#nav_styled {
left: 50%;
margin-left: -272px;

width: 540px;
height: 25px;
padding: 0;
background: url('image_replacement_menu.png');
position:absolute;
z-index: 20;
margin-top: 10px; *margin-top: 130px; 
}


#nav_styled li {
display: block;
height: 25px;
margin: 0;
padding: 0;
list-style: none;
position: absolute;
top: 0;
}


#nav_styled li a {
display:block;
height:50px;
}


li#i1 {
left: 0px;
width: 145px;
}

li#i2 {
left: 255px;
width: 90px;
}

li#i3 {
left: 460px;
width: 140px;
}


#nav_styled li a {
text-indent: -9000px; 
background-color:transparent; 
}

#i1 a:hover {
background: transparent url(image_replacement_menu.png) 0px -30px no-repeat;
}
#i2 a:hover {
background: transparent url(image_replacement_menu.png) -255px -30px no-repeat;
}
#i3 a:hover {
background: transparent url(image_replacement_menu.png) -460px -30px no-repeat;
}