forked from w3c/csswg-drafts
-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathOverview.html
More file actions
1368 lines (1051 loc) · 55 KB
/
Overview.html
File metadata and controls
1368 lines (1051 loc) · 55 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
<!DOCTYPE html>
<html lang=en>
<head>
<meta content="text/html; charset=utf-8" http-equiv=Content-Type>
<title>CSS Intrinsic & Extrinsic Sizing Module Level 3</title>
<!--
<link href="http://purl.org/dc/terms/" rel="schema.dcterms">
<link href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright" rel="dcterms.rights">
-->
<meta content="CSS Intrinsic & Extrinsic Sizing Module Level 3"
name=dcterms.title>
<meta content=text name=dcterms.type>
<meta content=2013-02-20 name=dcterms.issued>
<meta content="http://dev.w3.org/csswg/css3-sizing/" name=dcterms.creator>
<meta content=W3C name=dcterms.publisher>
<meta content="http://dev.w3.org/csswg/css3-sizing/"
name=dcterms.identifier>
<link href="#contents" rel=contents>
<link href="#index" rel=index>
<link href="../default.css" rel=stylesheet type="text/css">
<link href="../csslogo.ico" rel="shortcut icon" type="image/x-icon">
<link href="http://www.w3.org/StyleSheets/TR/W3C-ED.css" rel=stylesheet
type="text/css">
<body>
<div class=head> <!--begin-logo-->
<p><a href="http://www.w3.org/"><img alt=W3C height=48
src="http://www.w3.org/Icons/w3c_home" width=72></a> <!--end-logo-->
<h1>CSS Intrinsic & Extrinsic Sizing Module Level 3</h1>
<h2 class="no-num no-toc" id=longstatus-date>Editor's Draft 20 February
2013</h2>
<dl><!--
<dt>This version:
<dd><a href="http://dev.w3.org/csswg/css3-sizing/">http://www.w3.org/TR/2013/ED-css3-sizing-20130220/</a>
-->
<dt>Latest version:
<dd><a
href="http://www.w3.org/TR/css3-sizing/">http://www.w3.org/TR/css3-sizing/</a>
<dt>Editor's draft:
<dd><a
href="http://dev.w3.org/csswg/css3-sizing/">http://dev.w3.org/csswg/css3-sizing/</a>
<dt>Previous Versions:
<dd><a
href="http://www.w3.org/TR/2012/WD-css3-sizing-20120927/">http://www.w3.org/TR/2012/WD-css3-sizing-20120927/</a>
<dt>Issue Tracking:
<dd><a
href="https://www.w3.org/Bugs/Public/buglist.cgi?product=CSS&component=Sizing&resolution=---">W3C
Bugzilla</a>
<dt>Feedback:
<dd><a href="mailto:www-style@w3.org?subject=%5Bcss-sizing%5D%20feedback">www-style@w3.org</a>
with subject line “<kbd>[css-sizing] <var>… message topic …</var></kbd>”
(<a rel="discussion" href="http://lists.w3.org/Archives/Public/www-style/">archives</a>)
<dt>Editors:
<dd class=hcard><a class="fn url"
href="http://www.xanthir.com/contact">Tab Atkins Jr.</a>, <span
class=org>Google Inc.</span>
<dd class=hcard><a class="fn url"
href="http://fantasai.inkedblade.net/contact">Elika J. Etemad</a>, <span
class=org>Mozilla</span>
</dl>
<!--begin-copyright-->
<p class=copyright><a
href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright"
rel=license>Copyright</a> © 2013 <a href="http://www.w3.org/"><abbr
title="World Wide Web Consortium">W3C</abbr></a><sup>®</sup> (<a
href="http://www.csail.mit.edu/"><abbr
title="Massachusetts Institute of Technology">MIT</abbr></a>, <a
href="http://www.ercim.eu/"><abbr
title="European Research Consortium for Informatics and Mathematics">ERCIM</abbr></a>,
<a href="http://www.keio.ac.jp/">Keio</a>, <a
href="http://ev.buaa.edu.cn/">Beihang</a>), All Rights Reserved. W3C <a
href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>,
<a
href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a>
and <a
href="http://www.w3.org/Consortium/Legal/copyright-documents">document
use</a> rules apply.</p>
<!--end-copyright-->
<hr title="Separator for header">
</div>
<h2 class="no-num no-toc" id=abstract>Abstract</h2>
<p>This module extends the CSS sizing properties with keywords that
represent content-based "intrinsic" sizes and context-based "extrinsic"
sizes, allowing CSS to more easily describe boxes that fit their content
or fit into a particular layout context. <a
href="http://www.w3.org/TR/CSS/">CSS</a> is a language for describing the
rendering of structured documents (such as HTML and XML) on screen, on
paper, in speech, etc.
<h2 class="no-num no-toc" id=status>Status of this document</h2>
<!--begin-status-->
<p>This is a public copy of the editors' draft. It is provided for
discussion only and may change at any moment. Its publication here does
not imply endorsement of its contents by W3C. Don't cite this document
other than as work in progress.
<p>The (<a
href="http://lists.w3.org/Archives/Public/www-style/">archived</a>) public
mailing list <a
href="mailto:www-style@w3.org?Subject=%5Bcss3-sizing%5D%20PUT%20SUBJECT%20HERE">
www-style@w3.org</a> (see <a
href="http://www.w3.org/Mail/Request">instructions</a>) is preferred for
discussion of this specification. When sending e-mail, please put the text
“css3-sizing” in the subject, preferably like this:
“[<!---->css3-sizing<!---->] <em>…summary of comment…</em>”
<p>This document was produced by the <a href="/Style/CSS/members">CSS
Working Group</a> (part of the <a href="/Style/">Style Activity</a>).
<p>This document was produced by a group operating under the <a
href="/Consortium/Patent-Policy-20040205/">5 February 2004 W3C Patent
Policy</a>. W3C maintains a <a href="/2004/01/pp-impl/32061/status"
rel=disclosure>public list of any patent disclosures</a> made in
connection with the deliverables of the group; that page also includes
instructions for disclosing a patent. An individual who has actual
knowledge of a patent which the individual believes contains <a
href="/Consortium/Patent-Policy-20040205/#def-essential">Essential
Claim(s)</a> must disclose the information in accordance with <a
href="/Consortium/Patent-Policy-20040205/#sec-Disclosure">section 6 of the
W3C Patent Policy</a>.</p>
<!--end-status-->
<p>The following features are at risk: …
<h2 class="no-num no-toc" id=contents> Table of contents</h2>
<!--begin-toc-->
<ul class=toc>
<li><a href="#intro"><span class=secno>1. </span> Introduction</a>
<ul class=toc>
<li><a href="#placement"><span class=secno>1.1. </span> Module
interactions</a>
<li><a href="#values"><span class=secno>1.2. </span> Values</a>
</ul>
<li><a href="#terms"><span class=secno>2. </span> Terminology</a>
<li><a href="#size-keywords"><span class=secno>3. </span> New Sizing
Keywords</a>
<ul class=toc>
<li><a href="#width-height-keywords"><span class=secno>3.1. </span> New
Keywords for ‘<code class=property>width</code>’ and ‘<code
class=property>height</code>’</a>
<li><a href="#the-contain-floats-value"><span class=secno>3.2. </span>
Containing Floats</a>
<li><a href="#column-sizing"><span class=secno>3.3. </span> Column
Sizing Keywords</a>
</ul>
<li><a href="#intrinsic-sizing"><span class=secno>4. </span> Intrinsic
Size Determination</a>
<ul class=toc>
<li><a href="#replaced-intrinsic"><span class=secno>4.1. </span>
Intrinsic Sizes of Replaced Elements</a>
<li><a href="#inline-intrinsic"><span class=secno>4.2. </span> Intrinsic
Sizes of Non-Replaced Inlines</a>
<li><a href="#block-intrinsic"><span class=secno>4.3. </span> Intrinsic
Sizes of Non-Replaced Blocks</a>
<li><a href="#table-intrinsic"><span class=secno>4.4. </span> Intrinsic
Sizes in Table Layout</a>
<li><a href="#multicol-intrinsic"><span class=secno>4.5. </span>
Intrinsic Sizes in Multi-column Layout</a>
</ul>
<li><a href="#extrinsic-sizing"><span class=secno>5. </span> Extrinsic
Size Determination</a>
<li><a href="#conformance"><span class=secno>6. </span> Conformance</a>
<ul class=toc>
<li><a href="#conventions"><span class=secno>6.1. </span> Document
conventions</a>
<li><a href="#conformance-classes"><span class=secno>6.2. </span>
Conformance classes</a>
<li><a href="#partial"><span class=secno>6.3. </span> Partial
implementations</a>
<li><a href="#experimental"><span class=secno>6.4. </span> Experimental
implementations</a>
<li><a href="#testing"><span class=secno>6.5. </span> Non-experimental
implementations</a>
<li><a href="#cr-exit-criteria"><span class=secno>6.6. </span> CR exit
criteria</a>
</ul>
<li class=no-num><a href="#acknowledgments"> Acknowledgments</a>
<li class=no-num><a href="#references"> References</a>
<ul class=toc>
<li class=no-num><a href="#normative-references"> Normative
references</a>
<li class=no-num><a href="#other-references"> Other references</a>
</ul>
<li class=no-num><a href="#index"> Index</a>
<li class=no-num><a href="#property-index"> Property index</a>
</ul>
<!--end-toc-->
<h2 id=intro><span class=secno>1. </span> Introduction</h2>
<p><em>This section is not normative.</em>
<p> CSS layout has several different concepts of automatic sizing that are
used in various layout calculations. This section defines some more
precise terminology to help connect the layout behaviors of this spec to
the calculations used in other modules, and some new keywords for the
‘<code class=property>width</code>’ and ‘<code
class=property>height</code>’ properties to allow authors to assign
elements the dimensions resulting from these size calculations.
<h3 id=placement><span class=secno>1.1. </span> Module interactions</h3>
<p>This module extends the ‘<code class=property>width</code>’,
‘<code class=property>height</code>’, ‘<code
class=property>min-width</code>’, ‘<code
class=property>min-height</code>’, ‘<code
class=property>max-width</code>’, ‘<code
class=property>max-height</code>’, and ‘<code
class=property>column-width</code>’ features defined in <a href="#CSS21"
rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a> chapter 10 and in <a
href="#CSS3COL" rel=biblioentry>[CSS3COL]<!--{{!CSS3COL}}--></a>
<h3 id=values><span class=secno>1.2. </span> Values</h3>
<p>This specification follows the <a
href="http://www.w3.org/TR/CSS21/about.html#property-defs">CSS property
definition conventions</a> from <a href="#CSS21"
rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a>. Value types not defined in
this specification are defined in CSS Level 2 Revision 1 <a
href="#CSS21" rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a>. Other CSS
modules may expand the definitions of these value types: for example <a
href="#CSS3COLOR" rel=biblioentry>[CSS3COLOR]<!--{{CSS3COLOR}}--></a>,
when combined with this module, expands the definition of the
<color> value type as used in this specification.
<p>In addition to the property-specific values listed in their definitions,
all properties defined in this specification also accept the <a
href="http://www.w3.org/TR/CSS21/cascade.html#value-def-inherit">inherit</a>
keyword as their property value. For readability it has not been repeated
explicitly.
<h2 id=terms><span class=secno>2. </span> Terminology</h2>
<dl>
<dt><dfn id=size>size</dfn>
<dd> A one- or two-dimensional measurement: a <a
href="http://www.w3.org/TR/css3-writing-modes/#measure"><i>measure</i></a>
and/or <a
href="http://www.w3.org/TR/css3-writing-modes/#extent"><i>extent</i></a>;
alternatively a width and/or height.
<dt><dfn id=definite title="definite|definite size">definite size</dfn>
<dd> A size that can be determined without measuring content; that is, a
<var><length></var>, a size of the <i>initial containing block</i>, or
a <var><percentage></var> that is resolved against a <a
href="#definite"><i>definite</i></a> size. Additionally, the size of the
<i>containing block</i> of an absolutely positioned element is always <a
href="#definite"><i>definite</i></a> with respect to that element.
<dt><dfn id=indefinite title="indefinite|indefinite size">indefinite
size</dfn>
<dd> A size that is not <a href="#definite"><i>definite</i></a>. An <a
href="#indefinite"><i>indefinite</i></a> <a
href="#available"><i>available size</i></a> is essentially infinite.
<dt><dfn id=available
title="available|available size|available measure|available extent|available space">available
size</dfn>
<dd> The space into which a box is laid out, typically either a
measurement of its <i>containing block</i> or an infinite size. An <a
href="#available"><i>available size</i></a> can alternatively be either a
<dfn id=min-content-constraint>min-content constraint</dfn> or a <dfn
id=max-content-constraint>max-content constraint</dfn>. <!--
<p>
The space <i>available</i> to a box is determined by the formatting context in which it participates.
In block, table, and inline formatting contexts [[!CSS21]],
the <i>available size</i> is infinite in the block-axis dimension.
<span class="issue">What, exactly, is the available size in the inline axis??? What about other formatting models?</span>
-->
<dt><dfn id=fill-available-fit>fill-available fit</dfn>
<dd> The <a href="#fill-available-fit"><i>fill-available fit</i></a> into
a given size is that size, minus the element's computed margins (not
collapsed, treating ‘<code class=css>auto</code>’ as zero), border,
and padding in the given dimension.
<p class=note> Note: This is the formula used to calculate widths of
non-replaced blocks in normal flow in <a
href="http://www.w3.org/TR/CSS21/visudet.html#blockwidth">CSS2.1§10.3.3</a>.
<dt><dfn id=fallback-size title="fallback|fallback size">fallback
size</dfn>
<dd> Some sizing algorithms do not work well with an infinite size. In
these cases, the <a href="#fallback-size"><i>fallback size</i></a> is
used instead. Unless otherwise specified, this is the size of the
<i>initial containing block</i>.
<dt><dfn id=fill-available-measure>fill-available measure</dfn>
<dd> Roughly, the <i>measure<i> a box would take if it filled its <a
href="#available"><i>available measure</i></a>. (See <a
href="http://dev.w3.org/csswg/css3-sizing/#extrinsic-sizing">Extrinsic
Size Determination</a>.) </i></i>
<p class=note> Note: This is called the <i>available width</i> in <a
href="http://www.w3.org/TR/CSS21/visudet.html#float-width">CSS2.1§10.3.5</a>
and computed by the rules in <a
href="http://www.w3.org/TR/CSS21/visudet.html#blockwidth">CSS2.1§10.3.3</a>.
<dt><dfn id=max-content-measure>max-content measure</dfn>
<dd> Roughly, the narrowest <i>measure</i> a box could take while fitting
around its contents if <em>none</em> of the soft wrap opportunities
within the box were taken. (See <a
href="http://dev.w3.org/csswg/css3-sizing/#intrinsic-sizing">Intrinsic
Size Determination</a>.)
<p class=note> Note: This is called the <i>preferred width</i> in <a
href="http://www.w3.org/TR/CSS21/visudet.html#float-width">CSS2.1§10.3.5</a>
and the <i>maximum cell width</i> in <a
href="http://www.w3.org/TR/CSS21/tables.html#auto-table-layout">CSS2.1§17.5.2.2</a>.
<dt><dfn id=min-content-measure>min-content measure</dfn>
<dd> The narrowest <i>measure</i> a box could take that doesn't lead to
inline-dimension overflow that could be avoided by choosing a larger
<i>measure</i>. Roughly, the <i>measure</i> that would fit around its
contents if <em>all</em> soft wrap opportunities within the box were
taken. (See <a
href="http://dev.w3.org/csswg/css3-sizing/#intrinsic-sizing">Intrinsic
Size Determination</a>.)
<p class=note> Note: This is called the <i>preferred minimum width</i> in
<a
href="http://www.w3.org/TR/CSS21/visudet.html#float-width">CSS2.1§10.3.5</a>
and the <i>minimum content width</i> in <a
href="http://www.w3.org/TR/CSS21/tables.html#auto-table-layout">CSS2.1§17.5.2.2</a>.
<dt><dfn id=fit-content-measure>fit-content measure</dfn>
<dd> If the <a href="#available"><i>available</i></a> measure is finite,
equal to <code>min(<a href="#max-content"><i>max-content</i></a>, max(<a
href="#min-content"><i>min-content</i></a>, <a
href="#fill-available"><i>fill-available</i></a>))</code>. Otherwise,
equal to the <a href="#max-content-measure"><i>max-content
measure</i></a>.
<p class=note> Note: This is called the <i>shrink-to-fit</i> width in <a
href="http://www.w3.org/TR/CSS21/visudet.html#float-width">CSS2.1§10.3.5</a>
and <a href="http://www.w3.org/TR/css3-multicol/#pseudo-algorithm">CSS
Multi-column Layout § 3.4</a>.
<dt><dfn id=fill-available-extent>fill-available extent</dfn>
<dd> Roughly, the <i>extent</i> a box would take if it filled its <a
href="#available"><i>available extent</i></a>. (See <a
href="http://dev.w3.org/csswg/css3-sizing/#intrinsic-sizing">Intrinsic
Size Determination</a>.)
<dt><dfn id=max-content-extent>max-content extent</dfn>
<dd> Roughly, the <i>extent</i> of the content after layout.
<dt><dfn id=min-content-extent>min-content extent</dfn>
<dd> Equivalent to the <a href="#max-content-extent"><i>max-content
extent</i></a>. <span class=issue>Or should this be the minimum between
allowed break points? It might make sense in multi-col contexts to have
min-content and max-content extents be different, even if they are the
same elsewhere.</span>
<dt><dfn id=fit-content-extent>fit-content extent</dfn>
<dd> Analogous to the <a href="#fit-content-measure"><i>fit-content
measure</i></a>.
<dt><dfn id=max-size-contribution>max-size contribution</dfn>
<dd> The size that a box contributes to its <i>containing
block</i>‘<code class=css>s <i>max-content size</i>. </code>
<dt><dfn id=min-size-contribution>min-size contribution</dfn>
<dd> The size that a box contributes to its <i>containing block</i>’s
<i>min-content size</i>.
<dt><dfn id=max-size-constraint>max-size constraint</dfn>
<dd> A sizing constraint imposed by the box's <i>containing block</i> that
causes it to produce its <a href="#max-size-contribution"><i>max-size
contribution</i></a>.
<dt><dfn id=min-size-constraint>min-size constraint</dfn>
<dd> A sizing constraint imposed by the box's <i>containing block</i> that
causes it to produce its <a href="#min-size-contribution"><i>min-size
contribution</i></a>.
</dl>
<h2 id=size-keywords><span class=secno>3. </span> New Sizing Keywords</h2>
<h3 id=width-height-keywords><span class=secno>3.1. </span> New Keywords
for ‘<code class=property>width</code>’ and ‘<code
class=property>height</code>’</h3>
<table class=propdef>
<tbody>
<tr>
<th>Properties:
<td>‘<code class=property>width</code>’, ‘<code
class=property>min-width</code>’, ‘<code
class=property>max-width</code>’, ‘<code
class=property>height</code>’, ‘<code
class=property>min-height</code>’, ‘<code
class=property>max-height</code>’
<tr>
<th>New Values:
<td>‘<a href="#fill-available"><code
class=css>fill-available</code></a>’ | ‘<a
href="#max-content"><code class=css>max-content</code></a>’ | ‘<a
href="#min-content"><code class=css>min-content</code></a>’ | ‘<a
href="#fit-content"><code class=css>fit-content</code></a>’
<tr>
<th>Initial:
<td>as defined in <a href="#CSS21"
rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a> and <a
href="#CSS3-FLEXBOX"
rel=biblioentry>[CSS3-FLEXBOX]<!--{{!CSS3-FLEXBOX}}--></a>
<tr>
<th>Applies to:
<td>as defined in <a href="#CSS21"
rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a>
<tr>
<th>Inherited:
<td>as defined in <a href="#CSS21"
rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a>
<tr>
<th>Percentages:
<td>as defined in <a href="#CSS21"
rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a>
<tr>
<th>Media:
<td>as defined in <a href="#CSS21"
rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a>
<tr>
<th>Computed value:
<td>specified value if keyword specified, else as defined in <a
href="#CSS21" rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a>
</table>
<p>There are four types of automatically-determined sizes in CSS (which are
represented in the width and height properties by the keywords defined
above):
<dl>
<dt><dfn id=fill-available>‘<code
class=css>fill-available</code>’</dfn>
<dd> Use the <a href="#fill-available-measure"><i>fill-available
measure</i></a> or <a href="#fill-available-extent"><i>fill-available
extent</i></a>, as appropriate to the writing mode.
<dt><dfn id=max-content>‘<code class=css>max-content</code>’</dfn>
<dd> Use the <a href="#max-content-measure"><i>max-content measure</i></a>
or <a href="#max-content-extent"><i>max-content extent</i></a>, as
appropriate to the writing mode.
<dt><dfn id=min-content>‘<code class=css>min-content</code>’</dfn>
<dd> Use the <a href="#min-content-measure"><i>min-content measure</i></a>
or <a href="#min-content-extent"><i>min-content extent</i></a>, as
appropriate to the writing mode.
<dt><dfn id=fit-content>‘<code class=css>fit-content</code>’</dfn>
<dd> Use the <a href="#fit-content-measure"><i>fit-content measure</i></a>
or <a href="#fit-content-extent"><i>fit-content extent</i></a>, as
appropriate to the writing mode.
<dt><dfn id=repudiate-floats>‘<code
class=css>repudiate-floats</code>’</dfn> <span class=issue>Less stupid
name?</span>
<dd> In the inline axis, use the larger of the min-content measure, and
the fill-available measure minus the size of any non-descendant floats in
the same formatting context. (This is similar to the behavior of a box
that establishes a formatting context next to a float.) In the block
axis, this is identical to ‘<code class=css>auto</code>’.
<p class=issue> Does this value work? Is it needed?
</dl>
<p class=issue> Right now all of these except ‘<a
href="#fill-available"><code class=css>fill-available</code></a>’ mean
the same thing for extents. This may or may not be ideal.
<p class=issue> If the measure is ‘<code class=css>auto</code>’, we
could have min-content extent imply a max-content measure, and vice versa.
<p class=note> Note that percentages resolved against the intrinsic sizes
(‘<a href="#max-content"><code class=css>max-content</code></a>’,
‘<a href="#min-content"><code class=css>min-content</code></a>’, ‘<a
href="#fit-content"><code class=css>fit-content</code></a>’, ‘<a
href="#repudiate-floats"><code class=css>repudiate-floats</code></a>’)
will compute to ‘<code class=css>auto</code>’, <a
href="http://www.w3.org/TR/CSS21/visudet.html#the-height-property">as
defined by CSS 2.1</a>. <a href="#CSS21"
rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a>
<h3 id=the-contain-floats-value><span class=secno>3.2. </span> Containing
Floats</h3>
<table class=propdef>
<tbody>
<tr>
<th>Properties:
<td>‘<code class=property>min-width</code>’, ‘<code
class=property>min-height</code>’
<tr>
<th>New Value:
<td>‘<a href="#contain-floats"><code
class=css>contain-floats</code></a>’
<tr>
<th>Initial:
<td>as defined in <a href="#CSS21"
rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a> and <a
href="#CSS3-FLEXBOX"
rel=biblioentry>[CSS3-FLEXBOX]<!--{{!CSS3-FLEXBOX}}--></a>
<tr>
<th>Applies to:
<td>as defined in <a href="#CSS21"
rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a>
<tr>
<th>Inherited:
<td>as defined in <a href="#CSS21"
rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a>
<tr>
<th>Percentages:
<td>as defined in <a href="#CSS21"
rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a>
<tr>
<th>Media:
<td>as defined in <a href="#CSS21"
rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a>
<tr>
<th>Computed value:
<td>specified value if keyword specified, else as defined in <a
href="#CSS21" rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a>
</table>
<dl>
<dt><dfn id=contain-floats>‘<code
class=css>contain-floats</code>’</dfn>
<dd> Equivalent to ‘<a href="#min-content"><code
class=css>min-content</code></a>’ except that when applied to the
extent of a block box it forces the inner extent to be large enough to
contain the margin boxes of any floats that originate inside the block
and that participate in the same block formatting context as the block's
immediate contents.
</dl>
<h3 id=column-sizing><span class=secno>3.3. </span> Column Sizing Keywords</h3>
<table class=propdef>
<tbody>
<tr>
<th>Property:
<td>‘<code class=property>column-width</code>’
<tr>
<th>New Values:
<td>‘<a href="#min-content"><code class=css>min-content</code></a>’
| ‘<a href="#max-content"><code class=css>max-content</code></a>’ |
‘<a href="#fill-available"><code
class=css>fill-available</code></a>’ | ‘<a
href="#fit-content"><code class=css>fit-content</code></a>’
<tr>
<th>Initial:
<td>as defined in <a href="#CSS3COL"
rel=biblioentry>[CSS3COL]<!--{{!CSS3COL}}--></a>
<tr>
<th>Applies to:
<td>as defined in <a href="#CSS3COL"
rel=biblioentry>[CSS3COL]<!--{{!CSS3COL}}--></a>
<tr>
<th>Inherited:
<td>as defined in <a href="#CSS3COL"
rel=biblioentry>[CSS3COL]<!--{{!CSS3COL}}--></a>
<tr>
<th>Percentages:
<td>as defined in <a href="#CSS3COL"
rel=biblioentry>[CSS3COL]<!--{{!CSS3COL}}--></a>
<tr>
<th>Media:
<td>as defined in <a href="#CSS3COL"
rel=biblioentry>[CSS3COL]<!--{{!CSS3COL}}--></a>
<tr>
<th>Computed value:
<td>specified value if keyword specified, else as defined in <a
href="#CSS3COL" rel=biblioentry>[CSS3COL]<!--{{!CSS3COL}}--></a>
</table>
<p>When used as values for <a
href="http://www.w3.org/TR/css3-multicol/#cw">‘<code
class=property>column-width</code>’</a>, the new keywords specify the
optimal column width:
<dl>
<dt>‘<a href="#min-content"><code class=css>min-content</code></a>’
<dd>Specifies the optimal column width as the <a
href="#min-content-measure"><i>min-content measure</i></a> of the
multi-column element's contents.
<dt>‘<a href="#max-content"><code class=css>max-content</code></a>’
<dd>Specifies the optimal column width as the <a
href="#max-content-measure"><i>max-content measure</i></a> of the
multi-column element's contents.
<dt>‘<a href="#fill-available"><code
class=css>fill-available</code></a>’
<dd>Specifies the optimal column width as the <a
href="#fill-available-measure"><i>fill-available measure</i></a> of the
multi-column element.
<dt>‘<a href="#fit-content"><code class=css>fit-content</code></a>’
<dd>Specifies the optimal column width as <code>min(<a
href="#max-content"><i>max-content</i></a>, max(<a
href="#min-content"><i>min-content</i></a>, <a
href="#fill-available"><i>fill-available</i></a>))</code>.
</dl>
<h2 id=intrinsic-sizing><span class=secno>4. </span> Intrinsic Size
Determination</h2>
<p> <dfn id=intrinsic-sizing0>Intrinsic sizing</dfn> determines sizes based
on the contents of an element, without regard for its context.
<h3 id=replaced-intrinsic><span class=secno>4.1. </span> Intrinsic Sizes of
Replaced Elements</h3>
<p> For replaced elements, the <a
href="#min-content"><i>min-content</i></a> and <a
href="#max-content"><i>max-content</i></a> sizes are equivalent and
correspond to the appropriate dimension of the concrete object size
returned by the <a
href="http://www.w3.org/TR/css3-images/#default-sizing">default sizing
algorithm</a> <a href="#CSS3-IMAGES"
rel=biblioentry>[CSS3-IMAGES]<!--{{!CSS3-IMAGES}}--></a> of the element,
calculated with an unconstrained specified size.
<h3 id=inline-intrinsic><span class=secno>4.2. </span> Intrinsic Sizes of
Non-Replaced Inlines</h3>
<p> The <a href="#min-content-measure"><i>min-content measure</i></a> of an
inline box is the length of the largest unbreakable sequence of inline
content. The <i>min-measure contribution</i> of an inline box is its <a
href="#min-content-measure"><i>min-content measure</i></a>, plus any
inline-axis margin, border, and padding adjacent to that sequence.
<p> The <a href="#max-content-measure"><i>max-content measure</i></a> of an
inline box is the length of the largest sequence of inline content on a
single line when only forced line breaks are taken. The <i>max-measure
contribution</i> of an inline box is its <a
href="#max-content-measure"><i>max-content measure</i></a>, plus any
inline-axis margin, border, and padding adjacent to that sequence.
<p> The <a href="#min-content-extent"><i>min-content extent</i></a>, <a
href="#max-content-extent"><i>max-content extent</i></a>, <i>min-extent
contribution</i>, and <i>max-content contribution</i> of an inline box are
the distance from the head edge of the first line box to the foot edge of
the last line box on which the inline appears.
<h3 id=block-intrinsic><span class=secno>4.3. </span> Intrinsic Sizes of
Non-Replaced Blocks</h3>
<p> The <a href="#min-content-measure"><i>min-content measure</i></a> of a
<i>block container box</i> is the largest <i>min-measure contribution</i>
of its in-flow or floated children.
<p> The <a href="#max-content-measure"><i>max-content measure</i></a> of a
<i>block container box</i> is the measure of the box after layout, if all
children are sized under a <a href="#max-size-constraint"><i>max-size
constraint</i></a>.
<p> If the computed measure of a <i>block-level box</i> is ‘<a
href="#min-content"><code class=css>min-content</code></a>’, ‘<a
href="#max-content"><code class=css>max-content</code></a>’, or a <a
href="#definite"><i>definite size</i></a>, its <i>min-measure
contribution</i> is that size plus any inline-axis margin, border, and
padding. Otherwise, if the computed measure of the block is ‘<a
href="#fit-content"><code class=css>fit-content</code></a>’, ‘<code
class=css>auto</code>’, or ‘<a href="#fill-available"><code
class=css>fill-available</code></a>’, its <i>min-measure
contribution</i> is its <a href="#min-content-measure"><i>min-content
measure</i></a> plus any inline-axis margin, border, and padding.
<p> If the computed measure of a <i>block-level box</i> is ‘<a
href="#min-content"><code class=css>min-content</code></a>’, ‘<a
href="#max-content"><code class=css>max-content</code></a>’, or a <a
href="#definite"><i>definite size</i></a>, its <i>max-measure
contribution</i> is that size plus any inline-axis margin, border, and
padding. Otherwise, if the computed measure of the block is ‘<a
href="#fit-content"><code class=css>fit-content</code></a>’, ‘<code
class=css>auto</code>’, or ‘<a href="#fill-available"><code
class=css>fill-available</code></a>’, its <i>max-measure
contribution</i> is its <a href="#max-content-measure"><i>max-content
measure</i></a> plus any inline-axis margin, border, and padding.
<p> The <a href="#min-content-extent"><i>min-content extent</i></a> and <a
href="#max-content-extent"><i>max-content extent</i></a> of a <i>block
container box</i> is the content extent as defined (for horizontal writing
modes) in <a
href="http://www.w3.org/TR/CSS21/visudet.html#normal-block">CSS2.1§10.6.3</a>
and <a
href="http://www.w3.org/TR/CSS21/tables.html#height-layout">CSS2.1§17.5.3</a>
for elements with ‘<code class=css>height: auto</code>’, and
analogously for vertical writing modes.
<p> The <i>min-extent contribution</i> and <i>max-extent contribution</i>
of a <i>block-level box</i> is the extent of the block after layout, plus
any block-axis margin, border, and padding.
<h3 id=table-intrinsic><span class=secno>4.4. </span> Intrinsic Sizes in
Table Layout</h3>
<p class=issue> ???
<h3 id=multicol-intrinsic><span class=secno>4.5. </span> Intrinsic Sizes in
Multi-column Layout</h3>
<p> The <a href="#min-content-measure"><i>min-content measure</i></a> of a
multi-column element with a computed ‘<code
class=property>column-width</code>’ not ‘<code
class=css>auto</code>’ is the smaller of its ‘<code
class=property>column-width</code>’ and the largest <i>min-measure
contribution</i> of its contents.
<p> The <a href="#min-content-measure"><i>min-content measure</i></a> of a
multi-column element with a computed ‘<code
class=property>column-width</code>’ of ‘<code class=css>auto</code>’
is the largest <i>min-measure contribution</i> of its contents multiplied
by its ‘<code class=property>column-count</code>’ (treating ‘<code
class=css>auto</code>’ as ‘<code class=css>1</code>’).
<p> The <a href="#max-content-measure"><i>max-content measure</i></a> of a
multi-column element with unrestrained column heights and a computed
‘<code class=property>column-count</code>’ not ‘<code
class=css>auto</code>’ is its ‘<code
class=property>column-count</code>’ multiplied by the larger of its
‘<code class=property>column-width</code>’ (treating ‘<code
class=css>auto</code>’ as 0) and the largest <i>max-measure
contribution</i> of its contents.
<p> The <a href="#max-content-measure"><i>max-content measure</i></a> of a
multi-column element with unrestrained column heights and a computed
‘<code class=property>column-count</code>’ of ‘<code
class=css>auto</code>’ is its ‘<code
class=property>column-width</code>’ multiplied by the number of columns
obtained by taking all allowed column breaks <a href="#CSS3-BREAK"
rel=biblioentry>[CSS3-BREAK]<!--{{CSS3-BREAK}}--></a>. <!--
The above was decided based on dholbert's example in http://lists.w3.org/Archives/Public/www-style/2012Oct/0017.html .
These definitions make multicols work well in flexbox,
both in 'stretch' and non-'stretch' cases,
without wasted space or needless overflow.
-->
<p> The <a href="#max-content-measure"><i>max-content measure</i></a> of a
multi-column element with restrained-height columns (i.e. a specified
‘<code class=property>extent</code>’ or ‘<code
class=property>max-extent</code>’) is the <i>measure</i> that would
exactly include all of its columns. It may be approximated by:
<ul>
<li> Laying out the element with column-spanning elements given ‘<code
class=css>display: none</code>’, and taking a measure that includes all
the columns.
<li> Laying out all of the column-spanning elements into that resulting
measure, and taking the resulting extent.
<li> Subtracting that resulting extent from the specified restraint,
laying out the element without column-spanning elements again into this
adjusted extent, and taking the measure of all its columns as its <a
href="#max-content-measure"><i>max-content measure</i></a>.
</ul>
<p> or by some more accurate method.
<p class=note> This approximation can result in some slack, but avoids
overflow in the most common cases, where the balanced height of the
columns above spanning elements are approximately equal.
<p class=note> In the common case of no column-spanning elements, this
approximation collapses to simply doing a layout, and measuring the
resulting columns.
<h2 id=extrinsic-sizing><span class=secno>5. </span> Extrinsic Size
Determination</h2>
<p> <dfn id=extrinsic-sizing0>Extrinsic sizing</dfn> determines sizes based
on the context of an element, without regard for its contents.
<p> The inner <a href="#fill-available-measure"><i>fill-available
measure</i></a> of a box is…
<ul>
<li> If the box is the root or is absolutely-positioned, the measure of
its containing block, else
<li> <code>max(<i>min-measure</i>|0, min(<i>max-measure</i>|infinity,
<i>measure</i>|<a
href="#fill-available"><i>fill-available</i></a>))</code> where the sizes
are inner measures of the element establishing the box's <i>containing
block</i>, and where the first value is used if it is <a
href="#definite"><i>definite</i></a> and the second value otherwise.
</ul>
<p> …less the box's inline-axis margins (after any <a
href="http://www.w3.org/TR/CSS21/box.html#collapsing-margins">margin
collapsing</a>, and treating ‘<code class=css>auto</code>’ margins as
zero), borders, and padding.
<p> The <a href="#fill-available-extent"><i>fill-available extent</i></a>
of a box is defined analogously, but in the other dimension.
<p class=issue> This definition might end up skipping further up the
ancestor chain than we'd like in some cases. <a
href="http://lists.w3.org/Archives/Public/www-style/2012Oct/0204.html">Example.</a>
Maybe it should stop at each formatting root, or something similar? <!--
dddddddd
TTTTTTTTTTTTTTTTTTTTTTThhhhhhh EEEEEEEEEEEEEEEEEEEEEE d::::::d
T:::::::::::::::::::::Th:::::h E::::::::::::::::::::E d::::::d
T:::::::::::::::::::::Th:::::h E::::::::::::::::::::E d::::::d
T:::::TT:::::::TT:::::Th:::::h EE::::::EEEEEEEEE::::E d:::::d
TTTTTT T:::::T TTTTTT h::::h hhhhh eeeeeeeeeeee E:::::E EEEEEEnnnn nnnnnnnn ddddddddd:::::d
T:::::T h::::hh:::::hhh ee::::::::::::ee E:::::E n:::nn::::::::nn dd::::::::::::::d
T:::::T h::::::::::::::hh e::::::eeeee:::::ee E::::::EEEEEEEEEE n::::::::::::::nn d::::::::::::::::d
T:::::T h:::::::hhh::::::h e::::::e e:::::e E:::::::::::::::E nn:::::::::::::::nd:::::::ddddd:::::d
T:::::T h::::::h h::::::he:::::::eeeee::::::e E:::::::::::::::E n:::::nnnn:::::nd::::::d d:::::d
T:::::T h:::::h h:::::he:::::::::::::::::e E::::::EEEEEEEEEE n::::n n::::nd:::::d d:::::d
T:::::T h:::::h h:::::he::::::eeeeeeeeeee E:::::E n::::n n::::nd:::::d d:::::d
T:::::T h:::::h h:::::he:::::::e E:::::E EEEEEE n::::n n::::nd:::::d d:::::d
TT:::::::TT h:::::h h:::::he::::::::e EE::::::EEEEEEEE:::::E n::::n n::::nd::::::ddddd::::::dd
T:::::::::T h:::::h h:::::h e::::::::eeeeeeee E::::::::::::::::::::E n::::n n::::n d:::::::::::::::::d
T:::::::::T h:::::h h:::::h ee:::::::::::::e E::::::::::::::::::::E n::::n n::::n d:::::::::ddd::::d
TTTTTTTTTTT hhhhhhh hhhhhhh eeeeeeeeeeeeee EEEEEEEEEEEEEEEEEEEEEE nnnnnn nnnnnn ddddddddd ddddd
-->
<h2 id=conformance><span class=secno>6. </span> Conformance</h2>
<h3 id=conventions><span class=secno>6.1. </span> Document conventions</h3>
<p>Conformance requirements are expressed with a combination of descriptive
assertions and RFC 2119 terminology. The key words “MUST”, “MUST
NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”,
“SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL” in the
normative parts of this document are to be interpreted as described in RFC
2119. However, for readability, these words do not appear in all uppercase
letters in this specification.
<p>All of the text of this specification is normative except sections
explicitly marked as non-normative, examples, and notes. <a
href="#RFC2119" rel=biblioentry>[RFC2119]<!--{{!RFC2119}}--></a>
<p>Examples in this specification are introduced with the words “for
example” or are set apart from the normative text with
<code>class="example"</code>, like this:
<div class=example>
<p>This is an example of an informative example.
</div>
<p>Informative notes begin with the word “Note” and are set apart from
the normative text with <code>class="note"</code>, like this:
<p class=note>Note, this is an informative note.
<h3 id=conformance-classes><span class=secno>6.2. </span> Conformance
classes</h3>
<p>Conformance to CSS Intrinsic & Extrinsic Sizing Level 3 is defined
for three conformance classes:
<dl>
<dt><dfn id=style-sheet title="style sheet!!as conformance class">style
sheet</dfn>
<dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#style-sheet">CSS
style sheet</a>.
<dt><dfn id=renderer>renderer</dfn>
<dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
that interprets the semantics of a style sheet and renders documents that
use them.
<dt><dfn id=authoring-tool>authoring tool</dfn>
<dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
that writes a style sheet.
</dl>
<p>A style sheet is conformant to CSS Intrinsic & Extrinsic Sizing
Level 3 if all of its statements that use syntax defined in this module
are valid according to the generic CSS grammar and the individual grammars
of each feature defined in this module.
<p>A renderer is conformant to CSS Intrinsic & Extrinsic Sizing Level 3
if, in addition to interpreting the style sheet as defined by the
appropriate specifications, it supports all the features defined by CSS
Intrinsic & Extrinsic Sizing Level 3 by parsing them correctly and
rendering the document accordingly. However, the inability of a UA to
correctly render a document due to limitations of the device does not make
the UA non-conformant. (For example, a UA is not required to render color
on a monochrome monitor.)
<p>An authoring tool is conformant to CSS Intrinsic & Extrinsic Sizing