li.menu_cascata {
position: relative;
}

ul.submenu {
display:none;
position: absolute;
top: 0px;
left: 135px;
width: 140px;
background-color: white;
border: 1px solid #888888;
z-index: 5000;
}

ul.submenu li {
position: relative;
}

li a:hover {
text-decoration: underline;
}