Le 14 juil. 2012 à 12:39, John a écrit :

> On Jul 13, 2012, at 8:19 PM, Philippe Wittenbergh wrote:
> 
>> You'll need to give some more information…
> 
> Here is a link to the html file:
> 
> http://coffeeonmars.com/testing/start.html
> 
> ah..seems I DO have block-level content, but why does that cause an adding to 
> the height?

Indeed it is what I thought. The (default) margins on the <h1> are prevented to 
collapse through the outer edge of the div. That is the normal behaviour.

When the parent element (#header in your case) has no border and no padding, 
the top/bottom margins of the child block-level element merge with the margins 
of the parent block and/or or the top/bottom margins of the 
preceding/subsequent block-level element.

Borders and padding (-top/-bottom) prevent those margins form protruding 
outside of that div.

The whole mechanism is described here:
http://www.w3.org/TR/CSS21/box.html#collapsing-margins

Philippe
--
Philippe Wittenbergh
http://l-c-n.com/






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