Re: [css-cascade-4] transition effects, accessibility and the cascade…

On Wednesday 2015-09-09 15:48 -0700, Tab Atkins Jr. wrote:
> On Wed, Sep 9, 2015 at 3:39 PM, Chaals McCathie Nevile
> <chaals@yandex-team.ru> wrote:
> > Cross-posted to PF and www-style (I am not a member of the latter, and
> > unless the CSS group thinks this needs internal discussion I think follow-up
> > should go to PF only).
> >
> > Hi,
> >
> > this spec is in last call:
> > <http://www.w3.org/TR/2015/WD-css-cascade-4-20150908/>
> >
> > I had a look, and it mostly seems good. The new cascade order means that
> > users can turn off animations, individually or en masse.
> >
> > The one edge case concern I can imagine is where a transition is specified,
> > which has some harmful effect (flash, movement, etc). Transitions are given
> > the highest priority in the Cascade.
> >
> > I *think* that in such a rare case, a user's !important transition would
> > still override one supplied by an author, but I don't see that clearly from
> > the spec since it lumps all transitions together.
> 
> The *transition style itself* (the temporary interpolating style
> applied *by the transition*, which overrides the actual property value
> that the tree would otherwise apply to the element) is super-high in
> the origin list.  The 'transition' property, on the other hand, is
> just part of the normal origin like every other property.
> 
> So yeah, a user can definitely apply "transition: none !important;" or
> the like and it'll win like normal.

And the other factor here is that a transition only happens when a
property changes through another mechanism; if a user style sheet
has a property set with !important, then the author can't change it,
and no transition can occur.

-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.
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