On Tuesday 2013-08-27 14:05 +0900, Philippe Wittenbergh wrote: > I'm absolutely not clear why the percentage based animation actually works in > Firefox (and incidentally, Presto based Opera 12.x). And Eric notes it > doesn't seem to work in IE 11 (and IE 10?). That seems correct per spec to > me. That is pure CSS 2.1: > http://www.w3.org/TR/CSS21/visuren.html#position-props > > specifically: > > > > Percentages: refer to height of containing block > > In the test case, the height of the containing block (.wrapper2) has a value > of 'auto', which means that 'top' can't be computed.
Many of the other references in the CSS spec to things that are based on the height of the containing block explicitly say that if the containing block's computed height is 'auto', then the percentage is as well. See, for example: http://www.w3.org/TR/CSS2/visudet.html#the-height-property http://www.w3.org/TR/CSS2/visudet.html#min-max-heights http://www.w3.org/TR/CSS21/visuren.html#position-props , however, does not say that, and you shouldn't infer it from the same thing being stated elsewhere. The working group explicitly decided *not* to change this in 2009; see: http://wiki.csswg.org/spec/css2.1#issue-134 http://lists.w3.org/Archives/Public/www-style/2009Jun/0056.html http://lists.w3.org/Archives/Public/www-style/2009Aug/0092.html -David -- 𝄞 L. David Baron http://dbaron.org/ 𝄂 𝄢 Mozilla https://www.mozilla.org/ 𝄂 Before I built a wall I'd ask to know What I was walling in or walling out, And to whom I was like to give offense. - Robert Frost, Mending Wall (1914) ______________________________________________________________________ css-discuss [css-d@lists.css-discuss.org] http://www.css-discuss.org/mailman/listinfo/css-d List wiki/FAQ -- http://css-discuss.incutio.com/ List policies -- http://css-discuss.org/policies.html Supported by evolt.org -- http://www.evolt.org/help_support_evolt/
