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Re: [CSS21] Collapsing Margins

From: Lachlan Hunt <lachlan.hunt@lachy.id.au>
Date: Tue, 09 Sep 2008 17:16:14 +0200
Message-ID: <48C6933E.1020400@lachy.id.au>
To: Bruno Fassino <fassino@gmail.com>
Cc: www-style <www-style@w3.org>

Bruno Fassino wrote:
> On Tue, Sep 9, 2008 at 12:55 PM, Lachlan Hunt wrote:
>> [1] http://lachy.id.au/dev/css/tests/adhoc/collapsing-margins-01.html
>> [2] http://www.w3.org/TR/CSS21/box.html#collapsing-margins
> There has recently been an accepted change of the wording of the 8.3.1
> paragraph that you mention, see [3]. This doesn't change the requested
> behavior except in some edge cases. Whichever the formulation of the
> spec, in your test case there should be no collapsing, If I understand
> well.
> Indeed the 'used height' of the element (body)  is affected by the
> min-height rule:
>  - it is equal to min-height (so there should be no collapsing
> according to the current formulation)

Yes, that's what I thought.

>  - it is NOT equal to what it would have been if min-height were its
> initial value (so there should be no collapsing according to the
> accepted change either)

OK, but what about this case instead.  Given the same HTML, but using 
this CSS instead:

body { min-height: 50px; margin: 0; padding: 0; }
div { height: 20px; margin-bottom: 80px; }

In this case, the height of the body would be 50px.  But the height of 
the div plus it's margin is 100px, so should the margin collapse through 
the body element by 50px?

Lachlan Hunt - Opera Software
Received on Tuesday, 9 September 2008 15:16:53 UTC

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