css.properties.column-rule-color - wrong spec and missing feature

[estelle]

What type of issue is this?

Missing compatibility data

What information was incorrect, unhelpful, or incomplete?

BCD is missing support for comma-separated values and the repeat() function.

The property is now defined in CSS gaps rather than multi-col.

This is true for column-rule color, style, and width.

What browsers does this problem apply to, if applicable?

No response

What did you expect to see?

see https://developer.mozilla.org/en-US/docs/Web/CSS/Reference/Properties/column-rule-color#formal_syntax and https://drafts.csswg.org/css-gaps-1/

Did you test this? If so, how?

bdc reflecting the new values

Can you link to any release notes, bugs, pull requests, or MDN pages related to this?

No response

Do you have anything more you want to share?

No response

MDN URL

https://developer.mozilla.org/en-US/docs/Web/CSS/Reference/Properties/column-rule-color

MDN metadata

MDN page report details

• Query: css.properties.column-rule-color
• Report started: 2026-07-01T13:30:16.977Z

[caugner]

• Old spec: <color> (https://drafts.csswg.org/css-multicol/#propdef-column-rule-color)
• New spec: <line-color-list> | <auto-line-color-list> (https://drafts.csswg.org/css-gaps-1/#propdef-column-rule-color)

Tested https://wpt.live/css/css-gaps/parsing/gap-decorations-color-valid.html locally in Chrome 150 (pass), Firefox 152 (fail), Safari 26.5 (fail), and via BrowserStack Live in Safari 27 (fail).

The question is how we model the new behavior in BCD. There seem to be multiple aspects:

1. Line color list: column-rule-color: red, green blue
2. Repeat line color: column-rule-color: repeat(2, white, black)
3. Auto repeat line color: column-rule-color: repeat(auto, #000 #fff)