[csswg-drafts] [css-conditional-5] Valid size query containers and box tree re-ordering (#11213)

lilles has just created a new issue for https://github.com/w3c/csswg-drafts:

== [css-conditional-5] Valid size query containers and box tree re-ordering ==
In the spec: [https://drafts.csswg.org/css-conditional-5/ref-for-query-container①⑧](https://drafts.csswg.org/css-conditional-5/#ref-for-query-container%E2%91%A0%E2%91%A6), valid query containers are said to be selected from the element's flat tree ancestors.

We have encountered an issue when the box tree order does not follow the flat tree order. The box for `::scroll-marker-group` becomes a sibling of its originating element. While normally pseudo elements can query the size of their originating element, this causes an issue with layout escaping the container causing circularity.

Can we say something generally about box tree re-ordering and size query container candidates?

For the `::scroll-marker-group` case we know that if it generates a box, it will be a sibling of its originating element's box. For future cases, if the box tree order depends on the element's style, we might not know at the time we query the container where the element's box will end up.

If we know about the box re-ordering at query time we could either:

1. Not consider ancestors which will not be box tree ancestors as valid size query containers
2. Always evaluate size queries to false for such containers


Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/11213 using your GitHub account


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Received on Thursday, 14 November 2024 14:57:50 UTC