1100582 - margin-top animation behaves different with css border presence at the parent node

Status: UNCONFIRMED

(Core :: Layout, defect)

Description

[/\/\arcio Galli]

I have two  cases: 

1) http://taboca.github.io/TagVisor/center-border.html 

2) http://taboca.github.io/TagVisor/center.html

The case 1) is correct, as designed.The only difference it 1px border which is placed in a DIV a div that is the parent for an inner DIV which is animated to become in the center (animation in the inner DIV is margin-top). 

If you say that this is a bug I can *try* to produce a testcase.

Comment 1

[Boris Zbarsky [:bzbarsky]]

It's not clear whether this is a bug, but chances are you're getting margin collapsing.  Whether you _should_ be getting it is hard to tell.  A page that just has the static rules for the point when you think things look wrong would make it a lot simpler to tell.

Comment 2

[/\/\arcio Galli]

Thanks, Boris, for this note — I think I had an old interaction bug with you guys where I learned a bit about the margin collapsing problem. I will re read that bug to understand. 

BTW the same happens with Chrome.

Comment 3

[Boris Zbarsky [:bzbarsky]]

That makes it pretty likely that this is a margin collapsing issue and not a bug, fwiw.