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

jav099 has just created a new issue for https://github.com/w3c/csswg-drafts:

== [css-gaps-1] Gap intersections for multicol containers ==
**Background**  
We resolved [csswg-drafts#12084](https://github.com/w3c/csswg-drafts/issues/12084) to allow intersections at the border of spanners when gaps are present.

**Open question**  
For containers using `row-wrap: wrap`, what default behavior should gap decorations have? The [reference diagram](https://github.com/w3c/csswg-drafts/issues/11976#issuecomment-2753981259) is helpful context.

We see two plausible approaches:

### Option 1 — Intersections at multicol line boundaries
Intersections are placed at the start/end of each multicol line. Decorations do **not** span the gaps created by `row-wrap` unless the author opts in (e.g., via `rule-outset`).

Example:  
<img width="1005" height="537" alt="Image" src="https://github.com/user-attachments/assets/3ab43d64-c429-4cb0-b6a9-d7558114f5dd" />

### Option 2 — Intersections at the center of row/column crossings
Intersections are placed at the midpoint where a row gap crosses a column gap. Decorations effectively “bridge” row gaps by default—similar to how a grid might behave—so rules continue across those breaks. While visually coherent, this may be less aligned with multicol semantics.

Example:  
<img width="834" height="560" alt="Image" src="https://github.com/user-attachments/assets/88aaa85c-73a1-449c-a28e-b2de6cafd705" />

---

**Request for feedback**  
We’d appreciate input, especially from folks steeped in multicol and from web authors, on which of these should be the default behavior:

- Should decorations stop at `row-wrap` breaks unless explicitly extended (Option 1)?  
- Or should they span across by default, meeting at row/column gap centers (Option 2)?  

Thanks in advance!


Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/12784 using your GitHub account


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Received on Thursday, 11 September 2025 22:40:37 UTC