Sure it is. But something you probably haven't realized yet is padding DOES count for overall width and height. If you use this for your .page CSS the content moves next to the nav.
Your HTML is a bit bad. Add this in between your head tags
font-family:Arial, Helvetica, sans-serif;
then validate your page at this site http://validator.w3.org it will tell you all of your coding errors. Word of advice. If you page looks right in IE but not FF good chance your code is wrong some how. Firefox for the most part displays what you code. IE displays what it thinks you want to see.
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">