CSS: Horizontally Centered List

gistfile1.txt

#centeredmenu {
   float:left;
   width:100%;
   overflow:hidden;
   position:relative;
}
#centeredmenu ul {
   clear:left;
   float:left;
   list-style:none;
   margin:0;
   padding:0;
   position:relative;
   left:50%;
}
#centeredmenu ul li {
   display:block;
   float:left;
   list-style:none;
   margin:0;
   padding:0;
   position:relative;
   right:50%;
}