Re: [csswg-drafts] [css-gaps-1] Gap intersections for multicol containers (#12784)

It occurred to me that the same question @jav099 posed for multicol also comes up for flexbox, and they should probably have the same answer.

Re-reading [the definition of flex container gaps](https://www.w3.org/TR/css-align-3/#gap-flex), I think it would make sense to do the flexbox equivalent of Option 1 (here I've colored the entirety of each gap and placed crosshairs at each "intersection point"):
<img width="528" height="367" alt="Image" src="https://github.com/user-attachments/assets/34fc15fe-d0a8-4a15-9432-99d928e541d0" />

However, right now, the spec calls for the flexbox equivalent of Option 2, placing cross-axis intersection points in the centers of main-axis gaps:
<img width="525" height="362" alt="Image" src="https://github.com/user-attachments/assets/b7a8c31e-dfeb-419d-b652-9f3a538e0f9b" />

That has some parallels with how we place intersection points in Grid, and it makes it simpler to continue decorations through flex lines when items line up with each other. But upon reflection, I think Option 1 is more in line with how flex layouts should be read.

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Received on Tuesday, 23 September 2025 23:00:05 UTC