Re: [csswg-drafts] [css-writing-modes] body propagation of writing-mode/direction/text-orientation and computed vs used styles (#12586)

The Houdini Task Force just discussed `[css-writing-modes] body propagation of writing-mode/direction/text-orientation and computed vs used styles`.

<details><summary>The full IRC log of that discussion</summary>
&lt;alisonmaher> fantasai: we have in writing mode spec, prop writing mode from body to IMCB and root<br>
&lt;alisonmaher> ...for compat reasons<br>
&lt;emilio> q+<br>
&lt;alisonmaher> ...we resolved that changing comp value is hard. Should change used was proposed by emilio<br>
&lt;alisonmaher> ...we resolved to say computed value on root doesn't change, but used does for correct layout<br>
&lt;alisonmaher> ...problem is webkit has opposite problem<br>
&lt;alisonmaher> ...it is more work to change computed value instead of used<br>
&lt;alisonmaher> emilio: you can't change computed style<br>
&lt;alisonmaher> ...you need to add storage for this for the root case<br>
&lt;alisonmaher> ...changing writing mode implies ??<br>
&lt;iank_> i'm going to drop - but likely need Rune for this.<br>
&lt;alisonmaher> ...I assume you are saying it is convenient to change without affecting any side effects<br>
&lt;alisonmaher> ...you are proposing to not change how inheritance works after<br>
&lt;alisonmaher> florian: writing mode is inherited. If you change val of root based on body, only thing that inherits is body<br>
&lt;alisonmaher> emilio: no other things inherit from root<br>
&lt;alisonmaher> florian: you're right<br>
&lt;emilio> s/no //<br>
&lt;alisonmaher> fantasai: you want it to inherit to view transitions<br>
&lt;alisonmaher> emilio: no you don't want that<br>
&lt;alisonmaher> florian: that's why we have prop in first place<br>
&lt;alisonmaher> emilio: if you set on root, you can run into circularities<br>
&lt;alisonmaher> ...if you use container queries??<br>
&lt;alisonmaher> ...you don't need to set containment for style container queries<br>
&lt;emilio> @container style(writing-mode: vertical-lr) { body { writing-mode: horizontal-tb } }<br>
&lt;alisonmaher> florian: this affects enough things we can't do the better thing<br>
&lt;alisonmaher> emilio: assume elika's proposal doesn't change how logical properties behave<br>
&lt;alisonmaher> florian: from body down it wouldn't but other cases will<br>
&lt;alisonmaher> emilio: we get into weird state with writing modes resolving in different cases<br>
&lt;alisonmaher> ...this changes things<br>
&lt;alisonmaher> florian: can we just emit warnings when setting body instead of root<br>
&lt;alisonmaher> fantasai: prob won't help<br>
&lt;alisonmaher> emilio: you need to add extra storage for this<br>
&lt;alisonmaher> ....same problem with tables<br>
&lt;alisonmaher> ...either special case root to look at body at used value or add storage at box construction time<br>
&lt;alisonmaher> ...ugly either way<br>
&lt;alisonmaher> ...only sound approach<br>
&lt;alisonmaher> fantasai: take back to webkit<br>
&lt;alisonmaher> emilio: happy to help with questions<br>
&lt;alisonmaher> ...other approach is add a field to comp style like used vs original display<br>
&lt;alisonmaher> ...that would be easier for webkit<br>
&lt;alisonmaher> ....add used writing mode field that lives in comp that isn't exposed, set that instead<br>
&lt;alisonmaher> fantasai: will need to chat with team<br>
</details>


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Received on Thursday, 21 August 2025 14:38:54 UTC