Re: [compositing] Various small fixes for Compositing & Blending Level 1

Thanks for the follow-up Rik.

On 26 April 2015 at 21:14, Rik Cabanier <> wrote:
> During the last TPAC, it was decided that the <svg> element creates a
> stacking context. Previously, the spec called out this element as not
> causing isolation but people felt that consistency was more important.
> So, the special case was dropped and someone was going to update (or
> create?) a spec to clearly say what causes stacking contexts.

Ah, glad there has been a clear decision on this.  Does the same decision
also apply to the root element of any document type?  That was the other
area where I found cross-browser inconsistency: Firefox treats the root as
isolated, with a transparent black background if no background property is
set, while Blink blends content into the opaque white canvas.

E.g., see which re-creates the
additive color figure using absolutely positioned HTML elements.

>> The table for  `background-blend-mode`  says "Applies to:All HTML
>> elements".  However, it could apply to any XML content that uses a CSS
>> layout model.  That includes a top-level inline SVG element; in practice
>> (and probably in SVG 2) it would also include a root <svg> element.
>> A more useful and future-proof description would be "Applies to: Any
>> element that renders the `background-image` property".  Another way to make
>> the same distinction is to use the language from the Transforms spec
>> is "elements with (or without) associated CSS layout box".
> That would be a normative change which would push the spec back.
> Maybe we can address this in level 2?

Fair enough.  I'm fairly certain all implementations will apply it to any
content with a CSS rendering model, HTML or otherwise, but I wouldn't want
such a fussy wording change to throw the whole spec back on the
recommendation track.

Received on Monday, 27 April 2015 03:41:44 UTC