Firefox has got me foxed

My blog Sandy Beach Almanac -- when I tried looking at it in Firefox, the posts column was down the bottom of the page below the sidebar, instead of next to the sidebar. Any codies out there who can tell me why the changes I make to the width of things in the template don't seem to get this to work? Of course, half the pages I've looked at in Firefox are always crazy in some way (typical example: Google Adsense ads that wiggle) ... I still can't figure why so many people like it, but maybe it's just me. Anyway, I'd like that blog to look right for Firefox users. Ta.