A div with auto width expands horizontally filling the whole available area.
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html>
<head>
<title> div with auto width </title>
<style type='text/css' media='all'>
div {
width: auto;
border: thin solid black;
}
</style>
</head>
<body>
<div> this is a test.
</div>
</body>
</html>