1. HTML source

<div id='cssmenu'>
<ul>
   <li class='active'><a href='index.html'><span>Home</span></a></li>
   <li><a href='#'><span>Products</span></a></li>
   <li><a href='#'><span>About</span></a></li>
   <li class='last'><a href='#'><span>Contact</span></a></li>
</ul>
</div>

2. CSS source

#cssmenu ul {
  margin: 0;
  padding: 0;
  list-style-type: none;
  position: relative;
  display: block;
  height: 40px;
  text-transform: uppercase;
  font-size: 13px;
  background: transparent url('blue.jpg') repeat-x top left;
  font-family: Helvetica, Arial, Verdana, sans-serif;
  width: auto;
}
#cssmenu li {
  display: block;
  float: left;
  margin: 0;
  pading: 0;
  border-right: 1px solid #ffffff;
}
#cssmenu li a {
  display: block;
  float: left;
  color: #ffffff;
  text-decoration: none;
  padding: 12px 20px 0 20px;
  height: 24px;
  height: 40px;
}
#cssmenu li a:hover {
  background: transparent url('black.jpg') repeat-x top left;
}