Re: [csswg-drafts] [css-values-4] Logical viewport units (vi, vb, etc) and writing-mode propagation (#6873)

The CSS Working Group just discussed `logical-viewport units and wm propagation`, and agreed to the following:

* `RESOLVED: Writing-mode sensitive viewport units (and analogous units) use the writing mode of the element they're used on.`

<details><summary>The full IRC log of that discussion</summary>
&lt;TabAtkins> Topic: logical-viewport units and wm propagation<br>
&lt;TabAtkins> github: https://github.com/w3c/csswg-drafts/issues/6873<br>
&lt;TabAtkins> fantasai: issue was raised to simplify some edges cases around writing modes and viewport units<br>
&lt;TabAtkins> fantasai: Also brought up the question - I think we got the issue wrong, as it says to resolve against the root element's writing mode, but I think generally you want the element's writing mode.<br>
&lt;TabAtkins> fantasai: So proposed resolution is to use the element's writing mode to resolve vi/vb, rather than the root element.<br>
&lt;fantasai_> s/edge cases around/edge cases around body propagation and/<br>
&lt;fantasai_> TabAtkins: I agree<br>
&lt;TabAtkins> smfr: Does tha tmake inheritance complicated?<br>
&lt;TabAtkins> fantasai_: No, they compute to lengths before inheritance<br>
&lt;TabAtkins> florian: Yeah, I think I remember that being what I wanted. If you're doing a font-size in viewport units, you want the logical axis you're using.<br>
&lt;TabAtkins> miriam: Might be confusing with container queries which have to be set up to be inline or block<br>
&lt;TabAtkins> miriam: So you set up a container with "inline", this might not match the container you've established.<br>
&lt;TabAtkins> emilio: What do we resolve our units against, the container or the element?<br>
&lt;Rossen_> q?<br>
&lt;TabAtkins> fantasai_: So this is about the container-relative units.<br>
&lt;TabAtkins> emilio: We added a way to resolve against different containers. It would be very bad if we resolved relative units against different axises for each property.<br>
&lt;TabAtkins> emilio: So think we should resolve them against the element's wm.<br>
&lt;TabAtkins> miriam: So when you use the "cq inline unit" it looks for the nearest container with inline containment.<br>
&lt;TabAtkins> miriam: Could potentially be confusing if the inline unit doesn't resolve against a container declaring "inline"<br>
&lt;fantasai_> TabAtkins: I agree that the potential of inline not matching inline is a general problem with mismatched writing modes, and agree that within an element you want inline to match what that element thinks its inline axis is<br>
&lt;TabAtkins> fantasai_: So proposed resolution is that viewport units (and analogues) use the writing mode of the element they're used on.<br>
&lt;TabAtkins> Rossen_: objections?<br>
&lt;TabAtkins> RESOLVED: Writing-mode sensitive viewport units (and analogous units) use the writing mode of the element they're used on.<br>
</details>


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Received on Wednesday, 15 December 2021 19:00:35 UTC