centering drop down menu

Can someone tell me what should I modify to make this drop down menu centered?

#coolMenu,

#coolMenu ul {

list-style: none;

}

#coolMenu {

width: 90%; margin:0 auto; position: relative;

}

#coolMenu > li {

}

#coolMenu li a {

display: block;

height: 2em;

line-height: 2em;

padding: 0 1.5em;

text-decoration: none;

}

#coolMenu ul {

position: absolute;

display: none;

z-index: 999;

}

#coolMenu ul li a {

width: 80px;

}

#coolMenu li:hover ul {

display: block;

}

I'd suggest taking this question to a more appropriate venue like StackOverflow (...also, before you make a post over there, they'll probably complain about you not providing enough info).