RE: column-span and margin-collapsing (was: [CSSWG] Minutes and Resolutions 2011-09-21)

Also sprach Alex Mogilevsky:

 > ±  > ±    <div style="overflow: hidden; margin: 100px 0;"></div> 
 > ±  > ±    <div style="overflow: hidden; margin: 100px 0;"></div>
 > ±  >
 > ±  > But this behavior is different for what one would expect for what  
 > ±  > appeared to be your main use case:
 > ±  > 
 > ±  > 	<h1 style="column-span:all">Title</h1>	
 > ±  > 	<h2 style="column-span:all">Subtitle</h2>	
 > ±  > 	<p style="column-span:all">Abstract...</p>
 > ±
 > ± I don't understand why it's different; in Opera's implementation, collapsing would occur in 
 > ± both examples. And float crossing would not occur in any of them.
 > 
 > H1, h2 etc. are normally not BFC 

True.

 > (their margins collapse with child margin and margins collapse
 > trough empty boxes). Then simply adding margin collapsing to
 > external margins of colspan doesn't really create compatibility
 > with single-column flow.

For the simple use cases above, they would be compatible.

-h&kon
              Håkon Wium Lie                          CTO °þe®ª
howcome@opera.com                  http://people.opera.com/howcome