Re: [CSS2.1] Margin collapse

On Thu, 5 Aug 2004, [ISO-8859-1] Staffan Måhlén wrote:
> 
> What is the intention of and examples of the collapse-through definition at 
> http://www.w3.org/TR/CSS21/box.html#collapsing-margins:
> "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.
> 
> * If the element's margins are collapsed with its parent's top margin, 
> the top border edge of the box is defined to be the same as the 
> parent's.
> * Otherwise, either the element's parent is not taking part in the 
> margin collapsing, or only the parent's bottom margin is involved. The 
> position of the element's top border edge is the same as it would have 
> been if the element had a non-zero top border."

An example of an element that has both top and bottom margins that 
collapse together would be the <div> in this example:

   div, p { margin: 1em; }

   <p>Test</p>
   <div></div> <!-- four margins collapse here -->
   <p>Test</p>


> I also think that the 8.3.1 section is rather elaborate description of a 
> difficult feature that often confuses authors, which should require at 
> least the following examples:
> 
> <p>...</p>
> <!-- trivial collapse here-->
> <p>...</p>
> 
> <p>...</p>
> <!-- tripple-collapse here-->
> <blockquote>
>   <p>...</p>
> </blockquote>
> 
> And possibly an example of the collapse-through feature, depending on 
> what its examples are.

Examples would be helpful, it's true.

-- 
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