Need HTML help!

Can someone more html savvy than I tell me what is going on here? No matter what I do, now both IE and Firefox drop my most recent post down until it starts below my sidebar (links and such to the right). Not sure what is going on here. It wasn't doing it at all, then it did it (without any changes by me) in IE. Now that I have downloaded Firefox 1.5, it's doing it with that one too.

A part of the html reads: .blogPost{margin:3px 0px 30px 0px;background:transparent;font-size:100%;} - even if I change that so it reads
.blogPost{margin:3px 200px 30px 0px;background:transparent;font-size:100%;} it still drops it down.