Navigationsleiste aufklappen lassen

  <div id="menu">
    <ul>
      <li class="topmenu">
        <a href="">Datei</a>
        <ul>
          <li class="submenu"><a href="index.php">Ende</a></li>
        </ul>
      </li>
      <li class="topmenu">
        <a href="">Bearbeiten</a>
        <ul>
          <li class="submenu"><a href="">alles makieren</a></li>
          <li class="submenu"><a href="">Kopieren</a></li>
	  <li class="submenu"><a href="">Einfügen</a></li>        
	</ul>
      </li>
     </ul>
  </div>

#menu {
  font-size:14px;
  position:absolute;
  
}

#menu ul {
  list-style-type:none;
  list-style-image:none;
  margin:0px;
  padding:0px;
}

#menu li.topmenu {
  float:left;
}

.topmenu a {
  float:left;
  width:110px;
  text-align:center;
}

.topmenu ul{
  display:none;
}

.topmenu a, .submenu a{
  padding:1px 5px;
  border:1px solid #000;
  border-collapse:collapse;
  color:#000;
  font-weight:bold;
  text-decoration:none;
  background-color:#CCC;
  margin:0;  
}

.submenu a{
  font-size:12px;
  width:110px;
  position:relative;
  clear:both; /* special IE6 */
}

#menu a:hover, .topmenu.on a {
  color:#FFF;
  background-color:#000 !important;
}

.topmenu:hover ul {
  display:block;  
  z-index:500;
}