Re: [csswg-drafts] [css-contain-3] Container Queries and pseudo elements (#6711)

It seems to me as though the [tree-abiding pseudo-elements](https://www.w3.org/TR/css-pseudo-4/#treelike) should behave like any other element when finding their containers. That would mean both `#inner::before` and `#inner::after` are inside the `#inner` container. That would also cover `::marker`, `::placeholder`, and `::file-selector-button`.

My instinct was to treat the typographic pseudo-elements also as though they are nested inside a block - but as @tabatkins [pointed out on Twitter](https://twitter.com/tabatkins/status/1444017728101109760):

> This would expose details of where in the tree the non-tree-abiding pseudos are, which seems bad

(I think `::backdrop` is similarly not tree-abiding, but there's not much detail in the spec. I don't think there is any use for it responding to containers other than the viewport, since it's always full-screen.)

-- 
GitHub Notification of comment by mirisuzanne
Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/6711#issuecomment-933632577 using your GitHub account


-- 
Sent via github-notify-ml as configured in https://github.com/w3c/github-notify-ml-config

Received on Monday, 4 October 2021 16:07:08 UTC