Try this css :
#content {
width: 40em;
margin: 0 auto;
padding: 40px 0;
}
ul#nav {
position: relative;
list-style: none;
margin: 0;
padding: 0;
}
ul#nav li {
position: relative;
float: left;
display: inline-block;
padding: 8px 5px 3px 5px;
margin-right: 5px;
background-color: #034a7f;
text-decoration: none;
padding: .2em 1em;
}