To really help with this, it would be useful to have a link to your page that shows the problem. That would make it relatively easy to experiment using FF's developer extension as to what style(s) might work out best in that browser.
I have had some experience with this sort of thing though the accommodations to get it to work cross browser can be quite complex, depending upon how everything is supposed to line up.
Please post a link to the page on your site that contains the problematic code so we can check it out.
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