the div #topmenu is empty, i.e. is not the menu you are trying to change;
start by changing the width and background image in this style in style.php:
.navigation {
background: url(images/navbar.png) no-repeat;
padding-right:0px;
font-size:12px;
position: absolute;
right: 0px;
bottom: 0px;
z-index: 6;
width: 691px;
vertical-align: baseline !important;
height: 48px;
float: right;
}
also will need changes to:
#header #navbar li { float:none; display: inline-block; }
#header #navbar{ float:none; }
and remove the fixed height from:
#header #navbar {
float:left;
height:150px;
line-height:50px;
padding-left:13px;
}
(only checked in Firefox with web developer add-on; not cross-browser tested)