Delicate theme how to center navigation bar

Please can someone help i dont now how to center navigation bar

/* =Navigation
————————————————————– */
#menu {
padding-top: 5px;
}
.topnav {
z-index: 99;
margin: 0;
padding: 0;
list-style: none;
line-height: 1;
}
.topnav li {
padding-right: 90px;
}
.topnav a {
position: relative;
text-transform: uppercase;
font-size: 17px;
display: block;
z-index: 100;
padding: 5px 0px;
line-height: 18px;
text-decoration: none;
font-family: “Trebuchet MS”, Arial, Helvetica, sans-serif;

}
.topnav a:hover {
text-shadow: 0 1px 1px rgba(0, 0, 0, 0.1);
}
.topnav li {
float: left;
width: auto;

}
.topnav li a.sf-with-ul {
padding-right: 0px;
}