Re: [CSS2.1] Clarifying 8.3.1 Collapsing Margins

On 16/09/2010 07:36, L. David Baron wrote:
> On Wednesday 2010-09-15 02:00 -0700, fantasai wrote:
>>   |   * both belong to normal-flow block-level boxes that participate
>>   |     in the same block formatting context
>
> How about changing this to something like the following two points:
>
>   * neither belongs to an out-of-flow box
>   * both belong to block-level boxes that participate in
>     the same block formatting context (where an in-flow block
>     that establishes a new block formatting context is considered to
>     participate in the block formatting context outside it)
>
> That makes it clear that the margins of 'overflow:hidden' elements
> can collapse with what's outside them but not what's inside them,
> and that margins of out-of-flows never collapse.

I agree with fantasai that participation in a block formatting context 
should be defined appropriately in 9.4.1 rather than worked around 
piecemeal in other places in the spec.

Cheers,
Anton Prowse
http://dev.moonhenge.net