1949064 - Firefox fails WPT css/css-multicol/multicol-span-all-rule-002.html

Status: NEW

(Core :: Layout: Columns, defect)

Description

[Ting-Yu Lin [:TYLin] (PST, UTC-8)]

This test is part of interop-2025 Writing modes:

WPT Results
wpt.live

Based on the screenshot comparison, Firefox almost passes the test except for the scrollbar. The expected result is that no scrollbar should be present.

Comment 1

[Daniel Holbert [:dholbert]]

The scrollbar is there because the elements with column-span: all (the ones with class="span") seem to be getting sized to the height of the viewport, which makes them overflow off the bottom a bit (and generate a scrollbar). You can see its height in devtools if you hover the element, or if you add a border to it.

Probably it shouldn't be ending up that tall. In Chrome, they end up as tall as the multicol element.

Comment 2

[Daniel Holbert [:dholbert]]

Attachment: reduced testcase 1

Here's a reduced testcase. The cyan element is much too tall in Firefox, and it's what generates the scrollable overflow and causes a scrollbar to appear.

Comment 3

[Ting-Yu Lin [:TYLin] (PST, UTC-8)]

This bug might be related to bug 1095937 or bug 1570039.

Comment 4

[Jonathan Kew [:jfkthame]]

Yeah, I'm going to revisit fantasai's (unlanded) patch in bug 1095937 to see what that can offer us, as I think it may be relevant to this example.