Re: [csswg-drafts] [css-overflow-4] Unexpected behavior of `continue: discard` on multicolumn containers with spanners (#8721)

The CSS Working Group just discussed ``[css-overflow-4] Unexpected behavior of `continue: discard` on multicolumn containers with spanners``, and agreed to the following:

* `RESOLVED: if there are overflow columns in a continue:discard element, any content starting with the the first overflow column is discarded`

<details><summary>The full IRC log of that discussion</summary>
&lt;TabAtkins> andreubotella: i opened this when i was working on continue:collapse<br>
&lt;TabAtkins> andreubotella: continue:discard can be applied to block containers, and also multicol<br>
&lt;TabAtkins> andreubotella: if you have overflow columns, you can have content after those columns; continue:discard is meant to discard the contents of a fragment<br>
&lt;TabAtkins> andreubotella: for some impls, they could just do the whole layout and discard the fragment, but hope is that in browsers that can do fragmentation during layout (chromium does this, webkit is transitioning to this), you could stop the layout just before the discarded part<br>
&lt;TabAtkins> andreubotella: if you have a spanner you'll resume the layout, and ther's content from the overflow columns that can affect the layout of things, like counters<br>
&lt;florian> q+<br>
&lt;TabAtkins> fantasai: so you're saying there's a break after column 3 in the text, then the overflow column...<br>
&lt;TabAtkins> andreubotella: for continue:discard, it's possible to ipmlement by laying out the whole thing then throwing away the excess, but for line-clamp the hope is that you can actually stop the layout at the clamp point<br>
&lt;astearns> ack florian<br>
&lt;TabAtkins> florian: there's a bunch of things you could do, but many dont' make sense. the general idea is continue:discard on an overflow discard the overflow columns... a spanner rooted in those columns gets discarded too<br>
&lt;TabAtkins> florian: if we let the spanner exist it would create weird content, you'd miss the content between the break point and the spanner<br>
&lt;TabAtkins> fantasai: right, once you get to the discard point all further content is discarded<br>
&lt;TabAtkins> andreubotella: i think that's consistent with a multicol in fragmented content and you just discard stuff after the first fragment<br>
&lt;TabAtkins> alisonmaher: does this mean you'll have to keep laying things out?<br>
&lt;TabAtkins> andreubotella: i don't think so. the moment you know there are columns that would overflow, you stop layout for them<br>
&lt;TabAtkins> astearns: so, proposal?<br>
&lt;TabAtkins> andreubotella: if there are overflow columns in a continue:discard element, any content after the first overflow column is discarded<br>
&lt;TabAtkins> s/after the/beginning with the/<br>
&lt;TabAtkins> RESOLVED: if there are overflow columns in a continue:discard element, any content starting with the the first overflow column is discarded<br>
</details>


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Received on Wednesday, 20 August 2025 12:30:12 UTC