286036 - Margin not filled with background color when outer div has no border

Status: RESOLVED INVALID

(Core :: Layout, defect)

Description

[Erlend Oftedal]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.6) Gecko/20050223 Firefox/1.0.1
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.6) Gecko/20050223 Firefox/1.0.1

See the example HTML-code below. When the outer div has a border, the margins of
the inner div are filled with the outer div's background color. When the border
is removed only left and right margin are filled, while the top and bottom
margin are left white.

<div style="width: 400px; margin: 0px; padding: 0px; background-color: red;
border: 1px solid #000;">
<div style="padding: 0px; margin: 5px 5px 5px 5px;">
width: 100px; margin: 0px; padding: 0px; background-color: red; border: 1px
solid #000;
</div>
</div>
<div style="width: 400px; margin: 0px; padding: 0px; background-color: red;">
<div style="padding: 0px; margin: 5px 5px 5px 5px;">
width: 100px; margin: 0px; padding: 0px; background-color: red;
</div>
</div>

Reproducible: Always

Steps to Reproduce:
1. Create a file with the HTML from details
2. Open the file in firefox :)

Actual Results:  
Margin top and bottom are not filled for the lower div

Expected Results:  
Margin top and bottom should have been filled

Comment 1

[Richard Brodie]

I think it's just normal collapsing margins at work here; the inner DIV margin
can overspill the outer when there is no border. Also Firefox and Opera have the
same layout here, they're not often both wrong.

See: http://www.w3.org/TR/CSS21/box.html#collapsing-margins

Comment 2

[Hermann Schwab]

Attachment: reporter´s testcase

Comment 3

[Boris Zbarsky [:bzbarsky]]

Comment 0 is right on; we're doing exactly what the spec says to do.