#menu_hori { width: 100%; background: #CCFFFF; float: left; }
#menu_hori ul { list-style: none; margin: 0; padding: 0; float: left;} 

#menu_hori a, #menu_hori h2
  { font: bold 11px/16px arial, helvetica, sans-serif;
  display: block; border-width: 1px; border-style: solid;
  border-color: #ccc #888 #555 #bbb;
  margin: 0; padding: 2px 3px; } 
#menu_hori h2 { color: #000000; background: #CCFFFF;} 
#menu_hori a { color: #000; background: #CCFFFF; text-decoration: none; }
#menu_hori a:hover { color: #a00; background: #fff; }
#menu_hori li {position: relative;} 
#menu_hori ul ul { position: absolute; z-index: 500; }
#menu_hori ul ul ul { position: absolute; top: 0; left: 100%; } 

div#menu_hori ul ul,
div#menu_hori ul li:hover ul ul,
div#menu_hori ul ul li:hover ul ul {display: none;} 
div#menu_hori ul li:hover ul,
div#menu_hori ul ul li:hover ul,
div#menu_hori ul ul ul li:hover ul {display: block;}