168003 - margin-top collapsed on a floating box and adjacent box

Status: RESOLVED INVALID

(Core :: Layout, defect)

Description

[Chris Lyon]

Using build 2002091004 on WinXP

Steps to reproduce:
Create a webpage with these two lines:
<div style="float:left; width:100%;">borderless floating div</div>
<div style="border:1px solid black">bordered div</div>

Expected Results:
According to the CSS2 spec, the margins should not collapse.  Therefore, the 
border should only enclose the 2nd div

Actual Results:
Border encloses both divs.  Furthermore, adding any margin-top properties to 
the second div has no effect.

Comment 1

[Chris Lyon]

Attachment: testcase

Comment 2

[Mats Palmgren (inactive)]

Attachment: Testcase #2

Comment 3

[Mats Palmgren (inactive)]

Normally the text in the second DIV would flow to the right of the floater, but
since you specified width:100% for the floater it was pushed to the next line.
The normal flow DIV is placed regardless of any floaters, you can see that this
is the case since the floaters overlaps the borders.
DIV doesn't have a default margin, so margin collapsing isn't involved here.

See http://www.w3.org/TR/CSS2/visuren.html#floats
"Since a float is not in the flow, non-positioned block boxes created before and
after the float box flow vertically as if the float didn't exist."

--> INVALID

Comment 4

[Chris Lyon]

>Normally the text in the second DIV would flow to the right of the floater, 
>but since you specified width:100% for the floater it was pushed to the next 
line.

Yes, I agree that this is the correct behaviour.

>The normal flow DIV is placed regardless of any floaters, you can see that 
this
>is the case since the floaters overlaps the borders.

I don't quite understand what you mean.  The first div isn't overlapping the 
border, the border is resized to enclose it.
It's hard to tell in your testcase because of the yellow background.

>DIV doesn't have a default margin, so margin collapsing isn't involved here

If that is true, why doesn't margin-top:100px; work when applied to the second 
div?

Reopening until I get a more complete explaination.

Comment 5

[Chris Lyon]

Ok, I get it now.  Sorry about the spam.