fixed elements shrinking for no apparent reason

[Abby]

I'd rather not make these pages live yet, but while testing it on my local computer, I'm encountering a really mysterious and frustrating problem. I don't even know what section of the code to paste here, since I have absolutely no clue what's causing it.The same set of CSS and HTML works fine for four pages. But for the fifth page, all the fixed elements (the left menu, specifically) shrink.I've ruled out everything obvious. I'm not using percentages. The fixed elements are exactly the same in the pages that work, and the page that doesn't work.My best guess is it's a conflict between style sheets. But I've systematically tested every style-defined element--removed them and put them back--and nothing affects the problem.Is there any known bug that would cause this?The CSS (excerpt):

body {width:100%;height:100%;font-size:100%;font-family:'Trebuchet MS', Helvetica, sans-serif;text-align:left;color:#ffc;background-color:#003;}img {border:none;}ul, div, a, p, h1, h2, h3, h4, h5, h6 {padding:0; margin:0;}.center {display:block;text-align:center;margin:0;padding:0;overflow:visible;}.small {font-size:85%;}.dark {color:#003;}a {color:#aff; outline:none;}a:hover {color:#6fb;}#home { /* home flower */width:132px;height:127px;position:fixed;top:2px;left:0;z-index:2;padding:0;margin:0;}#home a {display:block;width:132px;height:127px;padding:0;margin:0;outline:none;}#fade {position:fixed;top:0; left:0;z-index:0;width:150px;height:100%;padding:0;margin:0;}#decobox {position:fixed;top:120px; left:0;z-index:1;width:147px;height:437px;padding:0;margin:0;}#hometext {display:block;color:#ffc;font-size:80%;position:fixed;top:2px; left:2px;z-index:2;padding:0;margin:0;}#sitemap {width:142px;position:fixed;bottom:2px; left:2px;z-index:2;padding:0;margin:0;}#sitemap a {  display:block;  color:#000;  font-size:95%;  text-decoration:none;}#sitemap a:hover {  display:block;  color:#ffc;} /* left menu */#menu {font-size:100%;font-weight:bold;width:142px;height:auto;position:fixed;top:136px; left:0;z-index:4;padding:0;margin:0 0 0 2px;}#menu ul {list-style:none;}#menu li {color:#000;padding-left:4px;margin:0 0 4px;}#menu li a, #menu li a:link {color:#000;font-weight:bold;text-decoration:none;outline:none;}#menu li a:visited {color:#000;}#menu li a:hover {color:#ffc;}#menu li a:active {color:#600;}  #menu ul.sub {  list-style-position:outside;  list-style-image:none;  padding-left:10px;  overflow:hidden;  }  #menu ul.sub li.current a{  background-color:#af7;  font-weight:bold;  padding-left:5px;  padding-right:5px;  }  #menu ul.sub li.current a:hover{  color:#000;  font-weight:bold;  }  #menu ul.sub li {  padding-left:16px;  background:transparent url('../images/menu/bullet1.png') no-repeat;  background-position:0;  margin:0;  }  #menu ul.sub a {  font-weight:normal;  text-decoration:none;  }  #menu ul.sub a:hover {  color:#ffc;  font-weight:bold;  }

The HMTL:

<div><img id="fade" src="images/bg/cyanfade.png" alt="fade"></div><div><img id="decobox" src="images/bg/decobox.png" width="147px" height="437px" alt="decobox"></div><div id="hometext">HOME</div><div id="home"><a href="http://art.abbygoldsmith.com"><img src="images/menu/i_homefl.png" width="132px" height="127px" alt="art home"></a></div><ul id="menu">  <li>ANIMATION    <ul class="sub">    <li><a href="testanimation.html">Demo Reel</a>    <li><a href="testsprites2.html">Sprite Art</a>    <li><a href="teststudentfilms.html">Short Films</a>    <li><a href="test3dgames.html">3D Games</a>    <li class="current"><a href="testflash.html">Flash</a>    <li><a href="">Résumé</a>    </ul>  <li><a href="" title="Illustrations">ILLUSTRATION</a>  <li><a href="" title="Concept Art">DESIGN</a>  <li><a href="" title="Life Sketches">FINE ART</a>  <li><a href="" title="Aliens">FREE STUFF</a></ul><div id="sitemap"><a href="http://abbygoldsmith.com/sitemap" title="sitemap">Sitemap</a></div>

[Abby]

Holy crap!!! The problem had nothing to do with code. I'd resized the page using Windows CTRL -, and my FF browser apparently saved that info for that page.