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Re: [CSS2.1] Clarifying 8.3.1 Collapsing Margins

From: Anton Prowse <prowse@moonhenge.net>
Date: Fri, 20 Aug 2010 19:49:08 +0200
Message-ID: <4C6EC014.7090901@moonhenge.net>
To: fantasai <fantasai.lists@inkedblade.net>
CC: "www-style@w3.org" <www-style@w3.org>
On 19/08/2010 20:35, fantasai wrote:
> On 08/18/2010 12:25 PM, Anton Prowse wrote:
>> On 18/08/2010 10:11, fantasai wrote:
>>> This is for CSS2.1 Issue 159
>>> http://wiki.csswg.org/spec/css2.1#issue-159
>>> triggered by this email
>>> http://lists.w3.org/Archives/Public/www-style/2010Feb/0015.html
>>>
>>> This is version 2.

>>> | If the top and bottom margins of a box are adjoining, then it is
>>> | possible for margins to collapse through it. In this case, the
>>> | position of the element depends on its relationship with the other
>>> | elements whose margins are being collapsed. [...]
>>
>> As above:
>> s/are adjoining/collapse/
>>
>> and, for readability,
>> s/for margins/for other margins/
> 
> Fixed.
> 
>> Anyhow, this sentence was never correct, since there may not be any
>> other margins involved and so the applicability of this part is not just
>> restricted to "this case". Really, the whole sentence needs changing:
> 
> The sentence is correct. Even if no other elements are involved,
> the element's own top and bottom margins do collapse through its
> own box.

Ah, I was interpreting the "for margins" as "for other margins" in the
sentence I quoted above, hence my suggested change.  This is not what
the spec intends, so please ignore that suggestion.

However, we do still need
s/are adjoining/collapse/
which is missing from your Version 3; we need to define the position of
a collapsed-through element even when its top and bottom margins are not
adjoining, which would be when it has a (necessarily self-collapsing) child.

Cheers,
Anton Prowse
http://dev.moonhenge.net
Received on Friday, 20 August 2010 17:51:16 GMT

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