FireFox doesn't handle what you want the same as IE does. Quite frankly, I prefer IE's idea for it over FF, but to each their own.
I've developed a cross-browser layout which will work, if you add a centering wrapper div to the equation. This layout is unique in that it presents the content first and foremost.
3-column fixed width layout, with header and footer
Additional CSS required:
Code:
#centeringdiv {
margin-left: auto;
margin-right: auto;
margin-top: 0;
margin-bottom: 0;
padding: 0;
width: (your width here);
position: relative; /* This is so the absolutely positioned elements position properly. */
}
Additional HTML required:
Code:
<body>
<div id="centeringdiv">
....your HTML here
</div>
</body>
Give that a go and see how it works out for you.