Re: [csswg-drafts] [css-overflow-4] Allow scrollable overflow to be visible in the off-axis / overflow-clip-margin (#13445)

The CSS Working Group just discussed `[css-overflow-4] Allow scrollable overflow to be visible in the off-axis / overflow-clip-margin`, and agreed to the following:

* `RESOLVED: o-c-m restriction already resolved on continues to apply in this case`

<details><summary>The full IRC log of that discussion</summary>
&lt;TabAtkins> flackr: we resolved previously that you can create scrollable containers in one axis and not other<br>
&lt;TabAtkins> flackr: the immediate implicaction is you can have clip in the other axis<br>
&lt;TabAtkins> flackr: so q came up whether overflow-clip-margin should apply<br>
&lt;TabAtkins> flackr: and if so, and it can be arbitrarily large, should we support the use-case of not clipping in the non-scrollable axis? allowing visible?<br>
&lt;TabAtkins> flackr: dont' see reason to not do it, there's potential use cases<br>
&lt;TabAtkins> flackr: but wanted to get group agreement<br>
&lt;TabAtkins> flackr: with visible being initial value, we probably have to introduce new initial value that computes to visible<br>
&lt;TabAtkins> flackr: so we can tell the different between author specifying scroll in one axis, or scroll in one and visible in the other<br>
&lt;TabAtkins> flackr: so two proposals, one is less scary than the other<br>
&lt;TabAtkins> TabAtkins: is there any reason to not apply overflow-clip-margin?<br>
&lt;TabAtkins> fantasai: q is do we want to allow the content of a scroll container to be rendered outside?<br>
&lt;smfr> q+<br>
&lt;astearns> ack smfr<br>
&lt;TabAtkins> smfr: does the scrollbar show on top of the stuff that's not clipped?<br>
&lt;TabAtkins> flackr: that's a good question...<br>
&lt;TabAtkins> flackr: it probably should, a little weird<br>
&lt;TabAtkins> smfr: i'm also concerneda  bou tthe computation of things that need to overlap the scroller<br>
&lt;TabAtkins> smfr: worried this makes it harder, it's already complicated<br>
&lt;TabAtkins> flackr: note i'm not opposed to saying we don't respect overflow-clip-margin<br>
&lt;TabAtkins> TabAtkins: I agree that *if* we allow o-c-m we should allow visible<br>
&lt;TabAtkins> dbaron: issue is there are dependencies lying around CSS that might cause problems<br>
&lt;TabAtkins> dbaron: if we were going to allow visible in one dimension, we probably want to be clear that this is still a block formatting context<br>
&lt;TabAtkins> TabAtkins: yeah I think there should be no difference between clip+infinite margin, and 'visible', in this case<br>
&lt;TabAtkins> fantasai: I think it could be cool but not worth the complexity in impl and testing<br>
&lt;TabAtkins> fantasai: if it was important we could do it<br>
&lt;vmpstr> q+<br>
&lt;TabAtkins> fantasai: but it's a lot of effort<br>
&lt;smfr> +1<br>
&lt;astearns> ack vmpstr<br>
&lt;TabAtkins> vmpstr: I don't disagree with Elika. We do then want to explicitly say that o-c-m doesn't apply if it's only clipping in one axis.<br>
&lt;TabAtkins> vmpstr: per spec right now it should<br>
&lt;TabAtkins> fantasai: yeah<br>
&lt;TabAtkins> astearns: if we decide it doens't apply, and later find a use-case, are we stuck?<br>
&lt;TabAtkins> TabAtkins: we'd be compat constrained, is all<br>
&lt;TabAtkins> flackr: we have another issue about showing visible content outside of the scroller, could support it as part of that if reasoanble<br>
&lt;astearns> ack fantasai<br>
&lt;TabAtkins> fantasai: so o-c-m can clip both in and out of the econtainer<br>
&lt;TabAtkins> fantasai: these mostly apply to clipping out of the container. we could honor clipping into the container<br>
&lt;TabAtkins> emilio: I think we did have a resolution for that more generally<br>
&lt;TabAtkins> flackr: ah if this is supposed to be something more general it should work here<br>
&lt;TabAtkins> flackr: so barring more comments, sounds like we're leaning toward not allowing this any more than it is for general scroll containers<br>
&lt;emilio> https://github.com/w3c/csswg-drafts/issues/7246<br>
&lt;TabAtkins> emilio: we might have just discussed it, not resolved...<br>
&lt;emilio> https://github.com/w3c/csswg-drafts/issues/10745<br>
&lt;TabAtkins> emilio: ah we did resolve in another issue<br>
&lt;TabAtkins> emilio: we resolved that o-c-m on scroll containers is clamped to the padding box<br>
&lt;emilio> > RESOLVED: scrollable boxes can combine content-box and a positive margin (clamped to padding box), and content-box and padding box can use negative margins. border-box ignores margin either way.<br>
&lt;TabAtkins> astearns: so should we say this is just covered by the previous resolution?<br>
&lt;TabAtkins> TabAtkins: I need to get that edit in<br>
&lt;TabAtkins> astearns: so proposed resolution is we actually apply the previous resolution to the espec<br>
&lt;TabAtkins> RESOLVED: o-c-m restriction already resolved on continues to apply in this case<br>
</details>


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Received on Thursday, 2 April 2026 18:51:28 UTC