Re: [csswg-drafts] [css-grid-1] Abspos with an overflowing grid CB (#13930)

The CSS Working Group just discussed `[css-grid-1] Abspos with an overflowing grid CB`, and agreed to the following:

* `RESOLVED: when grid-placement is fully auto in an axis, use the scrollport edges (otherwise do as specced)`

<details><summary>The full IRC log of that discussion</summary>
&lt;sgill> TabAtkins: weird case with abspos and overflowing grids<br>
&lt;sgill> ... spec says one thing that is good that implementations never followed<br>
&lt;sgill> ... Ian wants to change and thinks he can<br>
&lt;sgill> ... want to make sure this is generally good with everyone else<br>
&lt;sgill> ... grid container 100x100<br>
&lt;sgill> ... its grid is 150x150<br>
&lt;sgill> ... abspos child with grid container as containing block<br>
&lt;sgill> ... if the grid placement properties on the abspos are auto then we take the container's padding edge<br>
&lt;sgill> ... if specific grid line we use that line<br>
&lt;sgill> ... parenthetical saying instead of using grid container's padding edge we use scrollable area's padding edge<br>
&lt;sgill> fantasai: assuming that means scrollable content area<br>
&lt;sgill> TabAtkins: behavior we want is if your abspos is using g grid lines do that<br>
&lt;sgill> ... if it is double auto in that axis act like normal abspos (padding edge of container)<br>
&lt;sgill> ... if grid line on one edge and auto other then you scrollable area<br>
&lt;sgill> ... current browser behavior is if you grid-row-start: 1 and end auto we put start edge on one grid line and end on the padding edge of the container<br>
&lt;astearns> ack fantasai<br>
&lt;sgill> fantasai: good problem statement<br>
&lt;sgill> ... think we should take the outer most of the padding edge vs the grid start line or end line<br>
&lt;sgill> ... basically the grid itself pushes out the effective padding edge<br>
&lt;sgill> ... things would continue to work as they do now unless they overflow in which we anchor to the appropriate edge<br>
&lt;sgill> TabAtkins: think it is ok but want to double check with Ian<br>
&lt;sgill> TabAtkins: think it is ok what fantasai said actually<br>
&lt;sgill> astearns: wish Emilio was here to see if it was ok to change<br>
&lt;TabAtkins> dholbert:<br>
&lt;TabAtkins> ping<br>
&lt;emilio> hm?<br>
&lt;sgill> fantasai: ok I think I see the potential compat issue<br>
&lt;sgill> ... seems ok though<br>
&lt;emilio> So proposal is using the bigger of grid area vs padding area?<br>
&lt;fantasai> PROPOSED: when grid-placement is fully auto in an axis, use the scrollport edges (otherwise do as specced)<br>
&lt;astearns> depending on whether things are using auto or not<br>
&lt;emilio> that seems fine iiuc<br>
&lt;fantasai> RESOLVED: when grid-placement is fully auto in an axis, use the scrollport edges (otherwise do as specced)<br>
</details>


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Received on Wednesday, 5 August 2026 15:28:28 UTC