I've added Default menu to Nav but now its loking like

Here is CSS
/* Styles for the standard dropdown menus.
------------------------------------------------------- */
#nav_menu
{
display: block;
position: relative;
height: 28px;
font-size: 11px;
font-weight: bold;
margin: 0;
float: left;
padding: 2px 0 0 5px;
font-family: "Segoe UI", Tahoma, Arial, Helvetica, sans-serif;
}
.dropnav, .dropnav ul
{
margin: 0;
padding: 0;
list-style-type: none;
width: auto;
float: left;
}
.dropnav
{
padding: 0 0.5em;
}
.dropnav a
{
display: block;
color: #FFF;
text-decoration: none;
}
.dropnav a span
{
display: block;
width: auto;
padding: 0 12px 0 0;
}
/* the backgrounds first level only*/
.dropnav li a.firstlevel
{
margin-right: 8px;
}
.dropnav li a.firstlevel span.firstlevel
{
display: block;
left: -5px;
padding-left: 10px;
height: 28px;
line-height: 28px;
}
.dropnav li
{
float: left;
padding: 0;
margin: 0;
position: relative;
}
.dropnav li ul
{
z-index: 90;
display: none;
position: absolute;
width: 19.2em;
font-weight: normal;
border-bottom: solid 1px #837a66;
background: url(../images/theme/menu_gfx.png) 0 -100px no-repeat;
padding: 7px 0 0 0;
}
.dropnav li li
{
width: 19em;
margin: 0;
border-left: solid 1px #837a66;
border-right: solid 1px #837a66;
}
.dropnav li li a span
{
display: block;
padding: 8px;
}
.dropnav li ul ul
{
margin: -1.8em 0 0 13em;
}
/* the active button */
.dropnav li a.active
{
color: #fff;
background: url(../images/custom/nav.png) 0 0 no-repeat;
font-weight: bold;
}
.dropnav li a.active span.firstlevel
{
background: url(../images/custom/nav.png) 0 0 no-repeat;
}
/* the hover effects */
.dropnav li a.firstlevel:hover
{
color: #000;
background: url(../images/custom/nav.png) 0 100% no-repeat;
cursor: pointer;
text-decoration: none;
}
.dropnav li a.firstlevel:hover span.firstlevel
{
background: url(../images/custom/nav.png) 100% 100% no-repeat;
}
/* the hover effects on level2 and 3*/
.dropnav li li a:hover
{
color: #fff;
text-decoration: underline;
}
.dropnav li:hover ul ul, .dropnav li:hover ul ul ul
{
top: -999em;
}
.dropnav li li:hover ul
{
top: auto;
}
.dropnav li:hover ul
{
display: block;
}
.dropnav li li.additional_items
{
background-color: #1c1c1c;
}
It should be Loking Like This:

I dont know what is the problem...

PlzZz do something....