1577002 - multicol element max-content size doesn't account for wide content, when column-count and column-width are both specified

Status: NEW

(Core :: Layout: Columns, defect, P3)

Description

[Daniel Holbert [:dholbert]]

Attachment: testcase 1

STR:

1. Load attatched testcase

ACTUAL RESULTS:
All of the red-bordered boxes are the same width, and all of the blue-bordered boxes are the same width.

EXPECTED RESULTS (just from a compat-with-Chrome perspective):
The bottom red/blue boxes should perhaps be wider to account for their wider content.

I'm pretty sure the spec doesn't define the correct behavior right now, so I'm simply filing this as a known incompatibility at this point.

Note on the spec:
https://www.w3.org/TR/css-multicol-1/#cw says U is the used width of the multi-column element, and that's used as an input for determining the resolved column-width and column-count. There's a green box that says This specification does not define how U is calculated, and it references css3-box and css3-sizing which are expected to define this (but do not define it currently AFAICT).

Comment 1

[Daniel Holbert [:dholbert]]

(This compat bug is the root of https://webcompat.com/issues/38365 BTW. The site there expects the Chrome behavior.)

Comment 2

[Thomas Wisniewski [:twisniewski]]

Removing the webcompat priority for now, as we don't have any known site breakage right now (the site reported here has a completely different layout now without the issue).