HELP :Horizental Menu for iphone

I added below CSS but it's not working

#hmenu {
float:left;
width:100%;
background:#fff;
border-bottom:4px solid #000;
overflow:hidden;
position:relative;
}
#hmenu ul {
clear:left;
float:left;
list-style:none;
margin:0;
padding:0;
position:relative;
left:50%;
text-align:center;
}
#hmenu ul li {
display:block;
float:left;
list-style:none;
margin:0;
padding:0;
position:relative;
right:50%;
}
#hmenu ul li a {
display:block;
margin:0 0 0 1px;
padding:3px 10px;
background:#ddd;
color:#000;
text-decoration:none;
line-height:1.3em;
}
#hmenu ul li a:hover {
background:#369;
color:#fff;
}
#hmenu ul li a.active,
#hmenu ul li a.active:hover {
color:#fff;
background:#000;
font-weight:bold;
}