787310 - <ul> with moz-column-count does not account for margin-top on <li>s

Status: RESOLVED INVALID

(Core :: Layout, defect)

Description

[Kyle Kalstabakken]

Attachment: Test case

Create a <ul> with moz-column-count:3
Create six <li> (with content) and margin-top:20px

Actual Result:
First <li>s in columns 2 and 3 have no top margin, causing the first column to look offset

Expected Result:
All <li>s have a top margin of 20px

Example html is attached.

Comment 1

[Loic]

It's a recent regression in Firefox 17.

m-c
good=2012-07-20
bad=2012-07-21
http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=3a05d298599e&tochange=446b788ab99d

Suspected bug:
Mats Palmgren — Bug 616722 - Make ColumnSetFrame a block margin root. Make the first column a margin root at the top edge, and the last column at the bottom. r=roc

Comment 2

[Mats Palmgren (inactive)]

This is an intentional change.  The tests in bug 616722 covers this case.

Comment 3

[Kyle Kalstabakken]

Could you please explain why this behavior is desired? For me at least it is completely unexpected and unintuitive, so I would like to understand the rationale behind it.

Comment 4

[Mats Palmgren (inactive)]

Sure, the rationale is that margins at column breaks should behave the
same as at page breaks, i.e. margins are suppressed at the top of
a column/page break, except if it's a forced break, then the margins
should appear.  That's what Elika (who writes the spec[1]) told me
when I asked her about it, IIRC.

[1] http://www.w3.org/TR/css3-break/