[css-contain] ruby container missing from size containment exclusions

[SebastianZ]

CSS Contain currently says this regarding size containment:

However, giving an element size containment has no effect if any of the following are true:

• if the element does not generate a principal box (as is the case with display: contents or display: none)
• if its inner display type is table
• if its principal box is an internal table box
• if its principal box is an internal ruby box or a non-atomic inline-level box

While it mentions internal ruby boxes, it seems to miss ruby containers, while a WPT tests for that.

So I believe the second point should be extended like this:

• if its inner display type is table or ruby

Sebastian

[Loirooriol]

I think it's perfectly fine to apply size containment to display: block ruby, affecting the wrapper (principal box).

And display: ruby should be covered by

if its principal box is [...] a non-atomic inline-level box

https://www.w3.org/TR/css-ruby-1/#formatting-context

Ruby containers are non-atomic inline-level boxes