Thu, 30 May 2013 17:21:45 +0900
[css-fonts] minor edits of font-variant subproperties
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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">
108 <body>
109 <div class=head> <!--begin-logo-->
110 <p><a href="http://www.w3.org/"><img alt=W3C height=48
111 src="http://www.w3.org/Icons/w3c_home" width=72></a> <!--end-logo-->
113 <h1>CSS Fonts Module Level 3</h1>
115 <h2 class="no-num no-toc" id=editors-draft-30-may-2013>Editor's Draft 30
116 May 2013</h2>
118 <dl id=authors>
119 <dt>This version:
121 <dd><a
122 href="http://dev.w3.org/csswg/css-fonts/">http://dev.w3.org/csswg/css-fonts/</a>
123 <!-- <dd><a href="http://www.w3.org/TR/2013/ED-css3-fonts-20130530/">http://www.w3.org/TR/2013/ED-css3-fonts-20130530/</a> -->
126 <dt>Latest version:
128 <dd><a
129 href="http://www.w3.org/TR/css3-fonts/">http://www.w3.org/TR/css3-fonts/</a>
131 <dt>Latest editor's draft:
133 <dd><a
134 href="http://dev.w3.org/csswg/css-fonts/">http://dev.w3.org/csswg/css-fonts/</a>
135 (<a
136 href="https://dvcs.w3.org/hg/csswg/log/tip/css-fonts/Fonts.html">change
137 log</a>)
139 <dt>Previous version:
141 <dd><a
142 href="http://www.w3.org/TR/2013/WD-css3-fonts-20130212/">http://www.w3.org/TR/2013/WD-css3-fonts-20130212/</a>
144 <dt>Issues List:
146 <dd><a href="http://www.w3.org/Style/CSS/Tracker/products/18">CSS3 Fonts
147 issues in Tracker</a>
149 <dd><a
150 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
151 Fonts issues in Bugzilla</a>
153 <dt>Discussion:
155 <dd><a
156 href="mailto:www-style@w3.org?subject=%5Bcss-fonts%5D%20feedback">www-style@w3.org</a>
157 with subject line “<kbd>[css-fonts] <var>… message topic
158 …</var></kbd>” (<a
159 href="http://lists.w3.org/Archives/Public/www-style/"
160 rel=discussion>archives</a>)
162 <dt>Editor:
164 <dd><a href="mailto:jdaggett@mozilla.com">John Daggett (Mozilla)</a>
165 </dl>
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184 <hr title="Separator for header">
185 </div>
187 <h2 class="no-num no-toc" id=abstract>Abstract</h2>
189 <p>This CSS3 module describes how font properties are specified and how
190 font resources are loaded dynamically. The contents of this specification
191 are a consolidation of content previously divided into <a
192 href="http://www.w3.org/TR/2002/WD-css3-fonts-20020802/">CSS3 Fonts</a>
193 and <a href="http://www.w3.org/TR/2002/WD-css3-webfonts-20020802/">CSS3
194 Web Fonts</a> modules. The description of font load events was moved into
195 the <a href="http://dev.w3.org/csswg/css3-font-load-events/">CSS3 Font
196 Load Events</a> module.
198 <h2 class="no-num no-toc" id=status>Status of this document</h2>
199 <!--begin-status-->
201 <p>This is a public copy of the editors' draft. It is provided for
202 discussion only and may change at any moment. Its publication here does
203 not imply endorsement of its contents by W3C. Don't cite this document
204 other than as work in progress.
206 <p>The (<a
207 href="http://lists.w3.org/Archives/Public/www-style/">archived</a>) public
208 mailing list <a
209 href="mailto:www-style@w3.org?Subject=%5Bcss3-fonts%5D%20PUT%20SUBJECT%20HERE">
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213 “css3-fonts” in the subject, preferably like this:
214 “[<!---->css3-fonts<!---->] <em>…summary of comment…</em>”
216 <p>This document was produced by the <a
217 href="http://www.w3.org/Style/CSS/members">CSS Working Group</a> (part of
218 the <a href="http://www.w3.org/Style/">Style Activity</a>).
220 <p>This document was produced by a group operating under the <a
221 href="http://www.w3.org/Consortium/Patent-Policy-20040205/">5 February
222 2004 W3C Patent Policy</a>. W3C maintains a <a
223 href="http://www.w3.org/2004/01/pp-impl/32061/status"
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232 <!--end-status-->
233 <!--
234 <h3 class="no-num no-toc" id="atrisk">Features at risk</h3>
236 <p>The following features are at risk and may be removed when exiting CR:</p>
238 <ul>
239 </ul>
240 -->
242 <h2 class="no-num no-toc" id=contents>Table of contents</h2>
243 <!--begin-toc-->
245 <ul class=toc>
246 <li><a href="#introduction"><span class=secno>1 </span>Introduction</a>
248 <li><a href="#typography-background"><span class=secno>2 </span>Typography
249 Background</a>
251 <li><a href="#basic-font-props"><span class=secno>3 </span>Basic Font
252 Properties</a>
253 <ul class=toc>
254 <li><a href="#font-family-prop"><span class=secno>3.1 </span>Font
255 family: the font-family property</a>
256 <ul class=toc>
257 <li><a href="#generic-font-families"><span class=secno>3.1.1
258 </span>Generic font families</a>
259 </ul>
261 <li><a href="#font-weight-prop"><span class=secno>3.2 </span>Font
262 weight: the font-weight property</a>
264 <li><a href="#font-stretch-prop"><span class=secno>3.3 </span>Font
265 width: the font-stretch property</a>
267 <li><a href="#font-style-prop"><span class=secno>3.4 </span>Font style:
268 the font-style property</a>
270 <li><a href="#font-size-prop"><span class=secno>3.5 </span>Font size:
271 the font-size property</a>
273 <li><a href="#font-size-adjust-prop"><span class=secno>3.6
274 </span>Relative sizing: the font-size-adjust property</a>
276 <li><a href="#font-prop"><span class=secno>3.7 </span>Shorthand font
277 property: the font property</a>
279 <li><a href="#font-synthesis-prop"><span class=secno>3.8
280 </span>Controlling synthetic faces: the font-synthesis property</a>
281 </ul>
283 <li><a href="#font-resources"><span class=secno>4 </span>Font
284 Resources</a>
285 <ul class=toc>
286 <li><a href="#font-face-rule"><span class=secno>4.1 </span>The
287 <code>@font-face</code> rule</a>
289 <li><a href="#font-family-desc"><span class=secno>4.2 </span>Font
290 family: the font-family descriptor</a>
292 <li><a href="#src-desc"><span class=secno>4.3 </span>Font reference: the
293 src descriptor</a>
295 <li><a href="#font-prop-desc"><span class=secno>4.4 </span>Font property
296 descriptors: the font-style, font-weight, font-stretch descriptors</a>
298 <li><a href="#unicode-range-desc"><span class=secno>4.5 </span>Character
299 range: the unicode-range descriptor</a>
301 <li><a href="#composite-fonts"><span class=secno>4.6 </span>Using
302 character ranges to define composite fonts</a>
304 <li><a href="#font-rend-desc"><span class=secno>4.7 </span>Font
305 features: the font-variant and font-feature-settings descriptors</a>
307 <li><a href="#font-face-loading"><span class=secno>4.8 </span>Font
308 loading guidelines</a>
310 <li><a href="#same-origin-restriction"><span class=secno>4.9
311 </span>Same-origin restriction for fonts</a>
312 <ul class=toc>
313 <li><a href="#default-same-origin-restriction"><span class=secno>4.9.1
314 </span>Default same-origin restriction</a>
316 <li><a href="#allowing-cross-origin-font-loading"><span
317 class=secno>4.9.2 </span>Allowing cross-origin font loading</a>
318 </ul>
319 </ul>
321 <li><a href="#font-matching-algorithm"><span class=secno>5 </span>Font
322 Matching Algorithm</a>
323 <ul class=toc>
324 <li><a href="#font-family-casing"><span class=secno>5.1 </span>Case
325 sensitivity of font family names</a>
327 <li><a href="#font-style-matching"><span class=secno>5.2 </span>Matching
328 font styles</a>
330 <li><a href="#cluster-matching"><span class=secno>5.3 </span>Cluster
331 matching</a>
333 <li><a href="#char-handling-issues"><span class=secno>5.4
334 </span>Character handling issues</a>
336 <li><a href="#font-matching-changes"><span class=secno>5.5 </span>Font
337 matching changes since CSS 2.1</a>
339 <li><a href="#font-matching-examples"><span class=secno>5.6 </span>Font
340 matching examples</a>
341 </ul>
343 <li><a href="#font-rend-props"><span class=secno>6 </span>Font Feature
344 Properties</a>
345 <ul class=toc>
346 <li><a href="#glyph-selection-positioning"><span class=secno>6.1
347 </span>Glyph selection and positioning</a>
349 <li><a href="#language-specific-support"><span class=secno>6.2
350 </span>Language-specific display</a>
352 <li><a href="#font-kerning-prop"><span class=secno>6.3 </span>Kerning:
353 the font-kerning property</a>
355 <li><a href="#font-variant-ligatures-prop"><span class=secno>6.4
356 </span>Ligatures: the font-variant-ligatures property</a>
358 <li><a href="#font-variant-position-prop"><span class=secno>6.5
359 </span>Subscript and superscript forms: the font-variant-position
360 property</a>
362 <li><a href="#font-variant-caps-prop"><span class=secno>6.6
363 </span>Capitalization: the font-variant-caps property</a>
365 <li><a href="#font-variant-numeric-prop"><span class=secno>6.7
366 </span>Numerical formatting: the font-variant-numeric property</a>
368 <li><a href="#font-variant-alternates-prop"><span class=secno>6.8
369 </span>Alternates and swashes: the font-variant-alternates property</a>
372 <li><a href="#font-feature-values"><span class=secno>6.9 </span>Defining
373 font specific alternates: the <code>@font-feature-values</code>
374 rule</a>
376 <li><a href="#font-variant-east-asian-prop"><span class=secno>6.10
377 </span>East Asian text rendering: the font-variant-east-asian
378 property</a>
380 <li><a href="#font-variant-prop"><span class=secno>6.11 </span>Overall
381 shorthand for font rendering: the font-variant property</a>
383 <li><a href="#font-feature-settings-prop"><span class=secno>6.12
384 </span>Low-level font feature settings control: the
385 font-feature-settings property</a>
387 <li><a href="#font-language-override-prop"><span class=secno>6.13
388 </span>Font language override: the font-language-override property</a>
389 </ul>
391 <li><a href="#font-feature-resolution"><span class=secno>7 </span>Font
392 Feature Resolution </a>
393 <ul class=toc>
394 <li><a href="#default-features"><span class=secno>7.1 </span>Default
395 features</a>
397 <li><a href="#feature-precedence"><span class=secno>7.2 </span>Feature
398 precedence</a>
400 <li><a href="#feature-precedence-examples"><span class=secno>7.3
401 </span>Feature precedence examples</a>
402 </ul>
404 <li><a href="#object-model"><span class=secno>8 </span>Object Model</a>
405 <ul class=toc>
406 <li><a href="#om-fontface"><span class=secno>8.1 </span>The
407 <code>CSSFontFaceRule</code> interface</a>
409 <li><a href="#om-fontfeaturevalues"><span class=secno>8.2 </span>The
410 <code>CSSFontFeatureValuesRule</code> interface</a>
411 </ul>
413 <li class=no-num><a href="#platform-props-to-css">Appendix A: Mapping
414 platform font properties to CSS properties</a>
416 <li class=no-num><a href="#ch-ch-ch-changes">Changes</a>
417 <ul class=toc>
418 <li class=no-num><a href="#recent-changes"> Changes from the February
419 2013 CSS3 Fonts Working Draft</a>
420 </ul>
422 <li class=no-num><a href="#acknowledgments">Acknowledgments</a>
424 <li class=no-num><a href="#conformance"> Conformance</a>
425 <ul class=toc>
426 <li class=no-num><a href="#conventions"> Document Conventions</a>
428 <li class=no-num><a href="#conformance-classes"> Conformance Classes</a>
431 <li class=no-num><a href="#partial"> Partial Implementations</a>
433 <li class=no-num><a href="#experimental"> Experimental
434 Implementations</a>
436 <li class=no-num><a href="#testing"> Non-Experimental
437 Implementations</a>
438 </ul>
440 <li class=no-num><a href="#references">References</a>
441 <ul class=toc>
442 <li class=no-num><a href="#normative-references">Normative
443 References</a>
445 <li class=no-num><a href="#other-references">Other References</a>
446 </ul>
448 <li class=no-num><a href="#index">Index</a>
450 <li class=no-num><a href="#property-index">Property index</a>
451 </ul>
452 <!--end-toc-->
454 <h2 id=introduction><span class=secno>1 </span>Introduction</h2>
456 <p>A font provides a resource containing the visual representation of
457 characters. At the simplest level it contains information that maps
458 character codes to shapes (called glyphs) that represent these characters.
459 Fonts sharing a common design style are commonly grouped into font
460 families classified by a set of standard font properties. Within a family,
461 the shape displayed for a given character can vary by stroke weight, slant
462 or relative width, among others. An individual font face is described by a
463 unique combination of these properties. For a given range of text, CSS
464 font properties are used to select a font family and a specific font face
465 within that family to be used when rendering that text. As a simple
466 example, to use the bold form of Helvetica one could use:
468 <pre>body {
469 font-family: Helvetica;
470 font-weight: bold;
471 }</pre>
473 <p>Font resources may be installed locally on the system on which a user
474 agent is running or downloadable. For local font resources descriptive
475 information can be obtained directly from the font resource. For
476 downloadable font resources (sometimes referred to as web fonts), the
477 descriptive information is included with the reference to the font
478 resource.
480 <p>Families of fonts typically don't contain a single face for each
481 possible variation of font properties. The CSS font selection mechanism
482 describes how to match a given set of CSS font properties to a single font
483 face.
485 <h2 id=typography-background><span class=secno>2 </span>Typography
486 Background</h2>
488 <p><em>This section is non-normative.</em>
490 <p> Typographic traditions vary across the globe, so there is no unique way
491 to classify all fonts across languages and cultures. For even common Latin
492 letters, wide variations are possible:
494 <div class=figure><img alt="variations in glyphs for a single character"
495 src=aaaaaa.png>
496 <p class=caption>One character, many glyph variations
497 </div>
499 <p>Differences in the anatomy of letterforms is one way to distinguish
500 fonts. For Latin fonts, flourishes at the ends of a character's main
501 strokes, or serifs, can distinguish a font from those without. Similar
502 comparisons exist in non-Latin fonts between fonts with tapered strokes
503 and those using primarily uniform strokes:
505 <div class=figure><img alt="serif vs. non-serifs" src=serifvssansserif.png>
506 <p class=caption>Letterforms with and without serifs
507 </div>
509 <div class=figure><img alt="serif vs. non-serifs for japanese"
510 src=minchovsgothic.png>
511 <p class=caption>Similar groupings for Japanese typefaces
512 </div>
514 <p>Fonts contain letterforms and the data needed to map characters to these
515 letterforms. Often this may be a simple one-to-one mapping, but more
516 complex mappings are also possible. The use of combining diacritic marks
517 creates many variations for an underlying letterform:
519 <div class=figure><img alt="diacritic marks" src=aaaaaa-diacritics.png>
520 <p class=caption>Variations with diacritic marks
521 </div>
523 <p>A sequence of characters can be represented by a single glyph known as a
524 ligature:
526 <div class=figure><img alt="example of a fi ligature"
527 src=final-ligature.png>
528 <p class=caption>Ligature example
529 </div>
531 <p>Visual transformations based on textual context are often stylistic
532 option in European languages. They are required to correctly render
533 languages like Arabic, the lam and alef characters below <em>must</em> be
534 combined when they exist in sequence:
536 <div class=figure><img alt="lam alef ligature" src=lamaleflig.png>
537 <p class=caption>Required Arabic ligature
538 </div>
540 <p>The relative complexity of these shaping transformations requires
541 additional data within the font.
543 <p>Sets of font faces with various stylistic variations are often grouped
544 together into font families. In the simplest case a regular face is
545 supplemented with bold and italic faces, but much more extensive groupings
546 are possible. Variations in the thickness of letterform strokes, the <dfn
547 id=weight>weight</dfn>, and the overall proportions of the letterform, the
548 <dfn id=width>width</dfn>, are most common. In the example below, each
549 letter uses a different font face within the Univers font family. The
550 width used increases from top to bottom and the weight increases from left
551 to right:
553 <div class=figure><img alt="various width and weight variations within a
554 single family" src=weightwidthvariations.png>
555 <p class=caption>Weight and width variations within a single font family
556 </div>
558 <p>Creating fonts that support multiple scripts is a difficult task;
559 designers need to understand the cultural traditions surrounding the use
560 of type in different scripts and come up with letterforms that somehow
561 share a common theme. Many languages often share a common script and each
562 of these languages may have noticeable stylistic differences. For example,
563 the Arabic script is shared by Persian and Urdu and Cyrillic is used with
564 many languages, not just Russian.
566 <p>The <a href="#character-map"><em>character map</em></a> of a font
567 defines the mapping of characters to glyphs for that font. If a document
568 contains characters not supported by the <a href="#character-map"><em
569 title="character map">character maps</em></a> of the fonts contained in a
570 font family list, a user agent may use a system font fallback procedure to
571 locate an appropriate font that does. If no appropriate font can be found,
572 some form of "missing glyph" character will be rendered by the user agent.
573 System fallback can occur when the specified list of font families does
574 not include a font that supports a given character.
576 <p>Although the <a href="#character-map"><em>character map</em></a> of a
577 font maps a given character to a glyph for that character, modern font
578 technologies such as OpenType and AAT (Apple Advanced Typography) provide
579 ways of mapping a character to different glyphs based upon feature
580 settings. Fonts in these formats allow these features to be embedded in
581 the font itself and controlled by applications. Common typographic
582 features which can be specified this way include ligatures, swashes,
583 contextual alternates, proportional and tabular figures, and automatic
584 fractions, to list just a few. For a visual overview of OpenType features,
585 see the <a href="#OPENTYPE-FONT-GUIDE"
586 rel=biblioentry>[OPENTYPE-FONT-GUIDE]<!--{{OPENTYPE-FONT-GUIDE}}--></a>.
588 <h2 id=basic-font-props><span class=secno>3 </span>Basic Font Properties</h2>
590 <p>The particular font face used to render a character is determined by the
591 font family and other font properties that apply to a given element. This
592 structure allows settings to be varied independent of each other.</p>
593 <!-- prop: font-family -->
595 <h3 id=font-family-prop><span class=secno>3.1 </span>Font family: the <a
596 href="#propdef-font-family">font-family</a> property</h3>
598 <table class=propdef id=namefont-familyvalue-ltfamily-namegt-ltg>
599 <tbody>
600 <tr>
601 <td>Name:
603 <td><dfn id=propdef-font-family
604 title="font-family!!property">font-family</dfn>
606 <tr>
607 <td>Value:
609 <td>[ <a href="#family-name-value"><var><family-name></var></a> |
610 <a href="#generic-family-value"><var><generic-family></var></a> ]
611 #
613 <tr>
614 <td>Initial:
616 <td>depends on user agent
618 <tr>
619 <td>Applies to:
621 <td>all elements
623 <tr>
624 <td>Inherited:
626 <td>yes
628 <tr>
629 <td>Percentages:
631 <td>N/A
633 <tr>
634 <td>Media:
636 <td>visual
638 <tr>
639 <td>Computed value:
641 <td>as specified
643 <tr>
644 <td>Animatable:
646 <td>no
647 </table>
649 <p>This property specifies a prioritized list of font family names or
650 generic family names. A font family defines a set of faces that vary in
651 weight, width or slope. CSS uses the combination of a family name with
652 other style attributes to select an individual face. Using this selection
653 mechanism, rather than selecting a face via the style name as is often
654 done in design applications, allows some degree of regularity in textual
655 display when fallback occurs.
657 <p class=note>Designers should note that the CSS definition of font
658 attributes used for selection are explicitly not intended to define a font
659 taxonomy. A type designer's idea of a family may often extend to a set of
660 faces that vary along axes other than just the standard axes of weight,
661 width and slope. A family may extend to include both a set of serif faces
662 and a set of sans-serif faces or vary along axes that are unique to that
663 family. The CSS font selection mechanism merely provides a way to
664 determine the “closest” substitute when substitution is necessary.
666 <p>Unlike other CSS properties, component values are a comma-separated list
667 indicating alternatives. A user agent iterates through the list of family
668 names until it matches an available font that contains a glyph for the
669 character to be rendered. This allows for differences in available fonts
670 across platforms and for differences in the range of characters supported
671 by individual fonts.
673 <p>A font family name only specifies a name given to a set of font faces,
674 it does not specify an individual face. For example, given the
675 availability of the fonts below, Futura would match but Futura Medium
676 would not:
678 <div class=figure><img alt="family and face names"
679 src=familyvsfacename.png>
680 <p class=caption>Family and individual face names
681 </div>
683 <p>Consider the example below:
685 <div class=example>
686 <pre>body {
687 font-family: Helvetica, Verdana, sans-serif;
688 }</pre>
690 <p>If Helvetica is available it will be used when rendering. If neither
691 Helvetica nor Verdana is present, then the user-agent-defined sans serif
692 font will be used.</p>
693 </div>
695 <p>There are two types of font family names:
697 <dl>
698 <dt><dfn id=family-name-value><var><family-name></var></dfn>
700 <dd>The name of a font family of choice such as Helvetica or Verdana in
701 the previous example.
703 <dt><dfn id=generic-family-value><var><generic-family></var></dfn>
705 <dd> The following generic family keywords are defined: ‘<a
706 href="#serif"><code class=property>serif</code></a>’, ‘<a
707 href="#sans-serif"><code class=property>sans-serif</code></a>’, ‘<a
708 href="#cursive"><code class=property>cursive</code></a>’, ‘<a
709 href="#fantasy"><code class=property>fantasy</code></a>’, and ‘<a
710 href="#monospace"><code class=property>monospace</code></a>’. These
711 keywords can be used as a general fallback mechanism when an author's
712 desired font choices are not available. As keywords, they must not be
713 quoted. Authors are encouraged to append a generic font family as a last
714 alternative for improved robustness.
715 </dl>
717 <p>Font family names other than generic families must either be given
718 quoted as <a
719 href="//www.w3.org/TR/CSS21/syndata.html#strings">strings,</a> or unquoted
720 as a sequence of one or more <a
721 href="//www.w3.org/TR/CSS21/syndata.html#value-def-identifier">identifiers.</a>
722 This means most punctuation characters and digits at the start of each
723 token must be escaped in unquoted font family names.
725 <p>To illustrate this, the following declarations are invalid:
727 <pre>
728 font-family: Red/Black, sans-serif;
729 font-family: "Lucida" Grande, sans-serif;
730 font-family: Ahem!, sans-serif;
731 font-family: test@foo, sans-serif;
732 font-family: #POUND, sans-serif;
733 font-family: Hawaii 5-0, sans-serif;
734 </pre>
736 <p>If a sequence of identifiers is given as a font family name, the
737 computed value is the name converted to a string by joining all the
738 identifiers in the sequence by single spaces.
740 <p>To avoid mistakes in escaping, it is recommended to quote font family
741 names that contain white space, digits, or punctuation characters other
742 than hyphens:
744 <pre>
745 body { font-family: "New Century Schoolbook", serif }
747 <BODY STYLE="font-family: '21st Century', fantasy">
748 </pre>
750 <p>Font family <em>names</em> that happen to be the same as a keyword value
751 (‘<code class=property>inherit</code>’, ‘<a href="#serif"><code
752 class=property>serif</code></a>’, ‘<a href="#sans-serif"><code
753 class=property>sans-serif</code></a>’, ‘<a href="#monospace"><code
754 class=property>monospace</code></a>’, ‘<a href="#fantasy"><code
755 class=property>fantasy</code></a>’, and ‘<a href="#cursive"><code
756 class=property>cursive</code></a>’) must be quoted to prevent confusion
757 with the keywords with the same names. The keywords ‘<code
758 class=property>initial</code>’ and ‘<code
759 class=property>default</code>’ are reserved for future use and must also
760 be quoted when used as font names. UAs must not consider these keywords as
761 matching the <a
762 href="#family-name-value"><var><family-name></var></a> type.
764 <p>The precise way a set of fonts are grouped into font families varies
765 depending upon the platform font management API's. The Windows GDI API
766 only allows four faces to be grouped into a family while the DirectWrite
767 API and API's on OSX and other platforms support font families with a
768 variety of weights, widths and slopes (see <a
769 href="#platform-props-to-css">Appendix A</a> for more details).
771 <p>Some font formats allow fonts to carry multiple localizations of the
772 family name. User agents must recognize and correctly match all of these
773 names independent of the underlying platform localization, system API used
774 or document encoding:
776 <div class=figure><img alt="examples of localized family names"
777 src=localizedfamilynames.png>
778 <p class=caption>Localized family names
779 </div>
781 <h4 id=generic-font-families><span class=secno>3.1.1 </span>Generic font
782 families</h4>
784 <p>All five generic font families are defined to exist in all CSS
785 implementations (they need not necessarily map to five distinct actual
786 fonts). User agents should provide reasonable default choices for the
787 generic font families, which express the characteristics of each family as
788 well as possible within the limits allowed by the underlying technology.
789 User agents are encouraged to allow users to select alternative choices
790 for the generic fonts.
792 <h5 class="no-num no-toc"> <span class=index-def id=serif0 title="serif,
793 definition of"><a name=serif-def><dfn id=serif>serif</dfn></a></span></h5>
795 <p>Serif fonts represent the formal text style for a script. This often
796 means but is not limited to glyphs that have finishing strokes, flared or
797 tapering ends, or have actual serifed endings (including slab serifs).
798 Serif fonts are typically proportionately-spaced. They often display a
799 greater variation between thick and thin strokes than fonts from the ‘<a
800 href="#sans-serif"><code class=property>sans-serif</code></a>’ generic
801 font family. CSS uses the term ‘<a href="#serif"><code
802 class=property>serif</code></a>’ to apply to a font for any script,
803 although other names may be more familiar for particular scripts, such as
804 Mincho (Japanese), Sung, Song or Kai (Chinese), Batang (Korean). For
805 Arabic, the Naskh style would correspond to ‘<a href="#serif"><code
806 class=property>serif</code></a>’ more due to its typographic role rather
807 than its actual design style. Any font that is so described may be used to
808 represent the generic ‘<a href="#serif"><code
809 class=property>serif</code></a>’ family.
811 <div class=figure><img alt="sample serif fonts" src=serifexamples.png>
812 <p class=caption>Sample serif fonts
813 </div>
815 <h5 class="no-num no-toc"> <span class=index-def id=sans-serif0
816 title="sans-serif, definition of"> <a name=sans-serif-def><dfn
817 id=sans-serif>sans-serif</dfn></a></span></h5>
819 <p>Glyphs in sans-serif fonts, as the term is used in CSS, are generally
820 low contrast (vertical and horizontal stems have the close to the same
821 thickness) and have stroke endings that are plain -- without any flaring,
822 cross stroke, or other ornamentation. Sans-serif fonts are typically
823 proportionately-spaced. They often have little variation between thick and
824 thin strokes, compared to fonts from the ‘<a href="#serif"><code
825 class=property>serif</code></a>’ family. CSS uses the term ‘<a
826 href="#sans-serif"><code class=property>sans-serif</code></a>’ to apply
827 to a font for any script, although other names may be more familiar for
828 particular scripts, such as Gothic (Japanese), Hei (Chinese), or Gulim
829 (Korean). Any font that is so described may be used to represent the
830 generic ‘<a href="#sans-serif"><code
831 class=property>sans-serif</code></a>’ family.
833 <div class=figure><img alt="sample sans-serif fonts"
834 src=sansserifexamples.png>
835 <p class=caption>Sample sans-serif fonts
836 </div>
838 <h5 class="no-num no-toc"> <span class=index-def id=cursive0
839 title="cursive, definition of"> <a name=cursive-def><dfn
840 id=cursive>cursive</dfn></a></span></h5>
842 <p>Glyphs in cursive fonts generally use a more informal script style, and
843 the result looks more like handwritten pen or brush writing than printed
844 letterwork. CSS uses the term ‘<a href="#cursive"><code
845 class=property>cursive</code></a>’ to apply to a font for any script,
846 although other names such as Chancery, Brush, Swing and Script are also
847 used in font names.
849 <div class=figure><img alt="sample cursive fonts" src=cursiveexamples.png>
850 <p class=caption>Sample cursive fonts
851 </div>
853 <h5 class="no-num no-toc"> <span class=index-def id=fantasy0
854 title="fantasy, definition of"> <a name=fantasy-def><dfn
855 id=fantasy>fantasy</dfn></a></span></h5>
857 <p>Fantasy fonts are primarily decorative or expressive fonts that contain
858 playful representations of characters. These do not include Pi or Picture
859 fonts which do not represent actual characters.
861 <div class=figure><img alt="sample fantasy fonts" src=fantasyexamples.png>
862 <p class=caption>Sample fantasy fonts
863 </div>
865 <h5 class="no-num no-toc"> <span class=index-def id=monospace0
866 title="monospace, definition of"> <a name=monospace-def><dfn
867 id=monospace>monospace</dfn></a></span></h5>
869 <p>The sole criterion of a monospace font is that all glyphs have the same
870 fixed width. This is often used to render samples of computer code.
872 <div class=figure><img alt="sample monospace fonts"
873 src=monospaceexamples.png>
874 <p class=caption>Sample monospace fonts
875 </div>
876 <!-- prop: font-weight -->
878 <h3 id=font-weight-prop><span class=secno>3.2 </span>Font weight: the <a
879 href="#propdef-font-weight">font-weight</a> property</h3>
881 <table class=propdef id=namefont-weightvaluenormal-bold-bolder-l>
882 <tbody>
883 <tr>
884 <td>Name:
886 <td><dfn id=propdef-font-weight
887 title="font-weight!!property">font-weight</dfn>
889 <tr>
890 <td>Value:
892 <td><a href="#font-weight-normal-value"
893 title="normal!!font-weight">normal</a> | <a href="#bold">bold</a> | <a
894 href="#bolder">bolder</a> | <a href="#lighter">lighter</a> | <a
895 href="#font-weight-numeric-values" title="100...900 weight
896 values">100</a> | <a href="#font-weight-numeric-values"
897 title="100...900 weight values">200</a> | <a
898 href="#font-weight-numeric-values" title="100...900 weight
899 values">300</a> | <a href="#font-weight-numeric-values"
900 title="100...900 weight values">400</a> | <a
901 href="#font-weight-numeric-values" title="100...900 weight
902 values">500</a> | <a href="#font-weight-numeric-values"
903 title="100...900 weight values">600</a> | <a
904 href="#font-weight-numeric-values" title="100...900 weight
905 values">700</a> | <a href="#font-weight-numeric-values"
906 title="100...900 weight values">800</a> | <a
907 href="#font-weight-numeric-values" title="100...900 weight
908 values">900</a>
910 <tr>
911 <td>Initial:
913 <td>normal
915 <tr>
916 <td>Applies to:
918 <td>all elements
920 <tr>
921 <td>Inherited:
923 <td>yes
925 <tr>
926 <td>Percentages:
928 <td>N/A
930 <tr>
931 <td>Media:
933 <td>visual
935 <tr>
936 <td>Computed value:
938 <td>numeric weight value (see description)
940 <tr>
941 <td>Animatable:
943 <td>as <a
944 href="http://dev.w3.org/csswg/css3-transitions/#animtype-font-weight">font
945 weight</a>
946 </table>
948 <p>The <a href="#propdef-font-weight"
949 title="font-weight!!property">‘<code
950 class=property>font-weight</code>’</a> property specifies the weight of
951 glyphs in the font, their degree of blackness or stroke thickness.
953 <p>Values have the following meanings:
955 <dl>
956 <dt><dfn id=font-weight-numeric-values title="100...900 weight values">100
957 to 900</dfn>
959 <dd>These values form an ordered sequence, where each number indicates a
960 weight that is at least as dark as its predecessor. These roughly
961 correspond to the commonly used weight names below:
962 </dl>
964 <ul>
965 <li>100 - Thin
967 <li>200 - Extra Light (Ultra Light)
969 <li>300 - Light
971 <li>400 - Normal
973 <li>500 - Medium
975 <li>600 - Semi Bold (Demi Bold)
977 <li>700 - Bold
979 <li>800 - Extra Bold (Ultra Bold)
981 <li>900 - Black (Heavy)
982 </ul>
984 <dl>
985 <dt><dfn id=font-weight-normal-value
986 title="normal!!font-weight">normal</dfn>
988 <dd>Same as ‘<code class=css>400</code>’.
990 <dt><dfn id=bold>bold</dfn>
992 <dd>Same as ‘<code class=css>700</code>’.
994 <dt><dfn id=bolder>bolder</dfn>
996 <dd>Specifies a bolder weight than the inherited value.
998 <dt><dfn id=lighter>lighter</dfn>
1000 <dd>Specifies a lighter weight than the inherited value.
1001 </dl>
1003 <p>Font formats that use a scale other than a nine-step scale should map
1004 their scale onto the CSS scale so that 400 roughly corresponds with a face
1005 that would be labeled as Regular, Book, Roman and 700 roughly matches a
1006 face that would be labeled as Bold. Or weights may be inferred from the
1007 style names, ones that correspond roughly with the scale above. The scale
1008 is relative, so a face with a larger weight value must never appear
1009 lighter. If style names are used to infer weights, care should be taken to
1010 handle variations in style names across locales.
1012 <p>Quite often there are only a few weights available for a particular font
1013 family. When a weight is specified for which no face exists, a face with a
1014 nearby weight is used. In general, bold weights map to faces with heavier
1015 weights and light weights map to faces with lighter weights (see the <a
1016 href="#font-matching-algorithm">font matching section below</a> for a
1017 precise definition). The examples here illustrate which face is used for
1018 different weights, grey indicates a face for that weight does not exist so
1019 a face with a nearby weight is used:
1021 <div class=figure><img alt="weight mappings for a family with 400, 700 and
1022 900 weights" src=optimaweights.png>
1023 <p class=caption>Weight mappings for a font family with 400, 700 and 900
1024 weight faces
1025 </div>
1027 <div class=figure><img alt="weight mappings for a family with 300, 600
1028 weights" src=hiraginoweights.png>
1029 <p class=caption>Weight mappings for a font family with 300 and 600 weight
1030 faces
1031 </div>
1033 <p>Although the practice is not well-loved by typographers, bold faces are
1034 often synthesized by user agents for faces that lack actual bold faces.
1035 For the purposes of style matching, these faces must be treated as if they
1036 exist within the family. Authors can explicitly avoid this behavior by
1037 using the ‘<a href="#propdef-font-synthesis"><code
1038 class=property>font-synthesis</code></a>’ property.
1040 <p>Specified values of ‘<a href="#bolder"><code
1041 class=property>bolder</code></a>’ and ‘<a href="#lighter"><code
1042 class=property>lighter</code></a>’ indicate weights relative to the
1043 weight of the parent element. The computed weight is calculated based on
1044 the inherited <a href="#propdef-font-weight"
1045 title="font-weight!!property">‘<code
1046 class=property>font-weight</code>’</a> value using the chart below.
1048 <table class=data id=bolderlighter summary="Bolder/lighter mappings">
1049 <thead>
1050 <tr>
1051 <th>Inherited value
1053 <th>bolder
1055 <th>lighter
1057 <tbody>
1058 <tr>
1059 <th>100
1061 <td>400
1063 <td>100
1065 <tr>
1066 <th>200
1068 <td>400
1070 <td>100
1072 <tr>
1073 <th>300
1075 <td>400
1077 <td>100
1079 <tr>
1080 <th>400
1082 <td>700
1084 <td>100
1086 <tr>
1087 <th>500
1089 <td>700
1091 <td>100
1093 <tr>
1094 <th>600
1096 <td>900
1098 <td>400
1100 <tr>
1101 <th>700
1103 <td>900
1105 <td>400
1107 <tr>
1108 <th>800
1110 <td>900
1112 <td>700
1114 <tr>
1115 <th>900
1117 <td>900
1119 <td>700
1120 </table>
1122 <p>The table above is equivalent to selecting the next relative bolder or
1123 lighter face, given a font family containing normal and bold faces along
1124 with a thin and a heavy face. Authors who desire finer control over the
1125 exact weight values used for a given element may use numerical values
1126 instead of relative weights.</p>
1127 <!-- prop: font-stretch -->
1129 <h3 id=font-stretch-prop><span class=secno>3.3 </span>Font width: the <a
1130 href="#propdef-font-stretch">font-stretch</a> property</h3>
1132 <table class=propdef id=namefont-stretchvalue-normal-ultra-conde>
1133 <tbody>
1134 <tr>
1135 <td>Name:
1137 <td><dfn id=propdef-font-stretch
1138 title="font-stretch!!property">font-stretch</dfn>
1140 <tr>
1141 <td>Value:
1143 <td> <a href="#font-stretch-normal-value"
1144 title="normal!!font-stretch">normal</a> | <a
1145 href="#ultra-condensed">ultra-condensed</a> | <a
1146 href="#extra-condensed">extra-condensed</a> | <a
1147 href="#condensed">condensed</a> | <a
1148 href="#semi-condensed-">semi-condensed</a> | <a
1149 href="#semi-expanded">semi-expanded</a> | <a
1150 href="#expanded">expanded</a> | <a
1151 href="#extra-expanded">extra-expanded</a> | <a
1152 href="#ultra-expanded">ultra-expanded</a>
1154 <tr>
1155 <td>Initial:
1157 <td>normal
1159 <tr>
1160 <td>Applies to:
1162 <td>all elements
1164 <tr>
1165 <td>Inherited:
1167 <td>yes
1169 <tr>
1170 <td>Percentages:
1172 <td>N/A
1174 <tr>
1175 <td>Media:
1177 <td>visual
1179 <tr>
1180 <td>Computed value:
1182 <td>as specified
1184 <tr>
1185 <td>Animatable:
1187 <td>as <a href="#font-stretch-animation">font stretch</a>
1188 </table>
1190 <p>The <a href="#propdef-font-stretch"
1191 title="font-stretch!!property">‘<code
1192 class=property>font-stretch</code>’</a> property selects a normal,
1193 condensed, or expanded face from a font family. Absolute keyword values
1194 have the following ordering, from narrowest to widest:
1196 <ul>
1197 <li><dfn id=ultra-condensed>ultra-condensed</dfn>
1199 <li><dfn id=extra-condensed>extra-condensed</dfn>
1201 <li><dfn id=condensed>condensed</dfn>
1203 <li><dfn id=semi-condensed->semi-condensed </dfn>
1205 <li><dfn id=font-stretch-normal-value
1206 title="normal!!font-stretch">normal</dfn>
1208 <li><dfn id=semi-expanded>semi-expanded</dfn>
1210 <li><dfn id=expanded>expanded</dfn>
1212 <li><dfn id=extra-expanded>extra-expanded</dfn>
1214 <li><dfn id=ultra-expanded>ultra-expanded</dfn>
1215 </ul>
1217 <p>When a face does not exist for a given width, normal or condensed values
1218 map to a narrower face, otherwise a wider face. Conversely, expanded
1219 values map to a wider face, otherwise a narrower face. The figure below
1220 shows how the nine font-stretch property settings affect font selection
1221 for font family containing a variety of widths, grey indicates a width for
1222 which no face exists and a different width is substituted:
1224 <div class=figure><img alt="width mappings for a family with condensed,
1225 normal and expanded faces" src=universwidths.png>
1226 <p class=caption>Width mappings for a font family with condensed, normal
1227 and expanded width faces
1228 </div>
1230 <p id=font-stretch-animation>Animation of font stretch: Font stretch is
1231 interpolated in discrete steps. The interpolation happens as though the
1232 ordered values are equally spaced real numbers. The interpolation result
1233 is rounded to the nearest value, with values exactly halfway between two
1234 values rounded towards the later value in the list above.</p>
1235 <!-- prop: font-style -->
1237 <h3 id=font-style-prop><span class=secno>3.4 </span>Font style: the <a
1238 href="#propdef-font-style">font-style</a> property</h3>
1240 <table class=propdef id=namefont-stylevaluenormal-italic-oblique>
1241 <tbody>
1242 <tr>
1243 <td>Name:
1245 <td><dfn id=propdef-font-style
1246 title="font-style!!property">font-style</dfn>
1248 <tr>
1249 <td>Value:
1251 <td><a href="#font-style-normal-value"
1252 title="normal!!font-style">normal</a> | <a href="#italic">italic</a> |
1253 <a href="#oblique">oblique</a>
1255 <tr>
1256 <td>Initial:
1258 <td>normal
1260 <tr>
1261 <td>Applies to:
1263 <td>all elements
1265 <tr>
1266 <td>Inherited:
1268 <td>yes
1270 <tr>
1271 <td>Percentages:
1273 <td>N/A
1275 <tr>
1276 <td>Media:
1278 <td>visual
1280 <tr>
1281 <td>Computed value:
1283 <td>as specified
1285 <tr>
1286 <td>Animatable:
1288 <td>no
1289 </table>
1291 <p>The <a href="#propdef-font-style" title="font-style!!property">‘<code
1292 class=property>font-style</code>’</a> property allows italic or oblique
1293 faces to be selected. Italic forms are generally cursive in nature while
1294 oblique faces are typically sloped versions of the regular face. Oblique
1295 faces can be simulated by artificially sloping the glyphs of the regular
1296 face. Compare the artificially sloped renderings of Palatino ‘<code
1297 class=property>a</code>’ and Baskerville ‘<code
1298 class=property>N</code>’ in grey with the actual italic versions:
1300 <div class=figure><img alt="artificial sloping vs. real italics"
1301 src=realvsfakeitalics.png>
1302 <p class=caption>Artificial sloping versus real italics
1303 </div>
1305 <p>Values have the following meanings:
1307 <dl>
1308 <dt><dfn id=font-style-normal-value
1309 title="normal!!font-style">normal</dfn>
1311 <dd>selects a face that is classified as a normal face, one that is
1312 neither italic or obliqued
1314 <dt><dfn id=italic>italic</dfn>
1316 <dd>selects a font that is labeled as an italic face, or an oblique face
1317 if one is not
1319 <dt><dfn id=oblique>oblique</dfn>
1321 <dd>selects a font that is labeled as an oblique face, or an italic face
1322 if one is not
1323 </dl>
1325 <p>If no italic or oblique face is available, oblique faces can be
1326 synthesized by rendering non-obliqued faces with a right sloping
1327 transformation applied. When synthesizing these faces, the transformation
1328 should apply to all glyphs in the same way and not vary based on codepoint
1329 or due to horizontal or vertical line orientation.
1331 <p class=issue>It has been <a
1332 href="http://lists.w3.org/Archives/Public/www-style/2013May/0272.html">proposed</a>
1333 that for vertical text runs, synthetic italics should not mimic normal
1334 italic glyphs but instead mimic the customs of Japanese obliquing
1335 (斜体、shatai), where the obliquing is applied across the text run
1336 regardless of glyph orientation.
1338 <p>Many scripts lack the tradition of mixing a cursive form within text
1339 rendered with a normal face. Chinese, Japanese and Korean fonts almost
1340 always lack italic or oblique faces. Fonts that support a mixture of
1341 scripts will sometimes omit specific scripts such as Arabic from the set
1342 of glyphs supported in the italic face. User agents should be careful
1343 about making <a href="#character-map"><em>character map</em></a>
1344 assumptions across faces.</p>
1345 <!-- prop: font-size -->
1347 <h3 id=font-size-prop><span class=secno>3.5 </span>Font size: the <a
1348 href="#propdef-font-size">font-size</a> property</h3>
1350 <table class=propdef id=namefont-sizevalueltabsolute-sizegt-ltre>
1351 <tbody>
1352 <tr>
1353 <td>Name:
1355 <td><dfn id=propdef-font-size>font-size</dfn>
1357 <tr>
1358 <td>Value:
1360 <td><a href="#absolute-size-value"><var><absolute-size></var></a>
1361 | <a href="#relative-size-value"><var><relative-size></var></a> |
1362 <a href="#length-size-value"><var><length></var></a> | <a
1363 href="#percentage-size-value"><var><percentage></var></a>
1365 <tr>
1366 <td>Initial:
1368 <td>medium
1370 <tr>
1371 <td>Applies to:
1373 <td>all elements
1375 <tr>
1376 <td>Inherited:
1378 <td>yes
1380 <tr>
1381 <td>Percentages:
1383 <td>refer to parent element's font size
1385 <tr>
1386 <td>Media:
1388 <td>visual
1390 <tr>
1391 <td>Computed value:
1393 <td>absolute length
1395 <tr>
1396 <td>Animatable:
1398 <td>as <a
1399 href="http://dev.w3.org/csswg/css3-transitions/#animtype-length">length</a>
1400 </table>
1402 <p>This property indicates the desired height of glyphs from the font. For
1403 scalable fonts, the font-size is a scale factor applied to the EM unit of
1404 the font. (Note that certain glyphs may bleed outside their EM box.) For
1405 non-scalable fonts, the font-size is converted into absolute units and
1406 matched against the declared font-size of the font, using the same
1407 absolute coordinate space for both of the matched values. Values have the
1408 following meanings:
1410 <dl>
1411 <dt><dfn id=absolute-size-value><var><absolute-size></var></dfn>
1413 <dd> An <a
1414 href="#absolute-size-value"><var><absolute-size></var></a> keyword
1415 refers to an entry in a table of font sizes computed and kept by the user
1416 agent. Possible values are:
1417 <p> [ xx-small | x-small | small | medium | large | x-large | xx-large ]</p>
1419 <dt><dfn id=relative-size-value><var><relative-size></var></dfn>
1421 <dd> A <a href="#relative-size-value"><var><relative-size></var></a>
1422 keyword is interpreted relative to the table of font sizes and the
1423 computed ‘<a href="#propdef-font-size"><code
1424 class=property>font-size</code></a>’ of the parent element. Possible
1425 values are:
1426 <p> [ larger | smaller ]
1428 <p> For example, if the parent element has a font size of ‘<code
1429 class=property>medium</code>’, a value of ‘<code
1430 class=property>larger</code>’ will make the font size of the current
1431 element be ‘<code class=property>large</code>’. If the parent
1432 element's size is not close to a table entry, the user agent is free to
1433 interpolate between table entries or round off to the closest one. The
1434 user agent may have to extrapolate table values if the numerical value
1435 goes beyond the keywords.
1437 <dt><dfn id=length-size-value><var><length></var></dfn>
1439 <dd>A length value specifies an absolute font size (independent of the
1440 user agent's font table). Negative lengths are illegal.
1442 <dt><dfn id=percentage-size-value><var><percentage></var></dfn>
1444 <dd>A percentage value specifies an absolute font size relative to the
1445 parent element's font size. Use of percentage values, or values in
1446 ‘<code class=property>em</code>’s, leads to more robust and
1447 cascadable style sheets.
1448 </dl>
1450 <p>The following table provides user agent guidelines for the absolute-size
1451 scaling factor and their mapping to HTML heading and absolute font-sizes.
1452 The ‘<code class=property>medium</code>’ value is used as the
1453 reference middle value. The user agent may fine-tune these values for
1454 different fonts or different types of display devices.
1456 <table class=data>
1457 <thead>
1458 <tr>
1459 <th>CSS absolute-size values
1461 <th>xx-small
1463 <th>x-small
1465 <th>small
1467 <th>medium
1469 <th>large
1471 <th>x-large
1473 <th>xx-large
1475 <th>
1477 <tbody>
1478 <tr>
1479 <th>scaling factor
1481 <td>3/5
1483 <td>3/4
1485 <td>8/9
1487 <td>1
1489 <td>6/5
1491 <td>3/2
1493 <td>2/1
1495 <td>3/1
1497 <tr>
1498 <th>HTML headings
1500 <td>h6
1502 <td>
1504 <td>h5
1506 <td>h4
1508 <td>h3
1510 <td>h2
1512 <td>h1
1514 <td>
1516 <tr>
1517 <th>HTML font sizes
1519 <td>1
1521 <td>
1523 <td>2
1525 <td>3
1527 <td>4
1529 <td>5
1531 <td>6
1533 <td>7
1534 </table>
1536 <p class=note><em><strong>Note 1.</strong> To preserve readability, an UA
1537 applying these guidelines should nevertheless avoid creating font-size
1538 resulting in less than 9 device pixels per EM unit on a computer
1539 display.</em>
1541 <p class=note><em><strong>Note 2.</strong> In CSS1, the suggested scaling
1542 factor between adjacent indexes was 1.5 which user experience proved to be
1543 too large. In CSS2, the suggested scaling factor for computer screen
1544 between adjacent indexes was 1.2 which still created issues for the small
1545 sizes. The new scaling factor varies between each index to provide a
1546 better readability.</em>
1548 <p>The actual value of this property may differ from the computed value due
1549 a numerical value on ‘<a href="#propdef-font-size-adjust"><code
1550 class=property>font-size-adjust</code></a>’ and the unavailability of
1551 certain font sizes.
1553 <p>Child elements inherit the computed <a class=noxref
1554 href="#font-size-prop"> <span class=property>‘<code
1555 class=property>font-size</code>’</span></a> value (otherwise, the effect
1556 of <a class=noxref href="#font-size-adjust-prop"><span
1557 class=property>‘<code
1558 class=property>font-size-adjust</code>’</span></a> would compound).
1560 <div class=example>
1561 <p style="display:none">Example(s):
1563 <p>
1565 <pre>p { font-size: 12pt; }
1566 blockquote { font-size: larger }
1567 em { font-size: 150% }
1568 em { font-size: 1.5em }
1569 </pre>
1570 </div>
1571 <!-- prop: font-size-adjust -->
1573 <h3 id=font-size-adjust-prop><span class=secno>3.6 </span>Relative sizing:
1574 the <a href="#propdef-font-size-adjust">font-size-adjust</a> property</h3>
1576 <table class=propdef id=namefont-size-adjustvaluenone-auto-ltnum>
1577 <tbody>
1578 <tr>
1579 <td>Name:
1581 <td><dfn id=propdef-font-size-adjust>font-size-adjust</dfn>
1583 <tr>
1584 <td>Value:
1586 <td><a href="#font-size-adjust-none-value"
1587 title="none!!font-size-adjust">none</a> | <a
1588 href="#font-size-adjust-auto-value"
1589 title="auto!!font-size-adjust">auto</a> | <a
1590 href="#aspect-ratio-value"><var><number></var></a>
1592 <tr>
1593 <td>Initial:
1595 <td>none
1597 <tr>
1598 <td>Applies to:
1600 <td>all elements
1602 <tr>
1603 <td>Inherited:
1605 <td>yes
1607 <tr>
1608 <td>Percentages:
1610 <td>N/A
1612 <tr>
1613 <td>Media:
1615 <td>visual
1617 <tr>
1618 <td>Computed value:
1620 <td>as specified
1622 <tr>
1623 <td>Animatable:
1625 <td>as <a
1626 href="http://dev.w3.org/csswg/css3-transitions/#animtype-number">number</a>
1627 </table>
1629 <p>For any given font size, the apparent size and legibility of text varies
1630 across fonts. For scripts such as Latin or Cyrillic that distinguish
1631 between upper and lowercase letters, the relative height of lowercase
1632 letters compared to their uppercase counterparts is a determining factor
1633 of legibility. This is commonly referred to as the <a class=index-def
1634 href="#aspect-value" id=aspect-value0 title="aspect value"><dfn
1635 id=aspect-value>aspect value</dfn></a>. Precisely defined, it is equal to
1636 the x-height of a font divided by the font size.
1638 <p>In situations where font fallback occurs, fallback fonts may not share
1639 the same aspect ratio as the desired font family and will thus appear less
1640 readable. The font-size-adjust property is a way to preserve the
1641 readability of text when font fallback occurs. It does this by adjusting
1642 the font-size so that the x-height is the same regardless of the font
1643 used.
1645 <div class=example>
1646 <p>The style defined below defines Verdana as the desired font family, but
1647 if Verdana is not available Futura or Times will be used.</p>
1649 <pre>p {
1650 font-family: Verdana, Futura, Times;
1651 }
1653 <p>Lorem ipsum dolor sit amet, ...</p>
1654 </pre>
1656 <p>Verdana has a relatively high aspect ratio, lowercase letters are
1657 relatively tall compared to uppercase letters, so at small sizes text
1658 appears legible. Times has a lower aspect ratio and so if fallback
1659 occurs, the text will be less legible at small sizes than Verdana.</p>
1660 </div>
1662 <p>How text rendered in each of these fonts compares is shown below, the
1663 columns show text rendered in Verdana, Futura and Times. The same
1664 font-size value is used across cells within each row and red lines are
1665 included to show the differences in x-height. In the upper half each row
1666 is rendered in the same font-size value. The same is true for the lower
1667 half but in this half the font-size-adjust property is also set so that
1668 the actual font size is adjusted to preserve the x-height across each row.
1669 Note how small text remains relatively legible across each row in the
1670 lower half.
1672 <div class=figure><img alt="text with and without font-size-adjust"
1673 src=fontsizeadjust.png>
1674 <p class=caption>Text with and without the use of font-size-adjust
1675 </div>
1677 <p>This property allows authors to specify an aspect value for an element
1678 that will effectively preserve the x-height of the first choice font,
1679 whether it is substituted or not. Values have the following meanings:
1681 <dl>
1682 <dt><dfn id=font-size-adjust-none-value
1683 title="none!!font-size-adjust">none</dfn>
1685 <dd>Do not preserve the font's x-height.
1687 <dt><dfn id=font-size-adjust-auto-value
1688 title="auto!!font-size-adjust">auto</dfn>
1690 <dd>Behaves just like <number>, except the number used is the aspect
1691 value calculated by user agents for the first font in the list of fonts
1692 defined for the initial value of the <a href="#propdef-font-family"
1693 title="font-family!!property">‘<code
1694 class=property>font-family</code>’</a> property. Effectively this is
1695 the default font used when <a href="#propdef-font-family"
1696 title="font-family!!property">‘<code
1697 class=property>font-family</code>’</a> is not otherwise specified.
1698 <p>Authors can use this value to specify that font size should be
1699 normalized across fonts based on the x-height without the need to
1700 specify the aspect ratio explicitly.</p>
1702 <dt><dfn id=aspect-ratio-value><var><number></var></dfn>
1704 <dd>Specifies the aspect value used in the calculation below to calculate
1705 the adjusted font size:
1706 <pre>c = ( a / a' ) s
1707 </pre>
1709 <p>where:</p>
1711 <pre>s = font-size value
1712 a = aspect value as specified by the font-size-adjust property
1713 a' = aspect value of actual font
1714 c = adjusted font-size to use
1715 </pre>
1717 <p>This value applies to any font that is selected but in typical usage
1718 it should be based on the aspect value of the first font in the
1719 font-family list. If this is specified accurately, the <tt>(a/a')</tt>
1720 term in the formula above is effectively 1 for the first font and no
1721 adjustment occurs. If the value is specified inaccurately, text rendered
1722 using the first font in the family list will display differently in
1723 older user agents that don't support font-size-adjust.</p>
1724 </dl>
1726 <p>Authors can calculate the aspect value for a given font by comparing
1727 spans with the same content but different font-size-adjust properties. If
1728 the same font-size is used, the spans will match when the font-size-adjust
1729 value is accurate for the given font.
1731 <div class=example>
1732 <p>Two spans with borders are used to determine the aspect value of a
1733 font. The font-size is the same for both spans but the font-size-adjust
1734 property is specified only for the right span. Starting with a value of
1735 0.5, the aspect value can be adjusted until the borders around the two
1736 letters line up.</p>
1738 <pre>p {
1739 font-family: Futura;
1740 font-size: 500px;
1741 }
1743 span {
1744 border: solid 1px red;
1745 }
1747 .adjust {
1748 font-size-adjust: 0.5;
1749 }
1751 <p><span>b</span><span class="adjust">b</span></p>
1752 </pre>
1754 <div class=figure><img alt="Futura with an aspect value of 0.5"
1755 src=beforefontsizeadjust.png>
1756 <p class=caption>Futura with an aspect value of 0.5
1757 </div>
1759 <p>The box on the right is a bit bigger than the one on the left, so the
1760 aspect value of this font is something less than 0.5. Adjust the value
1761 until the boxes align.</p>
1762 </div>
1763 <!-- prop: font -->
1765 <h3 id=font-prop><span class=secno>3.7 </span>Shorthand font property: the
1766 <a href="#propdef-font">font</a> property</h3>
1768 <table class=propdef id=namefontvalue-ltlsquofont-stylersquogt-l>
1769 <tbody>
1770 <tr>
1771 <td>Name:
1773 <td><dfn id=propdef-font>font</dfn>
1775 <tr>
1776 <td>Value:
1778 <td>[ [ <var><<a href="#propdef-font-style"
1779 title="font-style!!property">‘<code
1780 class=property>font-style</code>’</a>></var> || <a
1781 href="#font-variant-css21-values"><var><font-variant-css21></var></a>
1782 || <var><<a href="#propdef-font-weight"
1783 title="font-weight!!property">‘<code
1784 class=property>font-weight</code>’</a>></var> || <var><<a
1785 href="#propdef-font-stretch" title="font-stretch!!property">‘<code
1786 class=property>font-stretch</code>’</a></var> ]? <var><‘<a
1787 href="#propdef-font-size"><code
1788 class=property>font-size</code></a>’></var> [ / <var><‘<code
1789 class=property>line-height</code>’></var> ]? <var><<a
1790 href="#propdef-font-family" title="font-family!!property">‘<code
1791 class=property>font-family</code>’</a>></var> ] | caption | icon |
1792 menu | message-box | small-caption | status-bar
1794 <tr>
1795 <td>Initial:
1797 <td>see individual properties
1799 <tr>
1800 <td>Applies to:
1802 <td>all elements
1804 <tr>
1805 <td>Inherited:
1807 <td>yes
1809 <tr>
1810 <td>Percentages:
1812 <td>see individual properties
1814 <tr>
1815 <td>Media:
1817 <td>visual
1819 <tr>
1820 <td>Computed value:
1822 <td>see individual properties
1824 <tr>
1825 <td>Animatable:
1827 <td>see individual properties
1828 </table>
1830 <p>The <span class=property>‘<a href="#propdef-font"><code
1831 class=property>font</code></a>’</span> property is, except as described
1832 below, a shorthand property for setting <a href="#propdef-font-style"
1833 title="font-style!!property">‘<code
1834 class=property>font-style</code>’</a>, <a href="#propdef-font-variant"
1835 title="font-variant!!property">‘<code
1836 class=property>font-variant</code>’</a>, <a href="#propdef-font-weight"
1837 title="font-weight!!property">‘<code
1838 class=property>font-weight</code>’</a>, <a href="#propdef-font-stretch"
1839 title="font-stretch!!property">‘<code
1840 class=property>font-stretch</code>’</a>, <span class=property>‘<a
1841 href="#propdef-font-size"><code
1842 class=property>font-size</code></a>’</span>, <a class=property
1843 href="http://www.w3.org/TR/CSS2/visudet.html#propdef-line-height">‘<code
1844 class=property>line-height</code>’</a>, <a href="#propdef-font-family"
1845 title="font-family!!property">‘<code
1846 class=property>font-family</code>’</a> at the same place in the
1847 stylesheet. Values for the <a href="#propdef-font-variant"
1848 title="font-variant!!property">‘<code
1849 class=property>font-variant</code>’</a> property may also be included
1850 but only those supported in CSS 2.1, none of the font-variant values added
1851 in this specification can be used in the <span class=property>‘<a
1852 href="#propdef-font"><code class=property>font</code></a>’</span>
1853 shorthand:
1855 <pre
1856 class=prod><dfn id=font-variant-css21-values><var><font-variant-css21></var></dfn> = [normal | small-caps]</pre>
1858 <p>The syntax of this property is based on a traditional typographical
1859 shorthand notation to set multiple properties related to fonts.
1861 <p>All subproperties of the ‘<a href="#propdef-font"><code
1862 class=property>font</code></a>’ property are first reset to their
1863 initial values, including those listed above plus <span
1864 class=property>‘<a href="#propdef-font-size-adjust"><code
1865 class=property>font-size-adjust</code></a>’</span>, <span
1866 class=property>‘<a href="#propdef-font-kerning"><code
1867 class=property>font-kerning</code></a>’</span>, subproperties of <a
1868 href="#propdef-font-variant" title="font-variant!!property">‘<code
1869 class=property>font-variant</code>’</a> and and <span>‘<a
1870 href="#propdef-font-language-override"><code
1871 class=property>font-language-override</code></a>’</span>. Then, those
1872 properties that are given explicit values in the <span
1873 class=property>‘<a href="#propdef-font"><code
1874 class=property>font</code></a>’</span> shorthand are set to those
1875 values. For a definition of allowed and initial values, see the previously
1876 defined properties. For reasons of backwards compatibility, it is not
1877 possible to set <span class=property>‘<a
1878 href="#propdef-font-size-adjust"><code
1879 class=property>font-size-adjust</code></a>’</span> to anything other
1880 than its initial value using the <span class=property>‘<a
1881 href="#propdef-font"><code class=property>font</code></a>’</span>
1882 shorthand property; instead, use the individual property.
1884 <div class=example>
1885 <p style="display:none">Example(s):
1887 <p>
1889 <pre>p { font: 12pt/14pt sans-serif }
1890 p { font: 80% sans-serif }
1891 p { font: x-large/110% "new century schoolbook", serif }
1892 p { font: bold italic large Palatino, serif }
1893 p { font: normal small-caps 120%/120% fantasy }
1894 p { font: condensed oblique 12pt "Helvetica Neue", serif; }
1895 </pre>
1897 <p> In the second rule, the font size percentage value (‘<code
1898 class=css>80%</code>’) refers to the computed ‘<a
1899 href="#propdef-font-size"><code class=property>font-size</code></a>’ of
1900 the parent element. In the third rule, the line height percentage
1901 (‘<code class=css>110%</code>’) refers to the font size of the
1902 element itself.
1904 <p>The first three rules do not specify the <a
1905 href="#propdef-font-variant" title="font-variant!!property">‘<code
1906 class=property>font-variant</code>’</a> and <a
1907 href="#propdef-font-weight" title="font-weight!!property">‘<code
1908 class=property>font-weight</code>’</a> explicitly, so these properties
1909 receive their initial values (‘<a href="#normal"><code
1910 class=property>normal</code></a>’). Notice that the font family name
1911 "new century schoolbook", which contains spaces, is enclosed in quotes.
1912 The fourth rule sets the <a href="#propdef-font-weight"
1913 title="font-weight!!property">‘<code
1914 class=property>font-weight</code>’</a> to ‘<a href="#bold"><code
1915 class=property>bold</code></a>’, the <a href="#propdef-font-style"
1916 title="font-style!!property">‘<code
1917 class=property>font-style</code>’</a> to ‘<a href="#italic"><code
1918 class=property>italic</code></a>’, and implicitly sets <a
1919 href="#propdef-font-variant" title="font-variant!!property">‘<code
1920 class=property>font-variant</code>’</a> to ‘<a href="#normal"><code
1921 class=property>normal</code></a>’.
1923 <p> The fifth rule sets the <a href="#propdef-font-variant"
1924 title="font-variant!!property">‘<code
1925 class=property>font-variant</code>’</a> (‘<a href="#small-caps"><code
1926 class=property>small-caps</code></a>’), the <span class=property>‘<a
1927 href="#propdef-font-size"><code
1928 class=property>font-size</code></a>’</span> (120% of the parent's font
1929 size), the <a class=property
1930 href="http://www.w3.org/TR/CSS2/visudet.html#propdef-line-height">‘<code
1931 class=property>line-height</code>’</a> (120% of the font size) and the
1932 <a href="#propdef-font-family" title="font-family!!property">‘<code
1933 class=property>font-family</code>’</a> (‘<a href="#fantasy"><code
1934 class=property>fantasy</code></a>’). It follows that the keyword ‘<a
1935 href="#normal"><code class=property>normal</code></a>’ applies to the
1936 two remaining properties: <a href="#propdef-font-style"
1937 title="font-style!!property">‘<code
1938 class=property>font-style</code>’</a> and <a
1939 href="#propdef-font-weight" title="font-weight!!property">‘<code
1940 class=property>font-weight</code>’</a>.
1942 <p>The sixth rule sets the <a href="#propdef-font-style"
1943 title="font-style!!property">‘<code
1944 class=property>font-style</code>’</a>, <a href="#propdef-font-stretch"
1945 title="font-stretch!!property">‘<code
1946 class=property>font-stretch</code>’</a>, <span class=property>‘<a
1947 href="#propdef-font-size"><code
1948 class=property>font-size</code></a>’</span>, and <a
1949 href="#propdef-font-family" title="font-family!!property">‘<code
1950 class=property>font-family</code>’</a>, the other font properties being
1951 set to their initial values.
1952 </div>
1954 <p>Since the <a href="#propdef-font-stretch"
1955 title="font-stretch!!property">‘<code
1956 class=property>font-stretch</code>’</a> property was not defined in CSS
1957 2.1, when using <a href="#propdef-font-stretch"
1958 title="font-stretch!!property">‘<code
1959 class=property>font-stretch</code>’</a> values within ‘<a
1960 href="#propdef-font"><code class=property>font</code></a>’ rules,
1961 authors should include a extra version compatible with older user agents:
1963 <pre>p {
1964 font: 80% sans-serif; /* for older user agents */
1965 font: condensed 80% sans-serif;
1966 }</pre>
1968 <p>The following values refer to system fonts:
1970 <dl>
1971 <dt><strong>caption</strong>
1973 <dd>The font used for captioned controls (e.g., buttons, drop-downs,
1974 etc.).
1976 <dt><strong>icon</strong>
1978 <dd>The font used to label icons.
1980 <dt><strong>menu</strong>
1982 <dd>The font used in menus (e.g., dropdown menus and menu lists).
1984 <dt><strong>message-box</strong>
1986 <dd>The font used in dialog boxes.
1988 <dt><strong>small-caption</strong>
1990 <dd>The font used for labeling small controls.
1992 <dt><strong>status-bar</strong>
1994 <dd>The font used in window status bars.
1995 </dl>
1997 <p>System fonts may only be set as a whole; that is, the font family, size,
1998 weight, style, etc. are all set at the same time. These values may then be
1999 altered individually if desired. If no font with the indicated
2000 characteristics exists on a given platform, the user agent should either
2001 intelligently substitute (e.g., a smaller version of the ‘<code
2002 class=property>caption</code>’ font might be used for the ‘<code
2003 class=property>small-caption</code>’ font), or substitute a user agent
2004 default font. As for regular fonts, if, for a system font, any of the
2005 individual properties are not part of the operating system's available
2006 user preferences, those properties should be set to their initial values.
2008 <p>That is why this property is "almost" a shorthand property: system fonts
2009 can only be specified with this property, not with <a
2010 href="#propdef-font-family" title="font-family!!property">‘<code
2011 class=property>font-family</code>’</a> itself, so <span
2012 class=property>‘<a href="#propdef-font"><code
2013 class=property>font</code></a>’</span> allows authors to do more than
2014 the sum of its subproperties. However, the individual properties such as
2015 <a href="#propdef-font-weight" title="font-weight!!property">‘<code
2016 class=property>font-weight</code>’</a> are still given values taken from
2017 the system font, which can be independently varied.
2019 <p>Note that the keywords used for the system fonts listed above are only
2020 treated as keywords when they occur in the initial position, in other
2021 positions the same string is treated as part of the font family name:
2023 <pre> font: menu; /* use the font settings for system menus */
2024 font: large menu; /* use a font family named "menu" */</pre>
2026 <div class=example>
2027 <p style="display:none">Example(s):
2029 <p>
2031 <pre>button { font: 300 italic 1.3em/1.7em "FB Armada", sans-serif }
2032 button p { font: menu }
2033 button p em { font-weight: bolder }
2034 </pre>
2036 <p>If the font used for dropdown menus on a particular system happened to
2037 be, for example, 9-point Charcoal, with a weight of 600, then P elements
2038 that were descendants of BUTTON would be displayed as if this rule were
2039 in effect:
2041 <pre>button p { font: 600 9pt Charcoal }
2042 </pre>
2044 <p>Because the <span class=property>‘<a href="#propdef-font"><code
2045 class=property>font</code></a>’</span> shorthand resets to its initial
2046 value any property not explicitly given a value, this has the same effect
2047 as this declaration:
2049 <pre>button p {
2050 font-style: normal;
2051 font-variant: normal;
2052 font-weight: 600;
2053 font-size: 9pt;
2054 line-height: normal;
2055 font-family: Charcoal
2056 }
2057 </pre>
2058 </div>
2059 <!-- prop: font-synthesis -->
2061 <h3 id=font-synthesis-prop><span class=secno>3.8 </span>Controlling
2062 synthetic faces: the <a href="#propdef-font-synthesis">font-synthesis</a>
2063 property</h3>
2065 <table class=propdef id=namefont-synthesisvaluenone-weight-style>
2066 <tbody>
2067 <tr>
2068 <td>Name:
2070 <td><dfn id=propdef-font-synthesis>font-synthesis</dfn>
2072 <tr>
2073 <td>Value:
2075 <td>none | [ weight || style ]
2077 <tr>
2078 <td>Initial:
2080 <td>weight style
2082 <tr>
2083 <td>Applies to:
2085 <td>all elements
2087 <tr>
2088 <td>Inherited:
2090 <td>yes
2092 <tr>
2093 <td>Percentages:
2095 <td>N/A
2097 <tr>
2098 <td>Media:
2100 <td>visual
2102 <tr>
2103 <td>Computed value:
2105 <td>as specified
2107 <tr>
2108 <td>Animatable:
2110 <td>no
2111 </table>
2113 <p>This property controls whether user agents are allowed to synthesize
2114 bold or oblique font faces when a font family lacks bold or italic faces.
2115 If ‘<a href="#weight"><code class=property>weight</code></a>’ is not
2116 specified, user agents must not synthesize bold faces and if ‘<code
2117 class=property>style</code>’ is not specified user agents must not
2118 synthesize italic faces. A value of ‘<code class=property>none</code>’
2119 disallows all synthetic faces.
2121 <div class=example>
2122 <p>The style rule below disables the use of synthetically obliqued Arabic:</p>
2124 <pre>*:lang(ar) { font-synthesis: none; }
2125 </pre>
2126 </div>
2128 <h2 id=font-resources><span class=secno>4 </span>Font Resources</h2>
2130 <h3 id=font-face-rule><span class=secno>4.1 </span>The
2131 <code>@font-face</code> rule</h3>
2133 <p>The <code>@font-face</code> rule allows for linking to fonts that are
2134 automatically fetched and activated when needed. This allows authors to
2135 select a font that closely matches the design goals for a given page
2136 rather than limiting the font choice to a set of fonts available on all
2137 platforms. A set of font descriptors define the location of a font
2138 resource, either locally or externally, along with the style
2139 characteristics of an individual face. Multiple <code>@font-face</code>
2140 rules can be used to construct font families with a variety of faces.
2141 Using CSS font matching rules, a user agent can selectively download only
2142 those faces that are needed for a given piece of text.
2144 <p>The @font-face rule consists of the @font-face at-keyword followed by a
2145 block of descriptor declarations. In terms of the grammar, this
2146 specification defines the following productions:
2148 <pre><dfn id=fontfacerule>font_face_rule</dfn>
2149 : <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>*
2150 ;
2152 <dfn id=descriptordeclaration>descriptor_declaration</dfn>
2153 : <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>
2154 ;</pre>
2156 <p>The following new definitions are introduced:
2158 <pre>- -|\\0{0,4}2d(\r\n|[ \t\r\n\f])?
2159 F f|\\0{0,4}(46|66)(\r\n|[ \t\r\n\f])?</pre>
2161 <p>The following new token is introduced:
2163 <pre>@{F}{O}{N}{T}{-}{F}{A}{C}{E} {return <dfn id=fontfacesym>FONT_FACE_SYM</dfn>;}</pre>
2165 <p>Each <span class=index-inst id=font-face
2166 title="@font-face"><code>@font-face</code></span> rule specifies a value
2167 for every font descriptor, either implicitly or explicitly. Those not
2168 given explicit values in the rule take the initial value listed with each
2169 descriptor in this specification. These descriptors apply solely within
2170 the context of the <code>@font-face</code> rule in which they are defined,
2171 and do not apply to document language elements. There is no notion of
2172 which elements the descriptors apply to or whether the values are
2173 inherited by child elements. When a given descriptor occurs multiple times
2174 in a given <code>@font-face</code> rule, only the last descriptor
2175 declaration is used and all prior declarations for that descriptor are
2176 ignored.
2178 <div class=example>
2179 <p>To use a downloadable font called Gentium:</p>
2181 <pre>
2182 @font-face {
2183 font-family: Gentium;
2184 src: url(http://example.com/fonts/Gentium.ttf);
2185 }
2187 p { font-family: Gentium, serif; }
2188 </pre>
2190 <p>The user agent will download Gentium and use it when rendering text
2191 within paragraph elements. If for some reason the site serving the font
2192 is unavailable, the default serif font will be used.</p>
2193 </div>
2195 <p>A given set of <code>@font-face</code> rules define a set of fonts
2196 available for use within the documents that contain these rules. When font
2197 matching is done, fonts defined using these rules are considered before
2198 other available fonts on a system.
2200 <p>Downloaded fonts are only available to documents that reference them.
2201 The process of activating these fonts must not make them available to
2202 other applications or to documents that don't directly link to the same
2203 font. User agent implementers might consider it convenient to use
2204 downloaded fonts when rendering characters in other documents for which no
2205 other available font exists as part of the system font fallback procedure.
2206 However, this would cause a security leak since the contents of one page
2207 would be able to affect other pages, something an attacker could use as an
2208 attack vector. These restrictions do not affect caching behavior, fonts
2209 are cached the same way other web resources are cached.
2211 <p>This at-rule follows the forward-compatible parsing rules of CSS. Like
2212 properties in a declaration block, declarations of any descriptors that
2213 are not supported by the user agent must be ignored.
2214 <code>@font-face</code> rules require a font-family and src descriptor; if
2215 either of these are missing, the <code>@font-face</code> rule is invalid
2216 and must be ignored entirely.
2218 <p>In cases where user agents have limited platform resources or implement
2219 the ability to disable downloadable font resources,
2220 <code>@font-face</code> rules must simply be ignored; the behavior of
2221 individual descriptors as defined in this specification should not be
2222 altered.
2224 <h3 id=font-family-desc><span class=secno>4.2 </span>Font family: the <a
2225 href="#descdef-font-family">font-family</a> descriptor</h3>
2227 <table class=descdef>
2228 <tbody>
2229 <tr>
2230 <td>Name:
2232 <td><dfn id=descdef-font-family
2233 title="font-family!!descriptor">font-family</dfn>
2235 <tr>
2236 <td>Value:
2238 <td><a href="#family-name-value"><var><family-name></var></a>
2240 <tr>
2241 <td><em>Initial:</em>
2243 <td>N/A
2244 </table>
2246 <p>This descriptor defines the font family name that will be used in all
2247 CSS font family name matching. It is required for the @font-face rule to
2248 be valid. It overrides the font family names contained in the underlying
2249 font data. If the font family name is the same as a font family available
2250 in a given user's environment, it effectively hides the underlying font
2251 for documents that use the stylesheet. This permits a web author to freely
2252 choose font-family names without worrying about conflicts with font family
2253 names present in a given user's environment. Likewise, platform
2254 substitutions for a given font family name must not be used.
2256 <h3 id=src-desc><span class=secno>4.3 </span>Font reference: the <a
2257 href="#descdef-src">src</a> descriptor</h3>
2259 <table class=descdef>
2260 <tbody>
2261 <tr>
2262 <td>Name:
2264 <td><dfn id=descdef-src>src</dfn>
2266 <tr>
2267 <td>Value:
2269 <td>[ <url> [format(<string> #)]? | <a
2270 href="#font-face-name-value"><var><font-face-name></var></a> ] #
2272 <tr>
2273 <td><em>Initial:</em>
2275 <td>N/A
2276 </table>
2278 <p>This descriptor specifies the resource containing font data. It is
2279 required for the <code>@font-face</code> rule to be valid. Its value is a
2280 prioritized, comma-separated list of external references or
2281 locally-installed font face names. When a font is needed the user agent
2282 iterates over the set of references listed, using the first one it can
2283 successfully activate. Fonts containing invalid data or local font faces
2284 that are not found are ignored and the user agent loads the next font in
2285 the list.
2287 <p>As with other URLs in CSS, the URL may be relative, in which case it is
2288 resolved relative to the location of the style sheet containing the <span
2289 class=index-inst id=font-face0
2290 title="@font-face"><code>@font-face</code></span> rule. In the case of SVG
2291 fonts, the URL points to an element within a document containing SVG font
2292 definitions. If the element reference is omitted, a reference to the first
2293 defined font is implied. Similarly, font container formats that can
2294 contain more than one font must load one and only one of the fonts for a
2295 given <code>@font-face</code> rule. Fragment identifiers are used to
2296 indicate which font to load. If a container format lacks a defined
2297 fragment identifier scheme, implementations should use a simple 1-based
2298 indexing scheme (e.g. "font-collection#1" for the first font,
2299 "font-collection#2" for the second font).
2301 <pre>
2302 src: url(fonts/simple.ttf); /* load simple.ttf relative to stylesheet location */
2303 src: url(/fonts/simple.ttf); /* load simple.ttf from absolute location */
2304 src: url(fonts.svg#simple); /* load SVG font with id 'simple' */
2305 </pre>
2307 <p>External references consist of a URL, followed by an optional hint
2308 describing the format of the font resource referenced by that URL. The
2309 format hint contains a comma-separated list of format strings that denote
2310 well-known font formats. Conformant user agents must skip downloading a
2311 font resource if the format hints indicate only unsupported or unknown
2312 font formats. If no format hints are supplied, the user agent should
2313 download the font resource.
2315 <pre>
2316 /* load WOFF font if possible, otherwise use OpenType font */
2317 @font-face {
2318 font-family: bodytext;
2319 src: url(ideal-sans-serif.woff) format("woff"),
2320 url(basic-sans-serif.ttf) format("opentype");
2321 }
2322 </pre>
2324 <p>Format strings defined by this specification:
2326 <table class=data id=fontformats>
2327 <thead>
2328 <tr>
2329 <th>String
2331 <th>Font Format
2333 <th>Common extensions
2335 <tbody>
2336 <tr>
2337 <th>"woff"
2339 <td><a href="http://www.w3.org/TR/WOFF/">WOFF (Web Open Font Format)</a>
2341 <td>.woff
2343 <tr>
2344 <th>"truetype"
2346 <td><a
2347 href="http://www.microsoft.com/typography/otspec/default.htm">TrueType</a>
2349 <td>.ttf
2351 <tr>
2352 <th>"opentype"
2354 <td><a
2355 href="http://www.microsoft.com/typography/otspec/default.htm">OpenType</a>
2357 <td>.ttf, .otf
2359 <tr>
2360 <th>"embedded-opentype"
2362 <td><a
2363 href="http://www.w3.org/Submission/2008/SUBM-EOT-20080305/">Embedded
2364 OpenType</a>
2366 <td>.eot
2368 <tr>
2369 <th>"svg"
2371 <td><a href="http://www.w3.org/TR/SVG/fonts.html">SVG Font</a>
2373 <td>.svg, .svgz
2374 </table>
2376 <p>Given the overlap in common usage between TrueType and OpenType, the
2377 format hints "truetype" and "opentype" must be considered as synonymous; a
2378 format hint of "opentype" does not imply that the font contains Postscript
2379 CFF style glyph data or that it contains OpenType layout information (see
2380 <a href="#platform-props-to-css">Appendix A</a> for more background on
2381 this).
2383 <p>When authors would prefer to use a locally available copy of a given
2384 font and download it if it's not, <code>local()</code> can be used. The
2385 locally-installed <dfn
2386 id=font-face-name-value><var><font-face-name></var></dfn> argument
2387 to <code>local()</code> is a format-specific string that uniquely
2388 identifies a single font face within a larger family. The syntax for a <a
2389 href="#font-face-name-value"><var><font-face-name></var></a> is a
2390 unique font face name enclosed by "local(" and ")". The name can
2391 optionally be enclosed in quotes. If unquoted, the unquoted font family
2392 name processing conventions apply; the name must be a sequence of
2393 identifiers separated by whitespace which is converted to a string by
2394 joining the identifiers together separated by a single space.
2396 <pre>
2397 /* regular face of Gentium */
2398 @font-face {
2399 font-family: MyGentium;
2400 src: local(Gentium), /* use locally available Gentium */
2401 url(Gentium.ttf); /* otherwise, download it */
2402 }
2403 </pre>
2405 <p>For OpenType and TrueType fonts, this string is used to match only the
2406 Postscript name or the full font name in the name table of locally
2407 available fonts. Which type of name is used varies by platform and font,
2408 so authors should include both of these names to assure proper matching
2409 across platforms. Platform substitutions for a given font name must not be
2410 used.
2412 <pre>
2413 /* bold face of Gentium */
2414 @font-face {
2415 font-family: MyGentium;
2416 src: local(Gentium Bold), /* full font name */
2417 local(Gentium-Bold), /* Postscript name */
2418 url(GentiumBold.ttf); /* otherwise, download it */
2419 font-weight: bold;
2420 }
2421 </pre>
2423 <p>Just as a <code>@font-face</code> rule specifies the characteristics of
2424 a single font within a family, the unique name used with
2425 <code>local()</code> specifies a single font, not an entire font family.
2426 Defined in terms of OpenType font data, the Postscript name is found in
2427 the font's <a
2428 href="http://www.microsoft.com/typography/otspec/name.htm">name table</a>,
2429 in the name record with nameID = 6 (see <a href="#OPENTYPE"
2430 rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a> for more details). The
2431 Postscript name is the commonly used key for all fonts on OSX and for
2432 Postscript CFF fonts under Windows. The full font name (nameID = 4) is
2433 used as a unique key for fonts with TrueType glyphs on Windows.
2435 <p>For OpenType fonts with multiple localizations of the full font name,
2436 the US English version is used (language ID = 0x409 for Windows and
2437 language ID = 0 for Macintosh) or the first localization when a US English
2438 full font name is not available (the OpenType specification recommends
2439 that <a href="http://www.microsoft.com/typography/otspec/recom.htm">all
2440 fonts minimally include US English names</a>). User agents that also match
2441 other full font names, e.g. matching the Dutch name when the current
2442 system locale is set to Dutch, are considered non-conformant. This is done
2443 not to prefer English but to avoid matching inconsistencies across font
2444 versions and OS localizations, since font style names (e.g. "Bold") are
2445 frequently localized into many languages and the set of localizations
2446 available varies widely across platform and font version. User agents that
2447 match a concatenation of family name (nameID = 1) with style name (nameID
2448 = 2) are considered non-conformant.
2450 <p>This also allows for referencing faces that belong to larger families
2451 that cannot otherwise be referenced.
2453 <div class=example>
2454 <p>Use a local font or reference an SVG font in another document:</p>
2456 <pre>
2457 @font-face {
2458 font-family: Headline;
2459 src: local(Futura-Medium),
2460 url(fonts.svg#MyGeometricModern) format("svg");
2461 }
2462 </pre>
2464 <p>Create an alias for local Japanese fonts on different platforms:</p>
2466 <pre>
2467 @font-face {
2468 font-family: jpgothic;
2469 src: local(HiraKakuPro-W3), local(Meiryo), local(IPAPGothic);
2470 }
2471 </pre>
2473 <p>Reference a font face that cannot be matched within a larger family:</p>
2475 <pre>
2476 @font-face {
2477 font-family: Hoefler Text Ornaments;
2478 /* has the same font properties as Hoefler Text Regular */
2479 src: local(HoeflerText-Ornaments);
2480 }
2481 </pre>
2483 <p>Since localized fullnames never match, a document with the header style
2484 rules below would always render using the default serif font, regardless
2485 whether a particular system locale parameter is set to Finnish or not:</p>
2487 <pre>
2488 @font-face {
2489 font-family: SectionHeader;
2490 src: local("Arial Lihavoitu"); /* Finnish fullname for Arial Bold, should fail */
2491 font-weight: bold;
2492 }
2494 h2 { font-family: SectionHeader, serif; }
2495 </pre>
2497 <p>A conformant user agent would never load the font ‘<code
2498 class=css>gentium.eot</code>’ in the example below, since it is
2499 included in the first definition of the ‘<a href="#descdef-src"><code
2500 class=property>src</code></a>’ descriptor which is overridden by the
2501 second definition in the same <code>@font-face</code> rule:</p>
2503 <pre>
2504 @font-face {
2505 font-family: MainText;
2506 src: url(gentium.eot); /* for use with older non-conformant user agents */
2507 src: local("Gentium"), url(gentium.ttf); /* Overrides src definition */
2508 }
2509 </pre>
2510 </div>
2512 <h3 id=font-prop-desc><span class=secno>4.4 </span>Font property
2513 descriptors: the <a href="#descdef-font-style">font-style</a>, <a
2514 href="#descdef-font-weight">font-weight</a>, <a
2515 href="#descdef-font-stretch">font-stretch</a> descriptors</h3>
2517 <table class=descdef>
2518 <tbody>
2519 <tr>
2520 <td>Name:
2522 <td><dfn id=descdef-font-style
2523 title="font-style!!descriptor">font-style</dfn>
2525 <tr>
2526 <td>Value:
2528 <td>normal | italic | oblique
2530 <tr>
2531 <td><em>Initial:</em>
2533 <td>normal
2534 </table>
2536 <table class=descdef>
2537 <tbody>
2538 <tr>
2539 <td>Name:
2541 <td><dfn id=descdef-font-weight
2542 title="font-weight!!descriptor">font-weight</dfn>
2544 <tr>
2545 <td>Value:
2547 <td>normal | bold | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900
2549 <tr>
2550 <td><em>Initial:</em>
2552 <td>normal
2553 </table>
2555 <table class=descdef>
2556 <tbody>
2557 <tr>
2558 <td>Name:
2560 <td><dfn id=descdef-font-stretch
2561 title="font-stretch!!descriptor">font-stretch</dfn>
2563 <tr>
2564 <td>Value:
2566 <td>normal | ultra-condensed | extra-condensed | condensed |
2567 semi-condensed | semi-expanded | expanded | extra-expanded |
2568 ultra-expanded
2570 <tr>
2571 <td><em>Initial:</em>
2573 <td>normal
2574 </table>
2576 <p>These descriptors define the characteristics of a font face and are used
2577 in the process of matching styles to specific faces. For a font family
2578 defined with several <code>@font-face</code> rules, user agents can either
2579 download all faces in the family or use these descriptors to selectively
2580 download font faces that match actual styles used in document. The values
2581 for these descriptors are the same as those for the corresponding font
2582 properties except that relative keywords are not allowed, ‘<a
2583 href="#bolder"><code class=property>bolder</code></a>’ and ‘<a
2584 href="#lighter"><code class=property>lighter</code></a>’. If these
2585 descriptors are omitted, initial values are assumed.
2587 <p>The value for these font face style attributes is used in place of the
2588 style implied by the underlying font data. This allows authors to combine
2589 faces in flexible combinations, even in situations where the original font
2590 data was arranged differently. User agents that implement synthetic
2591 bolding and obliquing must only apply synthetic styling in cases where the
2592 font descriptors imply this is needed, rather than based on the style
2593 attributes implied by the font data.
2595 <h3 id=unicode-range-desc><span class=secno>4.5 </span>Character range: the
2596 <a href="#descdef-unicode-range">unicode-range</a> descriptor</h3>
2598 <table class=descdef>
2599 <tbody>
2600 <tr>
2601 <td>Name:
2603 <td><dfn id=descdef-unicode-range>unicode-range</dfn>
2605 <tr>
2606 <td>Value:
2608 <td><a href="#urange-value"><var><urange></var></a> #
2610 <tr>
2611 <td><em>Initial:</em>
2613 <td>U+0-10FFFF
2614 </table>
2616 <p>This descriptor defines the set of Unicode codepoints that may be
2617 supported by the font face for which it is declared. The descriptor value
2618 is a comma-delimited list of Unicode range (<a
2619 href="#urange-value"><var><urange></var></a>) values. The union of
2620 these ranges defines the set of codepoints that serves as a hint for user
2621 agents when deciding whether or not to download a font resource for a
2622 given text run.
2624 <p>Each <dfn id=urange-value><var><urange></var></dfn> value is a <a
2625 href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><code
2626 title="UNICODE-RANGE token">UNICODE-RANGE</code></a> token made up of a
2627 "U+" or "u+" prefix followed by a codepoint range in one of the three
2628 forms listed below. Ranges that do not fit one of the these forms are
2629 invalid and cause the declaration to be ignored.
2631 <dl>
2632 <dt>single codepoint (e.g. U+416)
2634 <dd>a valid Unicode codepoint, represented as one to six hexadecimal
2635 digits
2637 <dt>interval range (e.g. U+400-4ff)
2639 <dd>represented as two hyphen-separated valid Unicode codepoints
2640 indicating the inclusive start and end codepoints of a range
2642 <dt>wildcard range (e.g. U+4??)
2644 <dd>defined by the set of codepoints implied when trailing ‘<code
2645 class=css>?</code>’ characters signify any hexadeximal digit
2646 </dl>
2648 <p>Individual codepoints are written using hexadecimal values that
2649 correspond to <a href="http://www.unicode.org/charts/">Unicode character
2650 codepoints</a>. Valid Unicode codepoint values vary between 0 and 10FFFF
2651 inclusive. Digit values of codepoints are ASCII case-insensitive. For
2652 interval ranges, the start and end codepoints must be valid Unicode values
2653 and the end codepoint must be greater than or equal to the start
2654 codepoint.
2656 <p>Wildcard ranges specified with ‘?’ that lack an initial digit (e.g.
2657 "U+???") are valid and equivalent to a wildcard range with an initial zero
2658 digit (e.g. "U+0???" = "U+0000-0FFF"). Wildcard ranges that extend beyond
2659 the range of valid Unicode codepoints are invalid. Because of this, the
2660 maximum number of trailing ‘<code class=css>?</code>’ wildcard
2661 characters is five, even though the <a
2662 href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><code
2663 title="UNICODE-RANGE token">UNICODE-RANGE</code></a> token accepts six.
2665 <p>Within the comma-delimited list of Unicode ranges in a ‘<a
2666 href="#descdef-unicode-range"><code
2667 class=property>unicode-range</code></a>’ descriptor declaration, ranges
2668 may overlap. The union of these ranges defines the set of codepoints for
2669 which the corresponding font may be used. User agents must not download or
2670 use the font for codepoints outside this set. User agents may normalize
2671 the list of ranges into a list that is different but represents the same
2672 set of codepoints.
2674 <p>The associated font might not contain glyphs for the entire set of
2675 codepoints defined by the ‘<a href="#descdef-unicode-range"><code
2676 class=property>unicode-range</code></a>’ descriptor. When the font is
2677 used the effective <a href="#character-map"><em>character map</em></a> is
2678 the intersection of the codepoints defined by ‘<a
2679 href="#descdef-unicode-range"><code
2680 class=property>unicode-range</code></a>’ with the font's <a
2681 href="#character-map"><em>character map</em></a>. This allows authors to
2682 define supported ranges in terms of broad ranges without worrying about
2683 the precise codepoint ranges supported by the underlying font.
2685 <h3 id=composite-fonts><span class=secno>4.6 </span>Using character ranges
2686 to define composite fonts</h3>
2688 <p>Multiple <code>@font-face</code> rules with different unicode ranges for
2689 the same family and style descriptor values can be used to create
2690 composite fonts that mix the glyphs from different fonts for different
2691 scripts. This can be used to combine fonts that only contain glyphs for a
2692 single script (e.g. Latin, Greek, Cyrillic) or it can be used by authors
2693 as a way of segmenting a font into fonts for commonly used characters and
2694 less frequently used characters. Since the user agent will only pull down
2695 the fonts it needs this helps reduce page bandwidth.
2697 <p>If the unicode ranges overlap for a set of <code>@font-face</code> rules
2698 with the same family and style descriptor values, the rules are ordered in
2699 the reverse order they were defined; the last rule defined is the first to
2700 be checked for a given character.
2702 <p>Example ranges for specific languages or characters:
2704 <dl>
2705 <dt>unicode-range: U+A5;
2707 <dd>a single code point, the yen/yuan symbol
2709 <dt>unicode-range: U+0-7F;
2711 <dd>code range for basic ASCII characters
2713 <dt>unicode-range: U+590-5ff;
2715 <dd>code range for Hebrew characters
2717 <dt>unicode-range: U+A5, U+4E00-9FFF, U+30??, U+FF00-FF9F;
2719 <dd>code range for Japanese kanji, hiragana and katakana characters plus
2720 yen/yuan symbol
2721 </dl>
2723 <div class=example>
2724 <p>The BBC provides news services in a wide variety of languages, many
2725 that are not well supported across all platforms. Using an
2726 <code>@font-face</code> rule, the BBC could provide a font for any of
2727 these languages, as it already does via a manual font download.</p>
2729 <pre>
2730 @font-face {
2731 font-family: BBCBengali;
2732 src: url(fonts/BBCBengali.ttf) format("opentype");
2733 unicode-range: U+00-FF, U+980-9FF;
2734 }
2735 </pre>
2736 </div>
2738 <div class=example>
2739 <p>Technical documents often require a wide range of symbols. The STIX
2740 Fonts project is one project aimed at providing fonts to support a wide
2741 range of technical typesetting in a standardized way. The example below
2742 shows the use of a font that provides glyphs for many of the mathematical
2743 and technical symbol ranges within Unicode:</p>
2745 <pre>
2746 @font-face {
2747 font-family: STIXGeneral;
2748 src: local(STIXGeneral), url(/stixfonts/STIXGeneral.otf);
2749 unicode-range: U+000-49F, U+2000-27FF, U+2900-2BFF, U+1D400-1D7FF;
2750 }
2751 </pre>
2752 </div>
2754 <div class=example>
2755 <p>This example shows how an author can override the glyphs used for Latin
2756 characters in a Japanese font with glyphs from a different font. The
2757 first rule specifies no range so it defaults to the entire range. The
2758 range specified in the second rule overlaps but takes precedence because
2759 it is defined later.</p>
2761 <pre>
2762 @font-face {
2763 font-family: JapaneseWithGentium;
2764 src: local(MSMincho);
2765 /* no range specified, defaults to entire range */
2766 }
2768 @font-face {
2769 font-family: JapaneseWithGentium;
2770 src: url(../fonts/Gentium.ttf);
2771 unicode-range: U+0-2FF;
2772 }
2773 </pre>
2774 </div>
2776 <div class=example>
2777 <p>Consider a family constructed to optimize bandwidth by separating out
2778 Latin, Japanese and other characters into different font files:</p>
2780 <pre>
2781 /* fallback font - size: 4.5MB */
2782 @font-face {
2783 font-family: DroidSans;
2784 src: url(DroidSansFallback.ttf);
2785 /* no range specified, defaults to entire range */
2786 }
2788 /* Japanese glyphs - size: 1.2MB */
2789 @font-face {
2790 font-family: DroidSans;
2791 src: url(DroidSansJapanese.ttf);
2792 unicode-range: U+3000-9FFF, U+ff??;
2793 }
2795 /* Latin, Greek, Cyrillic along with some
2796 punctuation and symbols - size: 190KB */
2797 @font-face {
2798 font-family: DroidSans;
2799 src: url(DroidSans.ttf);
2800 unicode-range: U+000-5FF, U+1e00-1fff, U+2000-2300;
2801 }
2802 </pre>
2804 <p>For simple Latin text, only the font for Latin characters is
2805 downloaded:</p>
2807 <pre>
2808 body { font-family: DroidSans; }
2810 <p>This is that</p>
2811 </pre>
2813 <p>In this case the user agent first checks the unicode-range for the font
2814 containing Latin characters (DroidSans.ttf). Since all the characters
2815 above are in the range U+0-5FF, the user agent downloads the font and
2816 renders the text with that font.</p>
2818 <p>Next, consider text that makes use of an arrow character (⇨):</p>
2820 <pre>
2821 <p>This &#x21e8; that<p>
2822 </pre>
2824 <p>The user agent again first checks the unicode-range of the font
2825 containing Latin characters. Since U+2000-2300 includes the arrow code
2826 point (U+21E8), the user agent downloads the font. For this character
2827 however the Latin font does not have a matching glyph, so the effective
2828 unicode-range used for font matching excludes this code point. Next, the
2829 user agent evaluates the Japanese font. The unicode-range for the
2830 Japanese font, U+3000-9FFF and U+ff??, does not include U+21E8, so the
2831 user agent does not download the Japanese font. Next the fallback font is
2832 considered. The <code>@font-face</code> rule for the fallback font does
2833 not define unicode-range so its value defaults to the range of all
2834 Unicode code points. The fallback font is downloaded and used to render
2835 the arrow character.</p>
2836 </div>
2838 <h3 id=font-rend-desc><span class=secno>4.7 </span>Font features: the <a
2839 href="#descdef-font-variant">font-variant</a> and <a
2840 href="#descdef-font-feature-settings">font-feature-settings</a>
2841 descriptors</h3>
2843 <table class=descdef>
2844 <tbody>
2845 <tr>
2846 <td>Name:
2848 <td><dfn id=descdef-font-variant
2849 title="font-variant!!descriptor">font-variant</dfn>
2851 <tr>
2852 <td>Value:
2854 <td><a href="#font-variant-normal-value"
2855 title="normal!!font-variant">normal</a> | <a
2856 href="#font-variant-none-value" title="none!!font-variant">none</a> | [
2857 <a href="#common-lig-values"><var><common-lig-values></var></a>
2858 || <a
2859 href="#discretionary-lig-values"><var><discretionary-lig-values></var></a>
2860 || <a
2861 href="#historical-lig-values"><var><historical-lig-values></var></a>
2862 || <a
2863 href="#contextual-alt-values"><var><contextual-alt-values></var></a>
2864 || <a href="#stylistic"><var
2865 title=stylistic>stylistic(<feature-value-name>)</var></a> || <a
2866 href="#historical-forms"><var>historical-forms</var></a> || <a
2867 href="#styleset"><var
2868 title=styleset>styleset(<feature-value-name> #)</var></a> || <a
2869 href="#character-variant"><var
2870 title=character-variant>character-variant(<feature-value-name>
2871 #)</var></a> || <a href="#swash"><var
2872 title=swash>swash(<feature-value-name>)</var></a> || <a
2873 href="#ornaments"><var
2874 title=ornaments>ornaments(<feature-value-name>)</var></a> || <a
2875 href="#annotation"><var
2876 title=annotation>annotation(<feature-value-name>)</var></a> || [
2877 <a href="#small-caps"><i>small-caps</i></a> | <a
2878 href="#all-small-caps"><i>all-small-caps</i></a> | <a
2879 href="#petite-caps"><i>petite-caps</i></a> | <a
2880 href="#all-petite-caps"><i>all-petite-caps</i></a> | <a
2881 href="#unicase"><i>unicase</i></a> | <a
2882 href="#titling-caps"><i>titling-caps</i></a> ] || <a
2883 href="#numeric-figure-values"><var><numeric-figure-values></var></a>
2884 || <a
2885 href="#numeric-spacing-values"><var><numeric-spacing-values></var></a>
2886 || <a
2887 href="#numeric-fraction-values"><var><numeric-fraction-values></var></a>
2888 || <a href="#ordinal"><i>ordinal</i></a> || <a
2889 href="#slashed-zero"><i>slashed-zero</i></a> || <a
2890 href="#east-asian-variant-values"><var><east-asian-variant-values></var></a>
2891 || <a
2892 href="#east-asian-width-values"><var><east-asian-width-values></var></a>
2893 || <a href="#ruby"><i>ruby</i></a> ]
2895 <tr>
2896 <td><em>Initial:</em>
2898 <td>normal
2899 </table>
2901 <table class=descdef>
2902 <tbody>
2903 <tr>
2904 <td>Name:
2906 <td><dfn id=descdef-font-feature-settings
2907 title="font-feature-settings!!descriptor">font-feature-settings</dfn>
2909 <tr>
2910 <td>Value:
2912 <td><a href="#font-feature-settings-normal-value"
2913 title="normal!!font-feature-settings">normal</a> | <a
2914 href="#feature-tag-value"><var><feature-tag-value></var></a> #
2916 <tr>
2917 <td><em>Initial:</em>
2919 <td>normal
2920 </table>
2922 <p>These descriptors define initial settings that apply when the font
2923 defined by an <code>@font-face</code> rule is rendered. They do not affect
2924 font selection. Values are identical to those defined for the
2925 corresponding <a href="#propdef-font-variant"
2926 title="font-variant!!property">‘<code
2927 class=property>font-variant</code>’</a> and <a
2928 href="#propdef-font-feature-settings"
2929 title="font-feature-settings!!property">‘<code
2930 class=property>font-feature-settings</code>’</a> properties defined
2931 below except that the value ‘<code class=property>inherit</code>’ is
2932 omitted. When multiple font feature descriptors or properties are used,
2933 the cumulative effect on text rendering is detailed in the section <a
2934 href="#font-feature-resolution">Font Feature Resolution</a> below. In
2935 cases where specific values define synthesized fallback for certain <a
2936 href="#propdef-font-variant" title="font-variant!!property">‘<code
2937 class=property>font-variant</code>’</a> subproperties, the same
2938 synthesized fallback applies when used within those values are used with
2939 the <a href="#descdef-font-style" title="font-style!!descriptor">‘<code
2940 class=property>font-variant</code>’</a> descriptor.
2942 <h3 id=font-face-loading><span class=secno>4.8 </span>Font loading
2943 guidelines</h3>
2945 <p>The <code>@font-face</code> rule is designed to allow lazy loading of
2946 font resources that are only downloaded when used within a document. A
2947 stylesheet can include <code>@font-face</code> rules for a library of
2948 fonts of which only a select set are used; user agents must only download
2949 those fonts that are referred to within the style rules applicable to a
2950 given page. User agents that download all fonts defined in
2951 <code>@font-face</code> rules without considering whether those fonts are
2952 in fact used within a page are considered non-conformant. In cases where a
2953 font might be downloaded in character fallback cases, user agents may
2954 download a font if it's listed in a font list but is not actually used for
2955 a given text run.
2957 <pre>
2958 @font-face {
2959 font-family: GeometricModern;
2960 src: url(font.ttf);
2961 }
2963 p {
2964 /* font will be downloaded for pages with p elements */
2965 font-family: GeometricModern, sans-serif;
2966 }
2968 h2 {
2969 /* font may be downloaded for pages with h2 elements, even if Futura is available locally */
2970 font-family: Futura, GeometricModern, sans-serif;
2971 }
2972 </pre>
2974 <p>In cases where textual content is loaded before downloadable fonts are
2975 available, user agents may render text as it would be rendered if
2976 downloadable font resources are not available or they may render text
2977 transparently with fallback fonts to avoid a flash of text using a
2978 fallback font. In cases where the font download fails user agents must
2979 display text, simply leaving transparent text is considered non-conformant
2980 behavior. Authors are advised to use fallback fonts in their font lists
2981 that closely match the vertical metrics of the downloadable fonts to avoid
2982 large page reflows where possible.
2984 <h3 id=same-origin-restriction><span class=secno>4.9 </span>Same-origin
2985 restriction for fonts</h3>
2987 <h4 id=default-same-origin-restriction><span class=secno>4.9.1
2988 </span>Default same-origin restriction</h4>
2989 <!-- TPAC 2011 Resolution to require same-origin restriction for loading fonts:
2990 http://lists.w3.org/Archives/Public/www-style/2011Nov/0711.html
2991 http://www.w3.org/2011/10/31-webapps-minutes.html#item02
2992 -->
2994 <p>User agents must implement a same-origin restriction when loading fonts
2995 via the <code>@font-face</code> mechanism. This restriction limits the
2996 loading of fonts for a given document to fonts loaded from the same
2997 origin. Fonts can only be loaded via the same host, port, and method
2998 combination as the containing document, using the <a
2999 href="http://www.w3.org/TR/html5/browsers.html#origin">origin matching
3000 algorithm</a> described in the <a href="#HTML5"
3001 rel=biblioentry>[HTML5]<!--{{!HTML5}}--></a> specification. The origin of
3002 the stylesheet containing <code>@font-face</code> rules is not used when
3003 deciding whether a font is same origin or not, only the origin of the
3004 containing document is used. The restriction applies to all font types.
3006 <p>Given a document located at http://example.com/page.html, fonts defined
3007 with ‘<a href="#descdef-src"><code class=property>src</code></a>’
3008 definitions considered cross origin must not be loaded:
3010 <pre>
3011 /* same origin (i.e. domain, protocol, port match document) */
3012 src: url(fonts/simple.ttf);
3013 src: url(//fonts/simple.ttf);
3015 /* cross origin, different protocol */
3016 src: url(https://example.com/fonts/simple.ttf);
3018 /* cross origin, different domain */
3019 src: url(http://another.example.com/fonts/simple.ttf);
3020 </pre>
3022 <h4 id=allowing-cross-origin-font-loading><span class=secno>4.9.2
3023 </span>Allowing cross-origin font loading</h4>
3025 <p>User agents must also implement the ability to relax this restriction
3026 using cross-site origin controls <a href="#CORS"
3027 rel=biblioentry>[CORS]<!--{{!CORS}}--></a> for fonts loaded via HTTP.
3028 Sites can explicitly allow cross-site downloading of font data using the
3029 <code>Access-Control-Allow-Origin</code> HTTP header. For other protocols,
3030 no explicit relaxation mechanism is defined or required.
3032 <p>For font loads over HTTP, cross-origin requests must be made with the
3033 following parameter settings which are used in conjunction with the <a
3034 href="http://www.w3.org/TR/cors/#cross-origin-request-0"> <em>cross-origin
3035 request algorithm</em></a> <a href="#CORS"
3036 rel=biblioentry>[CORS]<!--{{!CORS}}--></a>:
3038 <ul>
3039 <li><em>request URL</em> — the URL of the font resource in the <a
3040 href="#descdef-src"><code>src</code></a> descriptor
3042 <li><em>request method</em> — GET
3044 <li><em>author request headers</em> — none
3046 <li><em>request entity body</em> — empty
3048 <li><em>source origin</em> — the origin of the page which linked to the
3049 stylesheet
3051 <li><em>manual redirect flag</em> — false
3053 <li><em>omit credentials flag</em> — true
3055 <li><em>force preflight flag</em> — false
3056 </ul>
3058 <h2 id=font-matching-algorithm><span class=secno>5 </span>Font Matching
3059 Algorithm</h2>
3061 <p>The algorithm below describes how fonts are associated with individual
3062 runs of text. For each character in the run a font family is chosen and a
3063 particular font face is selected containing a glyph for that character.
3065 <h3 id=font-family-casing><span class=secno>5.1 </span>Case sensitivity of
3066 font family names</h3>
3068 <p>As part of the font matching algorithm outlined below, user agents must
3069 match font family names used in style rules with actual font family names
3070 contained in fonts available in a given environment or defined via
3071 <code>@font-face</code> rules. User agents must match these names case
3072 insensitively, using the "Default Caseless Matching" algorithm outlined in
3073 the Unicode specification <a href="#UNICODE6"
3074 rel=biblioentry>[UNICODE6]<!--{{!UNICODE6}}--></a>. This algorithm is
3075 detailed in section 3.13 entitled "Default Case Algorithms". Specifically,
3076 the algorithm must be applied without normalizing the strings involved and
3077 without applying any language-specific tailorings. The case folding method
3078 specified by this algorithm uses the case mappings with status field
3079 ‘<code class=property>C</code>’ or ‘<code class=property>F</code>’
3080 in the CaseFolding.txt file of the Unicode Character Database.
3082 <p class=note> Implementors should take care to verify that a given
3083 caseless string comparison implementation uses this precise algorithm and
3084 not assume that a given platform string matching routine follows it, as
3085 many of these have locale-specific behavior or use some level of string
3086 normalization.
3088 <p class=note> For authors this means that font family names are matched
3089 case insensitively, whether those names exist in a platform font or in the
3090 <code>@font-face</code> rules contained in a stylesheet. Authors should
3091 take care to ensure that names use a character sequence consistent with
3092 the actual font family name, particularly when using combining characters
3093 such as diacritical marks. For example, a family name that contains an
3094 uppercase A (U+0041) followed by a combining ring (U+030A) will
3095 <strong>not</strong> match a name that looks identical but which uses the
3096 precomposed lowercase a-ring character (U+00E5) instead of the combining
3097 sequence.
3099 <h3 id=font-style-matching><span class=secno>5.2 </span>Matching font
3100 styles</h3>
3102 <p>The procedure for choosing fonts consists of iterating over the font
3103 families determined by the font-family property, selecting a font face
3104 with the appropriate style based on other font properties and then
3105 determining whether a glyph exists for a given character. This is done
3106 using the <dfn id=character-map>character map</dfn> of the font, data
3107 which maps characters to the default glyph for that character. Codepoint
3108 sequences consisting of a base character followed by a sequence of
3109 combining characters are treated slightly differently, see the section on
3110 <a href="#cluster-matching">cluster matching</a> below.
3112 <p>For this procedure, the <dfn id=default-face>default face</dfn> for a
3113 given font family is defined to be the face that would be selected if all
3114 font style properties were set to their initial value.
3116 <ol id=fontmatchingalg>
3117 <li>Using the computed font property values for a given element, the user
3118 agent starts with the first family name in the fontlist specified by the
3119 <a href="#propdef-font-family" title="font-family!!property">‘<code
3120 class=property>font-family</code>’</a> property.
3122 <li>If the family name is unquoted and is a generic family name, the user
3123 agent looks up the appropriate font family name to be used. User agents
3124 may choose the generic font family to use based on the language of the
3125 containing element or the Unicode range of the character.
3127 <li>For other family names, the user agent attempts to find the family
3128 name among fonts defined via <code>@font-face</code> rules and then among
3129 available system fonts, matching names with a case-insensitive comparison
3130 as outlined <a href="#font-family-casing">in the section above</a>. On
3131 systems containing fonts with multiple localized font family names, user
3132 agents must match any of these names independent of the underlying system
3133 locale or platform API used. If the font resources defined for a given
3134 face in an @font-face rule are either not available or contain invalid
3135 font data, then the face should be treated as not present in the family.
3136 If no faces are present for a family defined via @font-face rules, the
3137 family should be treated as missing; matching a platform font with the
3138 same name must not occur in this case.
3140 <li>If a font family match occurs, the user agent assembles the set of
3141 font faces in that family and then narrows the set to a single face using
3142 other font properties in the order given below:
3143 <ol id=fontstylematchingalg>
3144 <li><a href="#propdef-font-stretch"
3145 title="font-stretch!!property">‘<code
3146 class=property>font-stretch</code>’</a> is tried first. If the
3147 matching set contains faces with width values matching the <a
3148 href="#propdef-font-stretch" title="font-stretch!!property">‘<code
3149 class=property>font-stretch</code>’</a> value, faces with other width
3150 values are removed from the matching set. If there is no face that
3151 exactly matches the width value the nearest width is used instead. If
3152 the value of <a href="#propdef-font-stretch"
3153 title="font-stretch!!property">‘<code
3154 class=property>font-stretch</code>’</a> is ‘<a href="#normal"><code
3155 class=property>normal</code></a>’ or one of the condensed values,
3156 narrower width values are checked first, then wider values. If the
3157 value of <a href="#propdef-font-stretch"
3158 title="font-stretch!!property">‘<code
3159 class=property>font-stretch</code>’</a> is one of the expanded
3160 values, wider values are checked first, followed by narrower values.
3161 Once the closest matching width has been determined by this process,
3162 faces with other widths are removed from the matching set.
3164 <li><a href="#propdef-font-style" title="font-style!!property">‘<code
3165 class=property>font-style</code>’</a> is tried next. If the value of
3166 <a href="#propdef-font-style" title="font-style!!property">‘<code
3167 class=property>font-style</code>’</a> is ‘<a href="#italic"><code
3168 class=property>italic</code></a>’, italic faces are checked first,
3169 then oblique, then normal faces. If the value is ‘<a
3170 href="#oblique"><code class=property>oblique</code></a>’, oblique
3171 faces are checked first, then italic faces and then normal faces. If
3172 the value is ‘<a href="#normal"><code
3173 class=property>normal</code></a>’, normal faces are checked first,
3174 then oblique faces, then italic faces. Faces with other style values
3175 are excluded from the matching set. User agents are permitted to
3176 distinguish between italic and oblique faces within platform font
3177 families but this is not required, they may treat all italic or oblique
3178 faces as italic faces. However, within font families defined via
3179 <code>@font-face</code> rules, italic and oblique faces must be
3180 distinguished using the value of the <a href="#descdef-font-style"
3181 title="font-style!!descriptor">‘<code
3182 class=property>font-style</code>’</a> descriptor.
3184 <li><a href="#propdef-font-weight"
3185 title="font-weight!!property">‘<code
3186 class=property>font-weight</code>’</a> is matched next, it will
3187 always reduce the matching set to a single font face. If bolder/lighter
3188 relative weights are used, the effective weight is calculated based on
3189 the inherited weight value, as described in the definition of the <a
3190 href="#propdef-font-weight" title="font-weight!!property">‘<code
3191 class=property>font-weight</code>’</a> property. Given the desired
3192 weight and the weights of faces in the matching set after the steps
3193 above, if the desired weight is available that face matches. Otherwise,
3194 a weight is chosen using the rules below:
3195 <ul>
3196 <li>If the desired weight is less than 400, weights below the desired
3197 weight are checked in descending order followed by weights above the
3198 desired weight in ascending order until a match is found.
3200 <li>If the desired weight is greater than 500, weights above the
3201 desired weight are checked in ascending order followed by weights
3202 below the desired weight in descending order until a match is found.
3204 <li>If the desired weight is 400, 500 is checked first and then the
3205 rule for desired weights less than 400 is used.
3207 <li>If the desired weight is 500, 400 is checked first and then the
3208 rule for desired weights less than 400 is used.
3209 </ul>
3211 <li><span class=property>‘<a href="#propdef-font-size"><code
3212 class=property>font-size</code></a>’</span> must be matched within a
3213 UA-dependent margin of tolerance. (Typically, sizes for scalable fonts
3214 are rounded to the nearest whole pixel, while the tolerance for
3215 bitmapped fonts could be as large as 20%.) Further computations, e.g.,
3216 by ‘<code class=property>em</code>’ values in other properties, are
3217 based on the <span class=property>‘<a href="#propdef-font-size"><code
3218 class=property>font-size</code></a>’</span> value that is used, not
3219 the one that is specified.
3220 </ol>
3222 <li>
3223 <p>If no matching face exists or the matched face does not contain a
3224 glyph for the character to be rendered, the next family name is selected
3225 and the previous two steps repeated. Glyphs from other faces in the
3226 family are not considered. The only exception is that user agents may
3227 optionally substitute a synthetic version of the <a
3228 href="#default-face"><em>default face</em></a> if that face supports a
3229 given glyph (e.g. a synthetic italic version of the regular face may be
3230 used if the italic face doesn't support glyphs for Arabic).</p>
3231 <!-- resolution on the above: http://lists.w3.org/Archives/Public/www-style/2012Nov/0292.html -->
3233 <p>If the matched font is defined via an <code>@font-face</code> rule and
3234 needs to be downloaded, the font resource is downloaded. While the
3235 download occurs, the user agent can either wait until the font is
3236 downloaded or render once with substituted font metrics and render again
3237 once the font is downloaded.</p>
3239 <li>If there are no more font families to be evaluated and no matching
3240 face has been found, then the user agent performs a <em>system font
3241 fallback</em> procedure to find the best match for the character to be
3242 rendered. The result of this procedure may vary across user agents.
3244 <li>If a particular character cannot be displayed using any font, the user
3245 agent should indicate by some means that a character is not being
3246 displayed, displaying either a symbolic representation of the missing
3247 glyph (e.g. using a <a
3248 href="http://en.wikipedia.org/wiki/Last_resort_font">Last Resort
3249 Font</a>) or using the missing character glyph from a default font.
3250 </ol>
3252 <h3 id=cluster-matching><span class=secno>5.3 </span>Cluster matching</h3>
3254 <p>When text contains characters such as combining diacritics, ideally the
3255 base character should be rendered using the same font as the diacritic,
3256 this assures proper placement of the diacritic. For this reason, the font
3257 matching algorithm for clusters is more specialized than the general case
3258 of matching a single character by itself. For sequences containing
3259 variation selectors, which indicate the precise glyph to be used for a
3260 given character, user agents always attempt system font fallback to find
3261 the appropriate glyph before using the default glyph of the base
3262 character.
3264 <p>A font is considered to <em>support</em> a given character if (1) the
3265 character is contained in the font's <a
3266 href="#character-map"><em>character map</em></a> and (2) if required by
3267 the containing script, shaping information is available for that
3268 character. Some legacy fonts may include a given character in the <a
3269 href="#character-map"><em>character map</em></a> but lack the shaping
3270 information (e.g. <a
3271 href="http://www.microsoft.com/typography/otspec/ttochap1.htm">OpenType
3272 layout tables</a> or <a
3273 href="http://scripts.sil.org/cms/scripts/page.php?site_id=projects&item_id=graphite_techAbout">Graphite
3274 tables</a>) necessary for correctly rendering text runs containing that
3275 character.
3277 <p>A sequence of codepoints containing combining diacritics or other
3278 modifiers is termed a grapheme cluster (see <a href="#CSS3TEXT"
3279 rel=biblioentry>[CSS3TEXT]<!--{{CSS3TEXT}}--></a> for a more complete
3280 description). For a given cluster containing a base character, <em>b</em>
3281 and a sequence of combining characters <em>c1, c2…</em>, the entire
3282 cluster is matched using these steps:
3284 <ol>
3285 <li>For each family in the font list, a face is chosen using the style
3286 selection rules defined in the previous section.
3287 <ol>
3288 <li>If all characters in the sequence <em>b + c1 + c2 …</em> are
3289 completely supported by the font, select this font for the sequence.
3291 <li>If a sequence of multiple codepoints is canonically equivalent to a
3292 single character and the font supports that character, select this font
3293 for the sequence.
3294 </ol>
3296 <li>If no font was found in the font list in step 1:
3297 <ol>
3298 <li>If <em>c1</em> is a variation selector, system fallback must be used
3299 to find a font that supports the full sequence of <em>b + c1</em>. If
3300 no font on the system supports the full sequence, match the single
3301 character <em>b</em> using the normal procedure for matching single
3302 characters and ignore the variation selector. Note: a sequence with
3303 more than one variation selector is treated as an encoding error and
3304 the trailing selectors are ignored.
3306 <li>Otherwise, the user agent may optionally use system font fallback to
3307 match a font that supports the entire cluster.
3308 </ol>
3310 <li>If no font is found in step 2, use the matching sequence from step 1
3311 to determine the longest sequence that is completely matched by a font in
3312 the font list and attempt to match the remaining combining characters
3313 separately using the rules for single characters.
3314 </ol>
3316 <h3 id=char-handling-issues><span class=secno>5.4 </span>Character handling
3317 issues</h3>
3319 <p>The procedure above is always performed on text runs containing Unicode
3320 characters, documents using legacy encodings are assumed to have been
3321 transcoded before matching fonts. For fonts containing <a
3322 href="#character-map"><em title="character map">character maps</em></a>
3323 for both legacy encodings and Unicode, the contents of the legacy encoding
3324 <a href="#character-map"><em>character map</em></a> must have no effect on
3325 the results of the font matching process.
3327 <p>The font matching process does not assume that text runs are in either
3328 normalized or denormalized form (see <a href="#CHARMOD-NORM"
3329 rel=biblioentry>[CHARMOD-NORM]<!--{{CHARMOD-NORM}}--></a> for more
3330 details). Layout engines often convert base character plus combining
3331 character sequences into precomposed characters if they exist. The font
3332 matching algorithm outlined here supports both ways and fonts can
3333 generally support either but variations can occur. Authors should always
3334 tailor their choice of fonts to their content, including whether that
3335 content contains normalized or denormalized character streams.
3337 <p>If a given character is a Private-Use Area Unicode codepoint and none of
3338 the fonts in the fontlist contain a glyph for that codepoint, user agents
3339 must display some form of missing glyph symbol for that character rather
3340 than attempting system font fallback for that codepoint. When matching the
3341 replacement character U+FFFD, user agents may skip the font matching
3342 process and immediately display some form of missing glyph symbol, they
3343 are not required to display the glyph from the font that would be selected
3344 by the font matching process.
3346 <p>In general, the fonts for a given family will all have the same or
3347 similar <a href="#character-map"><em title="character map">character
3348 maps</em></a>. The process outlined here is designed to handle even font
3349 families containing faces with widely variant <a href="#character-map"><em
3350 title="character map">character maps</em></a>. However, authors are
3351 cautioned that the use of such families can lead to unexpected results.
3353 <p>Optimizations of this process are allowed provided that an
3354 implementation behaves as if the algorithm had been followed exactly.
3355 Matching occurs in a well-defined order to insure that the results are as
3356 consistent as possible across user agents, given an identical set of
3357 available fonts and rendering technology.
3359 <h3 id=font-matching-changes><span class=secno>5.5 </span>Font matching
3360 changes since CSS 2.1</h3>
3362 <p>The algorithm above is different from CSS 2.1 in a number of key places.
3363 These changes were made to better reflect actual font matching behavior
3364 across user agent implementations.
3366 <p>Differences compared to the font matching algorithm in CSS 2.1:
3368 <ul>
3369 <li>The algorithm includes font-stretch matching.
3371 <li>All possible font-style matching scenarios are delineated.
3373 <li>Small-caps fonts are not matched as part of the font matching process,
3374 they are now handled via font features.
3376 <li>Unicode variation selector matching is required.
3378 <li>Cluster sequences are matched as a unit.
3379 </ul>
3381 <h3 id=font-matching-examples><span class=secno>5.6 </span>Font matching
3382 examples</h3>
3384 <div class=example>
3385 <p>It's useful to note that the CSS selector syntax may be used to create
3386 language-sensitive typography. For example, some Chinese and Japanese
3387 characters are unified to have the same Unicode code point, although the
3388 abstract glyphs are not the same in the two languages.
3390 <pre>*:lang(ja-jp) { font: 900 14pt/16pt "Heisei Mincho W9", serif; }
3391 *:lang(zh-tw) { font: 800 14pt/16.5pt "Li Sung", serif; }
3392 </pre>
3394 <p>This selects any element that has the given language - Japanese or
3395 Traditional Chinese - and uses the appropriate font.
3396 </div>
3398 <h2 id=font-rend-props><span class=secno>6 </span>Font Feature Properties</h2>
3400 <p>Modern font technologies support a variety of advanced typographic and
3401 language-specific font features. Using these features, a single font can
3402 provide glyphs for a wide range of ligatures, contextual and stylistic
3403 alternates, tabular and old-style figures, small capitals, automatic
3404 fractions, swashes, and alternates specific to a given language. To allow
3405 authors control over these font capabilities, the font-variant property
3406 has been expanded for CSS3, it now functions as a shorthand for a set of
3407 properties that provide control over stylistic font features.
3409 <h3 id=glyph-selection-positioning><span class=secno>6.1 </span>Glyph
3410 selection and positioning</h3>
3412 <p>Simple fonts used for displaying Latin text use a very basic processing
3413 model, fonts contain a <a href="#character-map"><em>character map</em></a>
3414 which maps a given character to a glyph for that character. Glyphs for
3415 subsequent characters are simply placed next in line along a run of text.
3416 Font formats such as OpenType and AAT (Apple Advanced Typography) use a
3417 richer processing model, the glyph for a given character can be chosen and
3418 positioned not just based on a single character, but also based on
3419 surrounding characters along with the language, script, and features
3420 enabled for the text. Font features may be required for specific scripts,
3421 or recommended as enabled by default or they may be stylistic features
3422 meant to be used under author control.
3424 <p>For a good visual overview of these features, see the <a
3425 href="#OPENTYPE-FONT-GUIDE"
3426 rel=biblioentry>[OPENTYPE-FONT-GUIDE]<!--{{OPENTYPE-FONT-GUIDE}}--></a>.
3427 For a detailed description of glyph processing for OpenType fonts, see <a
3428 href="#WINDOWS-GLYPH-PROC"
3429 rel=biblioentry>[WINDOWS-GLYPH-PROC]<!--{{WINDOWS-GLYPH-PROC}}--></a>.
3431 <p>Stylistic font features can be classified into two broad categories,
3432 ones that affect the harmonization of glyph shapes with the surrounding
3433 context, such as kerning and ligature features, and those such as the
3434 small-caps, subscript/superscript and alternate features that affect shape
3435 selection.
3437 <p>The subproperties of font-variant listed below are used to control these
3438 stylistic font features; they do not control features that are required
3439 for displaying certain scripts, such as the OpenType features used when
3440 displaying Arabic or Indic language text. They affect glyph selection and
3441 positioning, they do not affect font selection as described in the font
3442 matching section (except in cases required for compatibility with CSS
3443 2.1).
3445 <p>To assure consistent behavior across user agents, the equivalent
3446 OpenType property settings are listed for individual properties and must
3447 be considered normative. When using other font formats these should be
3448 used as a guideline to map CSS font feature property values to specific
3449 font features.
3451 <h3 id=language-specific-support><span class=secno>6.2
3452 </span>Language-specific display</h3>
3454 <p>OpenType also supports language-specific glyph selection and
3455 positioning, so that text can be displayed correctly in cases where the
3456 language dictates a specific display behavior. Languages often share a
3457 common script but the shape of certain letters may vary across those
3458 languages, such as the variations in certain Cyrillic letters used in
3459 Russian and Bulgarian text. In Latin text, it's common to render "fi" with
3460 an explicit fi-ligature that lacks a dot on the "i". However, in languages
3461 such as Turkish which uses both a dotted-i and a dotless-i, it's important
3462 to not use this ligature or use a specialized version that contains a dot
3463 over the "i". The example below shows language-specific variations based
3464 on stylistic traditions found in Spanish, Italian and French orthography:
3466 <div class=featex><img alt="language specific forms, spanish"
3467 src=locl-1.png></div>
3469 <div class=featex><img alt="language specific forms, italian"
3470 src=locl-2.png></div>
3472 <div class=featex><img alt="language specific forms, french"
3473 src=locl-3.png></div>
3475 <p>If the content language of the element is known, according to the rules
3476 of the <a
3477 href="http://www.w3.org/TR/CSS21/conform.html#doclanguage">document
3478 language</a>, user agents are required to infer the OpenType language
3479 system from the content language and use that when selecting and
3480 positioning glyphs using an OpenType font.
3482 <p>For OpenType fonts, in some cases it may be necessary to explicitly
3483 declare the OpenType language to be used, for example when displaying text
3484 in a given language that uses the typographic conventions of another
3485 language or when the font does not explicitly support a given language but
3486 supports a language that shares common typographic conventions. The ‘<a
3487 href="#propdef-font-language-override"><code
3488 class=property>font-language-override</code></a>’ property is used for
3489 this purpose.</p>
3490 <!-- prop: font-kerning -->
3492 <h3 id=font-kerning-prop><span class=secno>6.3 </span>Kerning: the <a
3493 href="#propdef-font-kerning">font-kerning</a> property</h3>
3495 <table class=propdef id=namefont-kerningvalueauto-normal-noneini>
3496 <tbody>
3497 <tr>
3498 <td>Name:
3500 <td><dfn id=propdef-font-kerning>font-kerning</dfn>
3502 <tr>
3503 <td>Value:
3505 <td><a href="#font-kerning-auto-value"
3506 title="auto!!font-kerning">auto</a> | <a
3507 href="#font-kerning-normal-value"
3508 title="normal!!font-kerning">normal</a> | <a
3509 href="#font-kerning-none-value" title="none!!font-kerning">none</a>
3511 <tr>
3512 <td>Initial:
3514 <td>auto
3516 <tr>
3517 <td>Applies to:
3519 <td>all elements
3521 <tr>
3522 <td>Inherited:
3524 <td>yes
3526 <tr>
3527 <td>Percentages:
3529 <td>N/A
3531 <tr>
3532 <td>Media:
3534 <td>visual
3536 <tr>
3537 <td>Computed value:
3539 <td>as specified
3541 <tr>
3542 <td>Animatable:
3544 <td>no
3545 </table>
3547 <p>Kerning is the contextual adjustment of inter-glyph spacing. This
3548 property controls metric kerning, kerning that utilizes adjustment data
3549 contained in the font.
3551 <dl>
3552 <dt><dfn id=font-kerning-auto-value title="auto!!font-kerning">auto</dfn>
3554 <dd>Specifies that kerning is applied at the discretion of the user agent
3556 <dt><dfn id=font-kerning-normal-value
3557 title="normal!!font-kerning">normal</dfn>
3559 <dd>Specifies that kerning is applied
3561 <dt><dfn id=font-kerning-none-value title="none!!font-kerning">none</dfn>
3563 <dd>Specifies that kerning is not applied
3564 </dl>
3566 <p>For fonts that do not include kerning data this property will have no
3567 visible effect. When rendering with OpenType fonts, the <a
3568 href="#OPENTYPE" rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a>
3569 specification suggests that kerning be enabled by default. When kerning is
3570 enabled, the OpenType <span class=tag>kern</span> feature is enabled (for
3571 vertical text runs the <span class=tag>vkrn</span> feature is enabled
3572 instead). User agents must also support fonts that only support kerning
3573 via data contained in a <span class=tag>kern</span> font table, as
3574 detailed in the OpenType specification. If the ‘<code
3575 class=property>letter-spacing</code>’ property is defined, kerning
3576 adjustments are considered part of the default spacing and letter spacing
3577 adjustments are made after kerning has been applied.
3579 <p>When set to ‘<code class=property>auto</code>’, user agents can
3580 determine whether to apply kerning or not based on a number of factors:
3581 text size, script, or other factors that influence text processing speed.
3582 Authors who want proper kerning should use ‘<a href="#normal"><code
3583 class=property>normal</code></a>’ to explicitly enable kerning.
3584 Likewise, some authors may prefer to disable kerning in situations where
3585 performance is more important than precise appearance. However, in
3586 well-designed modern implementations the use of kerning generally does not
3587 have a large impact on text rendering speed.</p>
3588 <!-- prop: font-variant-ligatures -->
3590 <h3 id=font-variant-ligatures-prop><span class=secno>6.4 </span>Ligatures:
3591 the <a href="#propdef-font-variant-ligatures">font-variant-ligatures</a>
3592 property</h3>
3594 <table class=propdef id=namefont-variant-ligaturesvaluenormal-no>
3595 <tbody>
3596 <tr>
3597 <td>Name:
3599 <td><dfn id=propdef-font-variant-ligatures>font-variant-ligatures</dfn>
3601 <tr>
3602 <td>Value:
3604 <td><a href="#font-variant-ligatures-normal-value"
3605 title="normal!!font-variant-ligatures">normal</a> | <a
3606 href="#font-variant-ligatures-none-value"
3607 title="none!!font-variant-ligatures">none</a> | [ <a
3608 href="#common-lig-values"><var><common-lig-values></var></a> ||
3609 <a
3610 href="#discretionary-lig-values"><var><discretionary-lig-values></var></a>
3611 || <a
3612 href="#historical-lig-values"><var><historical-lig-values></var></a>
3613 || <a
3614 href="#contextual-alt-values"><var><contextual-alt-values></var></a>
3615 ]
3617 <tr>
3618 <td>Initial:
3620 <td>normal
3622 <tr>
3623 <td>Applies to:
3625 <td>all elements
3627 <tr>
3628 <td>Inherited:
3630 <td>yes
3632 <tr>
3633 <td>Percentages:
3635 <td>N/A
3637 <tr>
3638 <td>Media:
3640 <td>visual
3642 <tr>
3643 <td>Computed value:
3645 <td>as specified
3647 <tr>
3648 <td>Animatable:
3650 <td>no
3651 </table>
3653 <p>Ligatures and contextual forms are ways of combining glyphs to produce
3654 more harmonized forms.
3656 <pre
3657 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>
3659 <pre
3660 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>
3662 <pre
3663 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>
3665 <pre
3666 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>
3668 <p>Individual values have the following meanings:
3670 <dl>
3671 <dt><dfn id=font-variant-ligatures-normal-value
3672 title="normal!!font-variant-ligatures">normal</dfn>
3674 <dd>A value of ‘<a href="#normal"><code
3675 class=property>normal</code></a>’ specifies that common default
3676 features are enabled, <a href="#font-feature-resolution">as described in
3677 detail in the next section</a>. For OpenType fonts, common ligatures and
3678 contextual forms are on by default, discretionary and historical
3679 ligatures are not.
3681 <dt><dfn id=font-variant-ligatures-none-value
3682 title="none!!font-variant-ligatures">none</dfn>
3684 <dd>Specifies that all types of ligatures and contextual forms covered by
3685 this property are explicitly disabled. In situations where ligatures are
3686 not considered necessary, this may improve the speed of text rendering.
3688 <dt><dfn id=common-ligatures>common-ligatures</dfn>
3690 <dd>Enables display of common ligatures (OpenType features: <span
3691 class=tag>liga, clig</span>). For OpenType fonts, common ligatures are
3692 enabled by default.
3693 </dl>
3695 <div class=featex><img alt="common ligature example" src=liga.png></div>
3697 <dl>
3698 <dt><dfn id=no-common-ligatures>no-common-ligatures</dfn>
3700 <dd>Disables display of common ligatures (OpenType features: <span
3701 class=tag>liga, clig</span>).
3703 <dt><dfn id=discretionary-ligatures>discretionary-ligatures</dfn>
3705 <dd>Enables display of discretionary ligatures (OpenType feature: <span
3706 class=tag>dlig</span>). Which ligatures are discretionary or optional is
3707 decided by the type designer, so authors will need to refer to the
3708 documentation of a given font to understand which ligatures are
3709 considered discretionary.
3710 </dl>
3712 <div class=featex><img alt="discretionary ligature example" src=dlig.png></div>
3714 <dl>
3715 <dt><dfn id=no-discretionary-ligatures>no-discretionary-ligatures</dfn>
3717 <dd>Disables display of discretionary ligatures (OpenType feature: <span
3718 class=tag>dlig</span>).
3720 <dt><dfn id=historical-ligatures>historical-ligatures</dfn>
3722 <dd>Enables display of historical ligatures (OpenType feature: <span
3723 class=tag>hlig</span>).
3724 </dl>
3726 <div class=featex><img alt="historical ligature example" src=hlig.png></div>
3728 <dl>
3729 <dt><dfn id=no-historical-ligatures>no-historical-ligatures</dfn>
3731 <dd>Disables display of historical ligatures (OpenType feature: <span
3732 class=tag>hlig</span>).
3734 <dt><dfn id=contextual>contextual</dfn>
3736 <dd>Enables display of contextual alternates (OpenType feature: <span
3737 class=tag>calt</span>). Although not strictly a ligature feature, like
3738 ligatures this feature is commonly used to harmonize the shapes of glyphs
3739 with the surrounding context. For OpenType fonts, this feature is on by
3740 default.
3741 </dl>
3743 <div class=featex><img alt="contextual alternate example" src=calt.png></div>
3745 <dl>
3746 <dt><dfn id=no-contextual>no-contextual</dfn>
3748 <dd>Disables display of contextual alternates (OpenType feature: <span
3749 class=tag>calt</span>).
3750 </dl>
3752 <p>Required ligatures, needed for correctly rendering complex scripts, are
3753 not affected by the settings above, including ‘<code
3754 class=property>none</code>’ (OpenType feature: <span
3755 class=tag>rlig</span>).</p>
3756 <!-- prop: font-variant-position -->
3758 <h3 id=font-variant-position-prop><span class=secno>6.5 </span>Subscript
3759 and superscript forms: the <a
3760 href="#propdef-font-variant-position">font-variant-position</a> property</h3>
3762 <table class=propdef id=namefont-variant-positionvaluenormal-sub>
3763 <tbody>
3764 <tr>
3765 <td>Name:
3767 <td><dfn id=propdef-font-variant-position>font-variant-position</dfn>
3769 <tr>
3770 <td>Value:
3772 <td><span title="normal!!font-variant-position">normal</span> | <a
3773 href="#sub">sub</a> | <a href="#super">super</a>
3775 <tr>
3776 <td>Initial:
3778 <td>normal
3780 <tr>
3781 <td>Applies to:
3783 <td>all elements
3785 <tr>
3786 <td>Inherited:
3788 <td>yes
3790 <tr>
3791 <td>Percentages:
3793 <td>N/A
3795 <tr>
3796 <td>Media:
3798 <td>visual
3800 <tr>
3801 <td>Computed value:
3803 <td>as specified
3805 <tr>
3806 <td>Animatable:
3808 <td>no
3809 </table>
3811 <p>This property is used to enable typographic subscript and superscript
3812 glyphs. These are alternate glyphs designed within the same em-box as
3813 default glyphs and are intended to be laid out on the same baseline as the
3814 default glyphs, with no resizing or repositioning of the baseline. They
3815 are explicitly designed to match the surrounding text and to be more
3816 readable without affecting the line height.
3818 <div class=figure><img alt="comparison between real subscript glyphs and
3819 synthesized ones" src=realsubscripts.png>
3820 <p class=caption>Subscript glyphs (top) vs. typical synthesized subscripts
3821 (bottom)
3822 </div>
3824 <p>Individual values have the following meanings:
3826 <dl>
3827 <dt><dfn id=normal>normal</dfn>
3829 <dd>None of the features listed below are enabled.
3831 <dt><dfn id=sub>sub</dfn>
3833 <dd>Enables display of subscript variants (OpenType feature: <span
3834 class=tag>subs</span>).
3836 <dt><dfn id=super>super</dfn>
3838 <dd>Enables display of superscript variants (OpenType feature: <span
3839 class=tag>sups</span>).
3840 </dl>
3842 <p>Because of the semantic nature of subscripts and superscripts, when the
3843 value is either ‘<a href="#sub"><code class=property>sub</code></a>’
3844 or ‘<a href="#super"><code class=property>super</code></a>’ for a
3845 given contiguous run of text, if a variant glyph is not available for all
3846 the characters in the run, simulated glyphs must be synthesized for all
3847 characters using reduced forms of the glyphs that would be used without
3848 this feature applied. This is done per run to avoid a mixture of variant
3849 glyphs and synthesized ones that would not align correctly. In the case of
3850 OpenType fonts that lack subscript or superscript glyphs for a given
3851 character, user agents must use the appropriate subscript and superscript
3852 metrics specified in the selected font's <a
3853 href="http://www.microsoft.com/typography/otspec/os2.htm#subxs">OS/2
3854 table</a> <a href="#OPENTYPE"
3855 rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a> to calculate the size
3856 and offset of the synthesized substitutes.
3858 <div class=figure><img alt="alternate superscripts vs. glyphs synthesized
3859 using superscript metrics" src=superscript-alt-synth.png>
3860 <p class=caption>Superscript alternate glyph (left), synthesized
3861 superscript glyphs (middle), and incorrect mixture of the two (right)
3862 </div>
3864 <p>In the past, user agents have used font-size and vertical-align to
3865 simulate subscripts and superscripts for the <a class=tag
3866 href="#sub">sub</a> and <span class=tag>sup</span> elements. To allow a
3867 backwards compatible way of defining subscripts and superscripts, it is
3868 recommended that authors use conditional rules <a href="#CSS3-CONDITIONAL"
3869 rel=biblioentry>[CSS3-CONDITIONAL]<!--{{CSS3-CONDITIONAL}}--></a> so that
3870 older user agents will still render subscripts and superscripts via the
3871 older mechanism.
3873 <p>Authors should note that fonts typically only provide subscript and
3874 superscript glyphs for a subset of all characters supported by the font.
3875 For example, while subscript and superscript glyphs are often available
3876 for Latin numbers, glyphs for punctuation and letter characters are less
3877 frequently provided. The synthetic fallback rules defined for this
3878 property assure that subscripts and superscripts will always appear but
3879 the appearance may not match author expectations if the font used does not
3880 provide the appropriate alternate glyph for all characters contained in a
3881 subscript or superscript.
3883 <p>This property is not cumulative. Applying it to elements within a
3884 subscript or superscript won't nest the placement of a subscript or
3885 superscript glyph. Images contained within text runs where the value of
3886 this property is ‘<a href="#sub"><code class=property>sub</code></a>’
3887 or ‘<a href="#super"><code class=property>super</code></a>’ will be
3888 drawn just as they would if the value was ‘<a href="#normal"><code
3889 class=property>normal</code></a>’. Likewise, text decorations such as
3890 underlines or emphasis marks will render in the same position as they
3891 would for the default glyphs, since this property does not affect the
3892 baseline position.
3894 <p class=issue>Some have suggested that text decorations should apply to
3895 the visual baseline of the variant glyphs, rather than the baseline
3896 defined by the font.
3898 <p>Because of these limitations, ‘<a
3899 href="#propdef-font-variant-position"><code
3900 class=property>font-variant-position</code></a>’ is not recommended for
3901 use in user agent stylesheets. Authors should use it in cases where
3902 subscripts or superscripts will only contain the narrow range of
3903 characters supported by the fonts specified.
3905 <div class=example>
3906 <p>A typical user agent default style for the <a class=tag
3907 href="#sub">sub</a> element:</p>
3909 <pre>sub {
3910 vertical-align: sub;
3911 font-size: smaller;
3912 line-height: normal;
3913 }
3914 </pre>
3916 <p>Using font-variant-position to specify typographic subscripts in a way
3917 that will still show subscripts in older user agents:</p>
3919 <pre>@supports ( font-variant-position: sub ) {
3921 sub {
3922 vertical-align: baseline;
3923 font-size: 100%;
3924 line-height: inherit;
3925 font-variant-position: sub;
3926 }
3928 }
3929 </pre>
3931 <p>User agents that support the ‘<a
3932 href="#propdef-font-variant-position"><code
3933 class=property>font-variant-position</code></a>’ property will select a
3934 subscript variant glyph and render this without adjusting the baseline or
3935 font-size. Older user agents will ignore the ‘<a
3936 href="#propdef-font-variant-position"><code
3937 class=property>font-variant-position</code></a>’ property definition
3938 and use the standard defaults for subscripts.</p>
3939 </div>
3940 <!-- prop: font-variant-caps -->
3942 <h3 id=font-variant-caps-prop><span class=secno>6.6 </span>Capitalization:
3943 the <a href="#propdef-font-variant-caps">font-variant-caps</a> property</h3>
3945 <table class=propdef id=namefont-variant-capsvaluenormal-small-c>
3946 <tbody>
3947 <tr>
3948 <td>Name:
3950 <td><dfn id=propdef-font-variant-caps>font-variant-caps</dfn>
3952 <tr>
3953 <td>Value:
3955 <td><a href="#font-variant-caps-normal-value"
3956 title="normal!!font-variant-caps">normal</a> | <a
3957 href="#small-caps">small-caps</a> | <a
3958 href="#all-small-caps">all-small-caps</a> | <a
3959 href="#petite-caps">petite-caps</a> | <a
3960 href="#all-petite-caps">all-petite-caps</a> | <a
3961 href="#unicase">unicase</a> | <a href="#titling-caps">titling-caps</a>
3963 <tr>
3964 <td>Initial:
3966 <td>normal
3968 <tr>
3969 <td>Applies to:
3971 <td>all elements
3973 <tr>
3974 <td>Inherited:
3976 <td>yes
3978 <tr>
3979 <td>Percentages:
3981 <td>N/A
3983 <tr>
3984 <td>Media:
3986 <td>visual
3988 <tr>
3989 <td>Computed value:
3991 <td>as specified
3993 <tr>
3994 <td>Animatable:
3996 <td>no
3997 </table>
3999 <p>This property allows the selection of alternate glyphs used for small or
4000 petite capitals or for titling. These glyphs are specifically designed to
4001 blend well with the surrounding normal glyphs, to maintain the weight and
4002 readability which suffers when text is simply resized to fit this purpose.
4004 <p>Individual values have the following meanings:
4006 <dl>
4007 <dt><dfn id=font-variant-caps-normal-value
4008 title="normal!!font-variant-caps">normal</dfn>
4010 <dd>None of the features listed below are enabled.
4012 <dt><dfn id=small-caps>small-caps</dfn>
4014 <dd>Enables display of small capitals (OpenType feature: <span
4015 class=tag>smcp</span>). Small-caps glyphs typically use the form of
4016 uppercase letters but are reduced to the size of lowercase letters.
4017 </dl>
4019 <div class=featex><img alt="small-caps example" src=smcp.png></div>
4021 <dl>
4022 <dt><dfn id=all-small-caps>all-small-caps</dfn>
4024 <dd>Enables display of small capitals for both upper and lowercase letters
4025 (OpenType features: <span class=tag>c2sc, smcp</span>).
4027 <dt><dfn id=petite-caps>petite-caps</dfn>
4029 <dd>Enables display of petite capitals (OpenType feature: <span
4030 class=tag>pcap</span>).
4032 <dt><dfn id=all-petite-caps>all-petite-caps</dfn>
4034 <dd>Enables display of petite capitals for both upper and lowercase
4035 letters (OpenType features: <span class=tag>c2pc, pcap</span>).
4037 <dt><dfn id=unicase>unicase</dfn>
4039 <dd>Enables display of mixture of small capitals for uppercase letters
4040 with normal lowercase letters (OpenType feature: <span
4041 class=tag>unic</span>).
4043 <dt><dfn id=titling-caps>titling-caps</dfn>
4045 <dd>Enables display of titling capitals (OpenType feature: <span
4046 class=tag>titl</span>). Uppercase letter glyphs are often designed for
4047 use with lowercase letters. When used in all uppercase titling sequences
4048 they can appear too strong. Titling capitals are designed specifically
4049 for this situation.
4050 </dl>
4052 <p>The availability of these glyphs is based on whether a given feature is
4053 defined or not in the feature list of the font. User agents can optionally
4054 decide this on a per-script basis but should explicitly not decide this on
4055 a per-character basis.
4057 <p>Some fonts may only support a subset or none of the features described
4058 for this property. For backwards compatibility with CSS 2.1, if ‘<a
4059 href="#small-caps"><code class=property>small-caps</code></a>’ or ‘<a
4060 href="#all-small-caps"><code class=property>all-small-caps</code></a>’
4061 is specified but small-caps glyphs are not available for a given font,
4062 user agents should simulate a small-caps font, for example by taking a
4063 normal font and replacing the glyphs for lowercase letters with scaled
4064 versions of the glyphs for uppercase characters (replacing the glyphs for
4065 both upper and lowercase letters in the case of ‘<a
4066 href="#all-small-caps"><code class=property>all-small-caps</code></a>’).
4068 <div class=figure style="padding: 0; margin: auto;"><img alt="synthetic vs.
4069 real small-caps" class=hires src=synthetic-vs-real-small-caps.png
4070 width=512px>
4071 <p class=caption>Synthetic vs. real small-caps
4072 </div>
4074 <p>To match the surrounding text, a font may provide alternate glyphs for
4075 caseless characters when these features are enabled but when a user agent
4076 simulates small capitals, it must not attempt to simulate alternates for
4077 codepoints which are considered caseless.
4079 <div class=figure style="padding: 0; margin: auto;"><img alt="caseless
4080 characters with small-caps, all-small-caps enabled" class=hires
4081 src=small-capitals-variations.png width=418px>
4082 <p class=caption>Caseless characters with small-caps, all-small-caps
4083 enabled
4084 </div>
4086 <p>If either ‘<a href="#petite-caps"><code
4087 class=property>petite-caps</code></a>’ or ‘<a
4088 href="#all-petite-caps"><code class=property>all-petite-caps</code></a>’
4089 is specified for a font that doesn't support these features, the property
4090 behaves as if ‘<a href="#small-caps"><code
4091 class=property>small-caps</code></a>’ or ‘<a
4092 href="#all-small-caps"><code class=property>all-small-caps</code></a>’,
4093 respectively, had been specified. If ‘<a href="#unicase"><code
4094 class=property>unicase</code></a>’ is specified for a font that doesn't
4095 support that feature, the property behaves as if ‘<a
4096 href="#small-caps"><code class=property>small-caps</code></a>’ was
4097 applied only to lowercased uppercase letters. If ‘<a
4098 href="#titling-caps"><code class=property>titling-caps</code></a>’ is
4099 specified with a font that does not support this feature, this property
4100 has no visible effect. When simulated small capital glyphs are used, for
4101 scripts that lack uppercase and lowercase letters, ‘<a
4102 href="#small-caps"><code class=property>small-caps</code></a>’, ‘<a
4103 href="#all-small-caps"><code class=property>all-small-caps</code></a>’,
4104 ‘<a href="#petite-caps"><code class=property>petite-caps</code></a>’,
4105 ‘<a href="#all-petite-caps"><code
4106 class=property>all-petite-caps</code></a>’ and ‘<a
4107 href="#unicase"><code class=property>unicase</code></a>’ have no visible
4108 effect.
4110 <p>When casing transforms are used to simulate small capitals, the casing
4111 transformations must match those used for the <span
4112 class=property>‘<code class=property>text-transform</code>’</span>
4113 property.
4115 <p>As a last resort, unscaled uppercase letter glyphs in a normal font may
4116 replace glyphs in a small-caps font so that the text appears in all
4117 uppercase letters.
4119 <div class=figure style="padding: 0; margin: auto;"><img alt="using
4120 all-small-caps in acronym-laden text" class=hires
4121 src=acronym-laden-text.png width=596px>
4122 <p class=caption>Using small capitals to improve readability in
4123 acronym-laden text
4124 </div>
4126 <div class=example>
4127 <p>Quotes rendered italicised, with small-caps on the first line:</p>
4129 <pre>blockquote { font-style: italic; }
4130 blockquote:first-line { font-variant: small-caps; }
4132 <blockquote><a href="http://lists.w3.org/Archives/Public/www-style/2009Dec/0036.html" style="text-decoration: none">I'll be honor-bound to slap them like a haddock.</a></blockquote>
4133 </pre>
4134 </div>
4135 <!-- prop: font-variant-numeric -->
4137 <h3 id=font-variant-numeric-prop><span class=secno>6.7 </span>Numerical
4138 formatting: the <a
4139 href="#propdef-font-variant-numeric">font-variant-numeric</a> property</h3>
4141 <table class=propdef id=namefont-variant-numericvaluenormal-ltnu>
4142 <tbody>
4143 <tr>
4144 <td>Name:
4146 <td><dfn id=propdef-font-variant-numeric>font-variant-numeric</dfn>
4148 <tr>
4149 <td>Value:
4151 <td><a href="#font-variant-numeric-normal-value"
4152 title="normal!!font-variant-numeric">normal</a> | [ <a
4153 href="#numeric-figure-values"><var><numeric-figure-values></var></a>
4154 || <a
4155 href="#numeric-spacing-values"><var><numeric-spacing-values></var></a>
4156 || <a
4157 href="#numeric-fraction-values"><var><numeric-fraction-values></var></a>
4158 || <a href="#ordinal">ordinal</a> || <a
4159 href="#slashed-zero">slashed-zero</a> ]
4161 <tr>
4162 <td>Initial:
4164 <td>normal
4166 <tr>
4167 <td>Applies to:
4169 <td>all elements
4171 <tr>
4172 <td>Inherited:
4174 <td>yes
4176 <tr>
4177 <td>Percentages:
4179 <td>N/A
4181 <tr>
4182 <td>Media:
4184 <td>visual
4186 <tr>
4187 <td>Computed value:
4189 <td>as specified
4191 <tr>
4192 <td>Animatable:
4194 <td>no
4195 </table>
4197 <p>Specifies control over numerical forms.
4199 <pre
4200 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>
4202 <pre
4203 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>
4205 <pre
4206 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>
4208 <p>Individual values have the following meanings:
4210 <dl>
4211 <dt><dfn id=font-variant-numeric-normal-value
4212 title="normal!!font-variant-numeric">normal</dfn>
4214 <dd>None of the features listed below are enabled.
4216 <dt><dfn id=lining-nums>lining-nums</dfn>
4218 <dd>Enables display of lining numerals (OpenType feature: <span
4219 class=tag>lnum</span>).
4221 <dt><dfn id=oldstyle-nums>oldstyle-nums</dfn>
4223 <dd>Enables display of old-style numerals (OpenType feature: <span
4224 class=tag>onum</span>).
4226 <dt><dfn id=proportional-nums>proportional-nums</dfn>
4228 <dd>Enables display of proportional numerals (OpenType feature: <span
4229 class=tag>pnum</span>).
4231 <dt><dfn id=tabular-nums>tabular-nums</dfn>
4233 <dd>Enables display of tabular numerals (OpenType feature: <span
4234 class=tag>tnum</span>).
4235 </dl>
4237 <p>The example below shows how these different properties can be combined
4238 to influence the rendering of tabular data with fonts that support these
4239 features. Within normal paragraph text, proportional numbers are used
4240 while tabular numbers are used so that columns of numbers line up
4241 properly:
4243 <div class=figure style="padding: 0; margin: auto;"><img alt="combining
4244 number styles" src=numberstyles.png>
4245 <p class=caption>Using number styles
4246 </div>
4248 <dl>
4249 <dt><dfn id=diagonal-fractions>diagonal-fractions</dfn>
4251 <dd>Enables display of lining diagonal fractions (OpenType feature: <span
4252 class=tag>frac</span>).
4253 </dl>
4255 <div class=featex><img alt="diagonal fraction example" src=frac.png></div>
4257 <dl>
4258 <dt><dfn id=stacked-fractions>stacked-fractions</dfn>
4260 <dd>Enables display of lining stacked fractions (OpenType feature: <span
4261 class=tag>afrc</span>).
4262 </dl>
4264 <div class=featex><img alt="stacked fraction example" src=afrc.png></div>
4266 <dl>
4267 <dt><dfn id=ordinal>ordinal</dfn>
4269 <dd>Enables display of forms used with ordinal numbers (OpenType feature:
4270 <span class=tag>ordn</span>).
4272 <dt><dfn id=slashed-zero>slashed-zero</dfn>
4274 <dd>Enables display of slashed zeros (OpenType feature: <span
4275 class=tag>zero</span>).
4276 </dl>
4278 <div class=featex><img alt="slashed zero example" src=zero.png></div>
4280 <div class=example id=steak-marinade>
4281 <p>A simple flank steak marinade recipe, rendered with automatic fractions
4282 and old-style numerals:</p>
4284 <pre>.amount { font-variant-numeric: oldstyle-nums diagonal-fractions; }
4286 <h4>Steak marinade:</h4>
4287 <ul>
4288 <li><span class="amount">2</span> tbsp olive oil</li>
4289 <li><span class="amount">1</span> tbsp lemon juice</li>
4290 <li><span class="amount">1</span> tbsp soy sauce</li>
4291 <li><span class="amount">1 1/2</span> tbsp dry minced onion</li>
4292 <li><span class="amount">2 1/2</span> tsp italian seasoning</li>
4293 <li>Salt &amp; pepper</li>
4294 </ul>
4296 <p>Mix the meat with the marinade and let it sit covered in the refrigerator
4297 for a few hours or overnight.</p>
4298 </pre>
4299 </div>
4300 <!-- prop: font-variant-alternates -->
4302 <h3 id=font-variant-alternates-prop><span class=secno>6.8 </span>Alternates
4303 and swashes: the <a
4304 href="#propdef-font-variant-alternates">font-variant-alternates</a>
4305 property</h3>
4307 <table class=propdef id=namefont-variant-alternatesvaluenormal-s>
4308 <tbody>
4309 <tr>
4310 <td>Name:
4312 <td><dfn
4313 id=propdef-font-variant-alternates>font-variant-alternates</dfn>
4315 <tr>
4316 <td>Value:
4318 <td>normal | [ <a href="#stylistic"
4319 title=stylistic>stylistic(<feature-value-name>)</a> || <a
4320 href="#historical-forms">historical-forms</a> || <a href="#styleset"
4321 title=styleset>styleset(<feature-value-name> #)</a> || <a
4322 href="#character-variant"
4323 title=character-variant>character-variant(<feature-value-name>
4324 #)</a> || <a href="#swash"
4325 title=swash>swash(<feature-value-name>)</a> || <a
4326 href="#ornaments"
4327 title=ornaments>ornaments(<feature-value-name>)</a> || <a
4328 href="#annotation"
4329 title=annotation>annotation(<feature-value-name>)</a> ]
4331 <tr>
4332 <td>Initial:
4334 <td>normal
4336 <tr>
4337 <td>Applies to:
4339 <td>all elements
4341 <tr>
4342 <td>Inherited:
4344 <td>yes
4346 <tr>
4347 <td>Percentages:
4349 <td>N/A
4351 <tr>
4352 <td>Media:
4354 <td>visual
4356 <tr>
4357 <td>Computed value:
4359 <td>as specified
4361 <tr>
4362 <td>Animatable:
4364 <td>no
4365 </table>
4367 <p>For any given character, fonts can provide a variety of alternate glyphs
4368 in addition to the default glyph for that character. This property
4369 provides control over the selection of these alternate glyphs.
4371 <p>In cases where multiple alternates are possible, authors define a
4372 <code><feature-value-name></code> using the
4373 <code>@font-feature-values</code> rule described below to indicate the
4374 specific alternate to be used. The nature of these alternates is font
4375 specific, so the rule defines values for a specific font family or set of
4376 families. When a particular value has not been defined for a given family,
4377 the named value is treated as if the feature had omitted from the style
4378 rule. If a given value is outside the range supported by a given font, the
4379 value is ignored. These values never apply to generic font families, nor
4380 to families selected as part of system font fallback. Values that behave
4381 this way are marked as <em>font specific</em>.
4383 <p>Individual values have the following meanings:
4385 <dl>
4386 <dt><dfn id=font-variant-alternates-normal-value
4387 title="normal!!font-variant-alternates">normal</dfn>
4389 <dd>None of the features listed below are enabled.
4391 <dt><dfn id=stylistic
4392 title=stylistic>stylistic(<feature-value-name>)</dfn>
4394 <dd>Enables display of stylistic alternates (<em>font specific</em>,
4395 OpenType feature: <span class=tag>salt
4396 <feature-value-name></span>).
4397 </dl>
4399 <div class=featex><img alt="stylistic alternate example" src=salt.png></div>
4401 <dl>
4402 <dt><dfn id=historical-forms>historical-forms</dfn>
4404 <dd>Enables display of historical forms (OpenType feature: <span
4405 class=tag>hist</span>).
4406 </dl>
4408 <div class=featex><img alt="historical form example" src=hist.png></div>
4410 <dl>
4411 <dt><dfn id=styleset title=styleset>styleset(<feature-value-name>
4412 #)</dfn>
4414 <dd>Enables display with stylistic sets (<em>font specific</em>, OpenType
4415 feature: <span class=tag>ss<feature-index></span> OpenType
4416 currently defines <span class=tag>ss01</span> through <span
4417 class=tag>ss20</span>).
4418 </dl>
4420 <div class=featex><img alt="styleset example" src=ssnn.png></div>
4422 <dl>
4423 <dt><dfn id=character-variant
4424 title=character-variant>character-variant(<feature-value-name>
4425 #)</dfn>
4427 <dd>Enables display of specific character variants (<em>font
4428 specific</em>, OpenType feature: <span
4429 class=tag>cv<feature-index></span> OpenType currently defines <span
4430 class=tag>cv01</span> through <span class=tag>cv99</span>).
4432 <dt><dfn id=swash title=swash>swash(<feature-value-name>)</dfn>
4434 <dd>Enables display of swash glyphs (<em>font specific</em>, OpenType
4435 feature: <span class=tag>swsh <feature-index>, cswh
4436 <feature-index></span>).
4437 </dl>
4439 <div class=featex><img alt="swash example" src=swsh.png></div>
4441 <dl>
4442 <dt><dfn id=ornaments
4443 title=ornaments>ornaments(<feature-value-name>)</dfn>
4445 <dd>Enables replacement of default glyphs with ornaments, if provided in
4446 the font (<em>font specific</em>, OpenType feature: <span class=tag>ornm
4447 <feature-index></span>). Some fonts may offer ornament glyphs as
4448 alternates for a wide collection of characters; however, displaying
4449 arbitrary characters (e.g., alphanumerics) as ornaments is poor practice
4450 as it distorts the semantics of the data. Font designers are encouraged
4451 to encode all ornaments (except those explicitly encoded in the Unicode
4452 Dingbats blocks, etc.) as alternates for the bullet character (U+2022) to
4453 allow authors to select the desired glyph using
4454 <feature-value-name>.
4455 </dl>
4457 <div class=featex><img alt="ornaments example" src=ornm.png></div>
4459 <dl>
4460 <dt><dfn id=annotation
4461 title=annotation>annotation(<feature-value-name>)</dfn>
4463 <dd>Enables display of alternate annotation forms (<em>font specific</em>,
4464 OpenType feature: <span class=tag>nalt <feature-index></span>).
4465 </dl>
4467 <div class=featex><img alt="alternate annotation form example"
4468 src=nalt.png></div>
4470 <h3 id=font-feature-values><span class=secno>6.9 </span>Defining font
4471 specific alternates: the <code>@font-feature-values</code> rule</h3>
4473 <p>Several of the possible values of ‘<a
4474 href="#propdef-font-variant-alternates"><code
4475 class=property>font-variant-alternates</code></a>’ listed above are
4476 labeled as "font specific". For these features fonts may define not just a
4477 single glyph but a set of alternate glyphs with an index to select a given
4478 alternate. Since these are font family specific, the
4479 <code>@font-feature-values</code> rule is used to define named-values for
4480 these indices for a given family.
4482 <p>In the case of the swash Q in the example shown above, the swash could
4483 be specified using these style rules:
4485 <pre>
4487 @font-feature-values Jupiter Sans {
4488 @swash {
4489 delicate: 1;
4490 flowing: 2;
4491 }
4492 }
4494 h2 { font-family: Jupiter Sans, sans-serif; }
4496 /* show the second swash variant in h2 headings */
4497 h2:first-letter { font-variant-alternates: swash(flowing); }
4499 <h2>Quick</h2></pre>
4501 <p>When Jupiter Sans is present, the second alternate swash alternate will
4502 be displayed. When not present, no swash character will be shown, since
4503 the specific named-value "flowing" is only defined for the Jupiter Sans
4504 family. The @-mark indicates the name of the property value for which a
4505 named-value can be used. The name "flowing" is chosen by the author, the
4506 values specified within a given font's data.
4508 <p>In terms of the grammar, this specification defines the following
4509 productions:</p>
4510 <!--
4511 <pre><dfn>supports_rule</dfn>
4512 : <i>SUPPORTS_SYM</i> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <i>supports_condition</i> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <i>group_rule_body</i>
4513 ;
4515 <dfn>supports_condition</dfn>
4516 : <i>supports_negation</i> | <i>supports_conjunction</i> | <i>supports_disjunction</i> |
4517 <i>supports_condition_in_parens</i>
4518 ;
4520 <dfn>supports_condition_in_parens</dfn>
4521 : ( '(' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <i>supports_condition</i> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* ')' ) | <i>supports_declaration_condition</i> |
4522 <i>general_enclosed</i>
4523 ;
4525 <dfn>supports_negation</dfn>
4526 : <a href="http://www.w3.org/TR/css3-mediaqueries/#syntax"><i>NOT</i></a> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>+ <i>supports_condition_in_parens</i>
4527 ;
4529 <dfn>supports_conjunction</dfn>
4530 : <i>supports_condition_in_parens</i> ( <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>+ <a href="http://www.w3.org/TR/css3-mediaqueries/#syntax"><i>AND</i></a> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>+ <i>supports_condition_in_parens</i> )+
4531 ;
4533 <dfn>supports_disjunction</dfn>
4534 : <i>supports_condition_in_parens</i> ( <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>+ <i>OR</i> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>+ <i>supports_condition_in_parens</i> )+
4535 ;
4537 <dfn>supports_declaration_condition</dfn>
4538 : '(' <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>declaration</i></a> ')'
4539 ;
4541 <dfn>general_enclosed</dfn>
4542 : ( <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>FUNCTION</i></a> | '(' ) ( <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>any</i></a> | <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>unused</i></a> )* ')'
4543 ;
4544 </pre>
4546 -->
4548 <pre><dfn id=fontfeaturevaluesrule>font_feature_values_rule</dfn>
4549 : <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>*
4550 '{' <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>*
4551 ;
4553 <dfn id=fontfamilynamelist>font_family_name_list</dfn>
4554 : <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> ]*
4555 ;
4557 <dfn id=fontfamilyname>font_family_name</dfn>
4558 : <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> ]* ]
4559 ;
4561 <dfn id=featurevalueblock>feature_value_block</dfn>
4562 : <a href="#featuretype"><i>feature_type</i></a> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>*
4563 '{' <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>*
4564 ;
4566 <dfn id=featuretype>feature_type</dfn>:
4567 <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>ATKEYWORD</i></a>
4568 ;
4570 <dfn id=featurevaluedefinition>feature_value_definition</dfn>
4571 : <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> ]*
4572 ;
4573 </pre>
4575 <p>The following new token is introduced:
4577 <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>;}
4578 </pre>
4580 <p>Feature value blocks are treated <a
4581 href="http://www.w3.org/TR/CSS2/syndata.html#at-rules">similar to
4582 at-rules</a>, they consist of everything up to the next block or
4583 semi-colon, whichever comes first.
4585 <p>Font feature values rules define a set of values for a specific font
4586 feature as used for a given set of families. Effectively, they define a
4587 mapping of ⟨family, feature, ident⟩ → ⟨values⟩ where
4588 ⟨values⟩ are the indices used for specific features defined for a
4589 given font.
4591 <p>The font family list uses the same syntax as that used for the <a
4592 href="#propdef-font-family" title="font-family!!property">‘<code
4593 class=property>font-family</code>’</a> property. Within feature value
4594 blocks, the feature type is ‘<code class=css>@</code>’ followed by the
4595 name of the font-specific property value (e.g. <a
4596 href="#swash"><code>@swash</code></a>). The feature type must match, using
4597 an ASCII case-insensitive comparison, one of the <em>font specific</em>
4598 values of the ‘<a href="#propdef-font-variant-alternates"><code
4599 class=property>font-variant-alternates</code></a>’ property. The values
4600 associated with a given idenitifier are limited to integer values 0 or
4601 greater.
4603 <p>If syntax errors occur within the font family list, the entire rule must
4604 be ignored. When syntax errors occur within a feature value definition,
4605 such as invalid identifiers or values, the entire feature value definition
4606 must be omitted, similar to the way syntax errors in style declarations
4607 are handled. When the <code><feature-type></code> is invalid, the
4608 entire associated feature value block must be ignored.
4610 <pre>@font-feature-values Bongo {
4611 @swash { ornate: 1; }
4612 annotation { boxed: 4; } /* should be @annotation! */
4613 @swash { double-loops: 1; flowing: -1; } /* negative value */
4614 @ornaments ; /* incomplete definition */
4615 @styleset { double-W: 14; sharp-terminals: 16 1 } /* missing ; */
4616 <a href="http://www.angryalien.com/0504/shiningbunnies.html" style="text-decoration: none;">redrum</a> /* random editing mistake */
4617 }</pre>
4619 <p>The example above is equivalent to:
4621 <pre>@font-feature-values Bongo {
4622 @swash { ornate: 1; }
4623 @swash { double-loops: 1; }
4624 @styleset { double-W: 14; sharp-terminals: 16 1; }
4625 }</pre>
4627 <p>If multiple <code>@font-feature-values</code> rules are defined for a
4628 given family, the resulting values defined are the union of these rules.
4629 This allows a set of named-values to be defined for a given font family
4630 globally for a site and specific additions made per-page. If the same
4631 <feature-value-name> is defined mulitple times for a given
4632 font-variant value, the last defined value is used.
4634 <pre>
4635 site.css:
4637 @font-feature-values Mercury Serif {
4638 @styleset {
4639 stacked-g: 3; /* "two-storey" versions of g, a */
4640 stacked-a: 4;
4641 }
4642 }
4644 page.css:
4646 @font-feature-values Mercury Serif {
4647 @styleset {
4648 geometric-m: 7; /* alternate version of m */
4649 }
4650 }
4652 body {
4653 font-family: Mercury Serif, serif;
4655 /* enable both the use of stacked g and alternate m */
4656 font-variant-alternates: styleset(stacked-g, geometric-m);
4657 }</pre>
4659 <p>Only named font families are allowed for <font-family>, rules that
4660 include generic or system fonts in the list of font families are
4661 considered syntax errors and the contents of the rules are ignored.
4662 However, if a user agent defines a generic font to be a specific named
4663 font (e.g. Helvetica), the settings associated with that family name will
4664 be used.
4666 <p>For <font-variant-property-value>, only font specific property value
4667 names supported by the <a href="#propdef-font-variant"
4668 title="font-variant!!property">‘<code
4669 class=property>font-variant</code>’</a> property are recognized,
4670 definitions for other value names cause a syntax error and are ignored.
4671 Each property value that is font specific is clearly marked as such.
4672 Feature value names follow the rules of CSS user identifiers and are
4673 case-sensitive. They are unique only for a given set of font families and
4674 font-variant property value; the same identifier used with a different
4675 font-variant property value is treated as a separate and distinct value.
4677 <p>Using a commonly named value allows authors to use a single style rule
4678 to cover a set of fonts for which the underlying selector is different for
4679 each font. If either font in the example below is found, a circled number
4680 glyph will be used:
4682 <pre>@font-feature-values Taisho Gothic {
4683 @annotation { boxed: 1; circled: 4; }
4684 }
4686 @font-feature-values Otaru Kisa {
4687 @annotation { circled: 1; black-boxed: 3; }
4688 }
4690 h3.title {
4691 /* circled form defined for both fonts */
4692 font-family: Taisho Gothic, Otaru Kisa;
4693 font-variant: annotation(circled);
4694 }</pre>
4696 <p>Most font specific font-variant property values take a single value
4697 (e.g. swash). The character-variant property value allows two values and
4698 styleset allows an unlimited number. If a larger number of values are
4699 assigned to a given name, a syntax error occurs and the entire
4700 <font-feature-values-declaration> is ignored.
4702 <p>For the styleset property value, multiple values indicate the style sets
4703 to be enabled. Values between 1 and 99 enable OpenType features <span
4704 class=tag>ss01</span> through <span class=tag>ss99</span>. However, the
4705 OpenType standard only officially defines <span class=tag>ss01</span>
4706 through <span class=tag>ss20</span>. Values greater than 99 or equal to 0
4707 are ignored but do not generate a syntax error when parsed.
4709 <pre>@font-feature-values Mars Serif {
4710 @styleset {
4711 alt-g: 1; /* implies ss01 = 1 */
4712 curly-quotes: 3; /* implies ss03 = 1 */
4713 code: 4 5; /* implies ss04 = 1, ss05 = 1 */
4714 }
4716 @styleset {
4717 dumb: 125; /* >99, ignored */
4718 }
4720 @swash {
4721 swishy: 3 5; /* more than 1 value for swash, syntax error */
4722 }
4723 }
4725 p.codeblock {
4726 /* implies ss03 = 1, ss04 = 1, ss05 = 1 */
4727 font-variant-alternates: styleset(curly-quotes, code);
4728 }</pre>
4730 <p>For character-variant, a single value between 1 and 99 indicates the
4731 enabling of OpenType feature <span class=tag>cv01</span> through <span
4732 class=tag>cv99</span>. For OpenType fonts, values greater than 99 or equal
4733 to 0 are ignored but do not generate a syntax error when parsed. When two
4734 values are listed, the first value indicates the feature used and the
4735 second the value passed for that feature. When two value names imply
4736 different settings for the same underlying feature the last setting is
4737 used.
4739 <pre>@font-feature-values MM Greek {
4740 @character-variant { alpha-2: 1 2; } /* implies cv01 = 2 */
4741 @character-variant { beta-3: 2 3; } /* implies cv02 = 3 */
4742 @character-variant { epsilon: 5 3 6; } /* more than 2 values, syntax error, ignored */
4743 @character-variant { gamma: 12; } /* implies cv12 = 1 */
4744 @character-variant { zeta: 20 3; } /* implies cv20 = 3 */
4745 @character-variant { zeta-2: 20 2; } /* implies cv20 = 2 */
4746 @character-variant { silly: 105; } /* >99, ignored */
4747 @character-variant { dumb: 323 3; } /* >99, ignored */
4748 }
4750 #title {
4751 /* use the third alternate beta, first alternate gamma */
4752 font-variant-alternates: character-variant(beta-3, gamma);
4753 }
4755 p {
4756 /* zeta-2 follows zeta, implies cv20 = 2 */
4757 font-variant-alternates: character-variant(zeta, zeta-2);
4758 }
4760 .special {
4761 /* zeta follows zeta-2, implies cv20 = 3 */
4762 font-variant-alternates: character-variant(zeta-2, zeta);
4763 }</pre>
4765 <p>See the <a href="#om-fontfeaturevalues">object model reference
4766 section</a> for a description of the interfaces used to modify these rules
4767 via the CSS Object Model.
4769 <div class=figure><img alt="Matching text on Byzantine seals using
4770 character variants" src=byzantineseal.png>
4771 <p class=caption>Byzantine seal text displayed with character variants
4772 </div>
4774 <div class=example>
4775 <p>In the figure above, the text in red is rendered using a font
4776 containing character variants that mimic the character forms found on a
4777 Byzantine seal from the 8th century A.D. Two lines below is the same text
4778 displayed in a font without variants. Note the two variants for U and N
4779 used on the seal.</p>
4781 <pre>@font-feature-values Athena Ruby {
4782 @character-variant {
4783 leo-B: 2 1;
4784 leo-M: 13 3;
4785 leo-alt-N: 14 1;
4786 leo-N: 14 2;
4787 leo-T: 20 1;
4788 leo-U: 21 2;
4789 leo-alt-U: 21 4;
4790 }
4791 }
4793 p {
4794 font-variant: discretionary-ligatures,
4795 character-variant(leo-B, leo-M, leo-N, leo-T, leo-U);
4796 }
4798 span.alt-N {
4799 font-variant-alternates: character-variant(leo-alt-N);
4800 }
4802 span.alt-U {
4803 font-variant-alternates: character-variant(leo-alt-U);
4804 }
4806 <p>ENO....UP͞RSTU<span class="alt-U">U</span>͞<span class="alt-U">U</span>ΚΑΙTỤẠG̣IUPNS</p>
4808 <p>LEON|ΚΑΙCONSTA|NTI<span class="alt-N">N</span>OS..|STOIBAṢ.|LIṢROM|AIO<span class="alt-N">N</span></p>
4809 </pre>
4810 </div>
4812 <h3 id=font-variant-east-asian-prop><span class=secno>6.10 </span>East
4813 Asian text rendering: the <a
4814 href="#propdef-font-variant-east-asian">font-variant-east-asian</a>
4815 property</h3>
4817 <table class=propdef id=namefont-variant-east-asianvaluenormal-l>
4818 <tbody>
4819 <tr>
4820 <td>Name:
4822 <td><dfn
4823 id=propdef-font-variant-east-asian>font-variant-east-asian</dfn>
4825 <tr>
4826 <td>Value:
4828 <td><a href="#font-variant-east-asian-normal-value"
4829 title="normal!!font-variant-east-asian">normal</a> | [ <a
4830 href="#east-asian-variant-values"><var><east-asian-variant-values></var></a>
4831 || <a
4832 href="#east-asian-width-values"><var><east-asian-width-values></var></a>
4833 || <a href="#ruby">ruby</a> ]
4835 <tr>
4836 <td>Initial:
4838 <td>normal
4840 <tr>
4841 <td>Applies to:
4843 <td>all elements
4845 <tr>
4846 <td>Inherited:
4848 <td>yes
4850 <tr>
4851 <td>Percentages:
4853 <td>N/A
4855 <tr>
4856 <td>Media:
4858 <td>visual
4860 <tr>
4861 <td>Computed value:
4863 <td>as specified
4865 <tr>
4866 <td>Animatable:
4868 <td>no
4869 </table>
4871 <p>Allows control of glyph substitution and sizing in East Asian text.
4873 <pre
4874 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>
4876 <pre
4877 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>
4879 <p>Individual values have the following meanings:
4881 <dl>
4882 <dt><dfn id=font-variant-east-asian-normal-value
4883 title="normal!!font-variant-east-asian">normal</dfn>
4885 <dd>None of the features listed below are enabled.
4887 <dt><dfn id=jis78>jis78</dfn>
4889 <dd>Enables rendering of JIS78 forms (OpenType feature: <span
4890 class=tag>jp78</span>).
4891 </dl>
4893 <div class=featex><img alt="JIS78 form example" src=jp78.png></div>
4895 <dl>
4896 <dt><dfn id=jis83>jis83</dfn>
4898 <dd>Enables rendering of JIS83 forms (OpenType feature: <span
4899 class=tag>jp83</span>).
4901 <dt><dfn id=jis90>jis90</dfn>
4903 <dd>Enables rendering of JIS90 forms (OpenType feature: <span
4904 class=tag>jp90</span>).
4906 <dt><dfn id=jis04>jis04</dfn>
4908 <dd>Enables rendering of JIS2004 forms (OpenType feature: <span
4909 class=tag>jp04</span>).
4910 <p>The various JIS variants reflect the glyph forms defined in different
4911 Japanese national standards. Fonts generally include glyphs defined by
4912 the most recent national standard but it's sometimes necessary to use
4913 older variants, to match signage for example.</p>
4915 <dt><dfn id=simplified>simplified</dfn>
4917 <dd>Enables rendering of simplified forms (OpenType feature: <span
4918 class=tag>smpl</span>).
4919 <p>The ‘<a href="#simplified"><code
4920 class=property>simplified</code></a>’ and ‘<a
4921 href="#traditional"><code class=property>traditional</code></a>’
4922 values allow control over the glyph forms for characters which have been
4923 simplified over time but for which the older, traditional form is still
4924 used in some contexts. The exact set of characters and glyph forms will
4925 vary to some degree by context for which a given font was designed.</p>
4927 <dt><dfn id=traditional>traditional</dfn>
4929 <dd>Enables rendering of traditional forms (OpenType feature: <span
4930 class=tag>trad</span>).
4931 </dl>
4933 <div class=featex><img alt="tradtional form example" src=trad.png></div>
4935 <dl>
4936 <dt><dfn id=full-width>full-width</dfn>
4938 <dd>Enables rendering of full-width variants (OpenType feature: <span
4939 class=tag>fwid</span>).
4941 <dt><dfn id=proportional-width>proportional-width</dfn>
4943 <dd>Enables rendering of proportionally-spaced variants (OpenType feature:
4944 <span class=tag>pwid</span>).
4945 </dl>
4947 <div class=featex><img alt="proportionally spaced Japanese example"
4948 src=pwid.png></div>
4950 <dl>
4951 <dt><dfn id=ruby>ruby</dfn>
4953 <dd>Enables display of ruby variant glyphs (OpenType feature: <span
4954 class=tag>ruby</span>). Since ruby text is generally smaller than the
4955 associated body text, font designers can design special glyphs for use
4956 with ruby that are more readable than scaled down versions of the default
4957 glyphs. Only glyph selection is affected, there is no associated font
4958 scaling or other change that affects line layout. The red ruby text below
4959 is shown with default glyphs (top) and with ruby variant glyphs (bottom).
4960 Note the slight difference in stroke thickness.
4961 </dl>
4963 <div class=featex><img alt="ruby variant example" src=rubyshinkansen.png></div>
4965 <h3 id=font-variant-prop><span class=secno>6.11 </span>Overall shorthand
4966 for font rendering: the <a href="#propdef-font-variant">font-variant</a>
4967 property</h3>
4969 <table class=propdef id=namefont-variantvaluenormal-none-ltcommo>
4970 <tbody>
4971 <tr>
4972 <td>Name:
4974 <td><dfn id=propdef-font-variant
4975 title="font-variant!!property">font-variant</dfn>
4977 <tr>
4978 <td>Value:
4980 <td><a href="#font-variant-normal-value"
4981 title="normal!!font-variant">normal</a> | <a
4982 href="#font-variant-none-value" title="none!!font-variant">none</a> | [
4983 <a href="#common-lig-values"><var><common-lig-values></var></a>
4984 || <a
4985 href="#discretionary-lig-values"><var><discretionary-lig-values></var></a>
4986 || <a
4987 href="#historical-lig-values"><var><historical-lig-values></var></a>
4988 || <a
4989 href="#contextual-alt-values"><var><contextual-alt-values></var></a>
4990 || <a href="#stylistic"><var
4991 title=stylistic>stylistic(<feature-value-name>)</var></a> || <a
4992 href="#historical-forms"><var>historical-forms</var></a> || <a
4993 href="#styleset"><var
4994 title=styleset>styleset(<feature-value-name> #)</var></a> || <a
4995 href="#character-variant"><var
4996 title=character-variant>character-variant(<feature-value-name>
4997 #)</var></a> || <a href="#swash"><var
4998 title=swash>swash(<feature-value-name>)</var></a> || <a
4999 href="#ornaments"><var
5000 title=ornaments>ornaments(<feature-value-name>)</var></a> || <a
5001 href="#annotation"><var
5002 title=annotation>annotation(<feature-value-name>)</var></a> || [
5003 <a href="#small-caps"><i>small-caps</i></a> | <a
5004 href="#all-small-caps"><i>all-small-caps</i></a> | <a
5005 href="#petite-caps"><i>petite-caps</i></a> | <a
5006 href="#all-petite-caps"><i>all-petite-caps</i></a> | <a
5007 href="#unicase"><i>unicase</i></a> | <a
5008 href="#titling-caps"><i>titling-caps</i></a> ] || <a
5009 href="#numeric-figure-values"><var><numeric-figure-values></var></a>
5010 || <a
5011 href="#numeric-spacing-values"><var><numeric-spacing-values></var></a>
5012 || <a
5013 href="#numeric-fraction-values"><var><numeric-fraction-values></var></a>
5014 || <a href="#ordinal"><i>ordinal</i></a> || <a
5015 href="#slashed-zero"><i>slashed-zero</i></a> || <a
5016 href="#east-asian-variant-values"><var><east-asian-variant-values></var></a>
5017 || <a
5018 href="#east-asian-width-values"><var><east-asian-width-values></var></a>
5019 || <a href="#ruby"><i>ruby</i></a> ]
5021 <tr>
5022 <td>Initial:
5024 <td>normal
5026 <tr>
5027 <td>Applies to:
5029 <td>all elements
5031 <tr>
5032 <td>Inherited:
5034 <td>yes
5036 <tr>
5037 <td>Percentages:
5039 <td>see individual properties
5041 <tr>
5042 <td>Media:
5044 <td>visual
5046 <tr>
5047 <td>Computed value:
5049 <td>see individual properties
5051 <tr>
5052 <td>Animatable:
5054 <td>see individual properties
5055 </table>
5057 <p>The value <dfn id=font-variant-normal-value
5058 title="normal!!font-variant">‘<code
5059 class=property>normal</code>’</dfn> resets all other font feature
5060 properties to their inital value. The <dfn id=font-variant-none-value
5061 title="none!!font-variant">‘<code class=property>none</code>’</dfn>
5062 value sets ‘<a href="#propdef-font-variant-ligatures"><code
5063 class=property>font-variant-ligatures</code></a>’ to ‘<code
5064 class=property>none</code>’ and resets all other font feature properties
5065 to their initial value. Like other shorthands, using <a
5066 href="#propdef-font-variant" title="font-variant!!property">‘<code
5067 class=property>font-variant</code>’</a> resets unspecified font-variant
5068 subproperties to their initial values. It does not reset the values of
5069 either ‘<a href="#propdef-font-language-override"><code
5070 class=property>font-language-override</code></a>’ or <a
5071 href="#propdef-font-feature-settings"
5072 title="font-feature-settings!!property">‘<code
5073 class=property>font-feature-settings</code>’</a>.
5075 <h3 id=font-feature-settings-prop><span class=secno>6.12 </span>Low-level
5076 font feature settings control: the <a
5077 href="#propdef-font-feature-settings">font-feature-settings</a> property</h3>
5079 <table class=propdef id=namefont-feature-settingsvaluenormal-ltf>
5080 <tbody>
5081 <tr>
5082 <td>Name:
5084 <td><dfn id=propdef-font-feature-settings
5085 title="font-feature-settings!!property">font-feature-settings</dfn>
5087 <tr>
5088 <td>Value:
5090 <td><a href="#font-feature-settings-normal-value"
5091 title="normal!!font-feature-settings">normal</a> | <a
5092 href="#feature-tag-value"><var><feature-tag-value></var></a> #
5094 <tr>
5095 <td>Initial:
5097 <td>normal
5099 <tr>
5100 <td>Applies to:
5102 <td>all elements
5104 <tr>
5105 <td>Inherited:
5107 <td>yes
5109 <tr>
5110 <td>Percentages:
5112 <td>N/A
5114 <tr>
5115 <td>Media:
5117 <td>visual
5119 <tr>
5120 <td>Computed value:
5122 <td>as specified
5124 <tr>
5125 <td>Animatable:
5127 <td>no
5128 </table>
5130 <p>This property provides low-level control over OpenType font features. It
5131 is intended as a way of providing access to font features that are not
5132 widely used but are needed for a particular use case. A value of <dfn
5133 id=font-feature-settings-normal-value
5134 title="normal!!font-feature-settings">‘<code
5135 class=property>normal</code>’</dfn> means that no change in glyph
5136 selection or positioning occurs due to this property.
5138 <p>
5140 <pre>/* enable small caps and use second swash alternate */
5141 font-feature-settings: "smcp", "swsh" 2;</pre>
5143 <p>Feature tag values have the following syntax:
5145 <pre
5146 class=prod><dfn id=feature-tag-value><var><feature-tag-value></var></dfn> = <string> [ <integer> | on | off ]?</pre>
5148 <p>The <string> is a case-sensitive OpenType feature tag. As
5149 specified in the OpenType specification, feature tags contain four ASCII
5150 characters. Tag strings longer or shorter than four characters, or
5151 containing characters outside the U+20–7E codepoint range are invalid.
5152 User agents must not use a feature tag created by truncating or padding
5153 the string to four characters. Feature tags need only match a feature tag
5154 defined in the font, they are not limited to explicitly registered
5155 OpenType features. Fonts defining custom feature tags should follow the <a
5156 href="http://www.microsoft.com/typography/otspec/featuretags.htm">tag name
5157 rules</a> defined in the OpenType specification <a
5158 href="#OPENTYPE-FEATURES"
5159 rel=biblioentry>[OPENTYPE-FEATURES]<!--{{!OPENTYPE-FEATURES}}--></a>.
5160 Feature tags not present in the font are ignored; a user agent must not
5161 attempt to synthesize fallback behavior based on these feature tags.
5163 <p>This means that explicitly disabling the <span class=tag>kern</span>
5164 feature will not affect the application of kerning data found in the
5165 ‘<code class=property>kern</code>’ table (as opposed to kerning data
5166 associated with the <span class=tag>kern</span> feature in the ‘<code
5167 class=property>GPOS</code>’ table). Authors should use the ‘<a
5168 href="#propdef-font-kerning"><code
5169 class=property>font-kerning</code></a>’ property to explictly enable or
5170 disable kerning since this property affects both types of kerning.
5172 <p>If present, a value indicates an index used for glyph selection. An
5173 <integer> value must be 0 or greater. A value of 0 indicates that
5174 the feature is disabled. For boolean features, a value of 1 enables the
5175 feature. For non-boolean features, a value of 1 or greater enables the
5176 feature and indicates the feature selection index. A value of ‘<code
5177 class=property>on</code>’ is synonymous with 1 and ‘<code
5178 class=property>off</code>’ is synonymous with 0. If the value is
5179 omitted, a value of 1 is assumed.
5181 <pre>
5182 font-feature-settings: "dlig" 1; /* dlig=1 enable discretionary ligatures */
5183 font-feature-settings: "smcp" on; /* smcp=1 enable small caps */
5184 font-feature-settings: 'c2sc'; /* c2sc=1 enable caps to small caps */
5185 font-feature-settings: "liga" off; /* liga=0 no common ligatures */
5186 font-feature-settings: "tnum", 'hist'; /* tnum=1, hist=1 enable tabular numbers and historical forms */
5187 font-feature-settings: "tnum" "hist"; /* invalid, need a comma-delimited list */
5188 font-feature-settings: "palin" off; /* good idea but invalid tagname */
5189 font-feature-settings: "PKRN"; /* PKRN=1 enable custom feature */
5190 font-feature-settings: dlig; /* invalid, tag must be a string */
5191 </pre>
5193 <p>When values greater than the range supported by the font are specified,
5194 the behavior is explicitly undefined. For boolean features, in general
5195 these will enable the feature. For non-boolean features, out of range
5196 values will in general be equivalent to a 0 value. However, in both cases
5197 the exact behavior will depend upon the way the font is designed
5198 (specifically, which type of lookup is used to define the feature).
5200 <p>Authors should generally use <a href="#propdef-font-variant"
5201 title="font-variant!!property">‘<code
5202 class=property>font-variant</code>’</a> and its related subproperties
5203 whenever possible and only use this property for special cases where its
5204 use is the only way of accessing a particular infrequently used font
5205 feature.
5207 <p>Although specifically defined for OpenType feature tags, feature tags
5208 for other modern font formats that support font features may be added in
5209 the future. Where possible, features defined for other font formats should
5210 attempt to follow the pattern of registered OpenType tags.
5212 <div class=example>
5213 <p>The Japanese text below will be rendered with half-width kana
5214 characters:</p>
5216 <pre lang=ja>
5217 body { font-feature-settings: "hwid"; /* Half-width OpenType feature */ }
5219 <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>
5220 </pre>
5221 </div>
5223 <h3 id=font-language-override-prop><span class=secno>6.13 </span>Font
5224 language override: the <a
5225 href="#propdef-font-language-override">font-language-override</a> property</h3>
5227 <table class=propdef id=namefont-language-overridevaluenormal-lt>
5228 <tbody>
5229 <tr>
5230 <td>Name:
5232 <td><dfn id=propdef-font-language-override>font-language-override</dfn>
5234 <tr>
5235 <td>Value:
5237 <td><a href="#font-language-override-normal-value"
5238 title="normal!!font-language-override">normal</a> | <a
5239 href="#font-language-override-string-value"><var><string></var></a>
5241 <tr>
5242 <td>Initial:
5244 <td><a href="#font-language-override-normal-value"
5245 title="normal!!font-language-override">normal</a>
5247 <tr>
5248 <td>Applies to:
5250 <td>all elements
5252 <tr>
5253 <td>Inherited:
5255 <td>yes
5257 <tr>
5258 <td>Percentages:
5260 <td>N/A
5262 <tr>
5263 <td>Media:
5265 <td>visual
5267 <tr>
5268 <td>Computed value:
5270 <td>as specified
5272 <tr>
5273 <td>Animatable:
5275 <td>no
5276 </table>
5278 <p>Normally, authors can control the use of language-specific glyph
5279 substitutions and positioning by setting the content language of an
5280 element, as <a href="#language-specific-support">described above</a>:
5282 <pre><!-- Display text using S'gaw Karen specific features -->
5283 <p lang="ksw">...</p></pre>
5285 <p>In some cases, authors may need to specify a language system that
5286 differs from the content language, for example due to the need to mimic
5287 another language's typographic traditions. The ‘<a
5288 href="#propdef-font-language-override"><code
5289 class=property>font-language-override</code></a>’ property allows
5290 authors to explicitly specify the language system of the font, overriding
5291 the language system implied by the content language.
5293 <p>Values have the following meanings:
5295 <dl>
5296 <dt><dfn id=font-language-override-normal-value
5297 title="normal!!font-language-override">normal</dfn>
5299 <dd>specifies that when rendering with OpenType fonts, the content
5300 language of the element is used to infer the OpenType language system
5302 <dt><dfn
5303 id=font-language-override-string-value><var><string></var></dfn>
5305 <dd>single three-letter OpenType <a
5306 href="http://www.microsoft.com/typography/otspec/languagetags.htm">language
5307 system tag</a>, specifies the OpenType language system to be used instead
5308 of the language system implied by the language of the element
5309 </dl>
5311 <div class=example>
5312 <p>The <a href="http://www.un.org/en/documents/udhr/index.shtml">Universal
5313 Declaration of Human Rights</a> has been translated into a wide variety
5314 of languages. In Turkish, Article 9 of this document might be marked up
5315 as below:</p>
5317 <pre lang=tr><body lang="tr">
5319 <h4>Madde 9</h4>
5320 <p>Hiç kimse keyfi olarak tutuklanamaz, alıkonulanamaz veya sürülemez.</p>
5321 </pre>
5323 <p>Here the user agent uses the value of the ‘<code
5324 class=property>lang</code>’ attribute when rendering text and
5325 appropriately renders this text without ‘<code
5326 class=property>fi</code>’ ligatures. There is no need to use the ‘<a
5327 href="#propdef-font-language-override"><code
5328 class=property>font-language-override</code></a>’ property.</p>
5330 <p>However, a given font may lack support for a specific language. In this
5331 situation authors may need to use the typographic conventions of a
5332 related language that are supported by that font:</p>
5334 <pre lang=mk><body lang="mk"> <!-- Macedonian lang code -->
5336 body { font-language-override: "SRB"; /* Serbian OpenType language tag */ }
5338 <h4>Члeн 9</h4>
5339 <p>Никoj чoвeк нeмa дa бидe пoдлoжeн нa прoизвoлнo aпсeњe, притвoр или прoгoнувaњe.</p>
5341 </pre>
5343 <p>The Macedonian text here will be rendered using Serbian typographic
5344 conventions, with the assumption that the font specified supports
5345 Serbian.</p>
5346 </div>
5348 <p><a id=rendering-considerations></a>
5350 <h2 id=font-feature-resolution><span class=secno>7 </span>Font Feature
5351 Resolution</h2>
5353 <p>As described in the previous section, font features can be enabled in a
5354 variety of ways, either via the use of <a href="#propdef-font-variant"
5355 title="font-variant!!property">‘<code
5356 class=property>font-variant</code>’</a> or <a
5357 href="#propdef-font-feature-settings"
5358 title="font-feature-settings!!property">‘<code
5359 class=property>font-feature-settings</code>’</a> in a style rule or
5360 within an <code>@font-face</code> rule. The resolution order for the union
5361 of these settings is defined below. Features defined via CSS properties
5362 are applied on top of layout engine default features.
5364 <h3 id=default-features><span class=secno>7.1 </span>Default features</h3>
5366 <p>For OpenType fonts, user agents must enable the default features defined
5367 in the OpenType documentation for a given script and writing mode.
5368 Required ligatures, common ligatures and contextual forms must be enabled
5369 by default (OpenType features: <span class=tag>rlig, liga, clig,
5370 calt</span>), along with localized forms (OpenType feature: <span
5371 class=tag>locl</span>), and features required for proper display of
5372 composed characters and marks (OpenType features: <span class=tag>ccmp,
5373 mark, mkmk</span>). These features must always be enabled, even when the
5374 value of the <a href="#propdef-font-variant"
5375 title="font-variant!!property">‘<code
5376 class=property>font-variant</code>’</a> and <a
5377 href="#propdef-font-feature-settings"
5378 title="font-feature-settings!!property">‘<code
5379 class=property>font-feature-settings</code>’</a> properties is ‘<a
5380 href="#normal"><code class=property>normal</code></a>’. Individual
5381 features are only disabled when explicitly overridden by the author, as
5382 when ‘<a href="#propdef-font-variant-ligatures"><code
5383 class=property>font-variant-ligatures</code></a>’ is set to ‘<a
5384 href="#no-common-ligatures"><code
5385 class=property>no-common-ligatures</code></a>’. For handling complex
5386 scripts such as <a
5387 href="http://www.microsoft.com/typography/otfntdev/arabicot/features.aspx">Arabic</a>,
5388 <a
5389 href="http://www.microsoft.com/typography/otfntdev/mongolot/features.htm">Mongolian</a>
5390 or <a
5391 href="http://www.microsoft.com/typography/otfntdev/devanot/features.aspx">Devanagari</a>
5392 additional features are required. For upright text within vertical text
5393 runs, vertical alternates (OpenType feature: <span class=tag>vert</span>)
5394 must be enabled.
5396 <h3 id=feature-precedence><span class=secno>7.2 </span>Feature precedence</h3>
5398 <p>General and font specific font feature property settings are resolved in
5399 the order below, in ascending precedence order. This ordering is used to
5400 construct a combined list of font features that affect a given text run.
5402 <ol>
5403 <li>Font features enabled by default, including features required for a
5404 given script.
5406 <li>If the font is defined via an <code>@font-face</code> rule, the font
5407 features implied by the font-variant descriptor in the
5408 <code>@font-face</code> rule.
5410 <li>If the font is defined via an <code>@font-face</code> rule, the font
5411 features implied by the font-feature-settings descriptor in the
5412 <code>@font-face</code> rule.
5414 <li>Feature settings determined by properties other than <a
5415 href="#propdef-font-variant" title="font-variant!!property">‘<code
5416 class=property>font-variant</code>’</a> or <a
5417 href="#propdef-font-feature-settings"
5418 title="font-feature-settings!!property">‘<code
5419 class=property>font-feature-settings</code>’</a>. For example, setting
5420 a non-default value for the ‘<code
5421 class=property>letter-spacing</code>’ property disables ligatures.
5423 <li>Font features implied by the value of the <a
5424 href="#propdef-font-variant" title="font-variant!!property">‘<code
5425 class=property>font-variant</code>’</a> property, the related
5426 font-variant subproperties and any other CSS property that may use
5427 OpenType features (e.g. the ‘<a href="#propdef-font-kerning"><code
5428 class=property>font-kerning</code></a>’ property).
5430 <li>Font features implied by the value of <a
5431 href="#propdef-font-feature-settings"
5432 title="font-feature-settings!!property">‘<code
5433 class=property>font-feature-settings</code>’</a> property.
5434 </ol>
5436 <p>This ordering allows authors to set up a general set of defaults for
5437 fonts within their <code>@font-face</code> rules, then override them with
5438 property settings for specific elements. General property settings
5439 override the settings in <code>@font-face</code> rules and low-level font
5440 feature settings override <a href="#propdef-font-variant"
5441 title="font-variant!!property">‘<code
5442 class=property>font-variant</code>’</a> property settings.
5444 <p>For situations where the combined list of font feature settings contains
5445 more than one value for the same feature, the last value is used. When a
5446 font lacks support for a given underlying font feature, text is simply
5447 rendered as if that font feature was not enabled; font fallback does not
5448 occur and no attempt is made to synthesize the feature except where
5449 explicitly noted for specific properties.
5451 <h3 id=feature-precedence-examples><span class=secno>7.3 </span>Feature
5452 precedence examples</h3>
5454 <div class=example>
5455 <p>With the styles below, numbers are rendered proportionally when used
5456 within a paragraph but are shown in tabular form within tables of prices:</p>
5458 <pre>body {
5459 font-variant-numeric: proportional-nums;
5460 }
5462 table.prices td {
5463 font-variant-numeric: tabular-nums;
5464 }
5465 </pre>
5466 </div>
5468 <div class=example>
5469 <p>When the font-variant descriptor is used within an
5470 <code>@font-face</code> rule, it only applies to the font defined by that
5471 rule.</p>
5473 <pre>@font-face {
5474 font-family: MainText;
5475 src: url(http://example.com/font.ttf);
5476 font-variant: oldstyle-nums proportional-nums styleset(1,3);
5477 }
5479 body {
5480 font-family: MainText, Helvetica;
5481 }
5483 table.prices td {
5484 font-variant-numeric: tabular-nums;
5485 }
5486 </pre>
5488 <p>In this case, old-style numerals will be used throughout but only where
5489 the font "MainText" is used. Just as in the previous example, tabular
5490 values will be used in price tables since ‘<a
5491 href="#tabular-nums"><code class=property>tabular-nums</code></a>’
5492 appears in a general style rule and its use is mutually exclusive with
5493 ‘<a href="#proportional-nums"><code
5494 class=property>proportional-nums</code></a>’. Stylistic alternate sets
5495 will only be used where MainText is used.</p>
5496 </div>
5498 <div class=example>
5499 <p>The <code>@font-face</code> rule can also be used to access font
5500 features in locally available fonts via the use of <code>local()</code>
5501 in the ‘<a href="#descdef-src"><code class=property>src</code></a>’
5502 descriptor of the <code>@font-face</code> definition:</p>
5504 <pre>@font-face {
5505 font-family: BodyText;
5506 src: local("HiraMaruPro-W4");
5507 font-variant: proportional-width;
5508 font-feature-settings: "ital"; /* Latin italics within CJK text feature */
5509 }
5511 body { font-family: BodyText, serif; }
5512 </pre>
5514 <p>If available, a Japanese font "Hiragino Maru Gothic" will be used. When
5515 text rendering occurs, Japanese kana will be proportionally spaced and
5516 Latin text will be italicised. Text rendered with the fallback serif font
5517 will use default rendering properties.</p>
5518 </div>
5520 <div class=example>
5521 <p>In the example below, discretionary ligatures are enabled only for a
5522 downloadable font but are disabled within spans of class "special":</p>
5524 <pre>@font-face {
5525 font-family: main;
5526 src: url(fonts/ffmeta.woff) format("woff");
5527 font-variant: discretionary-ligatures;
5528 }
5530 body { font-family: main, Helvetica; }
5531 span.special { font-variant-ligatures: no-discretionary-ligatures; }
5532 </pre>
5534 <p>Adding an discretionary style rule with the <code>@font-face</code>
5535 above:</p>
5537 <pre>body { font-family: main, Helvetica; }
5538 span { font-feature-settings: "dlig"; }
5539 span.special { font-variant-ligatures: no-discretionary-ligatures; }
5540 </pre>
5542 <p>Within spans of class "special", discretionary ligatures <em>will</em>
5543 be rendered. This is because both the <a
5544 href="#propdef-font-feature-settings"
5545 title="font-feature-settings!!property">‘<code
5546 class=property>font-feature-settings</code>’</a> and ‘<a
5547 href="#propdef-font-variant-ligatures"><code
5548 class=property>font-variant-ligatures</code></a>’ properties apply to
5549 these spans. Although the ‘<code class=css>no-discretionary
5550 ligatures</code>’ setting of ‘<a
5551 href="#propdef-font-variant-ligatures"><code
5552 class=property>font-variant-ligatures</code></a>’ effectively disables
5553 the OpenType <span class=tag>dlig</span> feature, because the <a
5554 href="#propdef-font-feature-settings"
5555 title="font-feature-settings!!property">‘<code
5556 class=property>font-feature-settings</code>’</a> is resolved after
5557 that, the ‘<code class=property>dlig</code>’ value reenables
5558 discretionary ligatures.</p>
5559 </div>
5561 <h2 id=object-model><span class=secno>8 </span>Object Model</h2>
5563 <p>The contents of <code>@font-face</code> and
5564 <code>@font-feature-values</code> rules can be accessed via the following
5565 extensions to the CSS Object Model.
5567 <h3 id=om-fontface><span class=secno>8.1 </span>The <a
5568 href="#cssfontfacerule"><code>CSSFontFaceRule</code></a> interface</h3>
5570 <p>The <dfn id=cssfontfacerule>CSSFontFaceRule</dfn> interface represents a
5571 <code>@font-face</code> rule.
5573 <pre class=idl>
5574 interface CSSFontFaceRule : CSSRule {
5575 attribute DOMString family;
5576 attribute DOMString src;
5577 attribute DOMString style;
5578 attribute DOMString weight;
5579 attribute DOMString stretch;
5580 attribute DOMString unicodeRange;
5581 attribute DOMString variant;
5582 attribute DOMString featureSettings;
5583 }</pre>
5585 <p>The DOM Level 2 Style specification <a href="#DOM-LEVEL-2-STYLE"
5586 rel=biblioentry>[DOM-LEVEL-2-STYLE]<!--{{DOM-LEVEL-2-STYLE}}--></a>
5587 defined a different variant of this rule. This definition supercedes that
5588 one.
5590 <h3 id=om-fontfeaturevalues><span class=secno>8.2 </span>The <a
5591 href="#cssfontfeaturevaluesrule"><code>CSSFontFeatureValuesRule</code></a>
5592 interface</h3>
5594 <p>The <code>CSSRule</code> interface is extended as follows:
5596 <pre class=idl>partial interface CSSRule {
5597 const unsigned short FONT_FEATURE_VALUES_RULE = 14;
5598 }</pre>
5600 <p>The <dfn id=cssfontfeaturevaluesrule>CSSFontFeatureValuesRule</dfn>
5601 interface represents a <code>@font-feature-values</code> rule.
5603 <pre class=idl>interface CSSFontFeatureValuesRule : CSSRule {
5604 readonly attribute DOMString familyList;
5605 readonly attribute DOMString valueText;
5606 };</pre>
5608 <dl class=idl-attributes>
5609 <dt><var>familyList</var> of type <code>DOMString</code>, readonly
5611 <dd>The list of one or more font families for which a given set of feature
5612 values is defined.
5614 <dt><var>valueText</var> of type <code>DOMString</code>, readonly
5616 <dd>Serialized set of feature values.
5617 </dl>
5619 <p class=issue>Should this be extended to make <a
5620 href="#cssfontfeaturevaluesrule"><code>CSSFontFeatureValuesRule</code></a>
5621 be a subclass of <code>CSSGroupingRule</code> with other CSSRule
5622 subclasses for each value definition block?
5624 <h2 class=no-num id=platform-props-to-css>Appendix A: Mapping platform font
5625 properties to CSS properties</h2>
5627 <p><em>This appendix is included as background for some of the problems and
5628 situations that are described in other sections. It should be viewed as
5629 informative only.</em>
5631 <p>Font properties in CSS are designed to be independent of the underlying
5632 font formats used; they can be used to specify bitmap fonts, Type1 fonts,
5633 SVG fonts in addition to the common TrueType and OpenType fonts. But there
5634 are facets of the TrueType and OpenType formats that often cause confusion
5635 for authors and present challenges to implementers on different platforms.
5637 <p>Originally developed at Apple, TrueType was designed as an outline font
5638 format for both screen and print. Microsoft joined Apple in developing the
5639 TrueType format and both platforms have supported TrueType fonts since
5640 then. Font data in the TrueType format consists of a set of tables
5641 distinguished with common four-letter tag names, each containing a
5642 specific type of data. For example, naming information, including
5643 copyright and license information, is stored in the ‘<code
5644 class=property>name</code>’ table. The <a
5645 href="#character-map"><em>character map</em></a> (‘<code
5646 class=property>cmap</code>’) table contains a mapping of character
5647 encodings to glyphs. Apple later added additional tables for supporting
5648 enhanced typographic functionality; these are now called Apple Advanced
5649 Typography, or AAT, fonts. Microsoft and Adobe developed a separate set of
5650 tables for advanced typography and called their format OpenType <a
5651 href="#OPENTYPE" rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a>.
5653 <p>In many cases the font data used under Microsoft Windows or Linux is
5654 slightly different from the data used under Apple's Mac OS X because the
5655 TrueType format allowed for explicit variation across platforms. This
5656 includes font metrics, names and <a href="#character-map"><em>character
5657 map</em></a> data.
5659 <p>Specifically, font family name data is handled differently across
5660 platforms. For TrueType and OpenType fonts these names are contained in
5661 the ‘<code class=property>name</code>’ table, in name records with
5662 name ID 1. Mulitple names can be stored for different locales, but
5663 Microsoft recommends fonts always include at least a US English version of
5664 the name. On Windows, Microsoft made the decision for backwards
5665 compatibility to limit this family name to a maximum of four faces; for
5666 larger groupings the "preferred family" (name ID 16) or "WWS family" (name
5667 ID 21) can be used. Other platforms such as OSX don't have this
5668 limitation, so the family name is used to define all possible groupings.
5670 <p>Other name table data provides names used to uniquely identify a
5671 specific face within a family. The full font name (name ID 4) and the
5672 Postscript name (name ID 6) describe a single face uniquely. For example,
5673 the bold face of the Gill Sans family has a fullname of "Gill Sans Bold"
5674 and a Postscript name of "GillSans-Bold". There can be multiple localized
5675 versions of the fullname for a given face, but the Postscript name is
5676 always a unique name made from a limited set of ASCII characters.
5678 <p>On various platforms, different names are used to search for a font. For
5679 example, with the Windows GDI CreateIndirectFont API, either a family or
5680 fullname can be used to lookup a face, while on Mac OS X the
5681 CTFontCreateWithName API call is used to lookup a given face using the
5682 fullname and Postscript name. Under Linux, the fontconfig API allows fonts
5683 to be searched using any of these names. In situations where platform
5684 API's automatically substitute other font choices, it may be necessary to
5685 verify a returned font matches a given name.
5687 <p>The weight of a given face can be determined via the usWeightClass field
5688 of the OS/2 table or inferred from the style name (name ID 2). Likewise,
5689 the width can be determined via the usWidthClass of the OS/2 table or
5690 inferred from the style name. For historical reasons related to synthetic
5691 bolding at weights 200 or lower with the Windows GDI API, font designers
5692 have sometimes skewed values in the OS/2 table to avoid these weights.
5694 <p>Rendering complex scripts that use contextual shaping such as Thai,
5695 Arabic and Devanagari requires features present only in OpenType or AAT
5696 fonts. Currently, complex script rendering is supported on Windows and
5697 Linux using OpenType font features while both OpenType and AAT font
5698 features are used under Mac OS X.
5700 <h2 class=no-num id=ch-ch-ch-changes>Changes</h2>
5702 <h3 class=no-num id=recent-changes> Changes from the <a
5703 href="http://www.w3.org/TR/2013/WD-css3-fonts-20130212/">February 2013
5704 CSS3 Fonts Working Draft</a></h3>
5706 <p>Major changes include:
5708 <ul>
5709 <li>Moved font load events into a separate <a
5710 href="http://dev.w3.org/csswg/css3-font-load-events/">spec</a>
5712 <li>Tightened error handling rules for <code>@font-feature-values</code>
5713 rules
5715 <li>Added grammar productions for <code>@font-face</code> and
5716 <code>@font-feature-values</code> rules
5718 <li>Tightened definition of synthetic oblique
5720 <li>Revised definition of ‘<a href="#descdef-unicode-range"><code
5721 class=property>unicode-range</code></a>’ descriptor
5722 </ul>
5724 <h2 class=no-num id=acknowledgments>Acknowledgments</h2>
5726 <p>I'd like to thank Tal Leming, Jonathan Kew and Christopher Slye for all
5727 their help and feedback. John Hudson was kind enough to take the time to
5728 explain the subtleties of OpenType language tags and provided the example
5729 of character variant usage for displaying text on Byzantine seals. Ken
5730 Lunde and Eric Muller provided valuable feedback on CJK OpenType features
5731 and Unicode variation selectors. The idea for supporting font features by
5732 using font-variant subproperties originated with Håkon Wium Lie, Adam
5733 Twardoch and Tal Leming. Elika Etemad supplied some of the initial design
5734 ideas for the <code>@font-feature-values</code> rule. Thanks also to House
5735 Industries for allowing the use of Ed Interlock in the discretionary
5736 ligatures example.
5738 <p>A special thanks to Robert Bringhurst for the sublime mind expansion
5739 that is <em>The Elements of Typographic Style</em>.
5741 <h2 class=no-num id=conformance> Conformance</h2>
5743 <h3 class=no-num id=conventions> Document Conventions</h3>
5745 <p>Conformance requirements are expressed with a combination of descriptive
5746 assertions and RFC 2119 terminology. The key words “MUST”, “MUST
5747 NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”,
5748 “SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL” in the
5749 normative parts of this document are to be interpreted as described in RFC
5750 2119. However, for readability, these words do not appear in all uppercase
5751 letters in this specification.
5753 <p>All of the text of this specification is normative except sections
5754 explicitly marked as non-normative, examples, and notes. <a
5755 href="#RFC2119" rel=biblioentry>[RFC2119]<!--{{!RFC2119}}--></a>
5757 <p>Examples in this specification are introduced with the words “for
5758 example” or are set apart from the normative text with
5759 <code>class="example"</code>, like this:
5761 <div class=example>
5762 <p>This is an example of an informative example.
5763 </div>
5765 <p>Informative notes begin with the word “Note” and are set apart from
5766 the normative text with <code>class="note"</code>, like this:
5768 <p class=note>Note, this is an informative note.
5770 <h3 class=no-num id=conformance-classes> Conformance Classes</h3>
5772 <p>Conformance to CSS Fonts Level 3 Module is defined for three conformance
5773 classes:
5775 <dl>
5776 <dt><dfn id=style-sheet title="style sheet!!as conformance class">style
5777 sheet</dfn>
5779 <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#style-sheet">CSS
5780 style sheet</a>.
5782 <dt><dfn id=renderer>renderer</dfn>
5784 <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
5785 that interprets the semantics of a style sheet and renders documents that
5786 use them.
5788 <dt><dfn id=authoring-tool>authoring tool</dfn>
5790 <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
5791 that writes a style sheet.
5792 </dl>
5794 <p>A style sheet is conformant to CSS Fonts Level 3 Module if all of its
5795 declarations that use properties defined in this module have values that
5796 are valid according to the generic CSS grammar and the individual grammars
5797 of each property as given in this module.
5799 <p>A renderer is conformant to CSS Fonts Level 3 Module if, in addition to
5800 interpreting the style sheet as defined by the appropriate specifications,
5801 it supports all the features defined by CSS Fonts Level 3 Module by
5802 parsing them correctly and rendering the document accordingly. However,
5803 the inability of a UA to correctly render a document due to limitations of
5804 the device does not make the UA non-conformant. (For example, a UA is not
5805 required to render color on a monochrome monitor.)
5807 <p>An authoring tool is conformant to CSS Fonts Level 3 Module if it writes
5808 style sheets that are syntactically correct according to the generic CSS
5809 grammar and the individual grammars of each feature in this module, and
5810 meet all other conformance requirements of style sheets as described in
5811 this module.
5813 <h3 class=no-num id=partial> Partial Implementations</h3>
5815 <p>So that authors can exploit the forward-compatible parsing rules to
5816 assign fallback values, CSS renderers <strong>must</strong> treat as
5817 invalid (and <a
5818 href="http://www.w3.org/TR/CSS21/conform.html#ignore">ignore as
5819 appropriate</a>) any at-rules, properties, property values, keywords, and
5820 other syntactic constructs for which they have no usable level of support.
5821 In particular, user agents <strong>must not</strong> selectively ignore
5822 unsupported component values and honor supported values in a single
5823 multi-value property declaration: if any value is considered invalid (as
5824 unsupported values must be), CSS requires that the entire declaration be
5825 ignored.
5827 <h3 class=no-num id=experimental> Experimental Implementations</h3>
5829 <p>To avoid clashes with future CSS features, the CSS2.1 specification
5830 reserves a <a
5831 href="http://www.w3.org/TR/CSS21/syndata.html#vendor-keywords">prefixed
5832 syntax</a> for proprietary and experimental extensions to CSS.
5834 <p>Prior to a specification reaching the Candidate Recommendation stage in
5835 the W3C process, all implementations of a CSS feature are considered
5836 experimental. The CSS Working Group recommends that implementations use a
5837 vendor-prefixed syntax for such features, including those in W3C Working
5838 Drafts. This avoids incompatibilities with future changes in the draft.
5840 <h3 class=no-num id=testing> Non-Experimental Implementations</h3>
5842 <p>Once a specification reaches the Candidate Recommendation stage,
5843 non-experimental implementations are possible, and implementors should
5844 release an unprefixed implementation of any CR-level feature they can
5845 demonstrate to be correctly implemented according to spec.
5847 <p>To establish and maintain the interoperability of CSS across
5848 implementations, the CSS Working Group requests that non-experimental CSS
5849 renderers submit an implementation report (and, if necessary, the
5850 testcases used for that implementation report) to the W3C before releasing
5851 an unprefixed implementation of any CSS features. Testcases submitted to
5852 W3C are subject to review and correction by the CSS Working Group.
5854 <p>Further information on submitting testcases and implementation reports
5855 can be found from on the CSS Working Group's website at <a
5856 href="http://www.w3.org/Style/CSS/Test/">http://www.w3.org/Style/CSS/Test/</a>.
5857 Questions should be directed to the <a
5858 href="http://lists.w3.org/Archives/Public/public-css-testsuite">public-css-testsuite@w3.org</a>
5859 mailing list.
5861 <h2 class=no-num id=references>References</h2>
5863 <h3 class=no-num id=normative-references>Normative References</h3>
5864 <!--begin-normative-->
5865 <!-- Sorted by label -->
5867 <dl class=bibliography>
5868 <dd style="display: none"><!-- keeps the doc valid if the DL is empty -->
5869 <!---->
5871 <dt id=CHARMOD>[CHARMOD]
5873 <dd>Martin J. Dürst; et al. <a
5874 href="http://www.w3.org/TR/2005/REC-charmod-20050215/"><cite>Character
5875 Model for the World Wide Web 1.0: Fundamentals.</cite></a> 15 February
5876 2005. W3C Recommendation. URL: <a
5877 href="http://www.w3.org/TR/2005/REC-charmod-20050215/">http://www.w3.org/TR/2005/REC-charmod-20050215/</a>
5878 </dd>
5879 <!---->
5881 <dt id=CORS>[CORS]
5883 <dd>Anne van Kesteren. <a
5884 href="http://www.w3.org/TR/2013/CR-cors-20130129/"><cite>Cross-Origin
5885 Resource Sharing.</cite></a> 29 January 2013. W3C Candidate
5886 Recommendation. (Work in progress.) URL: <a
5887 href="http://www.w3.org/TR/2013/CR-cors-20130129/">http://www.w3.org/TR/2013/CR-cors-20130129/</a>
5888 </dd>
5889 <!---->
5891 <dt id=CSS21>[CSS21]
5893 <dd>Bert Bos; et al. <a
5894 href="http://www.w3.org/TR/2011/REC-CSS2-20110607"><cite>Cascading Style
5895 Sheets Level 2 Revision 1 (CSS 2.1) Specification.</cite></a> 7 June
5896 2011. W3C Recommendation. URL: <a
5897 href="http://www.w3.org/TR/2011/REC-CSS2-20110607">http://www.w3.org/TR/2011/REC-CSS2-20110607</a>
5898 </dd>
5899 <!---->
5901 <dt id=CSS3VAL>[CSS3VAL]
5903 <dd>Håkon Wium Lie; Tab Atkins; Elika J. Etemad. <a
5904 href="http://www.w3.org/TR/2012/CR-css3-values-20120828/"><cite>CSS
5905 Values and Units Module Level 3.</cite></a> 28 August 2012. W3C Candidate
5906 Recommendation. (Work in progress.) URL: <a
5907 href="http://www.w3.org/TR/2012/CR-css3-values-20120828/">http://www.w3.org/TR/2012/CR-css3-values-20120828/</a>
5908 </dd>
5909 <!---->
5911 <dt id=HTML5>[HTML5]
5913 <dd>Ian Hickson. <a
5914 href="http://www.w3.org/TR/2012/CR-html5-20121217/"><cite>HTML5.</cite></a>
5915 17 December 2012. W3C Candidate Recommendation. (Work in progress.) URL:
5916 <a
5917 href="http://www.w3.org/TR/2012/CR-html5-20121217/">http://www.w3.org/TR/2012/CR-html5-20121217/</a>
5918 </dd>
5919 <!---->
5921 <dt id=OPEN-FONT-FORMAT>[OPEN-FONT-FORMAT]
5923 <dd><a
5924 href="http://standards.iso.org/ittf/PubliclyAvailableStandards/c052136_ISO_IEC_14496-22_2009(E).zip"><cite>Information
5925 technology — Coding of audio-visual objects — Part 22: Open Font
5926 Format.</cite></a> International Organization for Standardization.
5927 ISO/IEC 14496-22:2009. URL: <a
5928 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>
5929 </dd>
5930 <!---->
5932 <dt id=OPENTYPE>[OPENTYPE]
5934 <dd><a
5935 href="http://www.microsoft.com/typography/otspec/default.htm"><cite>OpenType
5936 specification.</cite></a> Microsoft. URL: <a
5937 href="http://www.microsoft.com/typography/otspec/default.htm">http://www.microsoft.com/typography/otspec/default.htm</a>
5938 </dd>
5939 <!---->
5941 <dt id=OPENTYPE-FEATURES>[OPENTYPE-FEATURES]
5943 <dd><a
5944 href="http://www.microsoft.com/typography/otspec/featurelist.htm"><cite>OpenType
5945 feature registry.</cite></a> Microsoft. URL: <a
5946 href="http://www.microsoft.com/typography/otspec/featurelist.htm">http://www.microsoft.com/typography/otspec/featurelist.htm</a>
5947 </dd>
5948 <!---->
5950 <dt id=RFC2119>[RFC2119]
5952 <dd>S. Bradner. <a href="http://www.ietf.org/rfc/rfc2119.txt"><cite>Key
5953 words for use in RFCs to Indicate Requirement Levels.</cite></a> Internet
5954 RFC 2119. URL: <a
5955 href="http://www.ietf.org/rfc/rfc2119.txt">http://www.ietf.org/rfc/rfc2119.txt</a>
5956 </dd>
5957 <!---->
5959 <dt id=UAX15>[UAX15]
5961 <dd>Mark Davis; Ken Whistler. <a
5962 href="http://www.unicode.org/reports/tr15/"><cite>Unicode Normalization
5963 Forms.</cite></a> 31 August 2012. Unicode Standard Annex #15. URL: <a
5964 href="http://www.unicode.org/reports/tr15/">http://www.unicode.org/reports/tr15/</a>
5965 </dd>
5966 <!---->
5968 <dt id=UAX29>[UAX29]
5970 <dd>Mark Davis. <a
5971 href="http://www.unicode.org/reports/tr29/"><cite>Unicode Text
5972 Segmentation.</cite></a> 12 September 2012. Unicode Standard Annex #29.
5973 URL: <a
5974 href="http://www.unicode.org/reports/tr29/">http://www.unicode.org/reports/tr29/</a>
5975 </dd>
5976 <!---->
5978 <dt id=UNICODE6>[UNICODE6]
5980 <dd>The Unicode Consortium. <a
5981 href="http://www.unicode.org/versions/Unicode6.2.0/"><cite>The Unicode
5982 Standard, Version 6.2.0.</cite></a> Defined by: The Unicode Standard,
5983 Version 6.2.0 URL: <a
5984 href="http://www.unicode.org/versions/Unicode6.2.0/">http://www.unicode.org/versions/Unicode6.2.0/</a>
5985 </dd>
5986 <!---->
5987 </dl>
5988 <!--end-normative-->
5989 <!--{{!CSS21}}-->
5990 <!--{{!CSS3VAL}}-->
5991 <!--{{!OPENTYPE}}-->
5992 <!--{{!OPENTYPE-FEATURES}}-->
5993 <!--{{!OPEN-FONT-FORMAT}}-->
5994 <!--{{!UNICODE6}}-->
5995 <!--{{!UAX15}}-->
5996 <!--{{!UAX29}}-->
5997 <!--{{!CORS}}-->
5998 <!--{{!HTML5}}-->
5999 <!--{{!CHARMOD}}-->
6001 <h3 class=no-num id=other-references>Other References</h3>
6002 <!--begin-informative-->
6003 <!-- Sorted by label -->
6005 <dl class=bibliography>
6006 <dd style="display: none"><!-- keeps the doc valid if the DL is empty -->
6007 <!---->
6009 <dt id=AAT-FEATURES>[AAT-FEATURES]
6011 <dd><a href="http://developer.apple.com/fonts/registry/"><cite>Apple
6012 Advanced Typography font feature registry.</cite></a> Apple. URL: <a
6013 href="http://developer.apple.com/fonts/registry/">http://developer.apple.com/fonts/registry/</a>
6014 </dd>
6015 <!---->
6017 <dt id=ARABIC-TYPO>[ARABIC-TYPO]
6019 <dd>Huda Smitshuijzen AbiFares. <cite>Arabic Typography: A Comprehensive
6020 Sourcebook.</cite> Saqi Books. 2001. ISBN 0-86356-347-3.</dd>
6021 <!---->
6023 <dt id=CHARMOD-NORM>[CHARMOD-NORM]
6025 <dd>François Yergeau; et al. <a
6026 href="http://www.w3.org/TR/2012/WD-charmod-norm-20120501/"><cite>Character
6027 Model for the World Wide Web 1.0: Normalization.</cite></a> 1 May 2012.
6028 W3C Working Draft. (Work in progress.) URL: <a
6029 href="http://www.w3.org/TR/2012/WD-charmod-norm-20120501/">http://www.w3.org/TR/2012/WD-charmod-norm-20120501/</a>
6030 </dd>
6031 <!---->
6033 <dt id=CJKV-INFO-PROCESSING>[CJKV-INFO-PROCESSING]
6035 <dd>Ken Lunde. <cite>CJKV Information Processing, Second Edition.</cite>
6036 O'Reilly Media, Inc. 2009. ISBN 0-596-51447-1.</dd>
6037 <!---->
6039 <dt id=CSS3-CONDITIONAL>[CSS3-CONDITIONAL]
6041 <dd>L. David Baron. <a
6042 href="http://www.w3.org/TR/2012/WD-css3-conditional-20121213/"><cite>CSS
6043 Conditional Rules Module Level 3.</cite></a> 13 December 2012. W3C
6044 Working Draft. (Work in progress.) URL: <a
6045 href="http://www.w3.org/TR/2012/WD-css3-conditional-20121213/">http://www.w3.org/TR/2012/WD-css3-conditional-20121213/</a>
6046 </dd>
6047 <!---->
6049 <dt id=CSS3TEXT>[CSS3TEXT]
6051 <dd>Elika J. Etemad; Koji Ishii. <a
6052 href="http://www.w3.org/TR/2012/WD-css3-text-20121113/"><cite>CSS Text
6053 Module Level 3.</cite></a> 13 November 2012. W3C Working Draft. (Work in
6054 progress.) URL: <a
6055 href="http://www.w3.org/TR/2012/WD-css3-text-20121113/">http://www.w3.org/TR/2012/WD-css3-text-20121113/</a>
6056 </dd>
6057 <!---->
6059 <dt id=DIGITAL-TYPOGRAPHY>[DIGITAL-TYPOGRAPHY]
6061 <dd>Richard Rubinstein. <cite>Digital Typography, An Introduction to Type
6062 and Composition for Computer System Design.</cite> Addison-Wesley. 1988.
6063 ISBN 0-201-17633-5.</dd>
6064 <!---->
6066 <dt id=DOM-LEVEL-2-STYLE>[DOM-LEVEL-2-STYLE]
6068 <dd>Chris Wilson; Philippe Le Hégaret; Vidur Apparao. <a
6069 href="http://www.w3.org/TR/2000/REC-DOM-Level-2-Style-20001113/"><cite>Document
6070 Object Model (DOM) Level 2 Style Specification.</cite></a> 13 November
6071 2000. W3C Recommendation. URL: <a
6072 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>
6073 </dd>
6074 <!---->
6076 <dt id=ELEMTYPO>[ELEMTYPO]
6078 <dd>Robert Bringhurst. <cite>The Elements of Typographic Style, Version
6079 4.</cite> Hartley & Marks. 2013. ISBN 0-88179-212-8.</dd>
6080 <!---->
6082 <dt id=LANGCULTTYPE>[LANGCULTTYPE]
6084 <dd>John D. Berry, Ed. <cite>Language Culture Type.</cite> Graphis. 2001.
6085 ISBN 1-932026-01-0.</dd>
6086 <!---->
6088 <dt id=OPENTYPE-FONT-GUIDE>[OPENTYPE-FONT-GUIDE]
6090 <dd><a
6091 href="https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf"><cite>OpenType
6092 User Guide.</cite></a> FontShop International. URL: <a
6093 href="https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf">https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf</a>
6094 </dd>
6095 <!---->
6097 <dt id=RASTER-TRAGEDY>[RASTER-TRAGEDY]
6099 <dd>Beat Stamm. <a href="http://www.rastertragedy.com/"><cite>The Raster
6100 Tragedy at Low-Resolution Revisited.</cite></a> 7 December 2011. URL: <a
6101 href="http://www.rastertragedy.com/">http://www.rastertragedy.com/</a></dd>
6102 <!---->
6104 <dt id=WINDOWS-GLYPH-PROC>[WINDOWS-GLYPH-PROC]
6106 <dd>John Hudson. <a
6107 href="http://www.microsoft.com/typography/developers/opentype/default.htm"><cite>Windows
6108 Glyph Processing.</cite></a> Microsoft Typogrraphy. URL: <a
6109 href="http://www.microsoft.com/typography/developers/opentype/default.htm">http://www.microsoft.com/typography/developers/opentype/default.htm</a>
6110 </dd>
6111 <!---->
6112 </dl>
6113 <!--end-informative-->
6114 <!--{{ARABIC-TYPO}}-->
6115 <!--{{CJKV-INFO-PROCESSING}}-->
6116 <!--{{DIGITAL-TYPOGRAPHY}}-->
6117 <!--{{DOM-LEVEL-2-STYLE}}-->
6118 <!--{{ELEMTYPO}}-->
6119 <!--{{LANGCULTTYPE}}-->
6120 <!--{{OPENTYPE-FONT-GUIDE}}-->
6121 <!--{{RASTER-TRAGEDY}}-->
6122 <!--{{WINDOWS-GLYPH-PROC}}-->
6123 <!--{{CHARMOD-NORM}}-->
6124 <!--{{AAT-FEATURES}}-->
6125 <!--{{CSS3-CONDITIONAL}}-->
6126 <!--{{CSS3TEXT}}-->
6128 <h2 class=no-num id=index>Index</h2>
6129 <!--begin-index-->
6131 <ul class=indexlist>
6132 <li>100...900 weight values, <a href="#font-weight-numeric-values"
6133 title="100...900 weight values"><strong>3.2</strong></a>
6135 <li><var><absolute-size></var>, <a href="#absolute-size-value"
6136 title="<absolute-size>"><strong>3.5</strong></a>
6138 <li><var><common-lig-values></var>, <a href="#common-lig-values"
6139 title="<common-lig-values>"><strong>6.4</strong></a>
6141 <li><var><contextual-alt-values></var>, <a
6142 href="#contextual-alt-values"
6143 title="<contextual-alt-values>"><strong>6.4</strong></a>
6145 <li><var><discretionary-lig-values></var>, <a
6146 href="#discretionary-lig-values"
6147 title="<discretionary-lig-values>"><strong>6.4</strong></a>
6149 <li><var><east-asian-variant-values></var>, <a
6150 href="#east-asian-variant-values"
6151 title="<east-asian-variant-values>"><strong>6.10</strong></a>
6153 <li><var><east-asian-width-values></var>, <a
6154 href="#east-asian-width-values"
6155 title="<east-asian-width-values>"><strong>6.10</strong></a>
6157 <li><var><family-name></var>, <a href="#family-name-value"
6158 title="<family-name>"><strong>3.1</strong></a>
6160 <li><var><feature-tag-value></var>, <a href="#feature-tag-value"
6161 title="<feature-tag-value>"><strong>6.12</strong></a>
6163 <li><var><font-face-name></var>, <a href="#font-face-name-value"
6164 title="<font-face-name>"><strong>4.3</strong></a>
6166 <li><var><font-variant-css21></var>, <a
6167 href="#font-variant-css21-values"
6168 title="<font-variant-css21>"><strong>3.7</strong></a>
6170 <li><var><generic-family></var>, <a href="#generic-family-value"
6171 title="<generic-family>"><strong>3.1</strong></a>
6173 <li><var><historical-lig-values></var>, <a
6174 href="#historical-lig-values"
6175 title="<historical-lig-values>"><strong>6.4</strong></a>
6177 <li><var><length></var>, <a href="#length-size-value"
6178 title="<length>"><strong>3.5</strong></a>
6180 <li><var><number></var>, <a href="#aspect-ratio-value"
6181 title="<number>"><strong>3.6</strong></a>
6183 <li><var><numeric-figure-values></var>, <a
6184 href="#numeric-figure-values"
6185 title="<numeric-figure-values>"><strong>6.7</strong></a>
6187 <li><var><numeric-fraction-values></var>, <a
6188 href="#numeric-fraction-values"
6189 title="<numeric-fraction-values>"><strong>6.7</strong></a>
6191 <li><var><numeric-spacing-values></var>, <a
6192 href="#numeric-spacing-values"
6193 title="<numeric-spacing-values>"><strong>6.7</strong></a>
6195 <li><var><percentage></var>, <a href="#percentage-size-value"
6196 title="<percentage>"><strong>3.5</strong></a>
6198 <li><var><relative-size></var>, <a href="#relative-size-value"
6199 title="<relative-size>"><strong>3.5</strong></a>
6201 <li><var><string></var>, <a
6202 href="#font-language-override-string-value"
6203 title="<string>"><strong>6.13</strong></a>
6205 <li><var><urange></var>, <a href="#urange-value"
6206 title="<urange>"><strong>4.5</strong></a>
6208 <li>@font-face, <a href="#font-face" title="@font-face">4.1</a>, <a
6209 href="#font-face0" title="@font-face">4.3</a>
6211 <li>all-petite-caps, <a href="#all-petite-caps"
6212 title=all-petite-caps><strong>6.6</strong></a>
6214 <li>all-small-caps, <a href="#all-small-caps"
6215 title=all-small-caps><strong>6.6</strong></a>
6217 <li>annotation, <a href="#annotation"
6218 title=annotation><strong>6.8</strong></a>
6220 <li>aspect value, <a href="#aspect-value0" title="aspect
6221 value"><strong>3.6</strong></a>
6223 <li>authoring tool, <a href="#authoring-tool" title="authoring
6224 tool"><strong>#</strong></a>
6226 <li>auto
6227 <ul>
6228 <li>font-kerning, <a href="#font-kerning-auto-value" title="auto,
6229 font-kerning"><strong>6.3</strong></a>
6231 <li>font-size-adjust, <a href="#font-size-adjust-auto-value"
6232 title="auto, font-size-adjust"><strong>3.6</strong></a>
6233 </ul>
6235 <li>bold, <a href="#bold" title=bold><strong>3.2</strong></a>
6237 <li>bolder, <a href="#bolder" title=bolder><strong>3.2</strong></a>
6239 <li>character map, <a href="#character-map" title="character
6240 map"><strong>5.2</strong></a>
6242 <li>character-variant, <a href="#character-variant"
6243 title=character-variant><strong>6.8</strong></a>
6245 <li>common-ligatures, <a href="#common-ligatures"
6246 title=common-ligatures><strong>6.4</strong></a>
6248 <li>condensed, <a href="#condensed"
6249 title=condensed><strong>3.3</strong></a>
6251 <li>contextual, <a href="#contextual"
6252 title=contextual><strong>6.4</strong></a>
6254 <li>CSSFontFaceRule, <a href="#cssfontfacerule"
6255 title=CSSFontFaceRule><strong>8.1</strong></a>
6257 <li>CSSFontFeatureValuesRule, <a href="#cssfontfeaturevaluesrule"
6258 title=CSSFontFeatureValuesRule><strong>8.2</strong></a>
6260 <li>cursive, definition of, <a href="#cursive0" title="cursive, definition
6261 of"><strong>#</strong></a>
6263 <li>default face, <a href="#default-face" title="default
6264 face"><strong>5.2</strong></a>
6266 <li>descriptor_declaration, <a href="#descriptordeclaration"
6267 title="descriptor_declaration"><strong>4.1</strong></a>
6269 <li>diagonal-fractions, <a href="#diagonal-fractions"
6270 title=diagonal-fractions><strong>6.7</strong></a>
6272 <li>discretionary-ligatures, <a href="#discretionary-ligatures"
6273 title=discretionary-ligatures><strong>6.4</strong></a>
6275 <li>expanded, <a href="#expanded" title=expanded><strong>3.3</strong></a>
6277 <li>extra-condensed, <a href="#extra-condensed"
6278 title=extra-condensed><strong>3.3</strong></a>
6280 <li>extra-expanded, <a href="#extra-expanded"
6281 title=extra-expanded><strong>3.3</strong></a>
6283 <li>fantasy, definition of, <a href="#fantasy0" title="fantasy, definition
6284 of"><strong>#</strong></a>
6286 <li>feature_type, <a href="#featuretype"
6287 title="feature_type"><strong>6.9</strong></a>
6289 <li>feature_value_block, <a href="#featurevalueblock"
6290 title="feature_value_block"><strong>6.9</strong></a>
6292 <li>feature_value_definition, <a href="#featurevaluedefinition"
6293 title="feature_value_definition"><strong>6.9</strong></a>
6295 <li>font, <a href="#propdef-font" title=font><strong>3.7</strong></a>
6297 <li>font-family
6298 <ul>
6299 <li>descriptor, <a href="#descdef-font-family" title="font-family,
6300 descriptor"><strong>4.2</strong></a>
6302 <li>property, <a href="#propdef-font-family" title="font-family,
6303 property"><strong>3.1</strong></a>
6304 </ul>
6306 <li>font-feature-settings
6307 <ul>
6308 <li>descriptor, <a href="#descdef-font-feature-settings"
6309 title="font-feature-settings, descriptor"><strong>4.7</strong></a>
6311 <li>property, <a href="#propdef-font-feature-settings"
6312 title="font-feature-settings, property"><strong>6.12</strong></a>
6313 </ul>
6315 <li>font-kerning, <a href="#propdef-font-kerning"
6316 title=font-kerning><strong>6.3</strong></a>
6318 <li>font-language-override, <a href="#propdef-font-language-override"
6319 title=font-language-override><strong>6.13</strong></a>
6321 <li>font-size, <a href="#propdef-font-size"
6322 title=font-size><strong>3.5</strong></a>
6324 <li>font-size-adjust, <a href="#propdef-font-size-adjust"
6325 title=font-size-adjust><strong>3.6</strong></a>
6327 <li>font-stretch
6328 <ul>
6329 <li>descriptor, <a href="#descdef-font-stretch" title="font-stretch,
6330 descriptor"><strong>4.4</strong></a>
6332 <li>property, <a href="#propdef-font-stretch" title="font-stretch,
6333 property"><strong>3.3</strong></a>
6334 </ul>
6336 <li>font-style
6337 <ul>
6338 <li>descriptor, <a href="#descdef-font-style" title="font-style,
6339 descriptor"><strong>4.4</strong></a>
6341 <li>property, <a href="#propdef-font-style" title="font-style,
6342 property"><strong>3.4</strong></a>
6343 </ul>
6345 <li>font-synthesis, <a href="#propdef-font-synthesis"
6346 title=font-synthesis><strong>3.8</strong></a>
6348 <li>font-variant
6349 <ul>
6350 <li>descriptor, <a href="#descdef-font-variant" title="font-variant,
6351 descriptor"><strong>4.7</strong></a>
6353 <li>property, <a href="#propdef-font-variant" title="font-variant,
6354 property"><strong>6.11</strong></a>
6355 </ul>
6357 <li>font-variant-alternates, <a href="#propdef-font-variant-alternates"
6358 title=font-variant-alternates><strong>6.8</strong></a>
6360 <li>font-variant-caps, <a href="#propdef-font-variant-caps"
6361 title=font-variant-caps><strong>6.6</strong></a>
6363 <li>font-variant-east-asian, <a href="#propdef-font-variant-east-asian"
6364 title=font-variant-east-asian><strong>6.10</strong></a>
6366 <li>font-variant-ligatures, <a href="#propdef-font-variant-ligatures"
6367 title=font-variant-ligatures><strong>6.4</strong></a>
6369 <li>font-variant-numeric, <a href="#propdef-font-variant-numeric"
6370 title=font-variant-numeric><strong>6.7</strong></a>
6372 <li>font-variant-position, <a href="#propdef-font-variant-position"
6373 title=font-variant-position><strong>6.5</strong></a>
6375 <li>font-weight
6376 <ul>
6377 <li>descriptor, <a href="#descdef-font-weight" title="font-weight,
6378 descriptor"><strong>4.4</strong></a>
6380 <li>property, <a href="#propdef-font-weight" title="font-weight,
6381 property"><strong>3.2</strong></a>
6382 </ul>
6384 <li>font_face_rule, <a href="#fontfacerule"
6385 title="font_face_rule"><strong>4.1</strong></a>
6387 <li>FONT_FACE_SYM, <a href="#fontfacesym"
6388 title="FONT_FACE_SYM"><strong>4.1</strong></a>
6390 <li>font_family_name, <a href="#fontfamilyname"
6391 title="font_family_name"><strong>6.9</strong></a>
6393 <li>font_family_name_list, <a href="#fontfamilynamelist"
6394 title="font_family_name_list"><strong>6.9</strong></a>
6396 <li>font_feature_values_rule, <a href="#fontfeaturevaluesrule"
6397 title="font_feature_values_rule"><strong>6.9</strong></a>
6399 <li>FONT_FEATURE_VALUES_SYM, <a href="#fontfeaturevaluessym"
6400 title="FONT_FEATURE_VALUES_SYM"><strong>6.9</strong></a>
6402 <li>full-width, <a href="#full-width"
6403 title=full-width><strong>6.10</strong></a>
6405 <li>historical-forms, <a href="#historical-forms"
6406 title=historical-forms><strong>6.8</strong></a>
6408 <li>historical-ligatures, <a href="#historical-ligatures"
6409 title=historical-ligatures><strong>6.4</strong></a>
6411 <li>italic, <a href="#italic" title=italic><strong>3.4</strong></a>
6413 <li>jis04, <a href="#jis04" title=jis04><strong>6.10</strong></a>
6415 <li>jis78, <a href="#jis78" title=jis78><strong>6.10</strong></a>
6417 <li>jis83, <a href="#jis83" title=jis83><strong>6.10</strong></a>
6419 <li>jis90, <a href="#jis90" title=jis90><strong>6.10</strong></a>
6421 <li>lighter, <a href="#lighter" title=lighter><strong>3.2</strong></a>
6423 <li>lining-nums, <a href="#lining-nums"
6424 title=lining-nums><strong>6.7</strong></a>
6426 <li>monospace, definition of, <a href="#monospace0" title="monospace,
6427 definition of"><strong>#</strong></a>
6429 <li>no-common-ligatures, <a href="#no-common-ligatures"
6430 title=no-common-ligatures><strong>6.4</strong></a>
6432 <li>no-contextual, <a href="#no-contextual"
6433 title=no-contextual><strong>6.4</strong></a>
6435 <li>no-discretionary-ligatures, <a href="#no-discretionary-ligatures"
6436 title=no-discretionary-ligatures><strong>6.4</strong></a>
6438 <li>no-historical-ligatures, <a href="#no-historical-ligatures"
6439 title=no-historical-ligatures><strong>6.4</strong></a>
6441 <li>none
6442 <ul>
6443 <li>font-kerning, <a href="#font-kerning-none-value" title="none,
6444 font-kerning"><strong>6.3</strong></a>
6446 <li>font-size-adjust, <a href="#font-size-adjust-none-value"
6447 title="none, font-size-adjust"><strong>3.6</strong></a>
6449 <li>font-variant, <a href="#font-variant-none-value" title="none,
6450 font-variant"><strong>6.11</strong></a>
6452 <li>font-variant-ligatures, <a href="#font-variant-ligatures-none-value"
6453 title="none, font-variant-ligatures"><strong>6.4</strong></a>
6454 </ul>
6456 <li>normal, <a href="#normal" title=normal><strong>6.5</strong></a>
6457 <ul>
6458 <li>font-feature-settings, <a href="#font-feature-settings-normal-value"
6459 title="normal, font-feature-settings"><strong>6.12</strong></a>
6461 <li>font-kerning, <a href="#font-kerning-normal-value" title="normal,
6462 font-kerning"><strong>6.3</strong></a>
6464 <li>font-language-override, <a
6465 href="#font-language-override-normal-value" title="normal,
6466 font-language-override"><strong>6.13</strong></a>
6468 <li>font-stretch, <a href="#font-stretch-normal-value" title="normal,
6469 font-stretch"><strong>3.3</strong></a>
6471 <li>font-style, <a href="#font-style-normal-value" title="normal,
6472 font-style"><strong>3.4</strong></a>
6474 <li>font-variant, <a href="#font-variant-normal-value" title="normal,
6475 font-variant"><strong>6.11</strong></a>
6477 <li>font-variant-alternates, <a
6478 href="#font-variant-alternates-normal-value" title="normal,
6479 font-variant-alternates"><strong>6.8</strong></a>
6481 <li>font-variant-caps, <a href="#font-variant-caps-normal-value"
6482 title="normal, font-variant-caps"><strong>6.6</strong></a>
6484 <li>font-variant-east-asian, <a
6485 href="#font-variant-east-asian-normal-value" title="normal,
6486 font-variant-east-asian"><strong>6.10</strong></a>
6488 <li>font-variant-ligatures, <a
6489 href="#font-variant-ligatures-normal-value" title="normal,
6490 font-variant-ligatures"><strong>6.4</strong></a>
6492 <li>font-variant-numeric, <a href="#font-variant-numeric-normal-value"
6493 title="normal, font-variant-numeric"><strong>6.7</strong></a>
6495 <li>font-weight, <a href="#font-weight-normal-value" title="normal,
6496 font-weight"><strong>3.2</strong></a>
6497 </ul>
6499 <li>oblique, <a href="#oblique" title=oblique><strong>3.4</strong></a>
6501 <li>oldstyle-nums, <a href="#oldstyle-nums"
6502 title=oldstyle-nums><strong>6.7</strong></a>
6504 <li>ordinal, <a href="#ordinal" title=ordinal><strong>6.7</strong></a>
6506 <li>ornaments, <a href="#ornaments"
6507 title=ornaments><strong>6.8</strong></a>
6509 <li>petite-caps, <a href="#petite-caps"
6510 title=petite-caps><strong>6.6</strong></a>
6512 <li>proportional-nums, <a href="#proportional-nums"
6513 title=proportional-nums><strong>6.7</strong></a>
6515 <li>proportional-width, <a href="#proportional-width"
6516 title=proportional-width><strong>6.10</strong></a>
6518 <li>renderer, <a href="#renderer" title=renderer><strong>#</strong></a>
6520 <li>ruby, <a href="#ruby" title=ruby><strong>6.10</strong></a>
6522 <li>sans-serif, definition of, <a href="#sans-serif0" title="sans-serif,
6523 definition of"><strong>#</strong></a>
6525 <li>semi-condensed, <a href="#semi-condensed-"
6526 title=semi-condensed><strong>3.3</strong></a>
6528 <li>semi-expanded, <a href="#semi-expanded"
6529 title=semi-expanded><strong>3.3</strong></a>
6531 <li>serif, definition of, <a href="#serif0" title="serif, definition
6532 of"><strong>#</strong></a>
6534 <li>simplified, <a href="#simplified"
6535 title=simplified><strong>6.10</strong></a>
6537 <li>slashed-zero, <a href="#slashed-zero"
6538 title=slashed-zero><strong>6.7</strong></a>
6540 <li>small-caps, <a href="#small-caps"
6541 title=small-caps><strong>6.6</strong></a>
6543 <li>src, <a href="#descdef-src" title=src><strong>4.3</strong></a>
6545 <li>stacked-fractions, <a href="#stacked-fractions"
6546 title=stacked-fractions><strong>6.7</strong></a>
6548 <li>style sheet
6549 <ul>
6550 <li>as conformance class, <a href="#style-sheet" title="style sheet, as
6551 conformance class"><strong>#</strong></a>
6552 </ul>
6554 <li>styleset, <a href="#styleset" title=styleset><strong>6.8</strong></a>
6556 <li>stylistic, <a href="#stylistic"
6557 title=stylistic><strong>6.8</strong></a>
6559 <li>sub, <a href="#sub" title=sub><strong>6.5</strong></a>
6561 <li>super, <a href="#super" title=super><strong>6.5</strong></a>
6563 <li>swash, <a href="#swash" title=swash><strong>6.8</strong></a>
6565 <li>tabular-nums, <a href="#tabular-nums"
6566 title=tabular-nums><strong>6.7</strong></a>
6568 <li>titling-caps, <a href="#titling-caps"
6569 title=titling-caps><strong>6.6</strong></a>
6571 <li>traditional, <a href="#traditional"
6572 title=traditional><strong>6.10</strong></a>
6574 <li>ultra-condensed, <a href="#ultra-condensed"
6575 title=ultra-condensed><strong>3.3</strong></a>
6577 <li>ultra-expanded, <a href="#ultra-expanded"
6578 title=ultra-expanded><strong>3.3</strong></a>
6580 <li>unicase, <a href="#unicase" title=unicase><strong>6.6</strong></a>
6582 <li>unicode-range, <a href="#descdef-unicode-range"
6583 title=unicode-range><strong>4.5</strong></a>
6585 <li>weight, <a href="#weight" title=weight><strong>2</strong></a>
6587 <li>width, <a href="#width" title=width><strong>2</strong></a>
6588 </ul>
6589 <!--end-index-->
6591 <h2 class=no-num id=property-index>Property index</h2>
6592 <!--begin-properties-->
6594 <table class=proptable>
6595 <thead>
6596 <tr>
6597 <th>Property
6599 <th>Values
6601 <th>Initial
6603 <th>Applies to
6605 <th>Inh.
6607 <th>Percentages
6609 <th>Media
6611 <tbody>
6612 <tr>
6613 <th><a class=property href="#propdef-font">font</a>
6615 <td>[ [ <‘font-style’> || <font-variant-css21> ||
6616 <‘font-weight’> || <‘font-stretch’ ]?
6617 <‘font-size’> [ / <‘line-height’> ]?
6618 <‘font-family’> ] | caption | icon | menu | message-box |
6619 small-caption | status-bar
6621 <td>see individual properties
6623 <td>all elements
6625 <td>yes
6627 <td>see individual properties
6629 <td>visual
6631 <tr>
6632 <th><span class=property>font-family</span>
6634 <td>[ <family-name> | <generic-family> ] #
6636 <td>depends on user agent
6638 <td>all elements
6640 <td>yes
6642 <td>N/A
6644 <td>visual
6646 <tr>
6647 <th><span class=property>font-feature-settings</span>
6649 <td>normal | <feature-tag-value> #
6651 <td>normal
6653 <td>all elements
6655 <td>yes
6657 <td>N/A
6659 <td>visual
6661 <tr>
6662 <th><a class=property href="#propdef-font-kerning">font-kerning</a>
6664 <td>auto | normal | none
6666 <td>auto
6668 <td>all elements
6670 <td>yes
6672 <td>N/A
6674 <td>visual
6676 <tr>
6677 <th><a class=property
6678 href="#propdef-font-language-override">font-language-override</a>
6680 <td>normal | <string>
6682 <td>normal
6684 <td>all elements
6686 <td>yes
6688 <td>N/A
6690 <td>visual
6692 <tr>
6693 <th><a class=property href="#propdef-font-size">font-size</a>
6695 <td><absolute-size> | <relative-size> | <length> |
6696 <percentage>
6698 <td>medium
6700 <td>all elements
6702 <td>yes
6704 <td>refer to parent element's font size
6706 <td>visual
6708 <tr>
6709 <th><a class=property
6710 href="#propdef-font-size-adjust">font-size-adjust</a>
6712 <td>none | auto | <number>
6714 <td>none
6716 <td>all elements
6718 <td>yes
6720 <td>N/A
6722 <td>visual
6724 <tr>
6725 <th><span class=property>font-stretch</span>
6727 <td>normal | ultra-condensed | extra-condensed | condensed |
6728 semi-condensed | semi-expanded | expanded | extra-expanded |
6729 ultra-expanded
6731 <td>normal
6733 <td>all elements
6735 <td>yes
6737 <td>N/A
6739 <td>visual
6741 <tr>
6742 <th><span class=property>font-style</span>
6744 <td>normal | italic | oblique
6746 <td>normal
6748 <td>all elements
6750 <td>yes
6752 <td>N/A
6754 <td>visual
6756 <tr>
6757 <th><a class=property href="#propdef-font-synthesis">font-synthesis</a>
6759 <td>none | [ weight || style ]
6761 <td>weight style
6763 <td>all elements
6765 <td>yes
6767 <td>N/A
6769 <td>visual
6771 <tr>
6772 <th><span class=property>font-variant</span>
6774 <td>normal | none | [ <common-lig-values> ||
6775 <discretionary-lig-values> || <historical-lig-values> ||
6776 <contextual-alt-values> || stylistic(<feature-value-name>)
6777 || historical-forms || styleset(<feature-value-name> #) ||
6778 character-variant(<feature-value-name> #) ||
6779 swash(<feature-value-name>) ||
6780 ornaments(<feature-value-name>) ||
6781 annotation(<feature-value-name>) || [ small-caps | all-small-caps
6782 | petite-caps | all-petite-caps | unicase | titling-caps ] ||
6783 <numeric-figure-values> || <numeric-spacing-values> ||
6784 <numeric-fraction-values> || ordinal || slashed-zero ||
6785 <east-asian-variant-values> || <east-asian-width-values> ||
6786 ruby ]
6788 <td>normal
6790 <td>all elements
6792 <td>yes
6794 <td>see individual properties
6796 <td>visual
6798 <tr>
6799 <th><a class=property
6800 href="#propdef-font-variant-alternates">font-variant-alternates</a>
6802 <td>normal | [ stylistic(<feature-value-name>) || historical-forms
6803 || styleset(<feature-value-name> #) ||
6804 character-variant(<feature-value-name> #) ||
6805 swash(<feature-value-name>) ||
6806 ornaments(<feature-value-name>) ||
6807 annotation(<feature-value-name>) ]
6809 <td>normal
6811 <td>all elements
6813 <td>yes
6815 <td>N/A
6817 <td>visual
6819 <tr>
6820 <th><a class=property
6821 href="#propdef-font-variant-caps">font-variant-caps</a>
6823 <td>normal | small-caps | all-small-caps | petite-caps | all-petite-caps
6824 | unicase | titling-caps
6826 <td>normal
6828 <td>all elements
6830 <td>yes
6832 <td>N/A
6834 <td>visual
6836 <tr>
6837 <th><a class=property
6838 href="#propdef-font-variant-east-asian">font-variant-east-asian</a>
6840 <td>normal | [ <east-asian-variant-values> ||
6841 <east-asian-width-values> || ruby ]
6843 <td>normal
6845 <td>all elements
6847 <td>yes
6849 <td>N/A
6851 <td>visual
6853 <tr>
6854 <th><a class=property
6855 href="#propdef-font-variant-ligatures">font-variant-ligatures</a>
6857 <td>normal | none | [ <common-lig-values> ||
6858 <discretionary-lig-values> || <historical-lig-values> ||
6859 <contextual-alt-values> ]
6861 <td>normal
6863 <td>all elements
6865 <td>yes
6867 <td>N/A
6869 <td>visual
6871 <tr>
6872 <th><a class=property
6873 href="#propdef-font-variant-numeric">font-variant-numeric</a>
6875 <td>normal | [ <numeric-figure-values> ||
6876 <numeric-spacing-values> || <numeric-fraction-values> ||
6877 ordinal || slashed-zero ]
6879 <td>normal
6881 <td>all elements
6883 <td>yes
6885 <td>N/A
6887 <td>visual
6889 <tr>
6890 <th><a class=property
6891 href="#propdef-font-variant-position">font-variant-position</a>
6893 <td>normal | sub | super
6895 <td>normal
6897 <td>all elements
6899 <td>yes
6901 <td>N/A
6903 <td>visual
6905 <tr>
6906 <th><span class=property>font-weight</span>
6908 <td>normal | bold | bolder | lighter | 100 | 200 | 300 | 400 | 500 | 600
6909 | 700 | 800 | 900
6911 <td>normal
6913 <td>all elements
6915 <td>yes
6917 <td>N/A
6919 <td>visual
6920 </table>
6921 <!--end-properties-->
6922 <!--begin-descriptors-->
6924 <table class=proptable>
6925 <thead>
6926 <tr>
6927 <th>Descriptor
6929 <th>Value
6931 <th>Initial
6933 <th>Percentages
6935 <th>Media
6937 <tbody>
6938 <tr>
6939 <th><span class=property>font-family</span>
6941 <td><family-name>
6943 <td>N/A
6945 <tr>
6946 <th><span class=property>font-feature-settings</span>
6948 <td>normal | <feature-tag-value> #
6950 <td>normal
6952 <tr>
6953 <th><span class=property>font-stretch</span>
6955 <td>normal | ultra-condensed | extra-condensed | condensed |
6956 semi-condensed | semi-expanded | expanded | extra-expanded |
6957 ultra-expanded
6959 <td>normal
6961 <tr>
6962 <th><span class=property>font-style</span>
6964 <td>normal | italic | oblique
6966 <td>normal
6968 <tr>
6969 <th><span class=property>font-variant</span>
6971 <td>normal | none | [ <common-lig-values> ||
6972 <discretionary-lig-values> || <historical-lig-values> ||
6973 <contextual-alt-values> || stylistic(<feature-value-name>)
6974 || historical-forms || styleset(<feature-value-name> #) ||
6975 character-variant(<feature-value-name> #) ||
6976 swash(<feature-value-name>) ||
6977 ornaments(<feature-value-name>) ||
6978 annotation(<feature-value-name>) || [ small-caps | all-small-caps
6979 | petite-caps | all-petite-caps | unicase | titling-caps ] ||
6980 <numeric-figure-values> || <numeric-spacing-values> ||
6981 <numeric-fraction-values> || ordinal || slashed-zero ||
6982 <east-asian-variant-values> || <east-asian-width-values> ||
6983 ruby ]
6985 <td>normal
6987 <tr>
6988 <th><span class=property>font-weight</span>
6990 <td>normal | bold | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900
6992 <td>normal
6994 <tr>
6995 <th><a class=property href="#descdef-src">src</a>
6997 <td>[ <url> [format(<string> #)]? | <font-face-name> ] #
6999 <td>N/A
7001 <tr>
7002 <th><a class=property href="#descdef-unicode-range">unicode-range</a>
7004 <td><urange> #
7006 <td>U+0-10FFFF
7007 </table>
7008 <!--end-descriptors-->
7009 <script type="text/javascript">
7010 window.onload = function () {
7011 if (!("devicePixelRatio" in window && window.devicePixelRatio > 1)) return;
7012 var i, hiresElements = document.getElementsByClassName("hires");
7013 for (i = 0; i < hiresElements.length; i++) {
7014 var h = hiresElements[i];
7015 if (h.tagName != "IMG") continue;
7016 var src = h.getAttribute("src");
7017 var src2x = src.replace(/\.\w+$/, function(m) { return "@2x" + m; });
7018 h.src = src2x;
7019 }
7020 }
7021 </script>
7022 </html>
7023 <!-- Keep this comment at the end of the file
7024 Local variables:
7025 mode: sgml
7026 sgml-declaration:"~/SGML/HTML4.decl"
7027 sgml-default-doctype-name:"html"
7028 sgml-minimize-attributes:t
7029 sgml-nofill-elements:("pre" "style" "br")
7030 sgml-live-element-indicator:t
7031 sgml-omittag:nil
7032 sgml-shorttag:nil
7033 sgml-namecase-general:t
7034 sgml-general-insert-case:lower
7035 sgml-always-quote-attributes:t
7036 sgml-indent-step:nil
7037 sgml-indent-data:t
7038 sgml-parent-document:nil
7039 sgml-exposed-tags:nil
7040 sgml-local-catalogs:nil
7041 sgml-local-ecat-files:nil
7042 End:
7043 -->
7044 <!--
7046 to do:
7048 - wording of OpenType family name handling
7049 - handling combining sequences in the font matching algorithm
7050 - fix-up fi ligature example
7052 -->