1957739 - [wpt-sync] Sync PR 51773 - layout: Allow collapsing bottom margins with any indefinite block size

Status: RESOLVED FIXED

(Core :: CSS Parsing and Computation, task, P4)

Description

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Sync web-platform-tests PR 51773 into mozilla-central (this bug is closed when the sync is complete).

PR: https://github.com/web-platform-tests/wpt/pull/51773
Details from upstream follow.

Oriol Brufau <[e-mail]> wrote:

layout: Allow collapsing bottom margins with any indefinite block size

According to CSS2, the bottom margin of a block container can collapse with the bottom margin of its last in-flow child if height computes to auto.

However, according to CSS Sizing, that was "legacy spec prose" and should be interpreted as "behaves as auto".

Therefore, cyclic percentages and intrinsic keywords like min-content shouldn't prevent margin collapse, because they behave as auto.

This change aligns Servo with Gecko and Blink, but diverges from WebKit.

https://www.w3.org/TR/CSS22/box.html#collapsing-margins
https://www.w3.org/TR/css-sizing/#behave-auto

Testing: TBD

Reviewed in servo/servo#36278

Comment 1

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Pushed to try (stability) https://treeherder.mozilla.org/#/jobs?repo=try&revision=bb5e3a5bf445d1fbbe2ef2db45d927ab8e9381e5

Comment 2

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

CI Results

Ran 0 Firefox configurations based on mozilla-central, and Firefox, and Chrome on GitHub CI

Total 5 tests

Status Summary

Firefox

PASS: 5

Chrome

PASS: 5

Links

GitHub PR Head
GitHub PR Base

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/1ee4a27f4f3f
[wpt PR 51773] - layout: Allow collapsing bottom margins with any indefinite block size, a=testonly

Comment 4

[Sandor Molnar[:smolnar]]

https://hg.mozilla.org/mozilla-central/rev/1ee4a27f4f3f