[css-cascade] all shorthand and UA defaults

Ok, so on the telecon we discussed the requirements of the 'all'
shorthand, and how it relies on being able to properly reset
both inherited and non-inherited properties.
   http://lists.w3.org/Archives/Public/www-style/2013Jul/0478.html
And then the related problem of the UA style sheet maybe having
rules that really ought to not be overridden.

Tab and I went through the Gecko UA style sheet
   http://mxr.mozilla.org/mozilla-central/source/layout/style/html.css
and it's fairly obvious from that that the 'all' shorthand
really should not be messing with the 'unicode-bidi' and
'direction' properties.

So we propose that the following properties be excluded from
'all', because they are really controlling the content rather
than the style (and generally shouldn't be set by authors):
   direction
   unicode-bidi

There are other rules that it might be nice not to reset (like
'display: none' rules from the UA style sheet), but these are
less straightforward to fix. It might be best just to caution
authors not to do * { all: unset; }

We're also considering whether properties set by UA rules tied
to the content language should also be excluded from 'all', e.g.
   quotes
   text-emphasis-position
   text-underline-position
But less sure about that.

~fantasai and TJ

Received on Monday, 22 July 2013 22:51:48 UTC