codice:
<!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=utf-8" />
<title>Documento senza titolo</title>
<style type="text/css">
<!--
#cont {
	display:block;
	position:relative
}
#cont span {
	background:#FF0000;
	position:absolute;
	top: 0;
	left: 0;
}
#cont a:hover span {
	background:#0000FF;
	position:absolute;
	top: 0;
	left: 0;
}
-->
</style>
</head>

<body>

<div id="cont">
	<span>clicca qui</span>
</div>

</body>
</html>