[css-contain-2] Updated Working Draft of the CSS Containment Module Level 2

The CSS Working Group has published an updated Working Draft of the CSS =
Containment Module Level 2.

    https://www.w3.org/TR/css-contain-2/

This CSS module describes the contain property, which indicates that the =
element=E2=80=99s subtree is independent of the rest of the page, and =
the related and content-visibility property. This enables heavy =
optimizations by user agents when used well.

The main changes brought by this update are defining the interaction =
between paint containment and the newly introduced overflow-clip-margin, =
and adding the content-visibility property. The content-visibility =
property controls whether or not an element renders its contents at all, =
along with forcing a strong set of containments, allowing user agents to =
potentially omit large swathes of layout and rendering work until it =
becomes needed.

See also the Changes section for further details.

    =
https://www.w3.org/TR/2020/WD-css-contain-2-20200603/#changes-since-2019-1=
1-11

Please send any comments to the mailing list <[email protected]>, =
prefixed with [css-contain-2] (as I did on this message) or (preferably) =
file them in the GitHub repository at =
https://github.com/w3c/csswg-drafts/issues with the spec code =
[css-contain-2] and your comment topic in the subject line.

For the CSS WG,
=E2=80=94Florian Rivoal=