This is not a bug since User Agents are free to use any default style sheet. I do think margins values should be zero in the browser's default style sheet, though. For a test case, See issue #6 in the attached URL

There actually isn't a margin on the DIVs. The parser is inserting a "Text <\n\n>" between them (probably correctly), and we're laying out a blank line of text. Should the (completely whitespace) text have a 0 height?

I'm slightly confused. By setting DIV { margin: 0 } in the test documetn, I'm able to remove the spacing between the two DIV elements. So it seems like the margin has something to do with it. I suggest making DIV { margin:0 } the default behavior (but you are, of course, free encode this any way you want interally) BTW, I tested Nav4 and the existance of a DIV elemement didn't seem to alter the spacing between the elements, so I think this is the best behavior for backwards compatibility as well.

DIV margins (top/bottom) are going to be auto for backwards compatability.

Verifying as fixed, Seamonkey Feb4