ul {
  padding: 0;
  margin: 0;
  list-style: none;
}
  
li {
  float: left;
  position: relative;
}
  
li ul {
  display: none;
  position: absolute; 
  top: 18px;
  left: 0;
}
  
li > ul {
	top: auto;
	left: auto;
}

li:hover ul, li.over ul {
	display: block; 
}