Float: left; behaving strangely in F-fox

Guys this is freaking me out - im starting to wonder if ive gone completely bonkers and am doing something really stupid…

this is my HTML

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
    <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
    <meta name="description" content="bla" />
    <meta name="keywords" content="bla" />
    <style type="text/css">
        #leftPanel {
            width: 230px;
            height: 590px;
            background-color: #000000;
            float: left;
        #topBanner {
            width: 500px;
            height: 230px;
            background-color: #666666;
        #nav {
            width: 500px;
            height: 40px;
            background-color: #C6C8CA;
            border-top: 4px solid #939598;

    <div id="leftPanel">
    <div id="topBanner">
    <div id="nav">


now youd think that the “leftPanel” div, with its height and width set, and a float: left set, would make all the following divs float next to it…which it does in IE…but in Ffox 2 it brings the divs up but ignores the width of the leftpanel div…

Please help me understand this! Whats going on?!?!?

Is it an FFox2 glitch? :huh: