
1737 a = aspect value as specified by the font-size-adjust property
1738 a' = aspect value of actual font
1739 c = adjusted font-size to use
1740 </pre>
1742 <p>This value applies to any font that is selected but in typical usage
1743 it should be based on the aspect value of the first font in the
1744 font-family list. If this is specified accurately, the <tt>(a/a')</tt>
1745 term in the formula above is effectively 1 for the first font and no
1746 adjustment occurs. If the value is specified inaccurately, text rendered
1747 using the first font in the family list will display differently in
1748 older user agents that don't support font-size-adjust.</p>
1749 </dl>
1751 <p>Authors can calculate the aspect value for a given font by comparing
1752 spans with the same content but different font-size-adjust properties. If
1753 the same font-size is used, the spans will match when the font-size-adjust
1754 value is accurate for the given font.
1756 <div class=example>
1757 <p>Two spans with borders are used to determine the aspect value of a
1758 font. The font-size is the same for both spans but the font-size-adjust
1759 property is specified only for the right span. Starting with a value of
1760 0.5, the aspect value can be adjusted until the borders around the two
1761 letters line up.</p>
1763 <pre>p {
1764 font-family: Futura;
1765 font-size: 500px;
1766 }
1768 span {
1769 border: solid 1px red;
1770 }
1772 .adjust {
1773 font-size-adjust: 0.5;
1774 }
1776 <p><span>b</span><span class="adjust">b</span></p>
1777 </pre>
1779 <div class=figure><img alt="Futura with an aspect value of 0.5"
1780 src=beforefontsizeadjust.png>
1781 <p class=caption>Futura with an aspect value of 0.5
1782 </div>
1784 <p>The box on the right is a bit bigger than the one on the left, so the
1785 aspect value of this font is something less than 0.5. Adjust the value
1786 until the boxes align.</p>
1787 </div>
1788 <!-- prop: font -->
1790 <h3 id=font-prop><span class=secno>3.7 </span>Shorthand font property: the
1791 <a href="#propdef-font">font</a> property</h3>
1793 <table class=propdef id=namefontvalue-ltlsquofont-stylersquogt-l>
1794 <tbody>
1795 <tr>
1796 <td>Name:
1798 <td><dfn id=propdef-font>font</dfn>
1800 <tr>
1801 <td>Value:
1803 <td>[ [ <var><<a href="#propdef-font-style"
1804 title="font-style!!property">‘<code
1805 class=property>font-style</code>’</a>></var> || <a
1806 href="#font-variant-css21-values"><var><font-variant-css21></var></a>
1807 || <var><<a href="#propdef-font-weight"
1808 title="font-weight!!property">‘<code
1809 class=property>font-weight</code>’</a>></var> || <var><<a
1810 href="#propdef-font-stretch" title="font-stretch!!property">‘<code
1811 class=property>font-stretch</code>’</a></var> ]? <var><‘<a
1812 href="#propdef-font-size"><code
1813 class=property>font-size</code></a>’></var> [ / <var><‘<code
1814 class=property>line-height</code>’></var> ]? <var><<a
1815 href="#propdef-font-family" title="font-family!!property">‘<code
1816 class=property>font-family</code>’</a>></var> ] | caption | icon |
1817 menu | message-box | small-caption | status-bar
1819 <tr>
1820 <td>Initial:
1822 <td>see individual properties
1824 <tr>
1825 <td>Applies to:
1827 <td>all elements
1829 <tr>
1830 <td>Inherited:
1832 <td>yes
1834 <tr>
1835 <td>Percentages:
1837 <td>see individual properties
1839 <tr>
1840 <td>Media:
1842 <td>visual
1844 <tr>
1845 <td>Computed value:
1847 <td>see individual properties
1849 <tr>
1850 <td>Animatable:
1852 <td>see individual properties
1853 </table>
1855 <p>The <span class=property>‘<a href="#propdef-font"><code
1856 class=property>font</code></a>’</span> property is, except as described
1857 below, a shorthand property for setting <a href="#propdef-font-style"
1858 title="font-style!!property">‘<code
1859 class=property>font-style</code>’</a>, <a href="#propdef-font-variant"
1860 title="font-variant!!property">‘<code
1861 class=property>font-variant</code>’</a>, <a href="#propdef-font-weight"
1862 title="font-weight!!property">‘<code
1863 class=property>font-weight</code>’</a>, <a href="#propdef-font-stretch"
1864 title="font-stretch!!property">‘<code
1865 class=property>font-stretch</code>’</a>, <span class=property>‘<a
1866 href="#propdef-font-size"><code
1867 class=property>font-size</code></a>’</span>, <a class=property
1868 href="http://www.w3.org/TR/CSS2/visudet.html#propdef-line-height">‘<code
1869 class=property>line-height</code>’</a>, <a href="#propdef-font-family"
1870 title="font-family!!property">‘<code
1871 class=property>font-family</code>’</a> at the same place in the
1872 stylesheet. Values for the <a href="#propdef-font-variant"
1873 title="font-variant!!property">‘<code
1874 class=property>font-variant</code>’</a> property may also be included
1875 but only those supported in CSS 2.1, none of the <a
1876 href="#propdef-font-variant" title="font-variant!!property">‘<code
1877 class=property>font-variant</code>’</a> values added in this
1878 specification can be used in the <span class=property>‘<a
1879 href="#propdef-font"><code class=property>font</code></a>’</span>
1880 shorthand:
1882 <pre
1883 class=prod><dfn id=font-variant-css21-values><var><font-variant-css21></var></dfn> = [normal | small-caps]</pre>
1885 <p>The syntax of this property is based on a traditional typographical
1886 shorthand notation to set multiple properties related to fonts.
1888 <p>All subproperties of the ‘<a href="#propdef-font"><code
1889 class=property>font</code></a>’ property are first reset to their
1890 initial values, including those listed above plus <span
1891 class=property>‘<a href="#propdef-font-size-adjust"><code
1892 class=property>font-size-adjust</code></a>’</span>, <span
1893 class=property>‘<a href="#propdef-font-kerning"><code
1894 class=property>font-kerning</code></a>’</span>, subproperties of <a
1895 href="#propdef-font-variant" title="font-variant!!property">‘<code
1896 class=property>font-variant</code>’</a> and and <span>‘<a
1897 href="#propdef-font-language-override"><code
1898 class=property>font-language-override</code></a>’</span>. Then, those
1899 properties that are given explicit values in the <span
1900 class=property>‘<a href="#propdef-font"><code
1901 class=property>font</code></a>’</span> shorthand are set to those
1902 values. For a definition of allowed and initial values, see the previously
1903 defined properties. For reasons of backwards compatibility, it is not
1904 possible to set <span class=property>‘<a
1905 href="#propdef-font-size-adjust"><code
1906 class=property>font-size-adjust</code></a>’</span> to anything other
1907 than its initial value using the <span class=property>‘<a
1908 href="#propdef-font"><code class=property>font</code></a>’</span>
1909 shorthand property; instead, use the individual property.
1911 <div class=example>
1912 <p style="display:none">Example(s):
1914 <p>
1916 <pre>p { font: 12pt/14pt sans-serif }
1917 p { font: 80% sans-serif }
1918 p { font: x-large/110% "new century schoolbook", serif }
1919 p { font: bold italic large Palatino, serif }
1920 p { font: normal small-caps 120%/120% fantasy }
1921 p { font: condensed oblique 12pt "Helvetica Neue", serif; }
1922 </pre>
1924 <p> In the second rule, the font size percentage value (‘<code
1925 class=css>80%</code>’) refers to the computed ‘<a
1926 href="#propdef-font-size"><code class=property>font-size</code></a>’ of
1927 the parent element. In the third rule, the line height percentage
1928 (‘<code class=css>110%</code>’) refers to the font size of the
1929 element itself.
1931 <p>The first three rules do not specify the <a
1932 href="#propdef-font-variant" title="font-variant!!property">‘<code
1933 class=property>font-variant</code>’</a> and <a
1934 href="#propdef-font-weight" title="font-weight!!property">‘<code
1935 class=property>font-weight</code>’</a> explicitly, so these properties
1936 receive their initial values (<span title="normal value">‘<code
1937 class=property>normal</code>’</span>). Notice that the font family name
1938 "new century schoolbook", which contains spaces, is enclosed in quotes.
1939 The fourth rule sets the <a href="#propdef-font-weight"
1940 title="font-weight!!property">‘<code
1941 class=property>font-weight</code>’</a> to ‘<a href="#bold"><code
1942 class=property>bold</code></a>’, the <a href="#propdef-font-style"
1943 title="font-style!!property">‘<code
1944 class=property>font-style</code>’</a> to ‘<a href="#italic"><code
1945 class=property>italic</code></a>’, and implicitly sets <a
1946 href="#propdef-font-variant" title="font-variant!!property">‘<code
1947 class=property>font-variant</code>’</a> to <a
1948 href="#font-variant-normal-value" title="normal!!font-variant">‘<code
1949 class=property>normal</code>’</a>.
1951 <p> The fifth rule sets the <a href="#propdef-font-variant"
1952 title="font-variant!!property">‘<code
1953 class=property>font-variant</code>’</a> (‘<a href="#small-caps"><code
1954 class=property>small-caps</code></a>’), the <span class=property>‘<a
1955 href="#propdef-font-size"><code
1956 class=property>font-size</code></a>’</span> (120% of the parent's font
1957 size), the <a class=property
1958 href="http://www.w3.org/TR/CSS2/visudet.html#propdef-line-height">‘<code
1959 class=property>line-height</code>’</a> (120% of the font size) and the
1960 <a href="#propdef-font-family" title="font-family!!property">‘<code
1961 class=property>font-family</code>’</a> (‘<a href="#fantasy"><code
1962 class=property>fantasy</code></a>’). It follows that the keyword <span
1963 title="normal value">‘<code class=property>normal</code>’</span>
1964 applies to the two remaining properties: <a href="#propdef-font-style"
1965 title="font-style!!property">‘<code
1966 class=property>font-style</code>’</a> and <a
1967 href="#propdef-font-weight" title="font-weight!!property">‘<code
1968 class=property>font-weight</code>’</a>.
1970 <p>The sixth rule sets the <a href="#propdef-font-style"
1971 title="font-style!!property">‘<code
1972 class=property>font-style</code>’</a>, <a href="#propdef-font-stretch"
1973 title="font-stretch!!property">‘<code
1974 class=property>font-stretch</code>’</a>, <span class=property>‘<a
1975 href="#propdef-font-size"><code
1976 class=property>font-size</code></a>’</span>, and <a
1977 href="#propdef-font-family" title="font-family!!property">‘<code
1978 class=property>font-family</code>’</a>, the other font properties being
1979 set to their initial values.
1980 </div>
1982 <p>Since the <a href="#propdef-font-stretch"
1983 title="font-stretch!!property">‘<code
1984 class=property>font-stretch</code>’</a> property was not defined in CSS
1985 2.1, when using <a href="#propdef-font-stretch"
1986 title="font-stretch!!property">‘<code
1987 class=property>font-stretch</code>’</a> values within ‘<a
1988 href="#propdef-font"><code class=property>font</code></a>’ rules,
1989 authors should include a extra version compatible with older user agents:
1991 <pre>p {
1992 font: 80% sans-serif; /* for older user agents */
1993 font: condensed 80% sans-serif;
1994 }</pre>
1996 <p>The following values refer to system fonts:
1998 <dl>
1999 <dt><strong>caption</strong>
2001 <dd>The font used for captioned controls (e.g., buttons, drop-downs,
2002 etc.).
2004 <dt><strong>icon</strong>
2006 <dd>The font used to label icons.
2008 <dt><strong>menu</strong>
2010 <dd>The font used in menus (e.g., dropdown menus and menu lists).
2012 <dt><strong>message-box</strong>
2014 <dd>The font used in dialog boxes.
2016 <dt><strong>small-caption</strong>
2018 <dd>The font used for labeling small controls.
2020 <dt><strong>status-bar</strong>
2022 <dd>The font used in window status bars.
2023 </dl>
2025 <p>System fonts may only be set as a whole; that is, the font family, size,
2026 weight, style, etc. are all set at the same time. These values may then be
2027 altered individually if desired. If no font with the indicated
2028 characteristics exists on a given platform, the user agent should either
2029 intelligently substitute (e.g., a smaller version of the ‘<code
2030 class=property>caption</code>’ font might be used for the ‘<code
2031 class=property>small-caption</code>’ font), or substitute a user agent
2032 default font. As for regular fonts, if, for a system font, any of the
2033 individual properties are not part of the operating system's available
2034 user preferences, those properties should be set to their initial values.
2036 <p>That is why this property is "almost" a shorthand property: system fonts
2037 can only be specified with this property, not with <a
2038 href="#propdef-font-family" title="font-family!!property">‘<code
2039 class=property>font-family</code>’</a> itself, so <span
2040 class=property>‘<a href="#propdef-font"><code
2041 class=property>font</code></a>’</span> allows authors to do more than
2042 the sum of its subproperties. However, the individual properties such as
2043 <a href="#propdef-font-weight" title="font-weight!!property">‘<code
2044 class=property>font-weight</code>’</a> are still given values taken from
2045 the system font, which can be independently varied.
2047 <p>Note that the keywords used for the system fonts listed above are only
2048 treated as keywords when they occur in the initial position, in other
2049 positions the same string is treated as part of the font family name:
2051 <pre> font: menu; /* use the font settings for system menus */
2052 font: large menu; /* use a font family named "menu" */</pre>
2054 <div class=example>
2055 <p style="display:none">Example(s):
2057 <p>
2059 <pre>button { font: 300 italic 1.3em/1.7em "FB Armada", sans-serif }
2060 button p { font: menu }
2061 button p em { font-weight: bolder }
2062 </pre>
2064 <p>If the font used for dropdown menus on a particular system happened to
2065 be, for example, 9-point Charcoal, with a weight of 600, then P elements
2066 that were descendants of BUTTON would be displayed as if this rule were
2067 in effect:
2069 <pre>button p { font: 600 9pt Charcoal }
2070 </pre>
2072 <p>Because the <span class=property>‘<a href="#propdef-font"><code
2073 class=property>font</code></a>’</span> shorthand resets to its initial
2074 value any property not explicitly given a value, this has the same effect
2075 as this declaration:
2077 <pre>button p {
2078 font-style: normal;
2079 font-variant: normal;
2080 font-weight: 600;
2081 font-size: 9pt;
2082 line-height: normal;
2083 font-family: Charcoal
2084 }
2085 </pre>
2086 </div>
2087 <!-- prop: font-synthesis -->
2089 <h3 id=font-synthesis-prop><span class=secno>3.8 </span>Controlling
2090 synthetic faces: the <a href="#propdef-font-synthesis">font-synthesis</a>
2091 property</h3>
2093 <table class=propdef id=namefont-synthesisvaluenone-weight-style>
2094 <tbody>
2095 <tr>
2096 <td>Name:
2098 <td><dfn id=propdef-font-synthesis>font-synthesis</dfn>
2100 <tr>
2101 <td>Value:
2103 <td>none | [ weight || style ]
2105 <tr>
2106 <td>Initial:
2108 <td>weight style
2110 <tr>
2111 <td>Applies to:
2113 <td>all elements
2115 <tr>
2116 <td>Inherited:
2118 <td>yes
2120 <tr>
2121 <td>Percentages:
2123 <td>N/A
2125 <tr>
2126 <td>Media:
2128 <td>visual
2130 <tr>
2131 <td>Computed value:
2133 <td>as specified
2135 <tr>
2136 <td>Animatable:
2138 <td>no
2139 </table>
2141 <p>This property controls whether user agents are allowed to synthesize
2142 bold or oblique font faces when a font family lacks bold or italic faces.
2143 If ‘<a href="#weight"><code class=property>weight</code></a>’ is not
2144 specified, user agents must not synthesize bold faces and if ‘<code
2145 class=property>style</code>’ is not specified user agents must not
2146 synthesize italic faces. A value of ‘<code class=property>none</code>’
2147 disallows all synthetic faces.
2149 <div class=example>
2150 <p>The style rule below disables the use of synthetically obliqued Arabic:</p>
2152 <pre>*:lang(ar) { font-synthesis: none; }
2153 </pre>
2154 </div>
2156 <h2 id=font-resources><span class=secno>4 </span>Font Resources</h2>
2158 <h3 id=font-face-rule><span class=secno>4.1 </span>The <dfn
2159 id=at-font-face-rule style="font-weight: inherit; font-style:
2160 inherit"><code>@font-face</code></dfn> rule</h3>
2162 <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule allows
2163 for linking to fonts that are automatically fetched and activated when
2164 needed. This allows authors to select a font that closely matches the
2165 design goals for a given page rather than limiting the font choice to a
2166 set of fonts available on all platforms. A set of font descriptors define
2167 the location of a font resource, either locally or externally, along with
2168 the style characteristics of an individual face. Multiple <a
2169 href="#at-font-face-rule"><code>@font-face</code></a> rules can be used to
2170 construct font families with a variety of faces. Using CSS font matching
2171 rules, a user agent can selectively download only those faces that are
2172 needed for a given piece of text.
2174 <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule
2175 consists of the <a href="#at-font-face-rule"><code>@font-face</code></a>
2176 at-keyword followed by a block of descriptor declarations. In terms of the
2177 grammar, this specification defines the following productions:
2179 <pre><dfn id=fontfacerule>font_face_rule</dfn>
2180 : <a href="#fontfacesym"><i>FONT_FACE_SYM</i></a> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* '{' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="#descriptordeclaration"><i>descriptor_declaration</i></a>? [ ';' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="#descriptordeclaration"><i>descriptor_declaration</i></a>? ]* '}' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>*
2181 ;
2183 <dfn id=descriptordeclaration>descriptor_declaration</dfn>
2184 : <a href="http://www.w3.org/TR/CSS21/grammar.html#grammar"><i>property</i></a> ':' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="http://www.w3.org/TR/CSS21/grammar.html#grammar"><i>expr</i></a>
2185 ;</pre>
2187 <p>The following new definitions are introduced:
2189 <pre>- -|\\0{0,4}2d(\r\n|[ \t\r\n\f])?
2190 F f|\\0{0,4}(46|66)(\r\n|[ \t\r\n\f])?</pre>
2192 <p>The following new token is introduced:
2194 <pre>@{F}{O}{N}{T}{-}{F}{A}{C}{E} {return <dfn id=fontfacesym>FONT_FACE_SYM</dfn>;}</pre>
2196 <p>Each <a href="#at-font-face-rule"><code>@font-face</code></a> rule
2197 specifies a value for every font descriptor, either implicitly or
2198 explicitly. Those not given explicit values in the rule take the initial
2199 value listed with each descriptor in this specification. These descriptors
2200 apply solely within the context of the <a
2201 href="#at-font-face-rule"><code>@font-face</code></a> rule in which they
2202 are defined, and do not apply to document language elements. There is no
2203 notion of which elements the descriptors apply to or whether the values
2204 are inherited by child elements. When a given descriptor occurs multiple
2205 times in a given <a href="#at-font-face-rule"><code>@font-face</code></a>
2206 rule, only the last descriptor declaration is used and all prior
2207 declarations for that descriptor are ignored.
2209 <div class=example>
2210 <p>To use a downloadable font called Gentium:</p>
2212 <pre>
2213 @font-face {
2214 font-family: Gentium;
2215 src: url(http://example.com/fonts/Gentium.ttf);
2216 }
2218 p { font-family: Gentium, serif; }
2219 </pre>
2221 <p>The user agent will download Gentium and use it when rendering text
2222 within paragraph elements. If for some reason the site serving the font
2223 is unavailable, the default serif font will be used.</p>
2224 </div>
2226 <p>A given set of <a href="#at-font-face-rule"><code>@font-face</code></a>
2227 rules define a set of fonts available for use within the documents that
2228 contain these rules. When font matching is done, fonts defined using these
2229 rules are considered before other available fonts on a system.
2231 <p>Downloaded fonts are only available to documents that reference them.
2232 The process of activating these fonts must not make them available to
2233 other applications or to documents that don't directly link to the same
2234 font. User agent implementers might consider it convenient to use
2235 downloaded fonts when rendering characters in other documents for which no
2236 other available font exists as part of the <a
2237 href="#system-font-fallback"><em>system font fallback</em></a> procedure.
2238 However, this would cause a security leak since the contents of one page
2239 would be able to affect other pages, something an attacker could use as an
2240 attack vector. These restrictions do not affect caching behavior, fonts
2241 are cached the same way other web resources are cached.
2243 <p>This at-rule follows the forward-compatible parsing rules of CSS. Like
2244 properties in a declaration block, declarations of any descriptors that
2245 are not supported by the user agent must be ignored. <a
2246 href="#at-font-face-rule"><code>@font-face</code></a> rules require a
2247 font-family and src descriptor; if either of these are missing, the <a
2248 href="#at-font-face-rule"><code>@font-face</code></a> rule is invalid and
2249 must be ignored entirely.
2251 <p>In cases where user agents have limited platform resources or implement
2252 the ability to disable downloadable font resources, <a
2253 href="#at-font-face-rule"><code>@font-face</code></a> rules must simply be
2254 ignored; the behavior of individual descriptors as defined in this
2255 specification should not be altered.
2257 <h3 id=font-family-desc><span class=secno>4.2 </span>Font family: the <a
2258 href="#descdef-font-family">font-family</a> descriptor</h3>
2260 <table class=descdef>
2261 <tbody>
2262 <tr>
2263 <td>Name:
2265 <td><dfn id=descdef-font-family
2266 title="font-family!!descriptor">font-family</dfn>
2268 <tr>
2269 <td>Value:
2271 <td><a href="#family-name-value"><var><family-name></var></a>
2273 <tr>
2274 <td><em>Initial:</em>
2276 <td>N/A
2277 </table>
2279 <p>This descriptor defines the font family name that will be used in all
2280 CSS font family name matching. It is required for the <a
2281 href="#at-font-face-rule"><code>@font-face</code></a> rule to be valid. It
2282 overrides the font family names contained in the underlying font data. If
2283 the font family name is the same as a font family available in a given
2284 user's environment, it effectively hides the underlying font for documents
2285 that use the stylesheet. This permits a web author to freely choose
2286 font-family names without worrying about conflicts with font family names
2287 present in a given user's environment. Likewise, platform substitutions
2288 for a given font family name must not be used.
2290 <h3 id=src-desc><span class=secno>4.3 </span>Font reference: the <a
2291 href="#descdef-src">src</a> descriptor</h3>
2293 <table class=descdef>
2294 <tbody>
2295 <tr>
2296 <td>Name:
2298 <td><dfn id=descdef-src>src</dfn>
2300 <tr>
2301 <td>Value:
2303 <td>[ <url> [format(<string> #)]? | <a
2304 href="#font-face-name-value"><var><font-face-name></var></a> ] #
2306 <tr>
2307 <td><em>Initial:</em>
2309 <td>N/A
2310 </table>
2312 <p>This descriptor specifies the resource containing font data. It is
2313 required for the <a href="#at-font-face-rule"><code>@font-face</code></a>
2314 rule to be valid. Its value is a prioritized, comma-separated list of
2315 external references or locally-installed font face names. When a font is
2316 needed the user agent iterates over the set of references listed, using
2317 the first one it can successfully activate. Fonts containing invalid data
2318 or local font faces that are not found are ignored and the user agent
2319 loads the next font in the list.
2321 <p>As with other URLs in CSS, the URL may be relative, in which case it is
2322 resolved relative to the location of the style sheet containing the <a
2323 href="#at-font-face-rule"><code>@font-face</code></a> rule. In the case of
2324 SVG fonts, the URL points to an element within a document containing SVG
2325 font definitions. If the element reference is omitted, a reference to the
2326 first defined font is implied. Similarly, font container formats that can
2327 contain more than one font must load one and only one of the fonts for a
2328 given <a href="#at-font-face-rule"><code>@font-face</code></a> rule.
2329 Fragment identifiers are used to indicate which font to load. If a
2330 container format lacks a defined fragment identifier scheme,
2331 implementations should use a simple 1-based indexing scheme (e.g.
2332 "font-collection#1" for the first font, "font-collection#2" for the second
2333 font).
2335 <pre>
2336 src: url(fonts/simple.ttf); /* load simple.ttf relative to stylesheet location */
2337 src: url(/fonts/simple.ttf); /* load simple.ttf from absolute location */
2338 src: url(fonts.svg#simple); /* load SVG font with id 'simple' */
2339 </pre>
2341 <p>External references consist of a URL, followed by an optional hint
2342 describing the format of the font resource referenced by that URL. The
2343 format hint contains a comma-separated list of format strings that denote
2344 well-known font formats. Conformant user agents must skip downloading a
2345 font resource if the format hints indicate only unsupported or unknown
2346 font formats. If no format hints are supplied, the user agent should
2347 download the font resource.
2349 <pre>
2350 /* load WOFF font if possible, otherwise use OpenType font */
2351 @font-face {
2352 font-family: bodytext;
2353 src: url(ideal-sans-serif.woff) format("woff"),
2354 url(basic-sans-serif.ttf) format("opentype");
2355 }
2356 </pre>
2358 <p>Format strings defined by this specification:
2360 <table class=data id=fontformats>
2361 <thead>
2362 <tr>
2363 <th>String
2365 <th>Font Format
2367 <th>Common extensions
2369 <tbody>
2370 <tr>
2371 <th>"woff"
2373 <td><a href="http://www.w3.org/TR/WOFF/">WOFF (Web Open Font Format)</a>
2375 <td>.woff
2377 <tr>
2378 <th>"truetype"
2380 <td><a
2381 href="http://www.microsoft.com/typography/otspec/default.htm">TrueType</a>
2383 <td>.ttf
2385 <tr>
2386 <th>"opentype"
2388 <td><a
2389 href="http://www.microsoft.com/typography/otspec/default.htm">OpenType</a>
2391 <td>.ttf, .otf
2393 <tr>
2394 <th>"embedded-opentype"
2396 <td><a
2397 href="http://www.w3.org/Submission/2008/SUBM-EOT-20080305/">Embedded
2398 OpenType</a>
2400 <td>.eot
2402 <tr>
2403 <th>"svg"
2405 <td><a href="http://www.w3.org/TR/SVG/fonts.html">SVG Font</a>
2407 <td>.svg, .svgz
2408 </table>
2410 <p>Given the overlap in common usage between TrueType and OpenType, the
2411 format hints "truetype" and "opentype" must be considered as synonymous; a
2412 format hint of "opentype" does not imply that the font contains Postscript
2413 CFF style glyph data or that it contains OpenType layout information (see
2414 <a href="#platform-props-to-css">Appendix A</a> for more background on
2415 this).
2417 <p>When authors would prefer to use a locally available copy of a given
2418 font and download it if it's not, <code>local()</code> can be used. The
2419 locally-installed <dfn
2420 id=font-face-name-value><var><font-face-name></var></dfn> argument
2421 to <code>local()</code> is a format-specific string that uniquely
2422 identifies a single font face within a larger family. The syntax for a <a
2423 href="#font-face-name-value"><var><font-face-name></var></a> is a
2424 unique font face name enclosed by "local(" and ")". The name can
2425 optionally be enclosed in quotes. If unquoted, the unquoted font family
2426 name processing conventions apply; the name must be a sequence of
2427 identifiers separated by whitespace which is converted to a string by
2428 joining the identifiers together separated by a single space.
2430 <pre>
2431 /* regular face of Gentium */
2432 @font-face {
2433 font-family: MyGentium;
2434 src: local(Gentium), /* use locally available Gentium */
2435 url(Gentium.ttf); /* otherwise, download it */
2436 }
2437 </pre>
2439 <p>For OpenType and TrueType fonts, this string is used to match only the
2440 Postscript name or the full font name in the name table of locally
2441 available fonts. Which type of name is used varies by platform and font,
2442 so authors should include both of these names to assure proper matching
2443 across platforms. Platform substitutions for a given font name must not be
2444 used.
2446 <pre>
2447 /* bold face of Gentium */
2448 @font-face {
2449 font-family: MyGentium;
2450 src: local(Gentium Bold), /* full font name */
2451 local(Gentium-Bold), /* Postscript name */
2452 url(GentiumBold.ttf); /* otherwise, download it */
2453 font-weight: bold;
2454 }
2455 </pre>
2457 <p>Just as a <a href="#at-font-face-rule"><code>@font-face</code></a> rule
2458 specifies the characteristics of a single font within a family, the unique
2459 name used with <code>local()</code> specifies a single font, not an entire
2460 font family. Defined in terms of OpenType font data, the Postscript name
2461 is found in the font's <a
2462 href="http://www.microsoft.com/typography/otspec/name.htm">name table</a>,
2463 in the name record with nameID = 6 (see <a href="#OPENTYPE"
2464 rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a> for more details). The
2465 Postscript name is the commonly used key for all fonts on OSX and for
2466 Postscript CFF fonts under Windows. The full font name (nameID = 4) is
2467 used as a unique key for fonts with TrueType glyphs on Windows.
2469 <p>For OpenType fonts with multiple localizations of the full font name,
2470 the US English version is used (language ID = 0x409 for Windows and
2471 language ID = 0 for Macintosh) or the first localization when a US English
2472 full font name is not available (the OpenType specification recommends
2473 that <a href="http://www.microsoft.com/typography/otspec/recom.htm">all
2474 fonts minimally include US English names</a>). User agents that also match
2475 other full font names, e.g. matching the Dutch name when the current
2476 system locale is set to Dutch, are considered non-conformant. This is done
2477 not to prefer English but to avoid matching inconsistencies across font
2478 versions and OS localizations, since font style names (e.g. "Bold") are
2479 frequently localized into many languages and the set of localizations
2480 available varies widely across platform and font version. User agents that
2481 match a concatenation of family name (nameID = 1) with style name (nameID
2482 = 2) are considered non-conformant.
2484 <p>This also allows for referencing faces that belong to larger families
2485 that cannot otherwise be referenced.
2487 <div class=example>
2488 <p>Use a local font or reference an SVG font in another document:</p>
2490 <pre>
2491 @font-face {
2492 font-family: Headline;
2493 src: local(Futura-Medium),
2494 url(fonts.svg#MyGeometricModern) format("svg");
2495 }
2496 </pre>
2498 <p>Create an alias for local Japanese fonts on different platforms:</p>
2500 <pre>
2501 @font-face {
2502 font-family: jpgothic;
2503 src: local(HiraKakuPro-W3), local(Meiryo), local(IPAPGothic);
2504 }
2505 </pre>
2507 <p>Reference a font face that cannot be matched within a larger family:</p>
2509 <pre>
2510 @font-face {
2511 font-family: Hoefler Text Ornaments;
2512 /* has the same font properties as Hoefler Text Regular */
2513 src: local(HoeflerText-Ornaments);
2514 }
2515 </pre>
2517 <p>Since localized fullnames never match, a document with the header style
2518 rules below would always render using the default serif font, regardless
2519 whether a particular system locale parameter is set to Finnish or not:</p>
2521 <pre>
2522 @font-face {
2523 font-family: SectionHeader;
2524 src: local("Arial Lihavoitu"); /* Finnish fullname for Arial Bold, should fail */
2525 font-weight: bold;
2526 }
2528 h2 { font-family: SectionHeader, serif; }
2529 </pre>
2531 <p>A conformant user agent would never load the font ‘<code
2532 class=css>gentium.eot</code>’ in the example below, since it is
2533 included in the first definition of the ‘<a href="#descdef-src"><code
2534 class=property>src</code></a>’ descriptor which is overridden by the
2535 second definition in the same <a
2536 href="#at-font-face-rule"><code>@font-face</code></a> rule:</p>
2538 <pre>
2539 @font-face {
2540 font-family: MainText;
2541 src: url(gentium.eot); /* for use with older non-conformant user agents */
2542 src: local("Gentium"), url(gentium.ttf); /* Overrides src definition */
2543 }
2544 </pre>
2545 </div>
2547 <h3 id=font-prop-desc><span class=secno>4.4 </span>Font property
2548 descriptors: the <a href="#descdef-font-style">font-style</a>, <a
2549 href="#descdef-font-weight">font-weight</a>, <a
2550 href="#descdef-font-stretch">font-stretch</a> descriptors</h3>
2552 <table class=descdef>
2553 <tbody>
2554 <tr>
2555 <td>Name:
2557 <td><dfn id=descdef-font-style
2558 title="font-style!!descriptor">font-style</dfn>
2560 <tr>
2561 <td>Value:
2563 <td>normal | italic | oblique
2565 <tr>
2566 <td><em>Initial:</em>
2568 <td>normal
2569 </table>
2571 <table class=descdef>
2572 <tbody>
2573 <tr>
2574 <td>Name:
2576 <td><dfn id=descdef-font-weight
2577 title="font-weight!!descriptor">font-weight</dfn>
2579 <tr>
2580 <td>Value:
2582 <td>normal | bold | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900
2584 <tr>
2585 <td><em>Initial:</em>
2587 <td>normal
2588 </table>
2590 <table class=descdef>
2591 <tbody>
2592 <tr>
2593 <td>Name:
2595 <td><dfn id=descdef-font-stretch
2596 title="font-stretch!!descriptor">font-stretch</dfn>
2598 <tr>
2599 <td>Value:
2601 <td>normal | ultra-condensed | extra-condensed | condensed |
2602 semi-condensed | semi-expanded | expanded | extra-expanded |
2603 ultra-expanded
2605 <tr>
2606 <td><em>Initial:</em>
2608 <td>normal
2609 </table>
2611 <p>These descriptors define the characteristics of a font face and are used
2612 in the process of matching styles to specific faces. For a font family
2613 defined with several <a
2614 href="#at-font-face-rule"><code>@font-face</code></a> rules, user agents
2615 can either download all faces in the family or use these descriptors to
2616 selectively download font faces that match actual styles used in document.
2617 The values for these descriptors are the same as those for the
2618 corresponding font properties except that relative keywords are not
2619 allowed, ‘<a href="#bolder"><code class=property>bolder</code></a>’
2620 and ‘<a href="#lighter"><code class=property>lighter</code></a>’. If
2621 these descriptors are omitted, initial values are assumed.
2623 <p>The value for these font face style attributes is used in place of the
2624 style implied by the underlying font data. This allows authors to combine
2625 faces in flexible combinations, even in situations where the original font
2626 data was arranged differently. User agents that implement synthetic
2627 bolding and obliquing must only apply synthetic styling in cases where the
2628 font descriptors imply this is needed, rather than based on the style
2629 attributes implied by the font data.
2631 <h3 id=unicode-range-desc><span class=secno>4.5 </span>Character range: the
2632 <a href="#descdef-unicode-range">unicode-range</a> descriptor</h3>
2634 <table class=descdef>
2635 <tbody>
2636 <tr>
2637 <td>Name:
2639 <td><dfn id=descdef-unicode-range>unicode-range</dfn>
2641 <tr>
2642 <td>Value:
2644 <td><a href="#urange-value"><var><urange></var></a> #
2646 <tr>
2647 <td><em>Initial:</em>
2649 <td>U+0-10FFFF
2650 </table>
2652 <p>This descriptor defines the set of Unicode codepoints that may be
2653 supported by the font face for which it is declared. The descriptor value
2654 is a comma-delimited list of Unicode range (<a
2655 href="#urange-value"><var><urange></var></a>) values. The union of
2656 these ranges defines the set of codepoints that serves as a hint for user
2657 agents when deciding whether or not to download a font resource for a
2658 given text run.
2660 <p>Each <dfn id=urange-value><var><urange></var></dfn> value is a <a
2661 href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><code
2662 title="UNICODE-RANGE token">UNICODE-RANGE</code></a> token made up of a
2663 "U+" or "u+" prefix followed by a codepoint range in one of the three
2664 forms listed below. Ranges that do not fit one of the these forms are
2665 invalid and cause the declaration to be ignored.
2667 <dl>
2668 <dt>single codepoint (e.g. U+416)
2670 <dd>a valid Unicode codepoint, represented as one to six hexadecimal
2671 digits
2673 <dt>interval range (e.g. U+400-4ff)
2675 <dd>represented as two hyphen-separated valid Unicode codepoints
2676 indicating the inclusive start and end codepoints of a range
2678 <dt>wildcard range (e.g. U+4??)
2680 <dd>defined by the set of codepoints implied when trailing ‘<code
2681 class=css>?</code>’ characters signify any hexadeximal digit
2682 </dl>
2684 <p>Individual codepoints are written using hexadecimal values that
2685 correspond to <a href="http://www.unicode.org/charts/">Unicode character
2686 codepoints</a>. Valid Unicode codepoint values vary between 0 and 10FFFF
2687 inclusive. Digit values of codepoints are ASCII case-insensitive. For
2688 interval ranges, the start and end codepoints are valid Unicode values and
2689 the end codepoint is greater than or equal to the start codepoint.
2691 <p>Wildcard ranges specified with ‘?’ that lack an initial digit (e.g.
2692 "U+???") are valid and equivalent to a wildcard range with an initial zero
2693 digit (e.g. "U+0???" = "U+0000-0FFF"). Wildcard ranges that extend beyond
2694 the range of valid Unicode codepoints are invalid. Because of this, the
2695 maximum number of trailing ‘<code class=css>?</code>’ wildcard
2696 characters is five, even though the <a
2697 href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><code
2698 title="UNICODE-RANGE token">UNICODE-RANGE</code></a> token accepts six.
2700 <p>Within the comma-delimited list of Unicode ranges in a ‘<a
2701 href="#descdef-unicode-range"><code
2702 class=property>unicode-range</code></a>’ descriptor declaration, ranges
2703 may overlap. The union of these ranges defines the set of codepoints for
2704 which the corresponding font may be used. User agents must not download or
2705 use the font for codepoints outside this set. User agents may normalize
2706 the list of ranges into a list that is different but represents the same
2707 set of codepoints.
2709 <p>The associated font might not contain glyphs for the entire set of
2710 codepoints defined by the ‘<a href="#descdef-unicode-range"><code
2711 class=property>unicode-range</code></a>’ descriptor. When the font is
2712 used, the <dfn id=effective-character-map>effective character map</dfn> is
2713 the intersection of the codepoints defined by ‘<a
2714 href="#descdef-unicode-range"><code
2715 class=property>unicode-range</code></a>’ with the font's <a
2716 href="#character-map"><em>character map</em></a>. This allows authors to
2717 define supported ranges in terms of broad ranges without worrying about
2718 the precise codepoint ranges supported by the underlying font.
2720 <h3 id=composite-fonts><span class=secno>4.6 </span>Using character ranges
2721 to define composite fonts</h3>
2723 <p>Multiple <a href="#at-font-face-rule"><code>@font-face</code></a> rules
2724 with different unicode ranges for the same family and style descriptor
2725 values can be used to create composite fonts that mix the glyphs from
2726 different fonts for different scripts. This can be used to combine fonts
2727 that only contain glyphs for a single script (e.g. Latin, Greek, Cyrillic)
2728 or it can be used by authors as a way of segmenting a font into fonts for
2729 commonly used characters and less frequently used characters. Since the
2730 user agent will only pull down the fonts it needs this helps reduce page
2731 bandwidth.
2733 <p>If the unicode ranges overlap for a set of <a
2734 href="#at-font-face-rule"><code>@font-face</code></a> rules with the same
2735 family and style descriptor values, the rules are ordered in the reverse
2736 order they were defined; the last rule defined is the first to be checked
2737 for a given character.
2739 <p>Example ranges for specific languages or characters:
2741 <dl>
2742 <dt>unicode-range: U+A5;
2744 <dd>a single code point, the yen/yuan symbol
2746 <dt>unicode-range: U+0-7F;
2748 <dd>code range for basic ASCII characters
2750 <dt>unicode-range: U+590-5ff;
2752 <dd>code range for Hebrew characters
2754 <dt>unicode-range: U+A5, U+4E00-9FFF, U+30??, U+FF00-FF9F;
2756 <dd>code range for Japanese kanji, hiragana and katakana characters plus
2757 yen/yuan symbol
2758 </dl>
2760 <div class=example>
2761 <p>The BBC provides news services in a wide variety of languages, many
2762 that are not well supported across all platforms. Using an <a
2763 href="#at-font-face-rule"><code>@font-face</code></a> rule, the BBC could
2764 provide a font for any of these languages, as it already does via a
2765 manual font download.</p>
2767 <pre>
2768 @font-face {
2769 font-family: BBCBengali;
2770 src: url(fonts/BBCBengali.ttf) format("opentype");
2771 unicode-range: U+00-FF, U+980-9FF;
2772 }
2773 </pre>
2774 </div>
2776 <div class=example>
2777 <p>Technical documents often require a wide range of symbols. The STIX
2778 Fonts project is one project aimed at providing fonts to support a wide
2779 range of technical typesetting in a standardized way. The example below
2780 shows the use of a font that provides glyphs for many of the mathematical
2781 and technical symbol ranges within Unicode:</p>
2783 <pre>
2784 @font-face {
2785 font-family: STIXGeneral;
2786 src: local(STIXGeneral), url(/stixfonts/STIXGeneral.otf);
2787 unicode-range: U+000-49F, U+2000-27FF, U+2900-2BFF, U+1D400-1D7FF;
2788 }
2789 </pre>
2790 </div>
2792 <div class=example>
2793 <p>This example shows how an author can override the glyphs used for Latin
2794 characters in a Japanese font with glyphs from a different font. The
2795 first rule specifies no range so it defaults to the entire range. The
2796 range specified in the second rule overlaps but takes precedence because
2797 it is defined later.</p>
2799 <pre>
2800 @font-face {
2801 font-family: JapaneseWithGentium;
2802 src: local(MSMincho);
2803 /* no range specified, defaults to entire range */
2804 }
2806 @font-face {
2807 font-family: JapaneseWithGentium;
2808 src: url(../fonts/Gentium.ttf);
2809 unicode-range: U+0-2FF;
2810 }
2811 </pre>
2812 </div>
2814 <div class=example>
2815 <p>Consider a family constructed to optimize bandwidth by separating out
2816 Latin, Japanese and other characters into different font files:</p>
2818 <pre>
2819 /* fallback font - size: 4.5MB */
2820 @font-face {
2821 font-family: DroidSans;
2822 src: url(DroidSansFallback.ttf);
2823 /* no range specified, defaults to entire range */
2824 }
2826 /* Japanese glyphs - size: 1.2MB */
2827 @font-face {
2828 font-family: DroidSans;
2829 src: url(DroidSansJapanese.ttf);
2830 unicode-range: U+3000-9FFF, U+ff??;
2831 }
2833 /* Latin, Greek, Cyrillic along with some
2834 punctuation and symbols - size: 190KB */
2835 @font-face {
2836 font-family: DroidSans;
2837 src: url(DroidSans.ttf);
2838 unicode-range: U+000-5FF, U+1e00-1fff, U+2000-2300;
2839 }
2840 </pre>
2842 <p>For simple Latin text, only the font for Latin characters is
2843 downloaded:</p>
2845 <pre>
2846 body { font-family: DroidSans; }
2848 <p>This is that</p>
2849 </pre>
2851 <p>In this case the user agent first checks the unicode-range for the font
2852 containing Latin characters (DroidSans.ttf). Since all the characters
2853 above are in the range U+0-5FF, the user agent downloads the font and
2854 renders the text with that font.</p>
2856 <p>Next, consider text that makes use of an arrow character (⇨):</p>
2858 <pre>
2859 <p>This &#x21e8; that<p>
2860 </pre>
2862 <p>The user agent again first checks the unicode-range of the font
2863 containing Latin characters. Since U+2000-2300 includes the arrow code
2864 point (U+21E8), the user agent downloads the font. For this character
2865 however the Latin font does not have a matching glyph, so the effective
2866 unicode-range used for font matching excludes this code point. Next, the
2867 user agent evaluates the Japanese font. The unicode-range for the
2868 Japanese font, U+3000-9FFF and U+ff??, does not include U+21E8, so the
2869 user agent does not download the Japanese font. Next the fallback font is
2870 considered. The <a href="#at-font-face-rule"><code>@font-face</code></a>
2871 rule for the fallback font does not define unicode-range so its value
2872 defaults to the range of all Unicode code points. The fallback font is
2873 downloaded and used to render the arrow character.</p>
2874 </div>
2876 <h3 id=font-rend-desc><span class=secno>4.7 </span>Font features: the <a
2877 href="#descdef-font-variant">font-variant</a> and <a
2878 href="#descdef-font-feature-settings">font-feature-settings</a>
2879 descriptors</h3>
2881 <table class=descdef>
2882 <tbody>
2883 <tr>
2884 <td>Name:
2886 <td><dfn id=descdef-font-variant
2887 title="font-variant!!descriptor">font-variant</dfn>
2889 <tr>
2890 <td>Value:
2892 <td><a href="#font-variant-normal-value"
2893 title="normal!!font-variant">normal</a> | <a
2894 href="#font-variant-none-value" title="none!!font-variant">none</a> | [
2895 <a href="#common-lig-values"><var><common-lig-values></var></a>
2896 || <a
2897 href="#discretionary-lig-values"><var><discretionary-lig-values></var></a>
2898 || <a
2899 href="#historical-lig-values"><var><historical-lig-values></var></a>
2900 || <a
2901 href="#contextual-alt-values"><var><contextual-alt-values></var></a>
2902 || <a href="#stylistic"><var
2903 title=stylistic>stylistic(<feature-value-name>)</var></a> || <a
2904 href="#historical-forms"><var>historical-forms</var></a> || <a
2905 href="#styleset"><var
2906 title=styleset>styleset(<feature-value-name> #)</var></a> || <a
2907 href="#character-variant"><var
2908 title=character-variant>character-variant(<feature-value-name>
2909 #)</var></a> || <a href="#swash"><var
2910 title=swash>swash(<feature-value-name>)</var></a> || <a
2911 href="#ornaments"><var
2912 title=ornaments>ornaments(<feature-value-name>)</var></a> || <a
2913 href="#annotation"><var
2914 title=annotation>annotation(<feature-value-name>)</var></a> || [
2915 <a href="#small-caps"><i>small-caps</i></a> | <a
2916 href="#all-small-caps"><i>all-small-caps</i></a> | <a
2917 href="#petite-caps"><i>petite-caps</i></a> | <a
2918 href="#all-petite-caps"><i>all-petite-caps</i></a> | <a
2919 href="#unicase"><i>unicase</i></a> | <a
2920 href="#titling-caps"><i>titling-caps</i></a> ] || <a
2921 href="#numeric-figure-values"><var><numeric-figure-values></var></a>
2922 || <a
2923 href="#numeric-spacing-values"><var><numeric-spacing-values></var></a>
2924 || <a
2925 href="#numeric-fraction-values"><var><numeric-fraction-values></var></a>
2926 || <a href="#ordinal"><i>ordinal</i></a> || <a
2927 href="#slashed-zero"><i>slashed-zero</i></a> || <a
2928 href="#east-asian-variant-values"><var><east-asian-variant-values></var></a>
2929 || <a
2930 href="#east-asian-width-values"><var><east-asian-width-values></var></a>
2931 || <a href="#ruby"><i>ruby</i></a> ]
2933 <tr>
2934 <td><em>Initial:</em>
2936 <td>normal
2937 </table>
2939 <table class=descdef>
2940 <tbody>
2941 <tr>
2942 <td>Name:
2944 <td><dfn id=descdef-font-feature-settings
2945 title="font-feature-settings!!descriptor">font-feature-settings</dfn>
2947 <tr>
2948 <td>Value:
2950 <td><a href="#font-feature-settings-normal-value"
2951 title="normal!!font-feature-settings">normal</a> | <a
2952 href="#feature-tag-value"><var><feature-tag-value></var></a> #
2954 <tr>
2955 <td><em>Initial:</em>
2957 <td>normal
2958 </table>
2960 <p>These descriptors define initial settings that apply when the font
2961 defined by an <a href="#at-font-face-rule"><code>@font-face</code></a>
2962 rule is rendered. They do not affect font selection. Values are identical
2963 to those defined for the corresponding <a href="#propdef-font-variant"
2964 title="font-variant!!property">‘<code
2965 class=property>font-variant</code>’</a> and <a
2966 href="#propdef-font-feature-settings"
2967 title="font-feature-settings!!property">‘<code
2968 class=property>font-feature-settings</code>’</a> properties defined
2969 below except that the value ‘<code class=property>inherit</code>’ is
2970 omitted. When multiple font feature descriptors or properties are used,
2971 the cumulative effect on text rendering is detailed in the section <a
2972 href="#font-feature-resolution">Font Feature Resolution</a> below. In
2973 cases where specific values define synthesized fallback for certain <a
2974 href="#propdef-font-variant" title="font-variant!!property">‘<code
2975 class=property>font-variant</code>’</a> subproperties, the same
2976 synthesized fallback applies when used within those values are used with
2977 the <a href="#descdef-font-style" title="font-style!!descriptor">‘<code
2978 class=property>font-variant</code>’</a> descriptor.
2980 <h3 id=font-face-loading><span class=secno>4.8 </span>Font loading
2981 guidelines</h3>
2983 <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule is
2984 designed to allow lazy loading of font resources that are only downloaded
2985 when used within a document. A stylesheet can include <a
2986 href="#at-font-face-rule"><code>@font-face</code></a> rules for a library
2987 of fonts of which only a select set are used; user agents must only
2988 download those fonts that are referred to within the style rules
2989 applicable to a given page. User agents that download all fonts defined in
2990 <a href="#at-font-face-rule"><code>@font-face</code></a> rules without
2991 considering whether those fonts are in fact used within a page are
2992 considered non-conformant. In cases where a font might be downloaded in
2993 character fallback cases, user agents may download a font if it's
2994 contained within the computed value of <a href="#propdef-font-family"
2995 title="font-family!!property">‘<code
2996 class=property>font-family</code>’</a> for a given text run.
2998 <pre>
2999 @font-face {
3000 font-family: GeometricModern;
3001 src: url(font.ttf);
3002 }
3004 p {
3005 /* font will be downloaded for pages with p elements */
3006 font-family: GeometricModern, sans-serif;
3007 }
3009 h2 {
3010 /* font may be downloaded for pages with h2 elements, even if Futura is available locally */
3011 font-family: Futura, GeometricModern, sans-serif;
3012 }
3013 </pre>
3015 <p>In cases where textual content is loaded before downloadable fonts are
3016 available, user agents may render text as it would be rendered if
3017 downloadable font resources are not available or they may render text
3018 transparently with fallback fonts to avoid a flash of text using a
3019 fallback font. In cases where the font download fails user agents must
3020 display text, simply leaving transparent text is considered non-conformant
3021 behavior. Authors are advised to use fallback fonts in their font lists
3022 that closely match the metrics of the downloadable fonts to avoid large
3023 page reflows where possible.
3025 <h3 id=same-origin-restriction><span class=secno>4.9 </span>Same-origin
3026 restriction for fonts</h3>
3028 <h4 id=default-same-origin-restriction><span class=secno>4.9.1
3029 </span>Default same-origin restriction</h4>
3030 <!-- TPAC 2011 Resolution to require same-origin restriction for loading fonts:
3031 http://lists.w3.org/Archives/Public/www-style/2011Nov/0711.html
3032 http://www.w3.org/2011/10/31-webapps-minutes.html#item02
3033 -->
3035 <p>User agents must implement a same-origin restriction when loading fonts
3036 via the <a href="#at-font-face-rule"><code>@font-face</code></a>
3037 mechanism. This restriction limits the loading of fonts for a given
3038 document to fonts loaded from the same origin. Fonts can only be loaded
3039 via the same host, port, and method combination as the containing
3040 document, using the <a
3041 href="http://www.w3.org/TR/html5/browsers.html#origin">origin matching
3042 algorithm</a> described in the <a href="#HTML5"
3043 rel=biblioentry>[HTML5]<!--{{!HTML5}}--></a> specification. The origin of
3044 the stylesheet containing <a
3045 href="#at-font-face-rule"><code>@font-face</code></a> rules is not used
3046 when deciding whether a font is same origin or not, only the origin of the
3047 containing document is used. The restriction applies to all font types.
3049 <p>Given a document located at http://example.com/page.html, fonts defined
3050 with ‘<a href="#descdef-src"><code class=property>src</code></a>’
3051 definitions considered cross origin must not be loaded:
3053 <pre>
3054 /* same origin (i.e. domain, protocol, port match document) */
3055 src: url(fonts/simple.ttf);
3056 src: url(//fonts/simple.ttf);
3058 /* cross origin, different protocol */
3059 src: url(https://example.com/fonts/simple.ttf);
3061 /* cross origin, different domain */
3062 src: url(http://another.example.com/fonts/simple.ttf);
3063 </pre>
3065 <h4 id=allowing-cross-origin-font-loading><span class=secno>4.9.2
3066 </span>Allowing cross-origin font loading</h4>
3068 <p>User agents must also implement the ability to relax this restriction
3069 using cross-site origin controls <a href="#CORS"
3070 rel=biblioentry>[CORS]<!--{{!CORS}}--></a> for fonts loaded via HTTP.
3071 Sites can explicitly allow cross-site downloading of font data using the
3072 <code>Access-Control-Allow-Origin</code> HTTP header. For other protocols,
3073 no explicit relaxation mechanism is defined or required.
3075 <p>For font loads over HTTP, cross-origin requests must be made with the
3076 following parameter settings which are used in conjunction with the <a
3077 href="http://www.w3.org/TR/cors/#cross-origin-request-0"> <em>cross-origin
3078 request algorithm</em></a> <a href="#CORS"
3079 rel=biblioentry>[CORS]<!--{{!CORS}}--></a>:
3081 <ul>
3082 <li><em>request URL</em> — the URL of the font resource in the <a
3083 href="#descdef-src"><code>src</code></a> descriptor
3085 <li><em>request method</em> — GET
3087 <li><em>author request headers</em> — none
3089 <li><em>request entity body</em> — empty
3091 <li><em>source origin</em> — the origin of the page which linked to the
3092 stylesheet
3094 <li><em>manual redirect flag</em> — false
3096 <li><em>omit credentials flag</em> — true
3098 <li><em>force preflight flag</em> — false
3099 </ul>
3101 <h2 id=font-matching-algorithm><span class=secno>5 </span>Font Matching
3102 Algorithm</h2>
3104 <p>The algorithm below describes how fonts are associated with individual
3105 runs of text. For each character in the run a font family is chosen and a
3106 particular font face is selected containing a glyph for that character.
3108 <h3 id=font-family-casing><span class=secno>5.1 </span>Case sensitivity of
3109 font family names</h3>
3111 <p>As part of the font matching algorithm outlined below, user agents must
3112 match font family names used in style rules with actual font family names
3113 contained in fonts available in a given environment or with font family
3114 names defined in <a href="#at-font-face-rule"><code>@font-face</code></a>
3115 rules. User agents must match these names case insensitively, using the
3116 "Default Caseless Matching" algorithm outlined in the Unicode
3117 specification <a href="#UNICODE6"
3118 rel=biblioentry>[UNICODE6]<!--{{!UNICODE6}}--></a>. This algorithm is
3119 detailed in section 3.13 entitled "Default Case Algorithms". Specifically,
3120 the algorithm must be applied without normalizing the strings involved and
3121 without applying any language-specific tailorings. The case folding method
3122 specified by this algorithm uses the case mappings with status field
3123 ‘<code class=property>C</code>’ or ‘<code class=property>F</code>’
3124 in the CaseFolding.txt file of the Unicode Character Database.
3126 <p class=note> For authors this means that font family names are matched
3127 case insensitively, whether those names exist in a platform font or in the
3128 <a href="#at-font-face-rule"><code>@font-face</code></a> rules contained
3129 in a stylesheet. Authors should take care to ensure that names use a
3130 character sequence consistent with the actual font family name,
3131 particularly when using combining characters such as diacritical marks.
3132 For example, a family name that contains an uppercase A (U+0041) followed
3133 by a combining ring (U+030A) will <strong>not</strong> match a name that
3134 looks identical but which uses the precomposed lowercase a-ring character
3135 (U+00E5) instead of the combining sequence.
3137 <p class=note> Implementors should take care to verify that a given
3138 caseless string comparison implementation uses this precise algorithm and
3139 not assume that a given platform string matching routine follows it, as
3140 many of these have locale-specific behavior or use some level of string
3141 normalization.
3143 <h3 id=font-style-matching><span class=secno>5.2 </span>Matching font
3144 styles</h3>
3146 <p>The procedure for choosing a font for a given character in a run of text
3147 consists of iterating over the font families named by the <a
3148 href="#propdef-font-family" title="font-family!!property">‘<code
3149 class=property>font-family</code>’</a> property, selecting a font face
3150 with the appropriate style based on other font properties and then
3151 determining whether a glyph exists for the given character. This is done
3152 using the <dfn id=character-map>character map</dfn> of the font, data
3153 which maps characters to the default glyph for that character. A font is
3154 considered to <dfn id=support>support</dfn> a given character if (1) the
3155 character is contained in the font's <a
3156 href="#character-map"><em>character map</em></a> and (2) if required by
3157 the containing script, shaping information is available for that
3158 character.
3160 <p>Some legacy fonts may include a given character in the <a
3161 href="#character-map"><em>character map</em></a> but lack the shaping
3162 information (e.g. <a
3163 href="http://www.microsoft.com/typography/otspec/ttochap1.htm">OpenType
3164 layout tables</a> or <a
3165 href="http://scripts.sil.org/cms/scripts/page.php?site_id=projects&item_id=graphite_techAbout">Graphite
3166 tables</a>) necessary for correctly rendering text runs containing that
3167 character.
3169 <p>Codepoint sequences consisting of a base character followed by a
3170 sequence of combining characters are treated slightly differently, see the
3171 section on <a href="#cluster-matching">cluster matching</a> below.
3173 <p>For this procedure, the <dfn id=default-face>default face</dfn> for a
3174 given font family is defined to be the face that would be selected if all
3175 font style properties were set to their initial value.
3177 <ol id=fontmatchingalg>
3178 <li>Using the computed font property values for a given element, the user
3179 agent starts with the first family name specified by the <a
3180 href="#propdef-font-family" title="font-family!!property">‘<code
3181 class=property>font-family</code>’</a> property.
3183 <li>If the family name is a generic family keyword, the user agent looks
3184 up the appropriate font family name to be used. User agents may choose
3185 the generic font family to use based on the language of the containing
3186 element or the Unicode range of the character.
3188 <li>For other family names, the user agent attempts to find the family
3189 name among fonts defined via <a
3190 href="#at-font-face-rule"><code>@font-face</code></a> rules and then
3191 among available system fonts, matching names with a <a
3192 href="#font-family-casing">case-insensitive comparison</a> as outlined in
3193 the section above. On systems containing fonts with multiple localized
3194 font family names, user agents must match any of these names independent
3195 of the underlying system locale or platform API used. If the font
3196 resources defined for a given face in an <a
3197 href="#at-font-face-rule"><code>@font-face</code></a> rule are either not
3198 available or contain invalid font data, then the face should be treated
3199 as not present in the family. If no faces are present for a family
3200 defined via <a href="#at-font-face-rule"><code>@font-face</code></a>
3201 rules, the family should be treated as missing; matching a platform font
3202 with the same name must not occur in this case.
3204 <li>If a font family match occurs, the user agent assembles the set of
3205 font faces in that family and then narrows the set to a single face using
3206 other font properties in the order given below. A group of faces defined
3207 via <a href="#at-font-face-rule"><code>@font-face</code></a> rules with
3208 identical font descriptor values but differing ‘<a
3209 href="#descdef-unicode-range"><code
3210 class=property>unicode-range</code></a>’ values are considered to be a
3211 single <dfn id=composite-face>composite face</dfn> for this step:
3212 <ol id=fontstylematchingalg>
3213 <li><a href="#propdef-font-stretch"
3214 title="font-stretch!!property">‘<code
3215 class=property>font-stretch</code>’</a> is tried first. If the
3216 matching set contains faces with width values matching the <a
3217 href="#propdef-font-stretch" title="font-stretch!!property">‘<code
3218 class=property>font-stretch</code>’</a> value, faces with other width
3219 values are removed from the matching set. If there is no face that
3220 exactly matches the width value the nearest width is used instead. If
3221 the value of <a href="#propdef-font-stretch"
3222 title="font-stretch!!property">‘<code
3223 class=property>font-stretch</code>’</a> is <a
3224 href="#font-stretch-normal-value" title="normal!!font-stretch">‘<code
3225 class=property>normal</code>’</a> or one of the condensed values,
3226 narrower width values are checked first, then wider values. If the
3227 value of <a href="#propdef-font-stretch"
3228 title="font-stretch!!property">‘<code
3229 class=property>font-stretch</code>’</a> is one of the expanded
3230 values, wider values are checked first, followed by narrower values.
3231 Once the closest matching width has been determined by this process,
3232 faces with other widths are removed from the matching set.
3234 <li><a href="#propdef-font-style" title="font-style!!property">‘<code
3235 class=property>font-style</code>’</a> is tried next. If the value of
3236 <a href="#propdef-font-style" title="font-style!!property">‘<code
3237 class=property>font-style</code>’</a> is ‘<a href="#italic"><code
3238 class=property>italic</code></a>’, italic faces are checked first,
3239 then oblique, then normal faces. If the value is ‘<a
3240 href="#oblique"><code class=property>oblique</code></a>’, oblique
3241 faces are checked first, then italic faces and then normal faces. If
3242 the value is <a href="#font-style-normal-value"
3243 title="normal!!font-style">‘<code
3244 class=property>normal</code>’</a>, normal faces are checked first,
3245 then oblique faces, then italic faces. Faces with other style values
3246 are excluded from the matching set. User agents are permitted to
3247 distinguish between italic and oblique faces within platform font
3248 families but this is not required, so all italic or oblique faces may
3249 be treated as italic faces. However, within font families defined via
3250 <a href="#at-font-face-rule"><code>@font-face</code></a> rules, italic
3251 and oblique faces must be distinguished using the value of the <a
3252 href="#descdef-font-style" title="font-style!!descriptor">‘<code
3253 class=property>font-style</code>’</a> descriptor. For families that
3254 lack any italic or oblique faces, users agents may create artificial
3255 oblique faces, if this is permitted by the value of the ‘<a
3256 href="#propdef-font-synthesis"><code
3257 class=property>font-synthesis</code></a>’ property.
3259 <li><a href="#propdef-font-weight"
3260 title="font-weight!!property">‘<code
3261 class=property>font-weight</code>’</a> is matched next, so it will
3262 always reduce the matching set to a single font face. If bolder/lighter
3263 relative weights are used, the effective weight is calculated based on
3264 the inherited weight value, as described in the definition of the <a
3265 href="#propdef-font-weight" title="font-weight!!property">‘<code
3266 class=property>font-weight</code>’</a> property. Given the desired
3267 weight and the weights of faces in the matching set after the steps
3268 above, if the desired weight is available that face matches. Otherwise,
3269 a weight is chosen using the rules below:
3270 <ul>
3271 <li>If the desired weight is less than 400, weights below the desired
3272 weight are checked in descending order followed by weights above the
3273 desired weight in ascending order until a match is found.
3275 <li>If the desired weight is greater than 500, weights above the
3276 desired weight are checked in ascending order followed by weights
3277 below the desired weight in descending order until a match is found.
3279 <li>If the desired weight is 400, 500 is checked first and then the
3280 rule for desired weights less than 400 is used.
3282 <li>If the desired weight is 500, 400 is checked first and then the
3283 rule for desired weights less than 400 is used.
3284 </ul>
3286 <li><span class=property>‘<a href="#propdef-font-size"><code
3287 class=property>font-size</code></a>’</span> must be matched within a
3288 UA-dependent margin of tolerance. (Typically, sizes for scalable fonts
3289 are rounded to the nearest whole pixel, while the tolerance for
3290 bitmapped fonts could be as large as 20%.) Further computations, e.g.,
3291 by ‘<code class=property>em</code>’ values in other properties, are
3292 based on the <span class=property>‘<a href="#propdef-font-size"><code
3293 class=property>font-size</code></a>’</span> value that is used, not
3294 the one that is specified.
3295 </ol>
3297 <li>
3298 <p>If the matched face is defined via <a
3299 href="#at-font-face-rule"><code>@font-face</code></a> rules, user agents
3300 must use the procedure below to select a single font:
3302 <ol>
3303 <li>If the font resource has not been loaded and the range of characters
3304 defined by the ‘<a href="#descdef-unicode-range"><code
3305 class=property>unicode-range</code></a>’ descriptor value includes
3306 the character in question, load the font.
3308 <li>After downloading, if the <a
3309 href="#effective-character-map"><em>effective character map</em></a>
3310 supports the character in question, select that font.
3311 </ol>
3313 <p>When the matched face is a <a href="#composite-face"><em>composite
3314 face</em></a>, user agents must use the procedure above on each of the
3315 faces in the <a href="#composite-face"><em>composite face</em></a> in
3316 reverse order of <a
3317 href="#at-font-face-rule"><code>@font-face</code></a> rule definition.</p>
3319 <p>While the download occurs, user agents may either wait until the font
3320 is downloaded or render once with substituted font metrics and render
3321 again once the font is downloaded.</p>
3323 <li>
3324 <p>If no matching face exists or the matched face does not contain a
3325 glyph for the character to be rendered, the next family name is selected
3326 and the previous three steps repeated. Glyphs from other faces in the
3327 family are not considered. The only exception is that user agents may
3328 optionally substitute a synthetically obliqued version of the <a
3329 href="#default-face"><em>default face</em></a> if that face supports a
3330 given glyph and synthesis of these faces is permitted by the value of
3331 the ‘<a href="#propdef-font-synthesis"><code
3332 class=property>font-synthesis</code></a>’ property. For example, a
3333 synthetic italic version of the regular face may be used if the italic
3334 face doesn't support glyphs for Arabic.</p>
3335 <!-- resolution on the above: http://lists.w3.org/Archives/Public/www-style/2012Nov/0292.html -->
3338 <li>If there are no more font families to be evaluated and no matching
3339 face has been found, then the user agent performs a <dfn
3340 id=system-font-fallback>system font fallback</dfn> procedure to find the
3341 best match for the character to be rendered. The result of this procedure
3342 may vary across user agents.
3344 <li>If a particular character cannot be displayed using any font, the user
3345 agent should indicate by some means that a character is not being
3346 displayed, displaying either a symbolic representation of the missing
3347 glyph (e.g. using a <a
3348 href="http://en.wikipedia.org/wiki/Last_resort_font">Last Resort
3349 Font</a>) or using the missing character glyph from a default font.
3350 </ol>
3352 <p>Optimizations of this process are allowed provided that an
3353 implementation behaves as if the algorithm had been followed exactly.
3354 Matching occurs in a well-defined order to insure that the results are as
3355 consistent as possible across user agents, given an identical set of
3356 available fonts and rendering technology.
3358 <p>The <dfn id=first-available-font>first available font</dfn>, used in the
3359 definition of <a
3360 href="http://www.w3.org/TR/css3-values/#font-relative-lengths"><em>font-relative
3361 lengths</em></a> such as ‘<code class=property>ex</code>’ and ‘<code
3362 class=property>ch</code>’, is defined to be the first available font
3363 that would match any character given font families in the ‘<code
3364 class=property>font-family</code>’ list (or a user agent's default font
3365 if none are available).
3367 <h3 id=cluster-matching><span class=secno>5.3 </span>Cluster matching</h3>
3369 <p>When text contains characters such as combining marks, ideally the base
3370 character should be rendered using the same font as the mark, this assures
3371 proper placement of the mark. For this reason, the font matching algorithm
3372 for clusters is more specialized than the general case of matching a
3373 single character by itself. For sequences containing variation selectors,
3374 which indicate the precise glyph to be used for a given character, user
3375 agents always attempt <a href="#system-font-fallback"><em>system font
3376 fallback</em></a> to find the appropriate glyph before using the default
3377 glyph of the base character.
3379 <p>A sequence of codepoints containing combining mark or other modifiers is
3380 termed a grapheme cluster (see <a href="#CSS3TEXT"
3381 rel=biblioentry>[CSS3TEXT]<!--{{CSS3TEXT}}--></a> for a more complete
3382 description). For a given cluster containing a base character, <em>b</em>
3383 and a sequence of combining characters <em>c1, c2…</em>, the entire
3384 cluster is matched using these steps:
3386 <ol>
3387 <li>For each family in the font list, a face is chosen using the style
3388 selection rules defined in the previous section.
3389 <ol>
3390 <li>If all characters in the sequence <em>b + c1 + c2 …</em> are
3391 completely supported by the font, select this font for the sequence.
3393 <li>If a sequence of multiple codepoints is canonically equivalent to a
3394 single character and the font <a href="#support"><em
3395 title=support>supports</em></a> that character, select this font for
3396 the sequence.
3397 </ol>
3399 <li>If no font was found in the font list in step 1:
3400 <ol>
3401 <li>If <em>c1</em> is a variation selector, system fallback must be used
3402 to find a font that <a href="#support"><em
3403 title=support>supports</em></a> the full sequence of <em>b + c1</em>.
3404 If no font on the system <a href="#support"><em
3405 title=support>supports</em></a> the full sequence, match the single
3406 character <em>b</em> using the normal procedure for matching single
3407 characters and ignore the variation selector. Note: a sequence with
3408 more than one variation selector must be treated as an encoding error
3409 and the trailing selectors must be ignored. <a href="#UNICODE6"
3410 rel=biblioentry>[UNICODE6]<!--{{!UNICODE6}}--></a>
3412 <li>Otherwise, the user agent may optionally use system font fallback to
3413 match a font that <a href="#support"><em
3414 title=support>supports</em></a> the entire cluster.
3415 </ol>
3417 <li>If no font is found in step 2, use the matching sequence from step 1
3418 to determine the longest sequence that is completely <a
3419 href="#support"><em title=support>supported</em></a> by a font in the
3420 font list and attempt to match the remaining combining characters
3421 separately using the rules for single characters.
3422 </ol>
3424 <h3 id=char-handling-issues><span class=secno>5.4 </span>Character handling
3425 issues</h3>
3427 <p>CSS font matching is always performed on text runs containing Unicode
3428 characters, so documents using legacy encodings are assumed to have been
3429 transcoded before matching fonts. For fonts containing <a
3430 href="#character-map"><em title="character map">character maps</em></a>
3431 for both legacy encodings and Unicode, the contents of the legacy encoding
3432 <a href="#character-map"><em>character map</em></a> must have no effect on
3433 the results of the font matching process.
3435 <p>The font matching process does not assume that text runs are in either
3436 normalized or denormalized form (see <a href="#CHARMOD-NORM"
3437 rel=biblioentry>[CHARMOD-NORM]<!--{{CHARMOD-NORM}}--></a> for more
3438 details). Fonts may only support precomposed forms and not the decomposed
3439 sequence of base character plus combining marks. Authors should always
3440 tailor their choice of fonts to their content, including whether that
3441 content contains normalized or denormalized character streams.
3443 <p>If a given character is a Private-Use Area Unicode codepoint, user
3444 agents must only match font families named in the ‘<code
3445 class=property>font-family</code>’ list that are not generic families.
3446 If none of the families named in the ‘<code
3447 class=property>font-family</code>’ list contain a glyph for that
3448 codepoint, user agents must display some form of missing glyph symbol for
3449 that character rather than attempting <a
3450 href="#system-font-fallback"><em>system font fallback</em></a> for that
3451 codepoint. When matching the replacement character U+FFFD, user agents may
3452 skip the font matching process and immediately display some form of
3453 missing glyph symbol, they are not required to display the glyph from the
3454 font that would be selected by the font matching process.
3456 <p>In general, the fonts for a given family will all have the same or
3457 similar <a href="#character-map"><em title="character map">character
3458 maps</em></a>. The process outlined here is designed to handle even font
3459 families containing faces with widely variant <a href="#character-map"><em
3460 title="character map">character maps</em></a>. However, authors are
3461 cautioned that the use of such families can lead to unexpected results.
3463 <h3 id=font-matching-changes><span class=secno>5.5 </span>Font matching
3464 changes since CSS 2.1</h3>
3466 <p>The algorithm above is different from CSS 2.1 in a number of key places.
3467 These changes were made to better reflect actual font matching behavior
3468 across user agent implementations.
3470 <p>Differences compared to the font matching algorithm in CSS 2.1:
3472 <ul>
3473 <li>The algorithm includes font-stretch matching.
3475 <li>All possible font-style matching scenarios are delineated.
3477 <li>Small-caps fonts are not matched as part of the font matching process,
3478 they are now handled via font features.
3480 <li>Unicode variation selector matching is required.
3482 <li>Cluster sequences are matched as a unit.
3483 </ul>
3485 <h3 id=font-matching-examples><span class=secno>5.6 </span>Font matching
3486 examples</h3>
3488 <div class=example>
3489 <p>It's useful to note that the CSS selector syntax may be used to create
3490 language-sensitive typography. For example, some Chinese and Japanese
3491 characters are unified to have the same Unicode code point, although the
3492 abstract glyphs are not the same in the two languages.
3494 <pre>*:lang(ja-jp) { font: 900 14pt/16pt "Heisei Mincho W9", serif; }
3495 *:lang(zh-tw) { font: 800 14pt/16.5pt "Li Sung", serif; }
3496 </pre>
3498 <p>This selects any element that has the given language — Japanese or
3499 Traditional Chinese — and uses the appropriate font.
3500 </div>
3502 <h2 id=font-rend-props><span class=secno>6 </span>Font Feature Properties</h2>
3504 <p>Modern font technologies support a variety of advanced typographic and
3505 language-specific font features. Using these features, a single font can
3506 provide glyphs for a wide range of ligatures, contextual and stylistic
3507 alternates, tabular and old-style figures, small capitals, automatic
3508 fractions, swashes, and alternates specific to a given language. To allow
3509 authors control over these font capabilities, the ‘<code
3510 class=property>font-variant</code>’ property has been expanded for CSS3.
3511 It now functions as a shorthand for a set of properties that provide
3512 control over stylistic font features.
3514 <h3 id=glyph-selection-positioning><span class=secno>6.1 </span>Glyph
3515 selection and positioning</h3>
3517 <p>Simple fonts used for displaying Latin text use a very basic processing
3518 model. Fonts contain a <a href="#character-map"><em>character map</em></a>
3519 which maps each character to a glyph for that character. Glyphs for
3520 subsequent characters are simply placed one after the other along a run of
3521 text. Modern font formats such as OpenType and AAT (Apple Advanced
3522 Typography) use a richer processing model. The glyph for a given character
3523 can be chosen and positioned not just based on the codepoint of the
3524 character itself, but also on adjacent characters as well as the language,
3525 script, and features enabled for the text. Font features may be required
3526 for specific scripts, or recommended as enabled by default or they might
3527 be stylistic features meant to be used under author control.
3529 <p>For a good visual overview of these features, see the <a
3530 href="#OPENTYPE-FONT-GUIDE"
3531 rel=biblioentry>[OPENTYPE-FONT-GUIDE]<!--{{OPENTYPE-FONT-GUIDE}}--></a>.
3532 For a detailed description of glyph processing for OpenType fonts, see <a
3533 href="#WINDOWS-GLYPH-PROC"
3534 rel=biblioentry>[WINDOWS-GLYPH-PROC]<!--{{WINDOWS-GLYPH-PROC}}--></a>.
3536 <p>Stylistic font features can be classified into two broad categories:
3537 ones that affect the harmonization of glyph shapes with the surrounding
3538 context, such as kerning and ligature features, and ones such as the
3539 small-caps, subscript/superscript and alternate features that affect shape
3540 selection.
3542 <p>The subproperties of <a href="#propdef-font-variant"
3543 title="font-variant!!property">‘<code
3544 class=property>font-variant</code>’</a> listed below are used to control
3545 these stylistic font features. They do not control features that are
3546 required for displaying certain scripts, such as the OpenType features
3547 used when displaying Arabic or Indic language text. They affect glyph
3548 selection and positioning, but do not affect font selection as described
3549 in the font matching section (except in cases required for compatibility
3550 with CSS 2.1).
3552 <p>To assure consistent behavior across user agents, the equivalent
3553 OpenType property settings are listed for individual properties and are
3554 normative. When using other font formats these should be used as a
3555 guideline to map CSS font feature property values to specific font
3556 features.
3558 <h3 id=language-specific-support><span class=secno>6.2
3559 </span>Language-specific display</h3>
3561 <p>OpenType also supports language-specific glyph selection and
3562 positioning, so that text can be displayed correctly in cases where the
3563 language dictates a specific display behavior. Many languages share a
3564 common script, but the shape of certain letters can vary across those
3565 languages. For example, certain Cyrillic letters have different shapes in
3566 Russian text than in Bulgarian. In Latin text, it's common to render "fi"
3567 with an explicit fi-ligature that lacks a dot on the "i". However, in
3568 languages such as Turkish which uses both a dotted-i and a dotless-i, it's
3569 important to not use this ligature or use a specialized version that
3570 contains a dot over the "i". The example below shows language-specific
3571 variations based on stylistic traditions found in Spanish, Italian and
3572 French orthography:
3574 <div class=featex><img alt="language specific forms, spanish"
3575 src=locl-1.png></div>
3577 <div class=featex><img alt="language specific forms, italian"
3578 src=locl-2.png></div>
3580 <div class=featex><img alt="language specific forms, french"
3581 src=locl-3.png></div>
3583 <p>If the content language of the element is known according to the rules
3584 of the <a
3585 href="http://www.w3.org/TR/CSS21/conform.html#doclanguage">document
3586 language</a>, user agents are required to infer the OpenType language
3587 system from the content language and use that when selecting and
3588 positioning glyphs using an OpenType font.
3590 <p>For OpenType fonts, in some cases it may be necessary to explicitly
3591 declare the OpenType language to be used, for example when displaying text
3592 in a given language that uses the typographic conventions of another
3593 language or when the font does not explicitly support a given language but
3594 supports a language that shares common typographic conventions. The ‘<a
3595 href="#propdef-font-language-override"><code
3596 class=property>font-language-override</code></a>’ property is used for
3597 this purpose.</p>
3598 <!-- prop: font-kerning -->
3600 <h3 id=font-kerning-prop><span class=secno>6.3 </span>Kerning: the <a
3601 href="#propdef-font-kerning">font-kerning</a> property</h3>
3603 <table class=propdef id=namefont-kerningvalueauto-normal-noneini>
3604 <tbody>
3605 <tr>
3606 <td>Name:
3608 <td><dfn id=propdef-font-kerning>font-kerning</dfn>
3610 <tr>
3611 <td>Value:
3613 <td><a href="#font-kerning-auto-value"
3614 title="auto!!font-kerning">auto</a> | <a
3615 href="#font-kerning-normal-value"
3616 title="normal!!font-kerning">normal</a> | <a
3617 href="#font-kerning-none-value" title="none!!font-kerning">none</a>
3619 <tr>
3620 <td>Initial:
3622 <td>auto
3624 <tr>
3625 <td>Applies to:
3627 <td>all elements
3629 <tr>
3630 <td>Inherited:
3632 <td>yes
3634 <tr>
3635 <td>Percentages:
3637 <td>N/A
3639 <tr>
3640 <td>Media:
3642 <td>visual
3644 <tr>
3645 <td>Computed value:
3647 <td>as specified
3649 <tr>
3650 <td>Animatable:
3652 <td>no
3653 </table>
3655 <p>Kerning is the contextual adjustment of inter-glyph spacing. This
3656 property controls metric kerning, kerning that utilizes adjustment data
3657 contained in the font.
3659 <dl>
3660 <dt><dfn id=font-kerning-auto-value title="auto!!font-kerning">auto</dfn>
3662 <dd>Specifies that kerning is applied at the discretion of the user agent
3664 <dt><dfn id=font-kerning-normal-value
3665 title="normal!!font-kerning">normal</dfn>
3667 <dd>Specifies that kerning is applied
3669 <dt><dfn id=font-kerning-none-value title="none!!font-kerning">none</dfn>
3671 <dd>Specifies that kerning is not applied
3672 </dl>
3674 <p>For fonts that do not include kerning data this property will have no
3675 visible effect. When rendering with OpenType fonts, the <a
3676 href="#OPENTYPE" rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a>
3677 specification suggests that kerning be enabled by default. When kerning is
3678 enabled, the OpenType <span class=tag>kern</span> feature is enabled (for
3679 vertical text runs the <span class=tag>vkrn</span> feature is enabled
3680 instead). User agents must also support fonts that only support kerning
3681 via data contained in a <span class=tag>kern</span> font table, as
3682 detailed in the OpenType specification. If the ‘<code
3683 class=property>letter-spacing</code>’ property is defined, kerning
3684 adjustments are considered part of the default spacing and letter spacing
3685 adjustments are made after kerning has been applied.
3687 <p>When set to ‘<code class=property>auto</code>’, user agents can
3688 determine whether to apply kerning or not based on a number of factors:
3689 text size, script, or other factors that influence text processing speed.
3690 Authors who want proper kerning should use <a
3691 href="#font-kerning-normal-value" title="normal!!font-kerning">‘<code
3692 class=property>normal</code>’</a> to explicitly enable kerning.
3693 Likewise, some authors may prefer to disable kerning in situations where
3694 performance is more important than precise appearance. However, in
3695 well-designed modern implementations the use of kerning generally does not
3696 have a large impact on text rendering speed.</p>
3697 <!-- prop: font-variant-ligatures -->
3699 <h3 id=font-variant-ligatures-prop><span class=secno>6.4 </span>Ligatures:
3700 the <a href="#propdef-font-variant-ligatures">font-variant-ligatures</a>
3701 property</h3>
3703 <table class=propdef id=namefont-variant-ligaturesvaluenormal-no>
3704 <tbody>
3705 <tr>
3706 <td>Name:
3708 <td><dfn id=propdef-font-variant-ligatures>font-variant-ligatures</dfn>
3710 <tr>
3711 <td>Value:
3713 <td><a href="#font-variant-ligatures-normal-value"
3714 title="normal!!font-variant-ligatures">normal</a> | <a
3715 href="#font-variant-ligatures-none-value"
3716 title="none!!font-variant-ligatures">none</a> | [ <a
3717 href="#common-lig-values"><var><common-lig-values></var></a> ||
3718 <a
3719 href="#discretionary-lig-values"><var><discretionary-lig-values></var></a>
3720 || <a
3721 href="#historical-lig-values"><var><historical-lig-values></var></a>
3722 || <a
3723 href="#contextual-alt-values"><var><contextual-alt-values></var></a>
3724 ]
3726 <tr>
3727 <td>Initial:
3729 <td>normal
3731 <tr>
3732 <td>Applies to:
3734 <td>all elements
3736 <tr>
3737 <td>Inherited:
3739 <td>yes
3741 <tr>
3742 <td>Percentages:
3744 <td>N/A
3746 <tr>
3747 <td>Media:
3749 <td>visual
3751 <tr>
3752 <td>Computed value:
3754 <td>as specified
3756 <tr>
3757 <td>Animatable:
3759 <td>no
3760 </table>
3762 <p>Ligatures and contextual forms are ways of combining glyphs to produce
3763 more harmonized forms.
3765 <pre
3766 class=prod><dfn id=common-lig-values><var><common-lig-values></var></dfn> = [ <a href="#common-ligatures">common-ligatures</a> | <a href="#no-common-ligatures">no-common-ligatures</a> ]</pre>
3768 <pre
3769 class=prod><dfn id=discretionary-lig-values><var><discretionary-lig-values></var></dfn> = [ <a href="#discretionary-ligatures">discretionary-ligatures</a> | <a href="#no-discretionary-ligatures">no-discretionary-ligatures</a> ]</pre>
3771 <pre
3772 class=prod><dfn id=historical-lig-values><var><historical-lig-values></var></dfn> = [ <a href="#historical-ligatures">historical-ligatures</a> | <a href="#no-historical-ligatures">no-historical-ligatures</a> ]</pre>
3774 <pre
3775 class=prod><dfn id=contextual-alt-values><var><contextual-alt-values></var></dfn> = [ <a href="#contextual">contextual</a> | <a href="#no-contextual">no-contextual</a> ]</pre>
3777 <p>Individual values have the following meanings:
3779 <dl>
3780 <dt><dfn id=font-variant-ligatures-normal-value
3781 title="normal!!font-variant-ligatures">normal</dfn>
3783 <dd>A value of <a href="#font-variant-ligatures-normal-value"
3784 title="normal!!font-variant-ligatures">‘<code
3785 class=property>normal</code>’</a> specifies that common default
3786 features are enabled, <a href="#font-feature-resolution">as described in
3787 detail in the next section</a>. For OpenType fonts, common ligatures and
3788 contextual forms are on by default, discretionary and historical
3789 ligatures are not.
3791 <dt><dfn id=font-variant-ligatures-none-value
3792 title="none!!font-variant-ligatures">none</dfn>
3794 <dd>Specifies that all types of ligatures and contextual forms covered by
3795 this property are explicitly disabled. In situations where ligatures are
3796 not considered necessary, this may improve the speed of text rendering.
3798 <dt><dfn id=common-ligatures>common-ligatures</dfn>
3800 <dd>Enables display of common ligatures (OpenType features: <span
3801 class=tag>liga, clig</span>). For OpenType fonts, common ligatures are
3802 enabled by default.
3803 </dl>
3805 <div class=featex><img alt="common ligature example" src=liga.png></div>
3807 <dl>
3808 <dt><dfn id=no-common-ligatures>no-common-ligatures</dfn>
3810 <dd>Disables display of common ligatures (OpenType features: <span
3811 class=tag>liga, clig</span>).
3813 <dt><dfn id=discretionary-ligatures>discretionary-ligatures</dfn>
3815 <dd>Enables display of discretionary ligatures (OpenType feature: <span
3816 class=tag>dlig</span>). Which ligatures are discretionary or optional is
3817 decided by the type designer, so authors will need to refer to the
3818 documentation of a given font to understand which ligatures are
3819 considered discretionary.
3820 </dl>
3822 <div class=featex><img alt="discretionary ligature example" src=dlig.png></div>
3824 <dl>
3825 <dt><dfn id=no-discretionary-ligatures>no-discretionary-ligatures</dfn>
3827 <dd>Disables display of discretionary ligatures (OpenType feature: <span
3828 class=tag>dlig</span>).
3830 <dt><dfn id=historical-ligatures>historical-ligatures</dfn>
3832 <dd>Enables display of historical ligatures (OpenType feature: <span
3833 class=tag>hlig</span>).
3834 </dl>
3836 <div class=featex><img alt="historical ligature example" src=hlig.png></div>
3838 <dl>
3839 <dt><dfn id=no-historical-ligatures>no-historical-ligatures</dfn>
3841 <dd>Disables display of historical ligatures (OpenType feature: <span
3842 class=tag>hlig</span>).
3844 <dt><dfn id=contextual>contextual</dfn>
3846 <dd>Enables display of contextual alternates (OpenType feature: <span
3847 class=tag>calt</span>). Although not strictly a ligature feature, like
3848 ligatures this feature is commonly used to harmonize the shapes of glyphs
3849 with the surrounding context. For OpenType fonts, this feature is on by
3850 default.
3851 </dl>
3853 <div class=featex><img alt="contextual alternate example" src=calt.png></div>
3855 <dl>
3856 <dt><dfn id=no-contextual>no-contextual</dfn>
3858 <dd>Disables display of contextual alternates (OpenType feature: <span
3859 class=tag>calt</span>).
3860 </dl>
3862 <p>Required ligatures, needed for correctly rendering complex scripts, are
3863 not affected by the settings above, including ‘<code
3864 class=property>none</code>’ (OpenType feature: <span
3865 class=tag>rlig</span>).</p>
3866 <!-- prop: font-variant-position -->
3868 <h3 id=font-variant-position-prop><span class=secno>6.5 </span>Subscript
3869 and superscript forms: the <a
3870 href="#propdef-font-variant-position">font-variant-position</a> property</h3>
3872 <table class=propdef id=namefont-variant-positionvaluenormal-sub>
3873 <tbody>
3874 <tr>
3875 <td>Name:
3877 <td><dfn id=propdef-font-variant-position>font-variant-position</dfn>
3879 <tr>
3880 <td>Value:
3882 <td><a href="#font-variant-position-normal-value"
3883 title="normal!!font-variant-position">normal</a> | <a
3884 href="#sub">sub</a> | <a href="#super">super</a>
3886 <tr>
3887 <td>Initial:
3889 <td>normal
3891 <tr>
3892 <td>Applies to:
3894 <td>all elements
3896 <tr>
3897 <td>Inherited:
3899 <td>yes
3901 <tr>
3902 <td>Percentages:
3904 <td>N/A
3906 <tr>
3907 <td>Media:
3909 <td>visual
3911 <tr>
3912 <td>Computed value:
3914 <td>as specified
3916 <tr>
3917 <td>Animatable:
3919 <td>no
3920 </table>
3922 <p>This property is used to enable typographic subscript and superscript
3923 glyphs. These are alternate glyphs designed within the same em-box as
3924 default glyphs and are intended to be laid out on the same baseline as the
3925 default glyphs, with no resizing or repositioning of the baseline. They
3926 are explicitly designed to match the surrounding text and to be more
3927 readable without affecting the line height.
3929 <div class=figure><img alt="comparison between real subscript glyphs and
3930 synthesized ones" src=realsubscripts.png>
3931 <p class=caption>Subscript glyphs (top) vs. typical synthesized subscripts
3932 (bottom)
3933 </div>
3935 <p>Individual values have the following meanings:
3937 <dl>
3938 <dt><dfn id=font-variant-position-normal-value
3939 title="normal!!font-variant-position">normal</dfn>
3941 <dd>None of the features listed below are enabled.
3943 <dt><dfn id=sub>sub</dfn>
3945 <dd>Enables display of subscript variants (OpenType feature: <span
3946 class=tag>subs</span>).
3948 <dt><dfn id=super>super</dfn>
3950 <dd>Enables display of superscript variants (OpenType feature: <span
3951 class=tag>sups</span>).
3952 </dl>
3954 <p>Because of the semantic nature of subscripts and superscripts, when the
3955 value is either ‘<a href="#sub"><code class=property>sub</code></a>’
3956 or ‘<a href="#super"><code class=property>super</code></a>’ for a
3957 given contiguous run of text, if a variant glyph is not available for all
3958 the characters in the run, simulated glyphs must be synthesized for all
3959 characters using reduced forms of the glyphs that would be used without
3960 this feature applied. This is done per run to avoid a mixture of variant
3961 glyphs and synthesized ones that would not align correctly. In the case of
3962 OpenType fonts that lack subscript or superscript glyphs for a given
3963 character, user agents must use the appropriate subscript and superscript
3964 metrics specified in the selected font's <a
3965 href="http://www.microsoft.com/typography/otspec/os2.htm#subxs">OS/2
3966 table</a> <a href="#OPENTYPE"
3967 rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a> to calculate the size
3968 and offset of the synthesized substitutes.
3970 <div class=figure><img alt="alternate superscripts vs. glyphs synthesized
3971 using superscript metrics" src=superscript-alt-synth.png>
3972 <p class=caption>Superscript alternate glyph (left), synthesized
3973 superscript glyphs (middle), and incorrect mixture of the two (right)
3974 </div>
3976 <p>In situations where text decorations are only applied to runs of text
3977 containing superscript or subscript glyphs, the synthesized glyphs must be
3978 used to avoid problems with the placement of decorations.
3980 <p>In the past, user agents have used font-size and vertical-align to
3981 simulate subscripts and superscripts for the <code title="HTML sub
3982 element">sub</code> and <code title="HTML sup element">sup</code>
3983 elements. To allow a backwards compatible way of defining subscripts and
3984 superscripts, it is recommended that authors use conditional rules <a
3985 href="#CSS3-CONDITIONAL"
3986 rel=biblioentry>[CSS3-CONDITIONAL]<!--{{CSS3-CONDITIONAL}}--></a> so that
3987 older user agents will still render subscripts and superscripts via the
3988 older mechanism.
3990 <p>Authors should note that fonts typically only provide subscript and
3991 superscript glyphs for a subset of all characters supported by the font.
3992 For example, while subscript and superscript glyphs are often available
3993 for Latin numbers, glyphs for punctuation and letter characters are less
3994 frequently provided. The synthetic fallback rules defined for this
3995 property assure that subscripts and superscripts will always appear but
3996 the appearance may not match author expectations if the font used does not
3997 provide the appropriate alternate glyph for all characters contained in a
3998 subscript or superscript.
4000 <p>This property is not cumulative. Applying it to elements within a
4001 subscript or superscript won't nest the placement of a subscript or
4002 superscript glyph. Images contained within text runs where the value of
4003 this property is ‘<a href="#sub"><code class=property>sub</code></a>’
4004 or ‘<a href="#super"><code class=property>super</code></a>’ will be
4005 drawn just as they would if the value was <a
4006 href="#font-variant-position-normal-value"
4007 title="normal!!font-variant-position">‘<code
4008 class=property>normal</code>’</a>.</p>
4009 <!-- due to lack of consensus, couldn't resolve on exact positioning of text decorations:
4010 http://www.w3.org/2013/06/06-css-minutes.html#item03 -->
4012 <p>Because of these limitations, ‘<a
4013 href="#propdef-font-variant-position"><code
4014 class=property>font-variant-position</code></a>’ is not recommended for
4015 use in user agent stylesheets. Authors should use it in cases where
4016 subscripts or superscripts will only contain the narrow range of
4017 characters supported by the fonts specified.
4019 <p class=note>The variant glyphs use the same baseline as the default
4020 glyphs would use. There is no shift in the placement along the baseline,
4021 so the use of variant glyphs doesn't affect the height of the inline box
4022 or alter the height of the linebox. This makes superscript and subscript
4023 variants ideal for situations where it's important that leading remain
4024 constant, such as in multi-column layout.
4026 <div class=example>
4027 <p>A typical user agent default style for the <a class=tag
4028 href="#sub">sub</a> element:</p>
4030 <pre>sub {
4031 vertical-align: sub;
4032 font-size: smaller;
4033 line-height: normal;
4034 }
4035 </pre>
4037 <p>Using font-variant-position to specify typographic subscripts in a way
4038 that will still show subscripts in older user agents:</p>
4040 <pre>@supports ( font-variant-position: sub ) {
4042 sub {
4043 vertical-align: baseline;
4044 font-size: 100%;
4045 line-height: inherit;
4046 font-variant-position: sub;
4047 }
4049 }
4050 </pre>
4052 <p>User agents that support the ‘<a
4053 href="#propdef-font-variant-position"><code
4054 class=property>font-variant-position</code></a>’ property will select a
4055 subscript variant glyph and render this without adjusting the baseline or
4056 font-size. Older user agents will ignore the ‘<a
4057 href="#propdef-font-variant-position"><code
4058 class=property>font-variant-position</code></a>’ property definition
4059 and use the standard defaults for subscripts.</p>
4060 </div>
4061 <!-- prop: font-variant-caps -->
4063 <h3 id=font-variant-caps-prop><span class=secno>6.6 </span>Capitalization:
4064 the <a href="#propdef-font-variant-caps">font-variant-caps</a> property</h3>
4066 <table class=propdef id=namefont-variant-capsvaluenormal-small-c>
4067 <tbody>
4068 <tr>
4069 <td>Name:
4071 <td><dfn id=propdef-font-variant-caps>font-variant-caps</dfn>
4073 <tr>
4074 <td>Value:
4076 <td><a href="#font-variant-caps-normal-value"
4077 title="normal!!font-variant-caps">normal</a> | <a
4078 href="#small-caps">small-caps</a> | <a
4079 href="#all-small-caps">all-small-caps</a> | <a
4080 href="#petite-caps">petite-caps</a> | <a
4081 href="#all-petite-caps">all-petite-caps</a> | <a
4082 href="#unicase">unicase</a> | <a href="#titling-caps">titling-caps</a>
4084 <tr>
4085 <td>Initial:
4087 <td>normal
4089 <tr>
4090 <td>Applies to:
4092 <td>all elements
4094 <tr>
4095 <td>Inherited:
4097 <td>yes
4099 <tr>
4100 <td>Percentages:
4102 <td>N/A
4104 <tr>
4105 <td>Media:
4107 <td>visual
4109 <tr>
4110 <td>Computed value:
4112 <td>as specified
4114 <tr>
4115 <td>Animatable:
4117 <td>no
4118 </table>
4120 <p>This property allows the selection of alternate glyphs used for small or
4121 petite capitals or for titling. These glyphs are specifically designed to
4122 blend well with the surrounding normal glyphs, to maintain the weight and
4123 readability which suffers when text is simply resized to fit this purpose.
4125 <p>Individual values have the following meanings:
4127 <dl>
4128 <dt><dfn id=font-variant-caps-normal-value
4129 title="normal!!font-variant-caps">normal</dfn>
4131 <dd>None of the features listed below are enabled.
4133 <dt><dfn id=small-caps>small-caps</dfn>
4135 <dd>Enables display of small capitals (OpenType feature: <span
4136 class=tag>smcp</span>). Small-caps glyphs typically use the form of
4137 uppercase letters but are reduced to the size of lowercase letters.
4138 </dl>
4140 <div class=featex><img alt="small-caps example" src=smcp.png></div>
4142 <dl>
4143 <dt><dfn id=all-small-caps>all-small-caps</dfn>
4145 <dd>Enables display of small capitals for both upper and lowercase letters
4146 (OpenType features: <span class=tag>c2sc, smcp</span>).
4148 <dt><dfn id=petite-caps>petite-caps</dfn>
4150 <dd>Enables display of petite capitals (OpenType feature: <span
4151 class=tag>pcap</span>).
4153 <dt><dfn id=all-petite-caps>all-petite-caps</dfn>
4155 <dd>Enables display of petite capitals for both upper and lowercase
4156 letters (OpenType features: <span class=tag>c2pc, pcap</span>).
4158 <dt><dfn id=unicase>unicase</dfn>
4160 <dd>Enables display of mixture of small capitals for uppercase letters
4161 with normal lowercase letters (OpenType feature: <span
4162 class=tag>unic</span>).
4164 <dt><dfn id=titling-caps>titling-caps</dfn>
4166 <dd>Enables display of titling capitals (OpenType feature: <span
4167 class=tag>titl</span>). Uppercase letter glyphs are often designed for
4168 use with lowercase letters. When used in all uppercase titling sequences
4169 they can appear too strong. Titling capitals are designed specifically
4170 for this situation.
4171 </dl>
4173 <p>The availability of these glyphs is based on whether a given feature is
4174 defined or not in the feature list of the font. User agents can optionally
4175 decide this on a per-script basis but should explicitly not decide this on
4176 a per-character basis.
4178 <p>Some fonts may only support a subset or none of the features described
4179 for this property. For backwards compatibility with CSS 2.1, if ‘<a
4180 href="#small-caps"><code class=property>small-caps</code></a>’ or ‘<a
4181 href="#all-small-caps"><code class=property>all-small-caps</code></a>’
4182 is specified but small-caps glyphs are not available for a given font,
4183 user agents should simulate a small-caps font, for example by taking a
4184 normal font and replacing the glyphs for lowercase letters with scaled
4185 versions of the glyphs for uppercase characters (replacing the glyphs for
4186 both upper and lowercase letters in the case of ‘<a
4187 href="#all-small-caps"><code class=property>all-small-caps</code></a>’).
4189 <div class=figure style="padding: 0; margin: auto;"><img alt="synthetic vs.
4190 real small-caps" class=hires src=synthetic-vs-real-small-caps.png
4191 width=512px>
4192 <p class=caption>Synthetic vs. real small-caps
4193 </div>
4195 <p>To match the surrounding text, a font may provide alternate glyphs for
4196 caseless characters when these features are enabled but when a user agent
4197 simulates small capitals, it must not attempt to simulate alternates for
4198 codepoints which are considered caseless.
4200 <div class=figure style="padding: 0; margin: auto;"><img alt="caseless
4201 characters with small-caps, all-small-caps enabled" class=hires
4202 src=small-capitals-variations.png width=418px>
4203 <p class=caption>Caseless characters with small-caps, all-small-caps
4204 enabled
4205 </div>
4207 <p>If either ‘<a href="#petite-caps"><code
4208 class=property>petite-caps</code></a>’ or ‘<a
4209 href="#all-petite-caps"><code class=property>all-petite-caps</code></a>’
4210 is specified for a font that doesn't support these features, the property
4211 behaves as if ‘<a href="#small-caps"><code
4212 class=property>small-caps</code></a>’ or ‘<a
4213 href="#all-small-caps"><code class=property>all-small-caps</code></a>’,
4214 respectively, had been specified. If ‘<a href="#unicase"><code
4215 class=property>unicase</code></a>’ is specified for a font that doesn't
4216 support that feature, the property behaves as if ‘<a
4217 href="#small-caps"><code class=property>small-caps</code></a>’ was
4218 applied only to lowercased uppercase letters. If ‘<a
4219 href="#titling-caps"><code class=property>titling-caps</code></a>’ is
4220 specified with a font that does not support this feature, this property
4221 has no visible effect. When simulated small capital glyphs are used, for
4222 scripts that lack uppercase and lowercase letters, ‘<a
4223 href="#small-caps"><code class=property>small-caps</code></a>’, ‘<a
4224 href="#all-small-caps"><code class=property>all-small-caps</code></a>’,
4225 ‘<a href="#petite-caps"><code class=property>petite-caps</code></a>’,
4226 ‘<a href="#all-petite-caps"><code
4227 class=property>all-petite-caps</code></a>’ and ‘<a
4228 href="#unicase"><code class=property>unicase</code></a>’ have no visible
4229 effect.
4231 <p>When casing transforms are used to simulate small capitals, the casing
4232 transformations must match those used for the <span
4233 class=property>‘<code class=property>text-transform</code>’</span>
4234 property.
4236 <p>As a last resort, unscaled uppercase letter glyphs in a normal font may
4237 replace glyphs in a small-caps font so that the text appears in all
4238 uppercase letters.
4240 <div class=figure style="padding: 0; margin: auto;"><img alt="using
4241 all-small-caps in acronym-laden text" class=hires
4242 src=acronym-laden-text.png width=596px>
4243 <p class=caption>Using small capitals to improve readability in
4244 acronym-laden text
4245 </div>
4247 <div class=example>
4248 <p>Quotes rendered italicised, with small-caps on the first line:</p>
4250 <pre>blockquote { font-style: italic; }
4251 blockquote:first-line { font-variant: small-caps; }
4253 <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>
4254 </pre>
4255 </div>
4256 <!-- prop: font-variant-numeric -->
4258 <h3 id=font-variant-numeric-prop><span class=secno>6.7 </span>Numerical
4259 formatting: the <a
4260 href="#propdef-font-variant-numeric">font-variant-numeric</a> property</h3>
4262 <table class=propdef id=namefont-variant-numericvaluenormal-ltnu>
4263 <tbody>
4264 <tr>
4265 <td>Name:
4267 <td><dfn id=propdef-font-variant-numeric>font-variant-numeric</dfn>
4269 <tr>
4270 <td>Value:
4272 <td><a href="#font-variant-numeric-normal-value"
4273 title="normal!!font-variant-numeric">normal</a> | [ <a
4274 href="#numeric-figure-values"><var><numeric-figure-values></var></a>
4275 || <a
4276 href="#numeric-spacing-values"><var><numeric-spacing-values></var></a>
4277 || <a
4278 href="#numeric-fraction-values"><var><numeric-fraction-values></var></a>
4279 || <a href="#ordinal">ordinal</a> || <a
4280 href="#slashed-zero">slashed-zero</a> ]
4282 <tr>
4283 <td>Initial:
4285 <td>normal
4287 <tr>
4288 <td>Applies to:
4290 <td>all elements
4292 <tr>
4293 <td>Inherited:
4295 <td>yes
4297 <tr>
4298 <td>Percentages:
4300 <td>N/A
4302 <tr>
4303 <td>Media:
4305 <td>visual
4307 <tr>
4308 <td>Computed value:
4310 <td>as specified
4312 <tr>
4313 <td>Animatable:
4315 <td>no
4316 </table>
4318 <p>Specifies control over numerical forms. The example below shows how some
4319 of these values can be combined to influence the rendering of tabular data
4320 with fonts that support these features. Within normal paragraph text,
4321 proportional numbers are used while tabular numbers are used so that
4322 columns of numbers line up properly:
4324 <div class=figure style="padding: 0; margin: auto;"><img alt="combining
4325 number styles" src=numberstyles.png>
4326 <p class=caption>Using number styles
4327 </div>
4329 <p>Possible combinations:
4331 <pre
4332 class=prod><dfn id=numeric-figure-values><var><numeric-figure-values></var></dfn> = [ <a href="#lining-nums">lining-nums</a> | <a href="#oldstyle-nums">oldstyle-nums</a> ]</pre>
4334 <pre
4335 class=prod><dfn id=numeric-spacing-values><var><numeric-spacing-values></var></dfn> = [ <a href="#proportional-nums">proportional-nums</a> | <a href="#tabular-nums">tabular-nums</a> ]</pre>
4337 <pre
4338 class=prod><dfn id=numeric-fraction-values><var><numeric-fraction-values></var></dfn> = [ <a href="#diagonal-fractions">diagonal-fractions</a> | <a href="#stacked-fractions">stacked-fractions</a> ]</pre>
4340 <p>Individual values have the following meanings:
4342 <dl>
4343 <dt><dfn id=font-variant-numeric-normal-value
4344 title="normal!!font-variant-numeric">normal</dfn>
4346 <dd>None of the features listed below are enabled.
4348 <dt><dfn id=lining-nums>lining-nums</dfn>
4350 <dd>Enables display of lining numerals (OpenType feature: <span
4351 class=tag>lnum</span>).
4353 <dt><dfn id=oldstyle-nums>oldstyle-nums</dfn>
4355 <dd>Enables display of old-style numerals (OpenType feature: <span
4356 class=tag>onum</span>).
4358 <dt><dfn id=proportional-nums>proportional-nums</dfn>
4360 <dd>Enables display of proportional numerals (OpenType feature: <span
4361 class=tag>pnum</span>).
4363 <dt><dfn id=tabular-nums>tabular-nums</dfn>
4365 <dd>Enables display of tabular numerals (OpenType feature: <span
4366 class=tag>tnum</span>).
4368 <dt><dfn id=diagonal-fractions>diagonal-fractions</dfn>
4370 <dd>Enables display of lining diagonal fractions (OpenType feature: <span
4371 class=tag>frac</span>).
4372 </dl>
4374 <div class=featex><img alt="diagonal fraction example" src=frac.png></div>
4376 <dl>
4377 <dt><dfn id=stacked-fractions>stacked-fractions</dfn>
4379 <dd>Enables display of lining stacked fractions (OpenType feature: <span
4380 class=tag>afrc</span>).
4381 </dl>
4383 <div class=featex><img alt="stacked fraction example" src=afrc.png></div>
4385 <dl>
4386 <dt><dfn id=ordinal>ordinal</dfn>
4388 <dd>Enables display of forms used with ordinal numbers (OpenType feature:
4389 <span class=tag>ordn</span>).
4391 <dt><dfn id=slashed-zero>slashed-zero</dfn>
4393 <dd>Enables display of slashed zeros (OpenType feature: <span
4394 class=tag>zero</span>).
4395 </dl>
4397 <div class=featex><img alt="slashed zero example" src=zero.png></div>
4399 <div class=example id=steak-marinade>
4400 <p>A simple flank steak marinade recipe, rendered with automatic fractions
4401 and old-style numerals:</p>
4403 <pre>.amount { font-variant-numeric: oldstyle-nums diagonal-fractions; }
4405 <h4>Steak marinade:</h4>
4406 <ul>
4407 <li><span class="amount">2</span> tbsp olive oil</li>
4408 <li><span class="amount">1</span> tbsp lemon juice</li>
4409 <li><span class="amount">1</span> tbsp soy sauce</li>
4410 <li><span class="amount">1 1/2</span> tbsp dry minced onion</li>
4411 <li><span class="amount">2 1/2</span> tsp italian seasoning</li>
4412 <li>Salt &amp; pepper</li>
4413 </ul>
4415 <p>Mix the meat with the marinade and let it sit covered in the refrigerator
4416 for a few hours or overnight.</p>
4417 </pre>
4419 <p>Note that the fraction feature is only applied to values not the entire
4420 paragraph. Fonts often implement this feature using contextual rules
4421 based on the use of the slash (‘<code class=css>/</code>’) character.
4422 As such, it's not suitable for use as a paragraph-level style.</p>
4423 </div>
4424 <!-- prop: font-variant-alternates -->
4426 <h3 id=font-variant-alternates-prop><span class=secno>6.8 </span>Alternates
4427 and swashes: the <a
4428 href="#propdef-font-variant-alternates">font-variant-alternates</a>
4429 property</h3>
4431 <table class=propdef id=namefont-variant-alternatesvaluenormal-s>
4432 <tbody>
4433 <tr>
4434 <td>Name:
4436 <td><dfn
4437 id=propdef-font-variant-alternates>font-variant-alternates</dfn>
4439 <tr>
4440 <td>Value:
4442 <td>normal | [ <a href="#stylistic"
4443 title=stylistic>stylistic(<feature-value-name>)</a> || <a
4444 href="#historical-forms">historical-forms</a> || <a href="#styleset"
4445 title=styleset>styleset(<feature-value-name> #)</a> || <a
4446 href="#character-variant"
4447 title=character-variant>character-variant(<feature-value-name>
4448 #)</a> || <a href="#swash"
4449 title=swash>swash(<feature-value-name>)</a> || <a
4450 href="#ornaments"
4451 title=ornaments>ornaments(<feature-value-name>)</a> || <a
4452 href="#annotation"
4453 title=annotation>annotation(<feature-value-name>)</a> ]
4455 <tr>
4456 <td>Initial:
4458 <td>normal
4460 <tr>
4461 <td>Applies to:
4463 <td>all elements
4465 <tr>
4466 <td>Inherited:
4468 <td>yes
4470 <tr>
4471 <td>Percentages:
4473 <td>N/A
4475 <tr>
4476 <td>Media:
4478 <td>visual
4480 <tr>
4481 <td>Computed value:
4483 <td>as specified
4485 <tr>
4486 <td>Animatable:
4488 <td>no
4489 </table>
4491 <p>For any given character, fonts can provide a variety of alternate glyphs
4492 in addition to the default glyph for that character. This property
4493 provides control over the selection of these alternate glyphs.
4495 <p>For many of the property values listed below, several different
4496 alternate glyphs are available. How many alternates are available and what
4497 they represent is font-specific, so these are each marked <dfn
4498 id=font-specific>font specific</dfn> in the value definitions below.
4499 Because the nature of these alternates is font-specific, the <a
4500 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
4501 rule is used to define values for a specific font family or set of
4502 families that associate a font-specific numeric
4503 <code><feature-index></code> with a custom
4504 <code><feature-value-name></code>, which is then used in this
4505 property to select specific alternates:
4507 <pre>@font-feature-values Noble Script { @swash { swishy: 1; flowing: 2; } }
4509 p {
4510 font-family: Noble Script;
4511 font-variant-alternates: swash(flowing); /* use swash alternate #2 */
4512 }</pre>
4514 <p>When a particular <code><feature-value-name></code> has not been
4515 defined for a given family or for a particular feature type, the computed
4516 value must be the same as if it had been defined. However, property values
4517 that contain these undefined <code><feature-value-name></code>
4518 identifiers must be ignored when choosing glyphs.
4520 <pre>/* these two style rules are effectively the same */
4521 p { font-variant-alternates: swash(unknown-value); } /* not a defined value, ignored */
4522 p { font-variant-alternates: normal; }
4523 </pre>
4525 <p>This allows values to be defined and used for a given set of font
4526 families but ignored if fallback occurs, since the font family name would
4527 be different. If a given value is outside the range supported by a given
4528 font, the value is ignored. These values never apply to generic font
4529 families.
4531 <p>Individual values have the following meanings:
4533 <dl>
4534 <dt><dfn id=font-variant-alternates-normal-value
4535 title="normal!!font-variant-alternates">normal</dfn>
4537 <dd>None of the features listed below are enabled.
4539 <dt><dfn id=historical-forms>historical-forms</dfn>
4541 <dd>Enables display of historical forms (OpenType feature: <span
4542 class=tag>hist</span>).
4543 </dl>
4545 <div class=featex><img alt="historical form example" src=hist.png></div>
4547 <dl>
4548 <dt><dfn id=stylistic
4549 title=stylistic>stylistic(<feature-value-name>)</dfn>
4551 <dd>Enables display of stylistic alternates (<a
4552 href="#font-specific"><em>font specific</em></a>, OpenType feature: <span
4553 class=tag>salt <feature-index></span>).
4554 </dl>
4556 <div class=featex><img alt="stylistic alternate example" src=salt.png></div>
4558 <dl>
4559 <dt><dfn id=styleset title=styleset>styleset(<feature-value-name>
4560 #)</dfn>
4562 <dd>Enables display with stylistic sets (<a href="#font-specific"><em>font
4563 specific</em></a>, OpenType feature: <span
4564 class=tag>ss<feature-index></span> OpenType currently defines <span
4565 class=tag>ss01</span> through <span class=tag>ss20</span>).
4566 </dl>
4568 <div class=featex><img alt="styleset example" src=ssnn.png></div>
4570 <dl>
4571 <dt><dfn id=character-variant
4572 title=character-variant>character-variant(<feature-value-name>
4573 #)</dfn>
4575 <dd>Enables display of specific character variants (<a
4576 href="#font-specific"><em>font specific</em></a>, OpenType feature: <span
4577 class=tag>cv<feature-index></span> OpenType currently defines <span
4578 class=tag>cv01</span> through <span class=tag>cv99</span>).
4580 <dt><dfn id=swash title=swash>swash(<feature-value-name>)</dfn>
4582 <dd>Enables display of swash glyphs (<a href="#font-specific"><em>font
4583 specific</em></a>, OpenType feature: <span class=tag>swsh
4584 <feature-index>, cswh <feature-index></span>).
4585 </dl>
4587 <div class=featex><img alt="swash example" src=swsh.png></div>
4589 <dl>
4590 <dt><dfn id=ornaments
4591 title=ornaments>ornaments(<feature-value-name>)</dfn>
4593 <dd>Enables replacement of default glyphs with ornaments, if provided in
4594 the font (<a href="#font-specific"><em>font specific</em></a>, OpenType
4595 feature: <span class=tag>ornm <feature-index></span>). Some fonts
4596 may offer ornament glyphs as alternates for a wide collection of
4597 characters; however, displaying arbitrary characters (e.g.,
4598 alphanumerics) as ornaments is poor practice as it distorts the semantics
4599 of the data. Font designers are encouraged to encode all ornaments
4600 (except those explicitly encoded in the Unicode Dingbats blocks, etc.) as
4601 alternates for the bullet character (U+2022) to allow authors to select
4602 the desired glyph using ‘<a href="#ornaments"><code
4603 class=property>ornaments</code></a>’.
4604 </dl>
4606 <div class=featex><img alt="ornaments example" src=ornm.png></div>
4608 <dl>
4609 <dt><dfn id=annotation
4610 title=annotation>annotation(<feature-value-name>)</dfn>
4612 <dd>Enables display of alternate annotation forms (<a
4613 href="#font-specific"><em>font specific</em></a>, OpenType feature: <span
4614 class=tag>nalt <feature-index></span>).
4615 </dl>
4617 <div class=featex><img alt="alternate annotation form example"
4618 src=nalt.png></div>
4620 <h3 id=font-feature-values><span class=secno>6.9 </span>Defining font
4621 specific alternates: the <dfn id=at-font-feature-values-rule
4622 style="font-weight: inherit; font-style:
4623 inherit"><code>@font-feature-values</code></dfn> rule</h3>
4625 <p>Several of the possible values of ‘<a
4626 href="#propdef-font-variant-alternates"><code
4627 class=property>font-variant-alternates</code></a>’ listed above are
4628 labeled as <a href="#font-specific"><em>font specific</em></a>. For these
4629 features fonts may define not just a single glyph but a set of alternate
4630 glyphs with an index to select a given alternate. Since these are font
4631 family specific, the <a
4632 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
4633 rule is used to define named values for these indices for a given family.
4635 <p class=note>See the <a href="#om-fontfeaturevalues">object model
4636 reference section</a> for a description of the interfaces used to modify
4637 these rules via the CSS Object Model.
4639 <div class=example>
4640 <p>In the case of the swash Q in the example shown above, the swash could
4641 be specified using these style rules:</p>
4643 <pre>
4645 @font-feature-values Jupiter Sans {
4646 @swash {
4647 delicate: 1;
4648 flowing: 2;
4649 }
4650 }
4652 h2 { font-family: Jupiter Sans, sans-serif; }
4654 /* show the second swash variant in h2 headings */
4655 h2:first-letter { font-variant-alternates: swash(flowing); }
4657 <h2>Quick</h2></pre>
4659 <p>When Jupiter Sans is present, the second alternate swash alternate will
4660 be displayed. When not present, no swash character will be shown, since
4661 the specific named value "flowing" is only defined for the Jupiter Sans
4662 family. The @-mark indicates the name of the property value for which a
4663 named value can be used. The name "flowing" is chosen by the author. The
4664 index that represents each alternate is defined within a given font's
4665 data.</p>
4666 </div>
4668 <h4 id=basic-syntax><span class=secno>6.9.1 </span>Basic syntax</h4>
4670 <p>An <a
4671 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
4672 rule is composed of a list of font families followed by a block containing
4673 individual <a href="#featurevalueblock"><i
4674 title="feature_value_block">feature value blocks</i></a> that take the
4675 form of @-rules. Each block defines a set of named values for a specific
4676 font feature when a given set of font families is used. Effectively, they
4677 define a mapping of ⟨family, feature, ident⟩ → ⟨values⟩ where
4678 ⟨values⟩ are the numeric indices used for specific features defined
4679 for a given font.
4681 <p>In terms of the grammar, this specification defines the following
4682 productions:
4684 <pre><dfn id=fontfeaturevaluesrule>font_feature_values_rule</dfn>
4685 : <a href="#fontfeaturevaluessym"><i>FONT_FEATURE_VALUES_SYM</i></a> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="#fontfamilynamelist"><i>font_family_name_list</i></a> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>*
4686 '{' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="#featurevalueblock"><i>feature_value_block</i></a>? [ <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="#featurevalueblock"><i>feature_value_block</i></a>? ]* '}' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>*
4687 ;
4689 <dfn id=fontfamilynamelist>font_family_name_list</dfn>
4690 : <a href="#fontfamilyname"><i>font_family_name</i></a> [ <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* ',' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="#fontfamilyname"><i>font_family_name</i></a> ]*
4691 ;
4693 <dfn id=fontfamilyname>font_family_name</dfn>
4694 : <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>STRING</i></a> | [ <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>IDENT</i></a> [ <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>IDENT</i></a> ]* ]
4695 ;
4697 <dfn id=featurevalueblock>feature_value_block</dfn>
4698 : <a href="#featuretype"><i>feature_type</i></a> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>*
4699 '{' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="#featurevaluedefinition"><i>feature_value_definition</i></a>? [ <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* ';' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="#featurevaluedefinition"><i>feature_value_definition</i></a>? ]* '}' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>*
4700 ;
4702 <dfn id=featuretype>feature_type</dfn>:
4703 <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>ATKEYWORD</i></a>
4704 ;
4706 <dfn id=featurevaluedefinition>feature_value_definition</dfn>
4707 : <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>IDENT</i></a> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* ':' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>NUMBER</i></a> [ <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>NUMBER</i></a> ]*
4708 ;
4709 </pre>
4711 <p>The following new token is introduced:
4713 <pre>@{F}{O}{N}{T}{-}{F}{E}{A}{T}{U}{R}{E}{-}{V}{A}{L}{U}{E}{S} {return <dfn id=fontfeaturevaluessym>FONT_FEATURE_VALUES_SYM</dfn>;}
4714 </pre>
4716 <p><a href="#featurevalueblock"><i title="feature_value_block">Feature
4717 value blocks</i></a> are handled as <a
4718 href="http://www.w3.org/TR/CSS2/syndata.html#at-rules">at-rules</a>, they
4719 consist of everything up to the next block or semi-colon, whichever comes
4720 first.
4722 <p>The <a href="#fontfamilynamelist"><i title="font_family_name_list">font
4723 family list</i></a> is a comma-delimited list of <a
4724 href="#fontfamilyname"><i title="font_family_name">font family
4725 names</i></a> that match the definition of <a
4726 href="#family-name-value"><var><family-name></var></a> for the <a
4727 href="#propdef-font-family" title="font-family!!property">‘<code
4728 class=property>font-family</code>’</a> property. This means that only
4729 named font families are allowed, rules that include generic or system
4730 fonts in the list of font families are syntax errors. However, if a user
4731 agent defines a generic font to be a specific named font (e.g. Helvetica),
4732 the settings associated with that family name will be used. If syntax
4733 errors occur within the font family list, the entire rule must be ignored.
4735 <p>Within <a href="#featurevalueblock"><i
4736 title="feature_value_block">feature value blocks</i></a>, the <a
4737 href="#featuretype"><i title="feature_type">feature type</i></a> is
4738 ‘<code class=css>@</code>’ followed by the name of one of the <a
4739 href="#font-specific"><em>font specific</em></a> property values of ‘<a
4740 href="#propdef-font-variant-alternates"><code
4741 class=property>font-variant-alternates</code></a>’ (e.g. <a
4742 href="#swash"><code>@swash</code></a>). The identifiers used within
4743 feature value definitions follow the rules of CSS user identifiers and are
4744 case-sensitive. They are unique only for a given set of font families and
4745 <a href="#featuretype"><i title="feature_type">feature type</i></a>. The
4746 same identifier used with a different <a href="#featuretype"><i
4747 title="feature_type">feature type</i></a> is treated as a separate and
4748 distinct value. If the same identifier is defined mulitple times for a
4749 given <a href="#featuretype"><i title="feature_type">feature type</i></a>
4750 and font family, the last defined value is used. Values associated with a
4751 given identifier are limited to integer values 0 or greater.
4753 <p>When syntax errors occur within a <a href="#featurevaluedefinition"><i
4754 title="feature_value_definition">feature value definition</i></a>, such as
4755 invalid identifiers or values, the entire <a
4756 href="#featurevaluedefinition"><i title="feature_value_definition">feature
4757 value definition</i></a> must be omitted, just as syntax errors in style
4758 declarations are handled. When the <a href="#featuretype"><i
4759 title="feature_type">feature type</i></a> is invalid, the entire
4760 associated <a href="#featurevalueblock"><i
4761 title="feature_value_block">feature value block</i></a> must be ignored.
4763 <div class=example>
4764 <p>Rules that are equivalent given syntax error handling:</p>
4766 <pre>@font-feature-values Bongo {
4767 @swash { ornate: 1; }
4768 annotation { boxed: 4; } /* should be @annotation! */
4769 @swash { double-loops: 1; flowing: -1; } /* negative value */
4770 @ornaments ; /* incomplete definition */
4771 @styleset { double-W: 14; sharp-terminals: 16 1 } /* missing ; */
4772 <a href="http://www.angryalien.com/0504/shiningbunnies.html" style="text-decoration: none; border: none;">redrum</a> /* random editing mistake */
4773 }</pre>
4775 <p>The example above is equivalent to:</p>
4777 <pre>@font-feature-values Bongo {
4778 @swash { ornate: 1; }
4779 @swash { double-loops: 1; }
4780 @styleset { double-W: 14; sharp-terminals: 16 1; }
4781 }</pre>
4782 </div>
4784 <p>If multiple <a
4785 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
4786 rules are defined for a given family, the resulting values definitions are
4787 the union of the definitions contained within these rules. This allows a
4788 set of named values to be defined for a given font family globally for a
4789 site and specific additions made per-page.
4791 <div class=example>
4792 <p>Using both site-wide and per-page feature values:</p>
4794 <pre>
4795 site.css:
4797 @font-feature-values Mercury Serif {
4798 @styleset {
4799 stacked-g: 3; /* "two-storey" versions of g, a */
4800 stacked-a: 4;
4801 }
4802 }
4804 page.css:
4806 @font-feature-values Mercury Serif {
4807 @styleset {
4808 geometric-m: 7; /* alternate version of m */
4809 }
4810 }
4812 body {
4813 font-family: Mercury Serif, serif;
4815 /* enable both the use of stacked g and alternate m */
4816 font-variant-alternates: styleset(stacked-g, geometric-m);
4817 }</pre>
4818 </div>
4820 <div class=example>
4821 <p>Using a commonly named value allows authors to use a single style rule
4822 to cover a set of fonts for which the underlying selector is different
4823 for each font. If either font in the example below is found, a circled
4824 number glyph will be used:</p>
4826 <pre>@font-feature-values Taisho Gothic {
4827 @annotation { boxed: 1; circled: 4; }
4828 }
4830 @font-feature-values Otaru Kisa {
4831 @annotation { circled: 1; black-boxed: 3; }
4832 }
4834 h3.title {
4835 /* circled form defined for both fonts */
4836 font-family: Taisho Gothic, Otaru Kisa;
4837 font-variant: annotation(circled);
4838 }</pre>
4839 </div>
4841 <h4 id=multi-valued-feature-value-definitions><span class=secno>6.9.2
4842 </span>Multi-valued feature value definitions</h4>
4844 <p>Most <a href="#font-specific"><em>font specific</em></a> ‘<a
4845 href="#propdef-font-variant-alternates"><code
4846 class=property>font-variant-alternates</code></a>’ property values take
4847 a single value (e.g. ‘<a href="#swash"><code
4848 class=property>swash</code></a>’). The ‘<a
4849 href="#character-variant"><code
4850 class=property>character-variant</code></a>’ property value allows two
4851 values and ‘<a href="#styleset"><code
4852 class=property>styleset</code></a>’ allows an unlimited number.
4854 <p>For the styleset property value, multiple values indicate the style sets
4855 to be enabled. Values between 1 and 99 enable OpenType features <span
4856 class=tag>ss01</span> through <span class=tag>ss99</span>. However, the
4857 OpenType standard only officially defines <span class=tag>ss01</span>
4858 through <span class=tag>ss20</span>. For OpenType fonts, values greater
4859 than 99 or equal to 0 do not generate a syntax error when parsed but
4860 enable no OpenType features.
4862 <pre>@font-feature-values Mars Serif {
4863 @styleset {
4864 alt-g: 1; /* implies ss01 = 1 */
4865 curly-quotes: 3; /* implies ss03 = 1 */
4866 code: 4 5; /* implies ss04 = 1, ss05 = 1 */
4867 }
4869 @styleset {
4870 dumb: 125; /* >99, ignored */
4871 }
4873 @swash {
4874 swishy: 3 5; /* more than 1 value for swash, syntax error */
4875 }
4876 }
4878 p.codeblock {
4879 /* implies ss03 = 1, ss04 = 1, ss05 = 1 */
4880 font-variant-alternates: styleset(curly-quotes, code);
4881 }</pre>
4883 <p>For character-variant, a single value between 1 and 99 indicates the
4884 enabling of OpenType feature <span class=tag>cv01</span> through <span
4885 class=tag>cv99</span>. For OpenType fonts, values greater than 99 or equal
4886 to 0 are ignored but do not generate a syntax error when parsed but enable
4887 no OpenType features. When two values are listed, the first value
4888 indicates the feature used and the second the value passed for that
4889 feature. If more than two values are assigned to a given name, a syntax
4890 error occurs and the entire <a href="#featurevaluedefinition"><i
4891 title="feature_value_definition">feature value definition</i></a> is
4892 ignored.
4894 <pre>@font-feature-values MM Greek {
4895 @character-variant { alpha-2: 1 2; } /* implies cv01 = 2 */
4896 @character-variant { beta-3: 2 3; } /* implies cv02 = 3 */
4897 @character-variant { epsilon: 5 3 6; } /* more than 2 values, syntax error, definition ignored */
4898 @character-variant { gamma: 12; } /* implies cv12 = 1 */
4899 @character-variant { zeta: 20 3; } /* implies cv20 = 3 */
4900 @character-variant { zeta-2: 20 2; } /* implies cv20 = 2 */
4901 @character-variant { silly: 105; } /* >99, ignored */
4902 @character-variant { dumb: 323 3; } /* >99, ignored */
4903 }
4905 #title {
4906 /* use the third alternate beta, first alternate gamma */
4907 font-variant-alternates: character-variant(beta-3, gamma);
4908 }
4910 p {
4911 /* zeta-2 follows zeta, implies cv20 = 2 */
4912 font-variant-alternates: character-variant(zeta, zeta-2);
4913 }
4915 .special {
4916 /* zeta follows zeta-2, implies cv20 = 3 */
4917 font-variant-alternates: character-variant(zeta-2, zeta);
4918 }</pre>
4920 <div class=figure><img alt="Matching text on Byzantine seals using
4921 character variants" src=byzantineseal.png>
4922 <p class=caption>Byzantine seal text displayed with character variants
4923 </div>
4925 <div class=example>
4926 <p>In the figure above, the text in red is rendered using a font
4927 containing character variants that mimic the character forms found on a
4928 Byzantine seal from the 8th century A.D. Two lines below is the same text
4929 displayed in a font without variants. Note the two variants for U and N
4930 used on the seal.</p>
4932 <pre>@font-feature-values Athena Ruby {
4933 @character-variant {
4934 leo-B: 2 1;
4935 leo-M: 13 3;
4936 leo-alt-N: 14 1;
4937 leo-N: 14 2;
4938 leo-T: 20 1;
4939 leo-U: 21 2;
4940 leo-alt-U: 21 4;
4941 }
4942 }
4944 p {
4945 font-variant: discretionary-ligatures,
4946 character-variant(leo-B, leo-M, leo-N, leo-T, leo-U);
4947 }
4949 span.alt-N {
4950 font-variant-alternates: character-variant(leo-alt-N);
4951 }
4953 span.alt-U {
4954 font-variant-alternates: character-variant(leo-alt-U);
4955 }
4957 <p>ENO....UP͞RSTU<span class="alt-U">U</span>͞<span class="alt-U">U</span>ΚΑΙTỤẠG̣IUPNS</p>
4959 <p>LEON|ΚΑΙCONSTA|NTI<span class="alt-N">N</span>OS..|STOIBAṢ.|LIṢROM|AIO<span class="alt-N">N</span></p>
4960 </pre>
4961 </div>
4963 <h3 id=font-variant-east-asian-prop><span class=secno>6.10 </span>East
4964 Asian text rendering: the <a
4965 href="#propdef-font-variant-east-asian">font-variant-east-asian</a>
4966 property</h3>
4968 <table class=propdef id=namefont-variant-east-asianvaluenormal-l>
4969 <tbody>
4970 <tr>
4971 <td>Name:
4973 <td><dfn
4974 id=propdef-font-variant-east-asian>font-variant-east-asian</dfn>
4976 <tr>
4977 <td>Value:
4979 <td><a href="#font-variant-east-asian-normal-value"
4980 title="normal!!font-variant-east-asian">normal</a> | [ <a
4981 href="#east-asian-variant-values"><var><east-asian-variant-values></var></a>
4982 || <a
4983 href="#east-asian-width-values"><var><east-asian-width-values></var></a>
4984 || <a href="#ruby">ruby</a> ]
4986 <tr>
4987 <td>Initial:
4989 <td>normal
4991 <tr>
4992 <td>Applies to:
4994 <td>all elements
4996 <tr>
4997 <td>Inherited:
4999 <td>yes
5001 <tr>
5002 <td>Percentages:
5004 <td>N/A
5006 <tr>
5007 <td>Media:
5009 <td>visual
5011 <tr>
5012 <td>Computed value:
5014 <td>as specified
5016 <tr>
5017 <td>Animatable:
5019 <td>no
5020 </table>
5022 <p>Allows control of glyph substitution and sizing in East Asian text.
5024 <pre
5025 class=prod><dfn id=east-asian-variant-values><var><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>
5027 <pre
5028 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>
5030 <p>Individual values have the following meanings:
5032 <dl>
5033 <dt><dfn id=font-variant-east-asian-normal-value
5034 title="normal!!font-variant-east-asian">normal</dfn>
5036 <dd>None of the features listed below are enabled.
5038 <dt><dfn id=jis78>jis78</dfn>
5040 <dd>Enables rendering of JIS78 forms (OpenType feature: <span
5041 class=tag>jp78</span>).
5042 </dl>
5044 <div class=featex><img alt="JIS78 form example" src=jp78.png></div>
5046 <dl>
5047 <dt><dfn id=jis83>jis83</dfn>
5049 <dd>Enables rendering of JIS83 forms (OpenType feature: <span
5050 class=tag>jp83</span>).
5052 <dt><dfn id=jis90>jis90</dfn>
5054 <dd>Enables rendering of JIS90 forms (OpenType feature: <span
5055 class=tag>jp90</span>).
5057 <dt><dfn id=jis04>jis04</dfn>
5059 <dd>Enables rendering of JIS2004 forms (OpenType feature: <span
5060 class=tag>jp04</span>).
5061 <p>The various JIS variants reflect the glyph forms defined in different
5062 Japanese national standards. Fonts generally include glyphs defined by
5063 the most recent national standard but it's sometimes necessary to use
5064 older variants, to match signage for example.</p>
5066 <dt><dfn id=simplified>simplified</dfn>
5068 <dd>Enables rendering of simplified forms (OpenType feature: <span
5069 class=tag>smpl</span>).
5071 <dt><dfn id=traditional>traditional</dfn>
5073 <dd>Enables rendering of traditional forms (OpenType feature: <span
5074 class=tag>trad</span>).
5075 </dl>
5077 <p>The ‘<a href="#simplified"><code
5078 class=property>simplified</code></a>’ and ‘<a
5079 href="#traditional"><code class=property>traditional</code></a>’ values
5080 allow control over the glyph forms for characters which have been
5081 simplified over time but for which the older, traditional form is still
5082 used in some contexts. The exact set of characters and glyph forms will
5083 vary to some degree by context for which a given font was designed.
5085 <div class=featex><img alt="tradtional form example" src=trad.png></div>
5087 <dl>
5088 <dt><dfn id=full-width>full-width</dfn>
5090 <dd>Enables rendering of full-width variants (OpenType feature: <span
5091 class=tag>fwid</span>).
5093 <dt><dfn id=proportional-width>proportional-width</dfn>
5095 <dd>Enables rendering of proportionally-spaced variants (OpenType feature:
5096 <span class=tag>pwid</span>).
5097 </dl>
5099 <div class=featex><img alt="proportionally spaced Japanese example"
5100 src=pwid.png></div>
5102 <dl>
5103 <dt><dfn id=ruby>ruby</dfn>
5105 <dd>Enables display of ruby variant glyphs (OpenType feature: <span
5106 class=tag>ruby</span>). Since ruby text is generally smaller than the
5107 associated body text, font designers can design special glyphs for use
5108 with ruby that are more readable than scaled down versions of the default
5109 glyphs. Only glyph selection is affected, there is no associated font
5110 scaling or other change that affects line layout. The red ruby text below
5111 is shown with default glyphs (top) and with ruby variant glyphs (bottom).
5112 Note the slight difference in stroke thickness.
5113 </dl>
5115 <div class=featex><img alt="ruby variant example" src=rubyshinkansen.png></div>
5117 <h3 id=font-variant-prop><span class=secno>6.11 </span>Overall shorthand
5118 for font rendering: the <a href="#propdef-font-variant">font-variant</a>
5119 property</h3>
5121 <table class=propdef id=namefont-variantvaluenormal-none-ltcommo>
5122 <tbody>
5123 <tr>
5124 <td>Name:
5126 <td><dfn id=propdef-font-variant
5127 title="font-variant!!property">font-variant</dfn>
5129 <tr>
5130 <td>Value:
5132 <td><a href="#font-variant-normal-value"
5133 title="normal!!font-variant">normal</a> | <a
5134 href="#font-variant-none-value" title="none!!font-variant">none</a> | [
5135 <a href="#common-lig-values"><var><common-lig-values></var></a>
5136 || <a
5137 href="#discretionary-lig-values"><var><discretionary-lig-values></var></a>
5138 || <a
5139 href="#historical-lig-values"><var><historical-lig-values></var></a>
5140 || <a
5141 href="#contextual-alt-values"><var><contextual-alt-values></var></a>
5142 || <a href="#stylistic"><var
5143 title=stylistic>stylistic(<feature-value-name>)</var></a> || <a
5144 href="#historical-forms"><var>historical-forms</var></a> || <a
5145 href="#styleset"><var
5146 title=styleset>styleset(<feature-value-name> #)</var></a> || <a
5147 href="#character-variant"><var
5148 title=character-variant>character-variant(<feature-value-name>
5149 #)</var></a> || <a href="#swash"><var
5150 title=swash>swash(<feature-value-name>)</var></a> || <a
5151 href="#ornaments"><var
5152 title=ornaments>ornaments(<feature-value-name>)</var></a> || <a
5153 href="#annotation"><var
5154 title=annotation>annotation(<feature-value-name>)</var></a> || [
5155 <a href="#small-caps"><i>small-caps</i></a> | <a
5156 href="#all-small-caps"><i>all-small-caps</i></a> | <a
5157 href="#petite-caps"><i>petite-caps</i></a> | <a
5158 href="#all-petite-caps"><i>all-petite-caps</i></a> | <a
5159 href="#unicase"><i>unicase</i></a> | <a
5160 href="#titling-caps"><i>titling-caps</i></a> ] || <a
5161 href="#numeric-figure-values"><var><numeric-figure-values></var></a>
5162 || <a
5163 href="#numeric-spacing-values"><var><numeric-spacing-values></var></a>
5164 || <a
5165 href="#numeric-fraction-values"><var><numeric-fraction-values></var></a>
5166 || <a href="#ordinal"><i>ordinal</i></a> || <a
5167 href="#slashed-zero"><i>slashed-zero</i></a> || <a
5168 href="#east-asian-variant-values"><var><east-asian-variant-values></var></a>
5169 || <a
5170 href="#east-asian-width-values"><var><east-asian-width-values></var></a>
5171 || <a href="#ruby"><i>ruby</i></a> ]
5173 <tr>
5174 <td>Initial:
5176 <td>normal
5178 <tr>
5179 <td>Applies to:
5181 <td>all elements
5183 <tr>
5184 <td>Inherited:
5186 <td>yes
5188 <tr>
5189 <td>Percentages:
5191 <td>see individual properties
5193 <tr>
5194 <td>Media:
5196 <td>visual
5198 <tr>
5199 <td>Computed value:
5201 <td>see individual properties
5203 <tr>
5204 <td>Animatable:
5206 <td>see individual properties
5207 </table>
5209 <p>The <a href="#propdef-font-variant"
5210 title="font-variant!!property">‘<code
5211 class=property>font-variant</code>’</a> property is a shorthand for all
5212 font-variant subproperties. The value <dfn id=font-variant-normal-value
5213 title="normal!!font-variant">‘<code
5214 class=property>normal</code>’</dfn> resets all subproperties of <a
5215 href="#propdef-font-variant" title="font-variant!!property">‘<code
5216 class=property>font-variant</code>’</a> to their inital value. The <dfn
5217 id=font-variant-none-value title="none!!font-variant">‘<code
5218 class=property>none</code>’</dfn> value sets ‘<a
5219 href="#propdef-font-variant-ligatures"><code
5220 class=property>font-variant-ligatures</code></a>’ to ‘<code
5221 class=property>none</code>’ and resets all other font feature properties
5222 to their initial value. Like other shorthands, using <a
5223 href="#propdef-font-variant" title="font-variant!!property">‘<code
5224 class=property>font-variant</code>’</a> resets unspecified <a
5225 href="#propdef-font-variant" title="font-variant!!property">‘<code
5226 class=property>font-variant</code>’</a> subproperties to their initial
5227 values. It does not reset the values of either ‘<a
5228 href="#propdef-font-language-override"><code
5229 class=property>font-language-override</code></a>’ or <a
5230 href="#propdef-font-feature-settings"
5231 title="font-feature-settings!!property">‘<code
5232 class=property>font-feature-settings</code>’</a>.
5234 <h3 id=font-feature-settings-prop><span class=secno>6.12 </span>Low-level
5235 font feature settings control: the <a
5236 href="#propdef-font-feature-settings">font-feature-settings</a> property</h3>
5238 <table class=propdef id=namefont-feature-settingsvaluenormal-ltf>
5239 <tbody>
5240 <tr>
5241 <td>Name:
5243 <td><dfn id=propdef-font-feature-settings
5244 title="font-feature-settings!!property">font-feature-settings</dfn>
5246 <tr>
5247 <td>Value:
5249 <td><a href="#font-feature-settings-normal-value"
5250 title="normal!!font-feature-settings">normal</a> | <a
5251 href="#feature-tag-value"><var><feature-tag-value></var></a> #
5253 <tr>
5254 <td>Initial:
5256 <td>normal
5258 <tr>
5259 <td>Applies to:
5261 <td>all elements
5263 <tr>
5264 <td>Inherited:
5266 <td>yes
5268 <tr>
5269 <td>Percentages:
5271 <td>N/A
5273 <tr>
5274 <td>Media:
5276 <td>visual
5278 <tr>
5279 <td>Computed value:
5281 <td>as specified
5283 <tr>
5284 <td>Animatable:
5286 <td>no
5287 </table>
5289 <p>This property provides low-level control over OpenType font features. It
5290 is intended as a way of providing access to font features that are not
5291 widely used but are needed for a particular use case.
5293 <p>Authors should generally use <a href="#propdef-font-variant"
5294 title="font-variant!!property">‘<code
5295 class=property>font-variant</code>’</a> and its related subproperties
5296 whenever possible and only use this property for special cases where its
5297 use is the only way of accessing a particular infrequently used font
5298 feature.
5300 <pre>/* enable small caps and use second swash alternate */
5301 font-feature-settings: "smcp", "swsh" 2;</pre>
5303 <p>A value of <dfn id=font-feature-settings-normal-value
5304 title="normal!!font-feature-settings">‘<code
5305 class=property>normal</code>’</dfn> means that no change in glyph
5306 selection or positioning occurs due to this property.
5308 <p>Feature tag values have the following syntax:
5310 <pre
5311 class=prod><dfn id=feature-tag-value><var><feature-tag-value></var></dfn> = <string> [ <integer> | on | off ]?</pre>
5313 <p>The <string> is a case-sensitive OpenType feature tag. As
5314 specified in the OpenType specification, feature tags contain four ASCII
5315 characters. Tag strings longer or shorter than four characters, or
5316 containing characters outside the U+20–7E codepoint range are invalid.
5317 Feature tags need only match a feature tag defined in the font, so they
5318 are not limited to explicitly registered OpenType features. Fonts defining
5319 custom feature tags should follow the <a
5320 href="http://www.microsoft.com/typography/otspec/featuretags.htm">tag name
5321 rules</a> defined in the OpenType specification <a
5322 href="#OPENTYPE-FEATURES"
5323 rel=biblioentry>[OPENTYPE-FEATURES]<!--{{!OPENTYPE-FEATURES}}--></a>.
5324 Feature tags not present in the font are ignored; a user agent must not
5325 attempt to synthesize fallback behavior based on these feature tags.
5327 <p>This means that explicitly disabling the <span class=tag>kern</span>
5328 feature will not affect the application of kerning data found in the
5329 ‘<code class=property>kern</code>’ table (as opposed to kerning data
5330 associated with the <span class=tag>kern</span> feature in the ‘<code
5331 class=property>GPOS</code>’ table). Authors should use the ‘<a
5332 href="#propdef-font-kerning"><code
5333 class=property>font-kerning</code></a>’ property to explictly enable or
5334 disable kerning since this property affects both types of kerning.
5336 <p>If present, a value indicates an index used for glyph selection. An
5337 <integer> value must be 0 or greater. A value of 0 indicates that
5338 the feature is disabled. For boolean features, a value of 1 enables the
5339 feature. For non-boolean features, a value of 1 or greater enables the
5340 feature and indicates the feature selection index. A value of ‘<code
5341 class=property>on</code>’ is synonymous with 1 and ‘<code
5342 class=property>off</code>’ is synonymous with 0. If the value is
5343 omitted, a value of 1 is assumed.
5345 <pre>
5346 font-feature-settings: "dlig" 1; /* dlig=1 enable discretionary ligatures */
5347 font-feature-settings: "smcp" on; /* smcp=1 enable small caps */
5348 font-feature-settings: 'c2sc'; /* c2sc=1 enable caps to small caps */
5349 font-feature-settings: "liga" off; /* liga=0 no common ligatures */
5350 font-feature-settings: "tnum", 'hist'; /* tnum=1, hist=1 enable tabular numbers and historical forms */
5351 font-feature-settings: "tnum" "hist"; /* invalid, need a comma-delimited list */
5352 font-feature-settings: "palin" off; /* good idea but invalid tagname */
5353 font-feature-settings: "PKRN"; /* PKRN=1 enable custom feature */
5354 font-feature-settings: dlig; /* invalid, tag must be a string */
5355 </pre>
5357 <p>When values greater than the range supported by the font are specified,
5358 the behavior is explicitly undefined. For boolean features, in general
5359 these will enable the feature. For non-boolean features, out of range
5360 values will in general be equivalent to a 0 value. However, in both cases
5361 the exact behavior will depend upon the way the font is designed
5362 (specifically, which type of lookup is used to define the feature).
5364 <p>Although specifically defined for OpenType feature tags, feature tags
5365 for other modern font formats that support font features may be added in
5366 the future. Where possible, features defined for other font formats should
5367 attempt to follow the pattern of registered OpenType tags.
5369 <div class=example>
5370 <p>The Japanese text below will be rendered with half-width kana
5371 characters:</p>
5373 <pre lang=ja>
5374 body { font-feature-settings: "hwid"; /* Half-width OpenType feature */ }
5376 <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>
5377 </pre>
5378 </div>
5380 <h3 id=font-language-override-prop><span class=secno>6.13 </span>Font
5381 language override: the <a
5382 href="#propdef-font-language-override">font-language-override</a> property</h3>
5384 <table class=propdef id=namefont-language-overridevaluenormal-lt>
5385 <tbody>
5386 <tr>
5387 <td>Name:
5389 <td><dfn id=propdef-font-language-override>font-language-override</dfn>
5391 <tr>
5392 <td>Value:
5394 <td><a href="#font-language-override-normal-value"
5395 title="normal!!font-language-override">normal</a> | <a
5396 href="#font-language-override-string-value"><var><string></var></a>
5398 <tr>
5399 <td>Initial:
5401 <td><a href="#font-language-override-normal-value"
5402 title="normal!!font-language-override">normal</a>
5404 <tr>
5405 <td>Applies to:
5407 <td>all elements
5409 <tr>
5410 <td>Inherited:
5412 <td>yes
5414 <tr>
5415 <td>Percentages:
5417 <td>N/A
5419 <tr>
5420 <td>Media:
5422 <td>visual
5424 <tr>
5425 <td>Computed value:
5427 <td>as specified
5429 <tr>
5430 <td>Animatable:
5432 <td>no
5433 </table>
5435 <p>Normally, authors can control the use of language-specific glyph
5436 substitutions and positioning by setting the content language of an
5437 element, as <a href="#language-specific-support">described above</a>:
5439 <pre><!-- Display text using S'gaw Karen specific features -->
5440 <p lang="ksw">...</p></pre>
5442 <p>In some cases, authors may need to specify a language system that
5443 differs from the content language, for example due to the need to mimic
5444 another language's typographic traditions. The ‘<a
5445 href="#propdef-font-language-override"><code
5446 class=property>font-language-override</code></a>’ property allows
5447 authors to explicitly specify the language system of the font, overriding
5448 the language system implied by the content language.
5450 <p>Values have the following meanings:
5452 <dl>
5453 <dt><dfn id=font-language-override-normal-value
5454 title="normal!!font-language-override">normal</dfn>
5456 <dd>specifies that when rendering with OpenType fonts, the content
5457 language of the element is used to infer the OpenType language system
5459 <dt><dfn
5460 id=font-language-override-string-value><var><string></var></dfn>
5462 <dd>single three-letter case-sensitive OpenType <a
5463 href="http://www.microsoft.com/typography/otspec/languagetags.htm">language
5464 system tag</a>, specifies the OpenType language system to be used instead
5465 of the language system implied by the language of the element
5466 </dl>
5467 <!-- For this level, string represents a single language code, there's no concept of "fallback"
5468 http://www.w3.org/2013/06/07-css-minutes.html#item04 -->
5470 <p>Use of invalid OpenType language system tags must not generate a parse
5471 error but must be ignored when doing glyph selection and placement.
5473 <div class=example>
5474 <p>The <a href="http://www.un.org/en/documents/udhr/index.shtml">Universal
5475 Declaration of Human Rights</a> has been translated into a wide variety
5476 of languages. In Turkish, Article 9 of this document might be marked up
5477 as below:</p>
5479 <pre lang=tr><body lang="tr">
5481 <h4>Madde 9</h4>
5482 <p>Hiç kimse keyfi olarak tutuklanamaz, alıkonulanamaz veya sürülemez.</p>
5483 </pre>
5485 <p>Here the user agent uses the value of the ‘<code
5486 class=property>lang</code>’ attribute when rendering text and
5487 appropriately renders this text without ‘<code
5488 class=property>fi</code>’ ligatures. There is no need to use the ‘<a
5489 href="#propdef-font-language-override"><code
5490 class=property>font-language-override</code></a>’ property.</p>
5492 <p>However, a given font may lack support for a specific language. In this
5493 situation authors may need to use the typographic conventions of a
5494 related language that are supported by that font:</p>
5496 <pre lang=mk><body lang="mk"> <!-- Macedonian lang code -->
5498 body { font-language-override: "SRB"; /* Serbian OpenType language tag */ }
5500 <h4>Члeн 9</h4>
5501 <p>Никoj чoвeк нeмa дa бидe пoдлoжeн нa прoизвoлнo aпсeњe, притвoр или прoгoнувaњe.</p>
5503 </pre>
5505 <p>The Macedonian text here will be rendered using Serbian typographic
5506 conventions, with the assumption that the font specified supports
5507 Serbian.</p>
5508 </div>
5510 <p><a id=rendering-considerations></a>
5512 <h2 id=font-feature-resolution><span class=secno>7 </span>Font Feature
5513 Resolution</h2>
5515 <p>As described in the previous section, font features can be enabled in a
5516 variety of ways, either via the use of <a href="#propdef-font-variant"
5517 title="font-variant!!property">‘<code
5518 class=property>font-variant</code>’</a> or <a
5519 href="#propdef-font-feature-settings"
5520 title="font-feature-settings!!property">‘<code
5521 class=property>font-feature-settings</code>’</a> in a style rule or
5522 within an <a href="#at-font-face-rule"><code>@font-face</code></a> rule.
5523 The resolution order for the union of these settings is defined below.
5524 Features defined via CSS properties are applied on top of layout engine
5525 default features.
5527 <h3 id=default-features><span class=secno>7.1 </span>Default features</h3>
5529 <p>For OpenType fonts, user agents must enable the default features defined
5530 in the OpenType documentation for a given script and writing mode.
5531 Required ligatures, common ligatures and contextual forms must be enabled
5532 by default (OpenType features: <span class=tag>rlig, liga, clig,
5533 calt</span>), along with localized forms (OpenType feature: <span
5534 class=tag>locl</span>), and features required for proper display of
5535 composed characters and marks (OpenType features: <span class=tag>ccmp,
5536 mark, mkmk</span>). These features must always be enabled, even when the
5537 value of the <a href="#propdef-font-variant"
5538 title="font-variant!!property">‘<code
5539 class=property>font-variant</code>’</a> and <a
5540 href="#propdef-font-feature-settings"
5541 title="font-feature-settings!!property">‘<code
5542 class=property>font-feature-settings</code>’</a> properties is <span
5543 title="normal value">‘<code class=property>normal</code>’</span>.
5544 Individual features are only disabled when explicitly overridden by the
5545 author, as when ‘<a href="#propdef-font-variant-ligatures"><code
5546 class=property>font-variant-ligatures</code></a>’ is set to ‘<a
5547 href="#no-common-ligatures"><code
5548 class=property>no-common-ligatures</code></a>’. For handling complex
5549 scripts such as <a
5550 href="http://www.microsoft.com/typography/otfntdev/arabicot/features.aspx">Arabic</a>,
5551 <a
5552 href="http://www.microsoft.com/typography/otfntdev/mongolot/features.htm">Mongolian</a>
5553 or <a
5554 href="http://www.microsoft.com/typography/otfntdev/devanot/features.aspx">Devanagari</a>
5555 additional features are required. For upright text within vertical text
5556 runs, vertical alternates (OpenType feature: <span class=tag>vert</span>)
5557 must be enabled.
5559 <h3 id=feature-precedence><span class=secno>7.2 </span>Feature precedence</h3>
5561 <p>General and <a href="#font-specific"><em>font specific</em></a> font
5562 feature property settings are resolved in the order below, in ascending
5563 order of precedence. This ordering is used to construct a combined list of
5564 font features that affect a given text run.
5566 <ol>
5567 <li>Font features enabled by default, including features required for a
5568 given script.
5570 <li>If the font is defined via an <a
5571 href="#at-font-face-rule"><code>@font-face</code></a> rule, the font
5572 features implied by the font-variant descriptor in the <a
5573 href="#at-font-face-rule"><code>@font-face</code></a> rule.
5575 <li>If the font is defined via an <a
5576 href="#at-font-face-rule"><code>@font-face</code></a> rule, the font
5577 features implied by the font-feature-settings descriptor in the <a
5578 href="#at-font-face-rule"><code>@font-face</code></a> rule.
5580 <li>Feature settings determined by properties other than <a
5581 href="#propdef-font-variant" title="font-variant!!property">‘<code
5582 class=property>font-variant</code>’</a> or <a
5583 href="#propdef-font-feature-settings"
5584 title="font-feature-settings!!property">‘<code
5585 class=property>font-feature-settings</code>’</a>. For example, setting
5586 a non-default value for the ‘<code
5587 class=property>letter-spacing</code>’ property disables common
5588 ligatures.
5590 <li>Font features implied by the value of the <a
5591 href="#propdef-font-variant" title="font-variant!!property">‘<code
5592 class=property>font-variant</code>’</a> property, the related <a
5593 href="#propdef-font-variant" title="font-variant!!property">‘<code
5594 class=property>font-variant</code>’</a> subproperties and any other CSS
5595 property that uses OpenType features (e.g. the ‘<a
5596 href="#propdef-font-kerning"><code
5597 class=property>font-kerning</code></a>’ property).
5599 <li>Font features implied by the value of <a
5600 href="#propdef-font-feature-settings"
5601 title="font-feature-settings!!property">‘<code
5602 class=property>font-feature-settings</code>’</a> property.
5603 </ol>
5605 <p>This ordering allows authors to set up a general set of defaults for
5606 fonts within their <a
5607 href="#at-font-face-rule"><code>@font-face</code></a> rules, then override
5608 them with property settings for specific elements. General property
5609 settings override the settings in <a
5610 href="#at-font-face-rule"><code>@font-face</code></a> rules and low-level
5611 font feature settings override <a href="#propdef-font-variant"
5612 title="font-variant!!property">‘<code
5613 class=property>font-variant</code>’</a> property settings.
5615 <p>For situations where the combined list of font feature settings contains
5616 more than one value for the same feature, the last value is used. When a
5617 font lacks support for a given underlying font feature, text is simply
5618 rendered as if that font feature was not enabled; font fallback does not
5619 occur and no attempt is made to synthesize the feature except where
5620 explicitly defined for specific properties.
5622 <h3 id=feature-precedence-examples><span class=secno>7.3 </span>Feature
5623 precedence examples</h3>
5625 <div class=example>
5626 <p>With the styles below, numbers are rendered proportionally when used
5627 within a paragraph but are shown in tabular form within tables of prices:</p>
5629 <pre>body {
5630 font-variant-numeric: proportional-nums;
5631 }
5633 table.prices td {
5634 font-variant-numeric: tabular-nums;
5635 }
5636 </pre>
5637 </div>
5639 <div class=example>
5640 <p>When the <a href="#descdef-font-variant"
5641 title="font-variant!!descriptor">font-variant</a> descriptor is used
5642 within an <a href="#at-font-face-rule"><code>@font-face</code></a> rule,
5643 it only applies to the font defined by that rule.</p>
5645 <pre>@font-face {
5646 font-family: MainText;
5647 src: url(http://example.com/font.ttf);
5648 font-variant: oldstyle-nums proportional-nums styleset(1,3);
5649 }
5651 body {
5652 font-family: MainText, Helvetica;
5653 }
5655 table.prices td {
5656 font-variant-numeric: tabular-nums;
5657 }
5658 </pre>
5660 <p>In this case, old-style numerals will be used throughout but only where
5661 the font "MainText" is used. Just as in the previous example, tabular
5662 values will be used in price tables since ‘<a
5663 href="#tabular-nums"><code class=property>tabular-nums</code></a>’
5664 appears in a general style rule and its use is mutually exclusive with
5665 ‘<a href="#proportional-nums"><code
5666 class=property>proportional-nums</code></a>’. Stylistic alternate sets
5667 will only be used where MainText is used.</p>
5668 </div>
5670 <div class=example>
5671 <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule can
5672 also be used to access font features in locally available fonts via the
5673 use of <code>local()</code> in the ‘<a href="#descdef-src"><code
5674 class=property>src</code></a>’ descriptor of the <a
5675 href="#at-font-face-rule"><code>@font-face</code></a> definition:</p>
5677 <pre>@font-face {
5678 font-family: BodyText;
5679 src: local("HiraMaruPro-W4");
5680 font-variant: proportional-width;
5681 font-feature-settings: "ital"; /* Latin italics within CJK text feature */
5682 }
5684 body { font-family: BodyText, serif; }
5685 </pre>
5687 <p>If available, a Japanese font "Hiragino Maru Gothic" will be used. When
5688 text rendering occurs, Japanese kana will be proportionally spaced and
5689 Latin text will be italicised. Text rendered with the fallback serif font
5690 will use default rendering properties.</p>
5691 </div>
5693 <div class=example>
5694 <p>In the example below, discretionary ligatures are enabled only for a
5695 downloadable font but are disabled within spans of class "special":</p>
5697 <pre>@font-face {
5698 font-family: main;
5699 src: url(fonts/ffmeta.woff) format("woff");
5700 font-variant: discretionary-ligatures;
5701 }
5703 body { font-family: main, Helvetica; }
5704 span.special { font-variant-ligatures: no-discretionary-ligatures; }
5705 </pre>
5707 <p>Suppose one adds a rule using ‘<code
5708 class=property>font-feature-settings</code>’ to enable discretionary
5709 ligatures:</p>
5711 <pre>body { font-family: main, Helvetica; }
5712 span { font-feature-settings: "dlig"; }
5713 span.special { font-variant-ligatures: no-discretionary-ligatures; }
5714 </pre>
5716 <p>In this case, discretionary ligatures <em>will</em> be rendered within
5717 spans of class "special". This is because both the <a
5718 href="#propdef-font-feature-settings"
5719 title="font-feature-settings!!property">‘<code
5720 class=property>font-feature-settings</code>’</a> and ‘<a
5721 href="#propdef-font-variant-ligatures"><code
5722 class=property>font-variant-ligatures</code></a>’ properties apply to
5723 these spans. Although the ‘<code class=css>no-discretionary
5724 ligatures</code>’ setting of ‘<a
5725 href="#propdef-font-variant-ligatures"><code
5726 class=property>font-variant-ligatures</code></a>’ effectively disables
5727 the OpenType <span class=tag>dlig</span> feature, because the <a
5728 href="#propdef-font-feature-settings"
5729 title="font-feature-settings!!property">‘<code
5730 class=property>font-feature-settings</code>’</a> is resolved after
5731 that, the ‘<code class=property>dlig</code>’ value reenables
5732 discretionary ligatures.</p>
5733 </div>
5735 <h2 id=object-model><span class=secno>8 </span>Object Model</h2>
5737 <p>The contents of <a href="#at-font-face-rule"><code>@font-face</code></a>
5738 and <a
5739 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
5740 rules can be accessed via the following extensions to the CSS Object
5741 Model.
5743 <h3 id=om-fontface><span class=secno>8.1 </span>The <a
5744 href="#cssfontfacerule"><code>CSSFontFaceRule</code></a> interface</h3>
5746 <p>The <dfn id=cssfontfacerule>CSSFontFaceRule</dfn> interface represents a
5747 <a href="#at-font-face-rule"><code>@font-face</code></a> rule.
5749 <pre class=idl>
5750 interface CSSFontFaceRule : CSSRule {
5751 attribute DOMString family;
5752 attribute DOMString src;
5753 attribute DOMString style;
5754 attribute DOMString weight;
5755 attribute DOMString stretch;
5756 attribute DOMString unicodeRange;
5757 attribute DOMString variant;
5758 attribute DOMString featureSettings;
5759 }</pre>
5761 <p>The DOM Level 2 Style specification <a href="#DOM-LEVEL-2-STYLE"
5762 rel=biblioentry>[DOM-LEVEL-2-STYLE]<!--{{DOM-LEVEL-2-STYLE}}--></a>
5763 defined a different variant of this rule. This definition supercedes that
5764 one.
5766 <h3 id=om-fontfeaturevalues><span class=secno>8.2 </span>The <a
5767 href="#cssfontfeaturevaluesrule"><code>CSSFontFeatureValuesRule</code></a>
5768 interface</h3>
5770 <p>The <code>CSSRule</code> interface is extended as follows:
5772 <pre class=idl>partial interface CSSRule {
5773 const unsigned short FONT_FEATURE_VALUES_RULE = 14;
5774 }</pre>
5776 <p>The <dfn id=cssfontfeaturevaluesrule>CSSFontFeatureValuesRule</dfn>
5777 interface represents a <a
5778 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
5779 rule.
5781 <pre class=idl>interface CSSFontFeatureValuesRule : CSSRule {
5782 readonly attribute DOMString familyList;
5783 readonly attribute DOMString valueText;
5784 };</pre>
5786 <dl class=idl-attributes>
5787 <dt><var>familyList</var> of type <code>DOMString</code>, readonly
5789 <dd>The list of one or more font families for which a given set of feature
5790 values is defined.
5792 <dt><var>valueText</var> of type <code>DOMString</code>, readonly
5794 <dd>Serialized set of feature values.
5795 </dl>
5797 <p class=issue>This needs to be reworked along the lines of <a
5798 href="http://lists.w3.org/Archives/Public/www-style/2013May/0781.html">Tab's
5799 proposal</a> for a rule containing a family list and map objects for each
5800 of the feature types.
5802 <h2 class=no-num id=platform-props-to-css>Appendix A: Mapping platform font
5803 properties to CSS properties</h2>
5805 <p><em>This appendix is included as background for some of the problems and
5806 situations that are described in other sections. It should be viewed as
5807 informative only.</em>
5809 <p>Font properties in CSS are designed to be independent of the underlying
5810 font formats used; they can be used to specify bitmap fonts, Type1 fonts,
5811 SVG fonts in addition to the common TrueType and OpenType fonts. But there
5812 are facets of the TrueType and OpenType formats that often cause confusion
5813 for authors and present challenges to implementers on different platforms.
5815 <p>Originally developed at Apple, TrueType was designed as an outline font
5816 format for both screen and print. Microsoft joined Apple in developing the
5817 TrueType format and both platforms have supported TrueType fonts since
5818 then. Font data in the TrueType format consists of a set of tables
5819 distinguished with common four-letter tag names, each containing a
5820 specific type of data. For example, naming information, including
5821 copyright and license information, is stored in the ‘<code
5822 class=property>name</code>’ table. The <a
5823 href="#character-map"><em>character map</em></a> (‘<code
5824 class=property>cmap</code>’) table contains a mapping of character
5825 encodings to glyphs. Apple later added additional tables for supporting
5826 enhanced typographic functionality; these are now called Apple Advanced
5827 Typography, or AAT, fonts. Microsoft and Adobe developed a separate set of
5828 tables for advanced typography and called their format OpenType <a
5829 href="#OPENTYPE" rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a>.
5831 <p>In many cases the font data used under Microsoft Windows or Linux is
5832 slightly different from the data used under Apple's Mac OS X because the
5833 TrueType format allowed for explicit variation across platforms. This
5834 includes font metrics, names and <a href="#character-map"><em>character
5835 map</em></a> data.
5837 <p>Specifically, font family name data is handled differently across
5838 platforms. For TrueType and OpenType fonts these names are contained in
5839 the ‘<code class=property>name</code>’ table, in name records with
5840 name ID 1. Mulitple names can be stored for different locales, but
5841 Microsoft recommends fonts always include at least a US English version of
5842 the name. On Windows, Microsoft made the decision for backwards
5843 compatibility to limit this family name to a maximum of four faces; for
5844 larger groupings the "preferred family" (name ID 16) or "WWS family" (name
5845 ID 21) can be used. Other platforms such as OSX don't have this
5846 limitation, so the family name is used to define all possible groupings.
5848 <p>Other name table data provides names used to uniquely identify a
5849 specific face within a family. The full font name (name ID 4) and the
5850 Postscript name (name ID 6) describe a single face uniquely. For example,
5851 the bold face of the Gill Sans family has a fullname of "Gill Sans Bold"
5852 and a Postscript name of "GillSans-Bold". There can be multiple localized
5853 versions of the fullname for a given face, but the Postscript name is
5854 always a unique name made from a limited set of ASCII characters.
5856 <p>On various platforms, different names are used to search for a font. For
5857 example, with the Windows GDI CreateIndirectFont API, either a family or
5858 fullname can be used to lookup a face, while on Mac OS X the
5859 CTFontCreateWithName API call is used to lookup a given face using the
5860 fullname and Postscript name. Under Linux, the fontconfig API allows fonts
5861 to be searched using any of these names. In situations where platform
5862 API's automatically substitute other font choices, it may be necessary to
5863 verify a returned font matches a given name.
5865 <p>The weight of a given face can be determined via the usWeightClass field
5866 of the OS/2 table or inferred from the style name (name ID 2). Likewise,
5867 the width can be determined via the usWidthClass of the OS/2 table or
5868 inferred from the style name. For historical reasons related to synthetic
5869 bolding at weights 200 or lower with the Windows GDI API, font designers
5870 have sometimes skewed values in the OS/2 table to avoid these weights.
5872 <p>Rendering complex scripts that use contextual shaping such as Thai,
5873 Arabic and Devanagari requires features present only in OpenType or AAT
5874 fonts. Currently, complex script rendering is supported on Windows and
5875 Linux using OpenType font features while both OpenType and AAT font
5876 features are used under Mac OS X.
5878 <h2 class=no-num id=ch-ch-ch-changes>Changes</h2>
5880 <h3 class=no-num id=recent-changes> Changes from the <a
5881 href="http://www.w3.org/TR/2013/WD-css3-fonts-20130212/">February 2013
5882 CSS3 Fonts Working Draft</a></h3>
5884 <p>Major changes include:
5886 <ul>
5887 <li>Moved font load events into a separate <a
5888 href="http://dev.w3.org/csswg/css3-font-load-events/">spec</a>
5890 <li>Tightened syntax rules for <a
5891 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
5892 rules
5894 <li>Added grammar productions for <a
5895 href="#at-font-face-rule"><code>@font-face</code></a> and <a
5896 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
5897 rules
5899 <li>Tightened definition of synthetic oblique
5901 <li>Revised definition of ‘<a href="#descdef-unicode-range"><code
5902 class=property>unicode-range</code></a>’ descriptor
5904 <li>Detailed font matching of composite faces
5905 </ul>
5907 <h2 class=no-num id=acknowledgments>Acknowledgments</h2>
5909 <p>I'd like to thank Tal Leming, Jonathan Kew and Christopher Slye for all
5910 their help and feedback. John Hudson was kind enough to take the time to
5911 explain the subtleties of OpenType language tags and provided the example
5912 of character variant usage for displaying text on Byzantine seals. Ken
5913 Lunde and Eric Muller provided valuable feedback on CJK OpenType features
5914 and Unicode variation selectors. The idea for supporting font features by
5915 using <a href="#propdef-font-variant"
5916 title="font-variant!!property">‘<code
5917 class=property>font-variant</code>’</a> subproperties originated with
5918 Håkon Wium Lie, Adam Twardoch and Tal Leming. Elika Etemad supplied some
5919 of the initial design ideas for the <a
5920 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
5921 rule. Thanks also to House Industries for allowing the use of Ed Interlock
5922 in the discretionary ligatures example.
5924 <p>A special thanks to Robert Bringhurst for the sublime mind expansion
5925 that is <em>The Elements of Typographic Style</em>.
5927 <h2 class=no-num id=conformance> Conformance</h2>
5929 <h3 class=no-num id=conventions> Document Conventions</h3>
5931 <p>Conformance requirements are expressed with a combination of descriptive
5932 assertions and RFC 2119 terminology. The key words “MUST”, “MUST
5933 NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”,
5934 “SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL” in the
5935 normative parts of this document are to be interpreted as described in RFC
5936 2119. However, for readability, these words do not appear in all uppercase
5937 letters in this specification.
5939 <p>All of the text of this specification is normative except sections
5940 explicitly marked as non-normative, examples, and notes. <a
5941 href="#RFC2119" rel=biblioentry>[RFC2119]<!--{{!RFC2119}}--></a>
5943 <p>Examples in this specification are introduced with the words “for
5944 example” or are set apart from the normative text with
5945 <code>class="example"</code>, like this:
5947 <div class=example>
5948 <p>This is an example of an informative example.
5949 </div>
5951 <p>Informative notes begin with the word “Note” and are set apart from
5952 the normative text with <code>class="note"</code>, like this:
5954 <p class=note>Note, this is an informative note.
5956 <h3 class=no-num id=conformance-classes> Conformance Classes</h3>
5958 <p>Conformance to CSS Fonts Level 3 Module is defined for three conformance
5959 classes:
5961 <dl>
5962 <dt><dfn id=style-sheet title="style sheet!!as conformance class">style
5963 sheet</dfn>
5965 <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#style-sheet">CSS
5966 style sheet</a>.
5968 <dt><dfn id=renderer>renderer</dfn>
5970 <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
5971 that interprets the semantics of a style sheet and renders documents that
5972 use them.
5974 <dt><dfn id=authoring-tool>authoring tool</dfn>
5976 <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
5977 that writes a style sheet.
5978 </dl>
5980 <p>A style sheet is conformant to CSS Fonts Level 3 Module if all of its
5981 declarations that use properties defined in this module have values that
5982 are valid according to the generic CSS grammar and the individual grammars
5983 of each property as given in this module.
5985 <p>A renderer is conformant to CSS Fonts Level 3 Module if, in addition to
5986 interpreting the style sheet as defined by the appropriate specifications,
5987 it supports all the features defined by CSS Fonts Level 3 Module by
5988 parsing them correctly and rendering the document accordingly. However,
5989 the inability of a UA to correctly render a document due to limitations of
5990 the device does not make the UA non-conformant. (For example, a UA is not
5991 required to render color on a monochrome monitor.)
5993 <p>An authoring tool is conformant to CSS Fonts Level 3 Module if it writes
5994 style sheets that are syntactically correct according to the generic CSS
5995 grammar and the individual grammars of each feature in this module, and
5996 meet all other conformance requirements of style sheets as described in
5997 this module.
5999 <h3 class=no-num id=partial> Partial Implementations</h3>
6001 <p>So that authors can exploit the forward-compatible parsing rules to
6002 assign fallback values, CSS renderers <strong>must</strong> treat as
6003 invalid (and <a
6004 href="http://www.w3.org/TR/CSS21/conform.html#ignore">ignore as
6005 appropriate</a>) any at-rules, properties, property values, keywords, and
6006 other syntactic constructs for which they have no usable level of support.
6007 In particular, user agents <strong>must not</strong> selectively ignore
6008 unsupported component values and honor supported values in a single
6009 multi-value property declaration: if any value is considered invalid (as
6010 unsupported values must be), CSS requires that the entire declaration be
6011 ignored.
6013 <h3 class=no-num id=experimental> Experimental Implementations</h3>
6015 <p>To avoid clashes with future CSS features, the CSS2.1 specification
6016 reserves a <a
6017 href="http://www.w3.org/TR/CSS21/syndata.html#vendor-keywords">prefixed
6018 syntax</a> for proprietary and experimental extensions to CSS.
6020 <p>Prior to a specification reaching the Candidate Recommendation stage in
6021 the W3C process, all implementations of a CSS feature are considered
6022 experimental. The CSS Working Group recommends that implementations use a
6023 vendor-prefixed syntax for such features, including those in W3C Working
6024 Drafts. This avoids incompatibilities with future changes in the draft.
6026 <h3 class=no-num id=testing> Non-Experimental Implementations</h3>
6028 <p>Once a specification reaches the Candidate Recommendation stage,
6029 non-experimental implementations are possible, and implementors should
6030 release an unprefixed implementation of any CR-level feature they can
6031 demonstrate to be correctly implemented according to spec.
6033 <p>To establish and maintain the interoperability of CSS across
6034 implementations, the CSS Working Group requests that non-experimental CSS
6035 renderers submit an implementation report (and, if necessary, the
6036 testcases used for that implementation report) to the W3C before releasing
6037 an unprefixed implementation of any CSS features. Testcases submitted to
6038 W3C are subject to review and correction by the CSS Working Group.
6040 <p>Further information on submitting testcases and implementation reports
6041 can be found from on the CSS Working Group's website at <a
6042 href="http://www.w3.org/Style/CSS/Test/">http://www.w3.org/Style/CSS/Test/</a>.
6043 Questions should be directed to the <a
6044 href="http://lists.w3.org/Archives/Public/public-css-testsuite">public-css-testsuite@w3.org</a>
6045 mailing list.
6047 <h2 class=no-num id=references>References</h2>
6049 <h3 class=no-num id=normative-references>Normative References</h3>
6050 <!--begin-normative-->
6051 <!-- Sorted by label -->
6053 <dl class=bibliography>
6054 <dd style="display: none"><!-- keeps the doc valid if the DL is empty -->
6055 <!---->
6057 <dt id=CHARMOD>[CHARMOD]
6059 <dd>Martin J. Dürst; et al. <a
6060 href="http://www.w3.org/TR/2005/REC-charmod-20050215/"><cite>Character
6061 Model for the World Wide Web 1.0: Fundamentals.</cite></a> 15 February
6062 2005. W3C Recommendation. URL: <a
6063 href="http://www.w3.org/TR/2005/REC-charmod-20050215/">http://www.w3.org/TR/2005/REC-charmod-20050215/</a>
6064 </dd>
6065 <!---->
6067 <dt id=CORS>[CORS]
6069 <dd>Anne van Kesteren. <a
6070 href="http://www.w3.org/TR/2013/CR-cors-20130129/"><cite>Cross-Origin
6071 Resource Sharing.</cite></a> 29 January 2013. W3C Candidate
6072 Recommendation. (Work in progress.) URL: <a
6073 href="http://www.w3.org/TR/2013/CR-cors-20130129/">http://www.w3.org/TR/2013/CR-cors-20130129/</a>
6074 </dd>
6075 <!---->
6077 <dt id=CSS21>[CSS21]
6079 <dd>Bert Bos; et al. <a
6080 href="http://www.w3.org/TR/2011/REC-CSS2-20110607"><cite>Cascading Style
6081 Sheets Level 2 Revision 1 (CSS 2.1) Specification.</cite></a> 7 June
6082 2011. W3C Recommendation. URL: <a
6083 href="http://www.w3.org/TR/2011/REC-CSS2-20110607">http://www.w3.org/TR/2011/REC-CSS2-20110607</a>
6084 </dd>
6085 <!---->
6087 <dt id=CSS3VAL>[CSS3VAL]
6089 <dd>Håkon Wium Lie; Tab Atkins; Elika J. Etemad. <a
6090 href="http://www.w3.org/TR/2013/CR-css3-values-20130404/"><cite>CSS
6091 Values and Units Module Level 3.</cite></a> 4 April 2013. W3C Candidate
6092 Recommendation. (Work in progress.) URL: <a
6093 href="http://www.w3.org/TR/2013/CR-css3-values-20130404/">http://www.w3.org/TR/2013/CR-css3-values-20130404/</a>
6094 </dd>
6095 <!---->
6097 <dt id=HTML5>[HTML5]
6099 <dd>Ian Hickson. <a
6100 href="http://www.w3.org/TR/2012/CR-html5-20121217/"><cite>HTML5.</cite></a>
6101 17 December 2012. W3C Candidate Recommendation. (Work in progress.) URL:
6102 <a
6103 href="http://www.w3.org/TR/2012/CR-html5-20121217/">http://www.w3.org/TR/2012/CR-html5-20121217/</a>
6104 </dd>
6105 <!---->
6107 <dt id=OPEN-FONT-FORMAT>[OPEN-FONT-FORMAT]
6109 <dd><a
6110 href="http://standards.iso.org/ittf/PubliclyAvailableStandards/c052136_ISO_IEC_14496-22_2009(E).zip"><cite>Information
6111 technology — Coding of audio-visual objects — Part 22: Open Font
6112 Format.</cite></a> International Organization for Standardization.
6113 ISO/IEC 14496-22:2009. URL: <a
6114 href="http://standards.iso.org/ittf/PubliclyAvailableStandards/c052136_ISO_IEC_14496-22_2009(E).zip">http://standards.iso.org/ittf/PubliclyAvailableStandards/c052136_ISO_IEC_14496-22_2009(E).zip</a>
6115 </dd>
6116 <!---->
6118 <dt id=OPENTYPE>[OPENTYPE]
6120 <dd><a
6121 href="http://www.microsoft.com/typography/otspec/default.htm"><cite>OpenType
6122 specification.</cite></a> Microsoft. URL: <a
6123 href="http://www.microsoft.com/typography/otspec/default.htm">http://www.microsoft.com/typography/otspec/default.htm</a>
6124 </dd>
6125 <!---->
6127 <dt id=OPENTYPE-FEATURES>[OPENTYPE-FEATURES]
6129 <dd><a
6130 href="http://www.microsoft.com/typography/otspec/featurelist.htm"><cite>OpenType
6131 feature registry.</cite></a> Microsoft. URL: <a
6132 href="http://www.microsoft.com/typography/otspec/featurelist.htm">http://www.microsoft.com/typography/otspec/featurelist.htm</a>
6133 </dd>
6134 <!---->
6136 <dt id=RFC2119>[RFC2119]
6138 <dd>S. Bradner. <a href="http://www.ietf.org/rfc/rfc2119.txt"><cite>Key
6139 words for use in RFCs to Indicate Requirement Levels.</cite></a> Internet
6140 RFC 2119. URL: <a
6141 href="http://www.ietf.org/rfc/rfc2119.txt">http://www.ietf.org/rfc/rfc2119.txt</a>
6142 </dd>
6143 <!---->
6145 <dt id=UAX15>[UAX15]
6147 <dd>Mark Davis; Ken Whistler. <a
6148 href="http://www.unicode.org/reports/tr15/"><cite>Unicode Normalization
6149 Forms.</cite></a> 31 August 2012. Unicode Standard Annex #15. URL: <a
6150 href="http://www.unicode.org/reports/tr15/">http://www.unicode.org/reports/tr15/</a>
6151 </dd>
6152 <!---->
6154 <dt id=UAX29>[UAX29]
6156 <dd>Mark Davis. <a
6157 href="http://www.unicode.org/reports/tr29/"><cite>Unicode Text
6158 Segmentation.</cite></a> 12 September 2012. Unicode Standard Annex #29.
6159 URL: <a
6160 href="http://www.unicode.org/reports/tr29/">http://www.unicode.org/reports/tr29/</a>
6161 </dd>
6162 <!---->
6164 <dt id=UNICODE6>[UNICODE6]
6166 <dd>The Unicode Consortium. <a
6167 href="http://www.unicode.org/versions/Unicode6.2.0/"><cite>The Unicode
6168 Standard, Version 6.2.0.</cite></a> Defined by: The Unicode Standard,
6169 Version 6.2.0 URL: <a
6170 href="http://www.unicode.org/versions/Unicode6.2.0/">http://www.unicode.org/versions/Unicode6.2.0/</a>
6171 </dd>
6172 <!---->
6173 </dl>
6174 <!--end-normative-->
6175 <!--{{!CSS21}}-->
6176 <!--{{!CSS3VAL}}-->
6177 <!--{{!OPENTYPE}}-->
6178 <!--{{!OPENTYPE-FEATURES}}-->
6179 <!--{{!OPEN-FONT-FORMAT}}-->
6180 <!--{{!UNICODE6}}-->
6181 <!--{{!UAX15}}-->
6182 <!--{{!UAX29}}-->
6183 <!--{{!CORS}}-->
6184 <!--{{!HTML5}}-->
6185 <!--{{!CHARMOD}}-->
6187 <h3 class=no-num id=other-references>Other References</h3>
6188 <!--begin-informative-->
6189 <!-- Sorted by label -->
6191 <dl class=bibliography>
6192 <dd style="display: none"><!-- keeps the doc valid if the DL is empty -->
6193 <!---->
6195 <dt id=AAT-FEATURES>[AAT-FEATURES]
6197 <dd><a href="http://developer.apple.com/fonts/registry/"><cite>Apple
6198 Advanced Typography font feature registry.</cite></a> Apple. URL: <a
6199 href="http://developer.apple.com/fonts/registry/">http://developer.apple.com/fonts/registry/</a>
6200 </dd>
6201 <!---->
6203 <dt id=ARABIC-TYPO>[ARABIC-TYPO]
6205 <dd>Huda Smitshuijzen AbiFares. <cite>Arabic Typography: A Comprehensive
6206 Sourcebook.</cite> Saqi Books. 2001. ISBN 0-86356-347-3.</dd>
6207 <!---->
6209 <dt id=CHARMOD-NORM>[CHARMOD-NORM]
6211 <dd>François Yergeau; et al. <a
6212 href="http://www.w3.org/TR/2012/WD-charmod-norm-20120501/"><cite>Character
6213 Model for the World Wide Web 1.0: Normalization.</cite></a> 1 May 2012.
6214 W3C Working Draft. (Work in progress.) URL: <a
6215 href="http://www.w3.org/TR/2012/WD-charmod-norm-20120501/">http://www.w3.org/TR/2012/WD-charmod-norm-20120501/</a>
6216 </dd>
6217 <!---->
6219 <dt id=CJKV-INFO-PROCESSING>[CJKV-INFO-PROCESSING]
6221 <dd>Ken Lunde. <cite>CJKV Information Processing, Second Edition.</cite>
6222 O'Reilly Media, Inc. 2009. ISBN 0-596-51447-1.</dd>
6223 <!---->
6225 <dt id=CSS3-CONDITIONAL>[CSS3-CONDITIONAL]
6227 <dd>L. David Baron. <a
6228 href="http://www.w3.org/TR/2013/CR-css3-conditional-20130404/"><cite>CSS
6229 Conditional Rules Module Level 3.</cite></a> 4 April 2013. W3C Candidate
6230 Recommendation. (Work in progress.) URL: <a
6231 href="http://www.w3.org/TR/2013/CR-css3-conditional-20130404/">http://www.w3.org/TR/2013/CR-css3-conditional-20130404/</a>
6232 </dd>
6233 <!---->
6235 <dt id=CSS3TEXT>[CSS3TEXT]
6237 <dd>Elika J. Etemad; Koji Ishii. <a
6238 href="http://www.w3.org/TR/2012/WD-css3-text-20121113/"><cite>CSS Text
6239 Module Level 3.</cite></a> 13 November 2012. W3C Working Draft. (Work in
6240 progress.) URL: <a
6241 href="http://www.w3.org/TR/2012/WD-css3-text-20121113/">http://www.w3.org/TR/2012/WD-css3-text-20121113/</a>
6242 </dd>
6243 <!---->
6245 <dt id=DIGITAL-TYPOGRAPHY>[DIGITAL-TYPOGRAPHY]
6247 <dd>Richard Rubinstein. <cite>Digital Typography, An Introduction to Type
6248 and Composition for Computer System Design.</cite> Addison-Wesley. 1988.
6249 ISBN 0-201-17633-5.</dd>
6250 <!---->
6252 <dt id=DOM-LEVEL-2-STYLE>[DOM-LEVEL-2-STYLE]
6254 <dd>Chris Wilson; Philippe Le Hégaret; Vidur Apparao. <a
6255 href="http://www.w3.org/TR/2000/REC-DOM-Level-2-Style-20001113/"><cite>Document
6256 Object Model (DOM) Level 2 Style Specification.</cite></a> 13 November
6257 2000. W3C Recommendation. URL: <a
6258 href="http://www.w3.org/TR/2000/REC-DOM-Level-2-Style-20001113/">http://www.w3.org/TR/2000/REC-DOM-Level-2-Style-20001113/</a>
6259 </dd>
6260 <!---->
6262 <dt id=ELEMTYPO>[ELEMTYPO]
6264 <dd>Robert Bringhurst. <cite>The Elements of Typographic Style, Version
6265 4.</cite> Hartley & Marks. 2013. ISBN 0-88179-212-8.</dd>
6266 <!---->
6268 <dt id=LANGCULTTYPE>[LANGCULTTYPE]
6270 <dd>John D. Berry, Ed. <cite>Language Culture Type.</cite> Graphis. 2001.
6271 ISBN 1-932026-01-0.</dd>
6272 <!---->
6274 <dt id=OPENTYPE-FONT-GUIDE>[OPENTYPE-FONT-GUIDE]
6276 <dd><a
6277 href="https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf"><cite>OpenType
6278 User Guide.</cite></a> FontShop International. URL: <a
6279 href="https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf">https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf</a>
6280 </dd>
6281 <!---->
6283 <dt id=RASTER-TRAGEDY>[RASTER-TRAGEDY]
6285 <dd>Beat Stamm. <a href="http://www.rastertragedy.com/"><cite>The Raster
6286 Tragedy at Low-Resolution Revisited.</cite></a> 7 December 2011. URL: <a
6287 href="http://www.rastertragedy.com/">http://www.rastertragedy.com/</a></dd>
6288 <!---->
6290 <dt id=WINDOWS-GLYPH-PROC>[WINDOWS-GLYPH-PROC]
6292 <dd>John Hudson. <a
6293 href="http://www.microsoft.com/typography/developers/opentype/default.htm"><cite>Windows
6294 Glyph Processing.</cite></a> Microsoft Typogrraphy. URL: <a
6295 href="http://www.microsoft.com/typography/developers/opentype/default.htm">http://www.microsoft.com/typography/developers/opentype/default.htm</a>
6296 </dd>
6297 <!---->
6298 </dl>
6299 <!--end-informative-->
6300 <!--{{ARABIC-TYPO}}-->
6301 <!--{{CJKV-INFO-PROCESSING}}-->
6302 <!--{{DIGITAL-TYPOGRAPHY}}-->
6303 <!--{{DOM-LEVEL-2-STYLE}}-->
6304 <!--{{ELEMTYPO}}-->
6305 <!--{{LANGCULTTYPE}}-->
6306 <!--{{OPENTYPE-FONT-GUIDE}}-->
6307 <!--{{RASTER-TRAGEDY}}-->
6308 <!--{{WINDOWS-GLYPH-PROC}}-->
6309 <!--{{CHARMOD-NORM}}-->
6310 <!--{{AAT-FEATURES}}-->
6311 <!--{{CSS3-CONDITIONAL}}-->
6312 <!--{{CSS3TEXT}}-->
6314 <h2 class=no-num id=index>Index</h2>
6315 <!--begin-index-->
6317 <ul class=indexlist>
6318 <li>100...900 weight values, <a href="#font-weight-numeric-values"
6319 title="100...900 weight values"><strong>3.2</strong></a>
6321 <li><var><absolute-size></var>, <a href="#absolute-size-value"
6322 title="<absolute-size>"><strong>3.5</strong></a>
6324 <li><var><common-lig-values></var>, <a href="#common-lig-values"
6325 title="<common-lig-values>"><strong>6.4</strong></a>
6327 <li><var><contextual-alt-values></var>, <a
6328 href="#contextual-alt-values"
6329 title="<contextual-alt-values>"><strong>6.4</strong></a>
6331 <li><var><discretionary-lig-values></var>, <a
6332 href="#discretionary-lig-values"
6333 title="<discretionary-lig-values>"><strong>6.4</strong></a>
6335 <li><var><east-asian-variant-values></var>, <a
6336 href="#east-asian-variant-values"
6337 title="<east-asian-variant-values>"><strong>6.10</strong></a>
6339 <li><var><east-asian-width-values></var>, <a
6340 href="#east-asian-width-values"
6341 title="<east-asian-width-values>"><strong>6.10</strong></a>
6343 <li><var><family-name></var>, <a href="#family-name-value"
6344 title="<family-name>"><strong>3.1</strong></a>
6346 <li><var><feature-tag-value></var>, <a href="#feature-tag-value"
6347 title="<feature-tag-value>"><strong>6.12</strong></a>
6349 <li><var><font-face-name></var>, <a href="#font-face-name-value"
6350 title="<font-face-name>"><strong>4.3</strong></a>
6352 <li><var><font-variant-css21></var>, <a
6353 href="#font-variant-css21-values"
6354 title="<font-variant-css21>"><strong>3.7</strong></a>
6356 <li><var><generic-family></var>, <a href="#generic-family-value"
6357 title="<generic-family>"><strong>3.1</strong></a>
6359 <li><var><historical-lig-values></var>, <a
6360 href="#historical-lig-values"
6361 title="<historical-lig-values>"><strong>6.4</strong></a>
6363 <li><var><length></var>, <a href="#length-size-value"
6364 title="<length>"><strong>3.5</strong></a>
6366 <li><var><number></var>, <a href="#aspect-ratio-value"
6367 title="<number>"><strong>3.6</strong></a>
6369 <li><var><numeric-figure-values></var>, <a
6370 href="#numeric-figure-values"
6371 title="<numeric-figure-values>"><strong>6.7</strong></a>
6373 <li><var><numeric-fraction-values></var>, <a
6374 href="#numeric-fraction-values"
6375 title="<numeric-fraction-values>"><strong>6.7</strong></a>
6377 <li><var><numeric-spacing-values></var>, <a
6378 href="#numeric-spacing-values"
6379 title="<numeric-spacing-values>"><strong>6.7</strong></a>
6381 <li><var><percentage></var>, <a href="#percentage-size-value"
6382 title="<percentage>"><strong>3.5</strong></a>
6384 <li><var><relative-size></var>, <a href="#relative-size-value"
6385 title="<relative-size>"><strong>3.5</strong></a>
6387 <li><var><string></var>, <a
6388 href="#font-language-override-string-value"
6389 title="<string>"><strong>6.13</strong></a>
6391 <li><var><urange></var>, <a href="#urange-value"
6392 title="<urange>"><strong>4.5</strong></a>
6394 <li><code>@font-face</code>, <a href="#at-font-face-rule"
6395 title="@font-face"><strong>4.1</strong></a>
6397 <li><code>@font-feature-values</code>, <a
6398 href="#at-font-feature-values-rule"
6399 title="@font-feature-values"><strong>6.9</strong></a>
6401 <li>all-petite-caps, <a href="#all-petite-caps"
6402 title=all-petite-caps><strong>6.6</strong></a>
6404 <li>all-small-caps, <a href="#all-small-caps"
6405 title=all-small-caps><strong>6.6</strong></a>
6407 <li>annotation, <a href="#annotation"
6408 title=annotation><strong>6.8</strong></a>
6410 <li>aspect value, <a href="#aspect-value0" title="aspect
6411 value"><strong>3.6</strong></a>
6413 <li>authoring tool, <a href="#authoring-tool" title="authoring
6414 tool"><strong>#</strong></a>
6416 <li>auto
6417 <ul>
6418 <li>font-kerning, <a href="#font-kerning-auto-value" title="auto,
6419 font-kerning"><strong>6.3</strong></a>
6421 <li>font-size-adjust, <a href="#font-size-adjust-auto-value"
6422 title="auto, font-size-adjust"><strong>3.6</strong></a>
6423 </ul>
6425 <li>bold, <a href="#bold" title=bold><strong>3.2</strong></a>
6427 <li>bolder, <a href="#bolder" title=bolder><strong>3.2</strong></a>
6429 <li>character map, <a href="#character-map" title="character
6430 map"><strong>5.2</strong></a>
6432 <li>character-variant, <a href="#character-variant"
6433 title=character-variant><strong>6.8</strong></a>
6435 <li>common-ligatures, <a href="#common-ligatures"
6436 title=common-ligatures><strong>6.4</strong></a>
6438 <li>composite face, <a href="#composite-face" title="composite
6439 face"><strong>5.2</strong></a>
6441 <li>condensed, <a href="#condensed"
6442 title=condensed><strong>3.3</strong></a>
6444 <li>contextual, <a href="#contextual"
6445 title=contextual><strong>6.4</strong></a>
6447 <li>CSSFontFaceRule, <a href="#cssfontfacerule"
6448 title=CSSFontFaceRule><strong>8.1</strong></a>
6450 <li>CSSFontFeatureValuesRule, <a href="#cssfontfeaturevaluesrule"
6451 title=CSSFontFeatureValuesRule><strong>8.2</strong></a>
6453 <li>cursive, definition of, <a href="#cursive0" title="cursive, definition
6454 of"><strong>#</strong></a>
6456 <li>default face, <a href="#default-face" title="default
6457 face"><strong>5.2</strong></a>
6459 <li>descriptor_declaration, <a href="#descriptordeclaration"
6460 title="descriptor_declaration"><strong>4.1</strong></a>
6462 <li>diagonal-fractions, <a href="#diagonal-fractions"
6463 title=diagonal-fractions><strong>6.7</strong></a>
6465 <li>discretionary-ligatures, <a href="#discretionary-ligatures"
6466 title=discretionary-ligatures><strong>6.4</strong></a>
6468 <li>effective character map, <a href="#effective-character-map"
6469 title="effective character map"><strong>4.5</strong></a>
6471 <li>expanded, <a href="#expanded" title=expanded><strong>3.3</strong></a>
6473 <li>extra-condensed, <a href="#extra-condensed"
6474 title=extra-condensed><strong>3.3</strong></a>
6476 <li>extra-expanded, <a href="#extra-expanded"
6477 title=extra-expanded><strong>3.3</strong></a>
6479 <li>fantasy, definition of, <a href="#fantasy0" title="fantasy, definition
6480 of"><strong>#</strong></a>
6482 <li>feature_type, <a href="#featuretype"
6483 title="feature_type"><strong>6.9.1</strong></a>
6485 <li>feature_value_block, <a href="#featurevalueblock"
6486 title="feature_value_block"><strong>6.9.1</strong></a>
6488 <li>feature_value_definition, <a href="#featurevaluedefinition"
6489 title="feature_value_definition"><strong>6.9.1</strong></a>
6491 <li>first available font, <a href="#first-available-font" title="first
6492 available font"><strong>5.2</strong></a>
6494 <li>font, <a href="#propdef-font" title=font><strong>3.7</strong></a>
6496 <li>font specific, <a href="#font-specific" title="font
6497 specific"><strong>6.8</strong></a>
6499 <li>font-family
6500 <ul>
6501 <li>descriptor, <a href="#descdef-font-family" title="font-family,
6502 descriptor"><strong>4.2</strong></a>
6504 <li>property, <a href="#propdef-font-family" title="font-family,
6505 property"><strong>3.1</strong></a>
6506 </ul>
6508 <li>font-feature-settings
6509 <ul>
6510 <li>descriptor, <a href="#descdef-font-feature-settings"
6511 title="font-feature-settings, descriptor"><strong>4.7</strong></a>
6513 <li>property, <a href="#propdef-font-feature-settings"
6514 title="font-feature-settings, property"><strong>6.12</strong></a>
6515 </ul>
6517 <li>font-kerning, <a href="#propdef-font-kerning"
6518 title=font-kerning><strong>6.3</strong></a>
6520 <li>font-language-override, <a href="#propdef-font-language-override"
6521 title=font-language-override><strong>6.13</strong></a>
6523 <li>font-size, <a href="#propdef-font-size"
6524 title=font-size><strong>3.5</strong></a>
6526 <li>font-size-adjust, <a href="#propdef-font-size-adjust"
6527 title=font-size-adjust><strong>3.6</strong></a>
6529 <li>font-stretch
6530 <ul>
6531 <li>descriptor, <a href="#descdef-font-stretch" title="font-stretch,
6532 descriptor"><strong>4.4</strong></a>
6534 <li>property, <a href="#propdef-font-stretch" title="font-stretch,
6535 property"><strong>3.3</strong></a>
6536 </ul>
6538 <li>font-style
6539 <ul>
6540 <li>descriptor, <a href="#descdef-font-style" title="font-style,
6541 descriptor"><strong>4.4</strong></a>
6543 <li>property, <a href="#propdef-font-style" title="font-style,
6544 property"><strong>3.4</strong></a>
6545 </ul>
6547 <li>font-synthesis, <a href="#propdef-font-synthesis"
6548 title=font-synthesis><strong>3.8</strong></a>
6550 <li>font-variant
6551 <ul>
6552 <li>descriptor, <a href="#descdef-font-variant" title="font-variant,
6553 descriptor"><strong>4.7</strong></a>
6555 <li>property, <a href="#propdef-font-variant" title="font-variant,
6556 property"><strong>6.11</strong></a>
6557 </ul>
6559 <li>font-variant-alternates, <a href="#propdef-font-variant-alternates"
6560 title=font-variant-alternates><strong>6.8</strong></a>
6562 <li>font-variant-caps, <a href="#propdef-font-variant-caps"
6563 title=font-variant-caps><strong>6.6</strong></a>
6565 <li>font-variant-east-asian, <a href="#propdef-font-variant-east-asian"
6566 title=font-variant-east-asian><strong>6.10</strong></a>
6568 <li>font-variant-ligatures, <a href="#propdef-font-variant-ligatures"
6569 title=font-variant-ligatures><strong>6.4</strong></a>
6571 <li>font-variant-numeric, <a href="#propdef-font-variant-numeric"
6572 title=font-variant-numeric><strong>6.7</strong></a>
6574 <li>font-variant-position, <a href="#propdef-font-variant-position"
6575 title=font-variant-position><strong>6.5</strong></a>
6577 <li>font-weight
6578 <ul>
6579 <li>descriptor, <a href="#descdef-font-weight" title="font-weight,
6580 descriptor"><strong>4.4</strong></a>
6582 <li>property, <a href="#propdef-font-weight" title="font-weight,
6583 property"><strong>3.2</strong></a>
6584 </ul>
6586 <li>font_face_rule, <a href="#fontfacerule"
6587 title="font_face_rule"><strong>4.1</strong></a>
6589 <li>FONT_FACE_SYM, <a href="#fontfacesym"
6590 title="FONT_FACE_SYM"><strong>4.1</strong></a>
6592 <li>font_family_name, <a href="#fontfamilyname"
6593 title="font_family_name"><strong>6.9.1</strong></a>
6595 <li>font_family_name_list, <a href="#fontfamilynamelist"
6596 title="font_family_name_list"><strong>6.9.1</strong></a>
6598 <li>font_feature_values_rule, <a href="#fontfeaturevaluesrule"
6599 title="font_feature_values_rule"><strong>6.9.1</strong></a>
6601 <li>FONT_FEATURE_VALUES_SYM, <a href="#fontfeaturevaluessym"
6602 title="FONT_FEATURE_VALUES_SYM"><strong>6.9.1</strong></a>
6604 <li>full-width, <a href="#full-width"
6605 title=full-width><strong>6.10</strong></a>
6607 <li>historical-forms, <a href="#historical-forms"
6608 title=historical-forms><strong>6.8</strong></a>
6610 <li>historical-ligatures, <a href="#historical-ligatures"
6611 title=historical-ligatures><strong>6.4</strong></a>
6613 <li>italic, <a href="#italic" title=italic><strong>3.4</strong></a>
6615 <li>jis04, <a href="#jis04" title=jis04><strong>6.10</strong></a>
6617 <li>jis78, <a href="#jis78" title=jis78><strong>6.10</strong></a>
6619 <li>jis83, <a href="#jis83" title=jis83><strong>6.10</strong></a>
6621 <li>jis90, <a href="#jis90" title=jis90><strong>6.10</strong></a>
6623 <li>lighter, <a href="#lighter" title=lighter><strong>3.2</strong></a>
6625 <li>lining-nums, <a href="#lining-nums"
6626 title=lining-nums><strong>6.7</strong></a>
6628 <li>monospace, definition of, <a href="#monospace0" title="monospace,
6629 definition of"><strong>#</strong></a>
6631 <li>no-common-ligatures, <a href="#no-common-ligatures"
6632 title=no-common-ligatures><strong>6.4</strong></a>
6634 <li>no-contextual, <a href="#no-contextual"
6635 title=no-contextual><strong>6.4</strong></a>
6637 <li>no-discretionary-ligatures, <a href="#no-discretionary-ligatures"
6638 title=no-discretionary-ligatures><strong>6.4</strong></a>
6640 <li>no-historical-ligatures, <a href="#no-historical-ligatures"
6641 title=no-historical-ligatures><strong>6.4</strong></a>
6643 <li>none
6644 <ul>
6645 <li>font-kerning, <a href="#font-kerning-none-value" title="none,
6646 font-kerning"><strong>6.3</strong></a>
6648 <li>font-size-adjust, <a href="#font-size-adjust-none-value"
6649 title="none, font-size-adjust"><strong>3.6</strong></a>
6651 <li>font-variant, <a href="#font-variant-none-value" title="none,
6652 font-variant"><strong>6.11</strong></a>
6654 <li>font-variant-ligatures, <a href="#font-variant-ligatures-none-value"
6655 title="none, font-variant-ligatures"><strong>6.4</strong></a>
6656 </ul>
6658 <li>normal
6659 <ul>
6660 <li>font-feature-settings, <a href="#font-feature-settings-normal-value"
6661 title="normal, font-feature-settings"><strong>6.12</strong></a>
6663 <li>font-kerning, <a href="#font-kerning-normal-value" title="normal,
6664 font-kerning"><strong>6.3</strong></a>
6666 <li>font-language-override, <a
6667 href="#font-language-override-normal-value" title="normal,
6668 font-language-override"><strong>6.13</strong></a>
6670 <li>font-stretch, <a href="#font-stretch-normal-value" title="normal,
6671 font-stretch"><strong>3.3</strong></a>
6673 <li>font-style, <a href="#font-style-normal-value" title="normal,
6674 font-style"><strong>3.4</strong></a>
6676 <li>font-variant, <a href="#font-variant-normal-value" title="normal,
6677 font-variant"><strong>6.11</strong></a>
6679 <li>font-variant-alternates, <a
6680 href="#font-variant-alternates-normal-value" title="normal,
6681 font-variant-alternates"><strong>6.8</strong></a>
6683 <li>font-variant-caps, <a href="#font-variant-caps-normal-value"
6684 title="normal, font-variant-caps"><strong>6.6</strong></a>
6686 <li>font-variant-east-asian, <a
6687 href="#font-variant-east-asian-normal-value" title="normal,
6688 font-variant-east-asian"><strong>6.10</strong></a>
6690 <li>font-variant-ligatures, <a
6691 href="#font-variant-ligatures-normal-value" title="normal,
6692 font-variant-ligatures"><strong>6.4</strong></a>
6694 <li>font-variant-numeric, <a href="#font-variant-numeric-normal-value"
6695 title="normal, font-variant-numeric"><strong>6.7</strong></a>
6697 <li>font-variant-position, <a href="#font-variant-position-normal-value"
6698 title="normal, font-variant-position"><strong>6.5</strong></a>
6700 <li>font-weight, <a href="#font-weight-normal-value" title="normal,
6701 font-weight"><strong>3.2</strong></a>
6702 </ul>
6704 <li>oblique, <a href="#oblique" title=oblique><strong>3.4</strong></a>
6706 <li>oldstyle-nums, <a href="#oldstyle-nums"
6707 title=oldstyle-nums><strong>6.7</strong></a>
6709 <li>ordinal, <a href="#ordinal" title=ordinal><strong>6.7</strong></a>
6711 <li>ornaments, <a href="#ornaments"
6712 title=ornaments><strong>6.8</strong></a>
6714 <li>petite-caps, <a href="#petite-caps"
6715 title=petite-caps><strong>6.6</strong></a>
6717 <li>proportional-nums, <a href="#proportional-nums"
6718 title=proportional-nums><strong>6.7</strong></a>
6720 <li>proportional-width, <a href="#proportional-width"
6721 title=proportional-width><strong>6.10</strong></a>
6723 <li>renderer, <a href="#renderer" title=renderer><strong>#</strong></a>
6725 <li>ruby, <a href="#ruby" title=ruby><strong>6.10</strong></a>
6727 <li>sans-serif, definition of, <a href="#sans-serif0" title="sans-serif,
6728 definition of"><strong>#</strong></a>
6730 <li>semi-condensed, <a href="#semi-condensed-"
6731 title=semi-condensed><strong>3.3</strong></a>
6733 <li>semi-expanded, <a href="#semi-expanded"
6734 title=semi-expanded><strong>3.3</strong></a>
6736 <li>serif, definition of, <a href="#serif0" title="serif, definition
6737 of"><strong>#</strong></a>
6739 <li>simplified, <a href="#simplified"
6740 title=simplified><strong>6.10</strong></a>
6742 <li>slashed-zero, <a href="#slashed-zero"
6743 title=slashed-zero><strong>6.7</strong></a>
6745 <li>small-caps, <a href="#small-caps"
6746 title=small-caps><strong>6.6</strong></a>
6748 <li>src, <a href="#descdef-src" title=src><strong>4.3</strong></a>
6750 <li>stacked-fractions, <a href="#stacked-fractions"
6751 title=stacked-fractions><strong>6.7</strong></a>
6753 <li>style sheet
6754 <ul>
6755 <li>as conformance class, <a href="#style-sheet" title="style sheet, as
6756 conformance class"><strong>#</strong></a>
6757 </ul>
6759 <li>styleset, <a href="#styleset" title=styleset><strong>6.8</strong></a>
6761 <li>stylistic, <a href="#stylistic"
6762 title=stylistic><strong>6.8</strong></a>
6764 <li>sub, <a href="#sub" title=sub><strong>6.5</strong></a>
6766 <li>super, <a href="#super" title=super><strong>6.5</strong></a>
6768 <li>support, <a href="#support" title=support><strong>5.2</strong></a>
6770 <li>swash, <a href="#swash" title=swash><strong>6.8</strong></a>
6772 <li>system font fallback, <a href="#system-font-fallback" title="system
6773 font fallback"><strong>5.2</strong></a>
6775 <li>tabular-nums, <a href="#tabular-nums"
6776 title=tabular-nums><strong>6.7</strong></a>
6778 <li>titling-caps, <a href="#titling-caps"
6779 title=titling-caps><strong>6.6</strong></a>
6781 <li>traditional, <a href="#traditional"
6782 title=traditional><strong>6.10</strong></a>
6784 <li>ultra-condensed, <a href="#ultra-condensed"
6785 title=ultra-condensed><strong>3.3</strong></a>
6787 <li>ultra-expanded, <a href="#ultra-expanded"
6788 title=ultra-expanded><strong>3.3</strong></a>
6790 <li>unicase, <a href="#unicase" title=unicase><strong>6.6</strong></a>
6792 <li>unicode-range, <a href="#descdef-unicode-range"
6793 title=unicode-range><strong>4.5</strong></a>
6795 <li>weight, <a href="#weight" title=weight><strong>2</strong></a>
6797 <li>width, <a href="#width" title=width><strong>2</strong></a>
6798 </ul>
6799 <!--end-index-->
6801 <h2 class=no-num id=property-index>Property index</h2>
6802 <!--begin-properties-->
6804 <table class=proptable>
6805 <thead>
6806 <tr>
6807 <th>Property
6809 <th>Values
6811 <th>Initial
6813 <th>Applies to
6815 <th>Inh.
6817 <th>Percentages
6819 <th>Media
6821 <tbody>
6822 <tr>
6823 <th><a class=property href="#propdef-font">font</a>
6825 <td>[ [ <‘font-style’> || <font-variant-css21> ||
6826 <‘font-weight’> || <‘font-stretch’ ]?
6827 <‘font-size’> [ / <‘line-height’> ]?
6828 <‘font-family’> ] | caption | icon | menu | message-box |
6829 small-caption | status-bar
6831 <td>see individual properties
6833 <td>all elements
6835 <td>yes
6837 <td>see individual properties
6839 <td>visual
6841 <tr>
6842 <th><span class=property>font-family</span>
6844 <td>[ <family-name> | <generic-family> ] #
6846 <td>depends on user agent
6848 <td>all elements
6850 <td>yes
6852 <td>N/A
6854 <td>visual
6856 <tr>
6857 <th><span class=property>font-feature-settings</span>
6859 <td>normal | <feature-tag-value> #
6861 <td>normal
6863 <td>all elements
6865 <td>yes
6867 <td>N/A
6869 <td>visual
6871 <tr>
6872 <th><a class=property href="#propdef-font-kerning">font-kerning</a>
6874 <td>auto | normal | none
6876 <td>auto
6878 <td>all elements
6880 <td>yes
6882 <td>N/A
6884 <td>visual
6886 <tr>
6887 <th><a class=property
6888 href="#propdef-font-language-override">font-language-override</a>
6890 <td>normal | <string>
6892 <td>normal
6894 <td>all elements
6896 <td>yes
6898 <td>N/A
6900 <td>visual
6902 <tr>
6903 <th><a class=property href="#propdef-font-size">font-size</a>
6905 <td><absolute-size> | <relative-size> | <length> |
6906 <percentage>
6908 <td>medium
6910 <td>all elements
6912 <td>yes
6914 <td>refer to parent element's font size
6916 <td>visual
6918 <tr>
6919 <th><a class=property
6920 href="#propdef-font-size-adjust">font-size-adjust</a>
6922 <td>none | auto | <number>
6924 <td>none
6926 <td>all elements
6928 <td>yes
6930 <td>N/A
6932 <td>visual
6934 <tr>
6935 <th><span class=property>font-stretch</span>
6937 <td>normal | ultra-condensed | extra-condensed | condensed |
6938 semi-condensed | semi-expanded | expanded | extra-expanded |
6939 ultra-expanded
6941 <td>normal
6943 <td>all elements
6945 <td>yes
6947 <td>N/A
6949 <td>visual
6951 <tr>
6952 <th><span class=property>font-style</span>
6954 <td>normal | italic | oblique
6956 <td>normal
6958 <td>all elements
6960 <td>yes
6962 <td>N/A
6964 <td>visual
6966 <tr>
6967 <th><a class=property href="#propdef-font-synthesis">font-synthesis</a>
6969 <td>none | [ weight || style ]
6971 <td>weight style
6973 <td>all elements
6975 <td>yes
6977 <td>N/A
6979 <td>visual
6981 <tr>
6982 <th><span class=property>font-variant</span>
6984 <td>normal | none | [ <common-lig-values> ||
6985 <discretionary-lig-values> || <historical-lig-values> ||
6986 <contextual-alt-values> || stylistic(<feature-value-name>)
6987 || historical-forms || styleset(<feature-value-name> #) ||
6988 character-variant(<feature-value-name> #) ||
6989 swash(<feature-value-name>) ||
6990 ornaments(<feature-value-name>) ||
6991 annotation(<feature-value-name>) || [ small-caps | all-small-caps
6992 | petite-caps | all-petite-caps | unicase | titling-caps ] ||
6993 <numeric-figure-values> || <numeric-spacing-values> ||
6994 <numeric-fraction-values> || ordinal || slashed-zero ||
6995 <east-asian-variant-values> || <east-asian-width-values> ||
6996 ruby ]
6998 <td>normal
7000 <td>all elements
7002 <td>yes
7004 <td>see individual properties
7006 <td>visual
7008 <tr>
7009 <th><a class=property
7010 href="#propdef-font-variant-alternates">font-variant-alternates</a>
7012 <td>normal | [ stylistic(<feature-value-name>) || historical-forms
7013 || styleset(<feature-value-name> #) ||
7014 character-variant(<feature-value-name> #) ||
7015 swash(<feature-value-name>) ||
7016 ornaments(<feature-value-name>) ||
7017 annotation(<feature-value-name>) ]
7019 <td>normal
7021 <td>all elements
7023 <td>yes
7025 <td>N/A
7027 <td>visual
7029 <tr>
7030 <th><a class=property
7031 href="#propdef-font-variant-caps">font-variant-caps</a>
7033 <td>normal | small-caps | all-small-caps | petite-caps | all-petite-caps
7034 | unicase | titling-caps
7036 <td>normal
7038 <td>all elements
7040 <td>yes
7042 <td>N/A
7044 <td>visual
7046 <tr>
7047 <th><a class=property
7048 href="#propdef-font-variant-east-asian">font-variant-east-asian</a>
7050 <td>normal | [ <east-asian-variant-values> ||
7051 <east-asian-width-values> || ruby ]
7053 <td>normal
7055 <td>all elements
7057 <td>yes
7059 <td>N/A
7061 <td>visual
7063 <tr>
7064 <th><a class=property
7065 href="#propdef-font-variant-ligatures">font-variant-ligatures</a>
7067 <td>normal | none | [ <common-lig-values> ||
7068 <discretionary-lig-values> || <historical-lig-values> ||
7069 <contextual-alt-values> ]
7071 <td>normal
7073 <td>all elements
7075 <td>yes
7077 <td>N/A
7079 <td>visual
7081 <tr>
7082 <th><a class=property
7083 href="#propdef-font-variant-numeric">font-variant-numeric</a>
7085 <td>normal | [ <numeric-figure-values> ||
7086 <numeric-spacing-values> || <numeric-fraction-values> ||
7087 ordinal || slashed-zero ]
7089 <td>normal
7091 <td>all elements
7093 <td>yes
7095 <td>N/A
7097 <td>visual
7099 <tr>
7100 <th><a class=property
7101 href="#propdef-font-variant-position">font-variant-position</a>
7103 <td>normal | sub | super
7105 <td>normal
7107 <td>all elements
7109 <td>yes
7111 <td>N/A
7113 <td>visual
7115 <tr>
7116 <th><span class=property>font-weight</span>
7118 <td>normal | bold | bolder | lighter | 100 | 200 | 300 | 400 | 500 | 600
7119 | 700 | 800 | 900
7121 <td>normal
7123 <td>all elements
7125 <td>yes
7127 <td>N/A
7129 <td>visual
7130 </table>
7131 <!--end-properties-->
7132 <!--begin-descriptors-->
7134 <table class=proptable>
7135 <thead>
7136 <tr>
7137 <th>Descriptor
7139 <th>Value
7141 <th>Initial
7143 <th>Percentages
7145 <th>Media
7147 <tbody>
7148 <tr>
7149 <th><span class=property>font-family</span>
7151 <td><family-name>
7153 <td>N/A
7155 <tr>
7156 <th><span class=property>font-feature-settings</span>
7158 <td>normal | <feature-tag-value> #
7160 <td>normal
7162 <tr>
7163 <th><span class=property>font-stretch</span>
7165 <td>normal | ultra-condensed | extra-condensed | condensed |
7166 semi-condensed | semi-expanded | expanded | extra-expanded |
7167 ultra-expanded
7169 <td>normal
7171 <tr>
7172 <th><span class=property>font-style</span>
7174 <td>normal | italic | oblique
7176 <td>normal
7178 <tr>
7179 <th><span class=property>font-variant</span>
7181 <td>normal | none | [ <common-lig-values> ||
7182 <discretionary-lig-values> || <historical-lig-values> ||
7183 <contextual-alt-values> || stylistic(<feature-value-name>)
7184 || historical-forms || styleset(<feature-value-name> #) ||
7185 character-variant(<feature-value-name> #) ||
7186 swash(<feature-value-name>) ||
7187 ornaments(<feature-value-name>) ||
7188 annotation(<feature-value-name>) || [ small-caps | all-small-caps
7189 | petite-caps | all-petite-caps | unicase | titling-caps ] ||
7190 <numeric-figure-values> || <numeric-spacing-values> ||
7191 <numeric-fraction-values> || ordinal || slashed-zero ||
7192 <east-asian-variant-values> || <east-asian-width-values> ||
7193 ruby ]
7195 <td>normal
7197 <tr>
7198 <th><span class=property>font-weight</span>
7200 <td>normal | bold | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900
7202 <td>normal
7204 <tr>
7205 <th><a class=property href="#descdef-src">src</a>
7207 <td>[ <url> [format(<string> #)]? | <font-face-name> ] #
7209 <td>N/A
7211 <tr>
7212 <th><a class=property href="#descdef-unicode-range">unicode-range</a>
7214 <td><urange> #
7216 <td>U+0-10FFFF
7217 </table>
7218 <!--end-descriptors-->
7219 <script type="text/javascript">
7220 window.onload = function () {
7221 if (!("devicePixelRatio" in window && window.devicePixelRatio > 1)) return;
7222 var i, hiresElements = document.getElementsByClassName("hires");
7223 for (i = 0; i < hiresElements.length; i++) {
7224 var h = hiresElements[i];
7225 if (h.tagName != "IMG") continue;
7226 var src = h.getAttribute("src");
7227 var src2x = src.replace(/\.\w+$/, function(m) { return "@2x" + m; });
7228 h.src = src2x;
7229 }
7230 }
7231 </script>
7232 </html>
7233 <!-- Keep this comment at the end of the file
7234 Local variables:
7235 mode: sgml
7236 sgml-declaration:"~/SGML/HTML4.decl"
7237 sgml-default-doctype-name:"html"
7238 sgml-minimize-attributes:t
7239 sgml-nofill-elements:("pre" "style" "br")
7240 sgml-live-element-indicator:t
7241 sgml-omittag:nil
7242 sgml-shorttag:nil
7243 sgml-namecase-general:t
7244 sgml-general-insert-case:lower
7245 sgml-always-quote-attributes:t
7246 sgml-indent-step:nil
7247 sgml-indent-data:t
7248 sgml-parent-document:nil
7249 sgml-exposed-tags:nil
7250 sgml-local-catalogs:nil
7251 sgml-local-ecat-files:nil
7252 End:
7253 -->
7254 <!--
7256 to do:
7258 - wording of OpenType family name handling
7259 - handling combining sequences in the font matching algorithm
7260 - fix-up fi ligature example
7262 -->