Bug 270046 – Add UA Stylesheet rules for `img` with `sizes=auto`

• Component: CSS
• Status: RESOLVED DUPLICATE

[Ahmad Saleem]

Hi Team,

While going through HTML Spec, I noticed that we are missing following UA stylesheet rule:

https://html.spec.whatwg.org/#images-3

img:is([sizes="auto" i], [sizes^="auto," i]) {
  contain: size !important;
  contain-intrinsic-size: 300px 150px;
}

___

It seems that we have WPT tests as well: https://wpt.fyi/results/html/rendering/replaced-elements/images/img-sizes-auto.html?label=master&label=experimental&aligned=

I think above will progress first two tests.

Although every browser is failing so it might be new standard or standard behind flag.

I can find this in our standard-position: https://github.com/WebKit/standards-positions/issues/9

but it seems to be for 'lazy loaded' images.

Appreciate if someone can confirm if it is safe to add or we have to do something before.

Thanks!

[Anne van Kesteren]

*** This bug has been marked as a duplicate of bug 253143 ***