If you'll check previous messages, you'll see that this has been discussed before for different things like tables. Basically, the browsers simply aren't compatable with each other. I used to have a terrible time with tables. In Netscape, they looked great, but IE squashed them up. I ended up working around it to make them look the way I wanted.
All this means you only have two choices: 1) You put up a notice saying "Works best with Internet Explorer" and provide a link for a download (which can alienate some of your audience) or 2) you can tailor your web site to work in both browsers.