Re: [csswg-drafts] [css-contain] :root/body viewport propagation and containment (#5913)

The CSS Working Group just discussed `[css-contain] :root/body viewport propagation and containment`, and agreed to the following:

* `RESOLVED: If there is containment on body or root it stops propagation from body to root`

<details><summary>The full IRC log of that discussion</summary>
&lt;dael> Topic:  [css-contain] :root/body viewport propagation and containment<br>
&lt;dael> github: https://github.com/w3c/csswg-drafts/issues/5913<br>
&lt;dael> miriam: Not the one that raise this but rune isn't here. Can't speak for browser engineers. Seems like users that would want to do containment at root. Would not like to disallow, but he has a few other proposals<br>
&lt;dael> miriam: No strong feelings<br>
&lt;dael> iank_: There's 3 solutions from prop direction writing modes.<br>
&lt;dael> iank_: The first is the giant hammer no one wants which is disallow on body<br>
&lt;dael> iank_: Second is when container quereis apply we stop body prop up to viewport<br>
&lt;dael> iank_: Third option is to do prop but don't let it change after that. Stuck at initial value<br>
&lt;dael> iank_: Means if you have container query on html element and spec body under 500px changes writing mode wouldn't work<br>
&lt;dael> iank_: I think I prefer the 2nd option. When we have containment applied we don't form propagation. However, 2 valid solutions<br>
&lt;dael> florian: Agree with iank_. Prop from body is for compat reasons. In general containment is not an operation that changes nothing. It changes layout b/c contains things. Saying it contains prop it's fine. If you need it on the root, set it there<br>
&lt;dael> iank_: Not allowing you to dynamically change those properties inside container queries seems bad to 2nd<br>
&lt;dael> fantasai: 2nd is if you apply containment to root or body we don't do body prop but do from html root element<br>
&lt;dael> florian: If you do on body doesn't prop to root but can't contain root<br>
&lt;dael> florian: No cotnainment on root. On body is possible, but stops prop from body<br>
&lt;dael> fantasai: Does contain apply to root general?<br>
&lt;dael> florian: Not defined<br>
&lt;dael> fantasai: If it does it would make sense that would aslo block prop.<br>
&lt;dael> iank_: Problematic case is html element then body. Put a container query and the body can change style and prop to root<br>
&lt;dael> fantasai: Yes, not allowed. Containment on root or body shoudl block body from prop.<br>
&lt;dael> fantasai: Nothing shoudl block root from prop<br>
&lt;dael> fantasai: Assuming containment on root can be done. If it does not apply if it blocks body no strong opinion<br>
&lt;dael> florian: Don't recall talking about cotnainment on root.<br>
&lt;dael> miriam: It is a use case people want. Might be able to get close with body containment. People are wanting the ability<br>
&lt;dael> florian: Can you explain why root?<br>
&lt;dael> miriam: I don't know people have thought through body or root. Main is you could adjust body based on root query. There is a case to use a cotnainer query isntead of MQ for viewport b/c cotnainer lets you respond to actual font size and dimensions rather than browser or user font size.<br>
&lt;dael> iank_: Once people get their hands on container queries they won't think about viewport MQs much anymore. They'll attach container query to root to adjust viewport<br>
&lt;dael> fantasai: Givenw e're expecting containment to apply to root with an effect of some kind it should also block body from propagating<br>
&lt;dael> fantasai: Prop: containment does nto block root from propagating, but it does block body<br>
&lt;dael> florian: Containment to the body makes sense. Still confused on root<br>
&lt;dael> fantasai: If containing the body and prevents prop, why wouldn't containing and ancestor block?<br>
&lt;dael> florian: Doing it outer edge of thing being container. Means root doesn't effect parent. Doesn't change how things inside are effected. Might be useful<br>
&lt;dael> fantasai: Containment means child doesn't interact with ancestors, right?<br>
&lt;dael> florian: Yeah, okay. I can see it<br>
&lt;miriam> +1 fantasai<br>
&lt;dael> fantasai: Interface of container some things applya nd some don't, but child shouldn't interact with grandparent<br>
&lt;dael> florian: Body to root maybe should be blocked.<br>
&lt;dael> fantasai: Body to root? Does that happen?<br>
&lt;dael> iank_: Root is HTML element?<br>
&lt;dael> florian: Yes<br>
&lt;dael> iank_: Containment applies to html element fine.<br>
&lt;dael> astearns: Prop: If there is containment on body it stops prop from body to root?<br>
&lt;dael> florian: On body or root<br>
&lt;dael> astearns: Prop: If there is cotnainment on body or root it stops prop from body to root<br>
&lt;dael> RESOLVED: If there is containment on body or root it stops propagation from body to root<br>
</details>


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Received on Wednesday, 5 May 2021 23:46:37 UTC