Untitled

<html>
<body>
<script type="text/javascript">
function menuon()
{
document.getElementById("menu").style.visibility="visible";
}
function menuoff()
{
document.getElementById("menu").style.visibility="hidden";
}
</script>
<span onmouseover="menuon();">
menu
</span>
<div id="menu" name="menu" onmouseout="menuoff();" style="background-color:rgb(0,255,0); position:absolute; top:200px; left:100px;width:200px; height:100px; z-index:30;visibility:hidden;">
SubMenu
</div>
</body>
</html>