#main_nav {
position: relative;
/*height: 29px;
width: 421px;
            background: url("bg.gif") no-repeat top;
*/            
overflow: hidden;
}

#main_nav li.back {
background: url("lava.gif") no-repeat right -30px;
width: 9px; height: 30px;
z-index: 8;
position: absolute;
}
#main_nav li.back .left {
background: url("lava.gif") no-repeat top left;
height: 30px;
margin-right: 9px; /* 7px is the width of the rounded shape */
}
#main_nav li a {
font: bold 14px arial;
text-decoration: none;
color: #fff;
outline: none;
text-align: center;
top: 7px;
text-transform: uppercase;
letter-spacing: 0;
z-index: 10;
display: block;
float: left;
height: 30px;
position: relative;
overflow: hidden;
    
}
#main_nav li a:hover, #main_nav li a:active, #main_nav li a:visited {
border: none;
}