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>
    <title>Pagina senza titolo</title>
</head>
<body>
    <div id="banner" style="border:1px red solid; background-color:Yellow; height:100px;" onmouseover="this.style.height='650px';" onmouseout="this.style.height='100px';">x</div>
</body>
</html>