div#menu {width: 100px;}
div#menu ul {padding: 0; width: 100px; border:1px solid; margin:0px; }
div#menu li.sousmenu {background: yellow;} /*fond jaune pr les sous-menu*/
div#menu ul li {position:relative; list-style: none; border-bottom:1px solid;}
div#menu ul ul {position: absolute; top: 0; left: 100px;}
div#menu li a {text-decoration: none;}