Firefox Viewing Problems

Hey, I’m new to WordPress and no coding expert, and I was hoping for some help on this one. In Firefox, the content of any page or post slides over to the center of the screen, pushing the sidebar down below. I just discovered that it’s displaying fine in Internet Explorer, and was wondering what changes I need to make to the code to get it to play nice with Mozilla. I can post the code if needed, otherwise you can download the template here.
Thanks!

Here’s the Link to my Site