Boy, does CSS hate me

Hello.

One night I was designing a page in dreamweaver using CSS. Then, I uploaded it and BAM, like a speeding trucker I ran into a roadblock. A big, nasty one that kept me from making an inch of progress. Here’s my problem:

This is how the page looks online in firefox.

This is how the page looks in dreamweaver.

Completely different. What gives? Thanks in advance. Oh, and here’s my CSS.