According to the spec, an @container rule can have multiple comma-separated conditions; we currently only support a single condition. We should extend this to parse and store a list of conditions, and consider the rule to match if any of its conditions matches.

Exposing the list via the CSSContainerRule interface is left for a separate bug (pending spec clarification).

[Why is this notable]: New CSS feature
[Affects Firefox for Android]: yes
[Suggested wording]: @container rules now allow to specify a list of container query conditions instead of just one condition.
[Links (documentation, blog post, etc)]:
https://drafts.csswg.org/css-conditional-5/#container-rule
https://developer.mozilla.org/en-US/docs/Web/CSS/Reference/At-rules/@container (describes it but currently still misses a proper example and BCD)

This should probably be mentioned together with the API implemented in bug 2022827.

Sebastian

https://hg.mozilla.org/mozilla-central/rev/ab684099bb0e
https://hg.mozilla.org/mozilla-central/rev/69852bffab54

Added to the Fx151 nightly release notes, please allow 30 minutes for the site to update.
Keeping the relnote-firefox flag as ? to keep it on the radar for inclusion in the final Fx151 release notes.