167210 - BR element before H2 causes extra spacing

Status: RESOLVED INVALID

(Core :: Layout, defect, P3)

Description

[/\/\arcio Galli]

I will add one testcase that demonstrates the problem. The first BR Element that
is next to the H2, causes some extra spacing.

Comment 1

[/\/\arcio Galli]

Attachment: simple testcase.

Testecase table with 4 columns. 

Col 1 = have two H2 elements next to each other
Col 2 = Have one h2, br and another h2
col 3 = have one h2, br, br, h2
col 4 = have one h2, br, br, br, h2

note that the difference of height space between 2-3-4 is one br. however the
diff between col 1 and 2 is more than one BR.

Comment 2

[Henri Sivonen (:hsivonen) (on vacation)]

I think this one is INVALID. In the first column, margin collapising occurs, but
in the second column there's an element between the headings so margin
collapsing  does not occur and, threfore, both the margin-bottom of the top
heading and the margin-top of the bottom heading are in effect.

Comment 3

[Jay Carson]

Henri, here are some questions/comments back:

[1]
So what is "margin collapsing" exactly?  For this test case, does this term have
to do specifically with tables, meaning the margins within the columns or
something like that?

[2]
So how can the HTML be changed to "correct" the behavour?  Meaning: How can it
be made such that in the first column in the test case, there is no whitespace
between the two lines?  ( I tried modifying the test case #1 such that the first
column has 200 pixels of horizontal width, to see if that's what you mean by
margins as far as margins/word wrap within the column, but the white space is
still there between the two text lines, even though the text is not hitting the
right edge/margin of its cell. )

[3]
If "margin collapsing" in this case --is-- specific to tables, then I've
attached a second test case that is even more extreme (even more extremely
buggy) that shows a non-tables version, with a single BR between two H2 text
blurbs, and it seems to show 3 blank H2-sized lines between the two text
blurbs/lines (!!!!) even though only on BR in the source code exists between them.

Comment 4

[Jay Carson]

Attachment: Test Case #2 (non-tables version of same bug; looks even more buggy)

Comment 5

[Henri Sivonen (:hsivonen) (on vacation)]

Attachment: zero top and bottom margins for h2

> So what is "margin collapsing" exactly?

http://www.w3.org/TR/REC-CSS2/box.html#collapsing-margins

> For this test case, does this term have to do specifically with tables,

No.

> So how can the HTML be changed to "correct" the behavour?  Meaning: How 
> can it be made such that in the first column in the test case, there is 
> no whitespace between the two lines?

h2 {
  margin-top: 0;
  margin-bottom: 0;
}

Comment 6

[Henri Sivonen (:hsivonen) (on vacation)]

Marking INVALID as per comment #2.