CSS Errors in Theme

I’m stumped.

I created the webpage: http://www.sustainableaustin.org/

Then I inserted wordpress into it using the loop. That all works fine, but when you click on a post title or archive it took you to kubrick. To fix that I went ahead and made my own theme using the exact same code I used on the homepage.

But now when you click on a post or archive the layout is goofed out. The floats arent working and the size seems to be off. Is there something obvious that I’m missing? It seems like the CSS isnt being read properly… because the fonts change…

I’d really appreciate it if anyone could help me out. Thanks.