Re: 'transform' style for fullscreen video elements

On Tue, Nov 18, 2014 at 10:43 AM, Robert O'Callahan <robert@ocallahan.org>
wrote:

> On Tue, Nov 18, 2014 at 8:07 AM, Dirk Schulze <dschulze@adobe.com> wrote:
>
>> fullscreen.css in WebKit has a bunch of styles (nearly all with
>> !important). The only one for transforms though is:
>>
>> :-webkit-full-screen-ancestor:not(iframe) {
>>     -webkit-transform: none !important;
>>     -webkit-transform-style: flat !important;
>>     …
>> }
>>
>
> I think we should put this in the spec (sans prefix of course).
>
> It's important for interop that browsers align on these and don't just add
> properties to the UA sheet fullscreen rules without standards discussion or
> even notification. Relevant sources:
> http://dxr.mozilla.org/mozilla-central/source/layout/style/ua.css#260
> http://trac.webkit.org/browser/trunk/Source/WebCore/css/fullscreen.css#L24
>
> https://chromium.googlesource.com/chromium/blink/+/master/Source/core/css/fullscreen.css
> Looks like Webkit/Blink have rules for "flex" and "transform" also. I'm
> happy if those get added to the spec too.
>

Oops, sorry, I added to some confusion here.

The full-screen-ancestor rule Dirk quoted above is a separate issue. Let's
ignore that for now.

Looks to me like the UA rules for fullscreen media elements have issues for
the following properties:
transform: overridden by Webkit/Blink only
transition: overridden by Webkit only (this doesn't look like a good idea)
flex: overridden by Webkit/Blink only
box-sizing: overridden by spec/Gecko only
object-fit: overridden by spec only

'background-color', 'display' and 'position' have different rules across
browsers but are less problematic since the differences there are probably
just due to the way fullscreen is implemented differently in different
browsers.

Interestingly Webkit/Blink have almost no UA rules for fullscreen elements
other than media elements and <iframe>s. That seems like a bug.

Rob
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