Sidebar pushed down in firefox

I’m having a problem with a theme I’m creating for a site. I’m basically laying out the structure at this point before I start to really style it as I wanted to code everything from scratch (as sort of a hobby/learning experience) and I’ve wanted to implement things like custom taxonomies and custom post types. Anyway I’ve got most of the structure (except the navigation) up and working. My single problem right now is that the sidebar is pushed down to the bottom of the page on Firefox on both mac and windows. Every other browser displays it fine, even IE8 (although that one has my footer pushed up below the sidebar instead of at the bottom of the page).

One thing I noticed while trying to diagnose this using the various browser developer tools available is that FireBug shows it as being in between some <section> tags (I’m using html5) and the other browsers show it being below the <section>, if you think of the section as the container div I think it’ll give you a better idea of what I mean.

Anyway here’s my css, it’s mostly just reset followed by blank and just enough to layout some things like the sidebar and footer.

[Large chunk of CSS moderated as per the Forum Rules. Please post a link to your site instead.]