Is there a current bug with FireFox 3 relating to clearing a float and it ignoring negative margins?

I've been doing some Googling, but haven't really f开发者_Python百科ound a straight answer. I'm curious to know if Firefox 3 has a bug when trying to apply a negative margin to a div that is either clearing a float or contains another element being floated?

Firefox seems to ignore the negative margin, but Web-kit browses respect it accordingly.

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After a lot of trial and error I read a few related snippets on display: inline-block; and after adding that to the div I am applying the negative margin, margin-top: -10px; it worked.