Re: [csswg-drafts] [css-grid-3][masonry] Handling negative margins and dense packing for baseline calculation in the masonry axis (#13165)

The CSS Working Group just discussed `[css-grid-3][masonry] Handling negative margins and dense packing for baseline calculation in the masonry axis`, and agreed to the following:

* `RESOLVED: Negative margins don't affect ordering for purpose of baseline determination; but dense packing does.`

<details><summary>The full IRC log of that discussion</summary>
&lt;sgill> yanling: this is follow up on baseline alignment<br>
&lt;sgill> when items shift or overlap due to dense packing or negative margins how we determine what item is first or last in track?<br>
&lt;sgill> order they were placed or original positions?<br>
&lt;sgill> tab suggested placement rules<br>
&lt;sgill> makes sense and keeps things predictable<br>
&lt;sgill> in example 3 of description<br>
&lt;sgill> item 5 has negative margin top and w/o dense packing item 2 would serve as candidate but w/ dense packing it is repositioned<br>
&lt;sgill> in that case we would still treat item 5 as the candidate<br>
&lt;astearns> ack fantasai<br>
&lt;sgill> fantasai: def negative margins and such should not affect just like we do in multicol and elsewhere<br>
&lt;sgill> not sure about dense packing<br>
&lt;sgill> TabAtkins: treat as same as grid<br>
&lt;fantasai> PROPOSED: Negative margins don't affect ordering for purpose of baseline determination; but dense packing does.<br>
&lt;TabAtkins> TabAtkins: if dense packing puts an item first in a track (because a spanner left that space open), then that item *is* first in its track and can influence baseline of the container<br>
&lt;fantasai> RESOLVED: Negative margins don't affect ordering for purpose of baseline determination; but dense packing does.<br>
</details>


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Received on Thursday, 29 January 2026 22:16:47 UTC