Ok so I have had a look though you code and notice that you have used positioning once, and that was on the searchbar, although it wasn’t actually positioned anywhere lol
You are using a 545px margin to position your sidebar, if you are using padding and margin to position elements in other parts of your site, which I have not had chance to look at – you are going to have issues cross browser, like you have…
I wrote this for you!!!
After you have read that you might want to rethink they way you lay everything out :) – I hope it helps!!!