codice:
ul {
  margin: 0;
  padding: 0;
  width: 100%;
}

li {
display: inline; /* ie5+  win */
float: left;
margin: 0 0.5em;
padding: 0;
}

a {
display: block;
width: 5em;
float: left;
padding: 0.2em 0;
margin: 0;
text-align: center;
font-weight: bold;
text-decoration: none;
}