I've recreated an example of the page but the problem doesn't occur in that simplified version. I'm really wondering what's causing it.
HTML Code:
<!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">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=windows-1250" />
<title>anchor problem</title>
<style type="text/css">
<!--
.margin_merging_stopper {
height: 0;
margin: 0;
}
#header {
position: relative;
height: 5em;
background-color: lime;
}
#menu {
position: absolute;
right: 0px;
bottom: 0px;
background-color: aqua;
}
#main {
background-color: orange;
}
#sidebar {
float: left;
width: 5em;
background-color: green
}
#content {
background-color: yellow;
margin-left: 5em;
}
#gallery {
background-color: purple;
}
#thumbnails {
background-color: red;
float: right;
}
-->
</style>
</head>
<body>
<div id="header">
<h3>logo and intro</h3>
<div id="menu">
<ul>
<li>page 1</li>
<li>page 2</li>
<li>...</li>
</ul>
</div>
</div>
<div id="main">
<div id="sidebar">
<h3>links and misc</h3>
</div>
<div id="content">
<p class="margin_merging_stopper"> </p>
<h3>useful information</h3>
<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Maecenas est. Etiam non odio. Aenean feugiat ultricies turpis. Maecenas faucibus felis in pede. Vestibulum ante ipsum primis in faucibus orci luctus et ultrices posuere cubilia Curae; Sed laoreet, risus non iaculis aliquet, augue est pharetra augue, in mollis dui nulla eget augue. Morbi sit amet magna ut nibh consectetur sodales. Nam gravida neque bibendum orci. Donec rutrum lacus nec neque. Fusce metus. Curabitur adipiscing malesuada felis. Integer sem augue, venenatis sed, faucibus non, vulputate ac, eros. Integer blandit felis non augue. Fusce arcu neque, sollicitudin et, consectetur nec, porta at, odio. Morbi vel lacus at ligula dignissim vehicula.</p>
<div id="gallery">
<div id="thumbnails">
<ul>
<li><a href="#gallery">thumbnail 1</a></li>
<li><a href="#gallery">thumbnail 2</a></li>
<li>...</li>
</ul>
</div>
<h3>image and thumbnails</h3>
<p>Curabitur dignissim fermentum dui. Suspendisse at neque id velit suscipit hendrerit. Vestibulum nisl neque, blandit at, egestas eget, malesuada a, mauris. Nunc consectetur mi quis nisi. Cum sociis natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. Nullam dictum, tellus vitae luctus vehicula, urna lacus euismod dui, eu dapibus felis nulla vitae odio. Suspendisse potenti. Fusce at magna. In sit amet mi sit amet odio condimentum dapibus. Nullam id dui. Suspendisse semper, leo non auctor adipiscing, nisi ipsum eleifend nulla, et pretium odio lorem at libero. Suspendisse pharetra. Morbi metus tellus, posuere ac, hendrerit a, ornare ut, magna. Donec pellentesque arcu vel diam euismod pretium. Phasellus at ipsum. Etiam lacinia, eros non ornare consequat, libero dolor elementum justo, at mollis urna libero vel orci. Duis ultrices. Duis luctus. </p>
</div>
<p>Sed condimentum. Nullam nulla dolor, feugiat vel, bibendum ut, luctus sed, risus.</p>
</div>
</div>
</body>
</html>