Here's what I have:
<!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>
<script type="text/javascript" src="/floatbox/floatbox.js"></script>
<link rel="stylesheet" type="text/css" href="/floatbox/floatbox.css" />
</head>
<body>
<div id="my_div">
<form>
<input type="text" name="my_text" />
</form>
</div>
<a href="#my_div" class="floatbox">Start</a>
</body>
</html>
I'm using Firefox 3.0.10 on Mac OS X.