[csswg-drafts] [css-gaps-1] Introduction of `auto` for `rule-break` properties. (#13127)

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

== [css-gaps-1] Introduction of `auto` for `rule-break` properties. ==
We would like to introduce an `auto` keyword for the [`rule-break`](https://www.w3.org/TR/css-gaps-1/#break) properties.

The goal is for `auto` to become the **initial value** for all `rule-break` longhands, with its resolved value depending on the layout type and axis. This makes the behavior future-extensible across layout models, and allows us control the default behavior to preserve reading behavior across different layout types.

## Proposed resolution behavior

### Grid containers
For grids, the default behavior would align naturally with how spanning items interrupt gap decorations:

- `rule-break: auto`
  - `column-rule-break: auto` → `spanning-item`
  - `row-rule-break: auto` → `spanning-item`

### Flex containers
Flex layouts do not have spanning behavior, so `auto` resolves to no interruptions:

- `rule-break: auto`
  - `column-rule-break: auto` → `none`
  - `row-rule-break: auto` → `none`

### Multicol containers
For multicol layouts, `auto` would currently resolve the same as Flex (pending resolutions in related issues):

- `rule-break: auto`
  - `column-rule-break: auto` → `none`  
    *(subject to change depending on future multicol decisions)*
  - `row-rule-break: auto` → `none`



Even though today many of these resolved values would look similar across layout types, defining `auto` now makes the model extensible if new break behaviors or layout models are added in the future.


Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/13127 using your GitHub account


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Received on Thursday, 20 November 2025 18:54:30 UTC