Navbar Adjustment

I’m modifying the MT-Dark Theme and I wanted a larger header so I’ve adjusted the style.css file as follows:

#header {
    height: 400px;
	background:transparent url(img/header.jpg) no-repeat top ;

By making the header height 400px, that worked great, but the navigation menu (Home, About, etc.) didn’t drop down with it an remains in the same location which is now about halfway down the header. I’m guessing the adjustment is part of the HTML Header portion of the style sheet here, but I’ve tried adjusting the positions tags to no avail:

/*------- /HTML --header */
#nav li {
	float:left;
	margin-right: 5px;
	background:#29150A;
	font-size: 16px;
	-webkit-border-radius: 5px;
    -moz-border-radius: 5px;
    -khtml-border-radius: 5px;
    border-radius: 5px;
	position:relative;
	min-height: 1px;		/* Sophie Dennis contribution for IE7 */
	vertical-align: bottom;		/* Sophie Dennis contribution for IE7 */
}
html>body #nav li{
	background: url(img/hover.png);
}
#nav li ul li{
	background:#29150A;
	width:200px;
}
html>body #nav li ul li{
	background:#29150A url(img/hover.png);
}
#nav .current_page_item a{
	color: #B06604;
}
#nav a{
	display:block;
	white-space:nowrap;
	padding:5px 8px 8px 8px;
}
#nav ul{
	margin:0;
	padding:0;
	float:left;
}
#nav ul ul{
	position:absolute;
	z-index:500;
	top:auto;
	display:none;
	padding: 1em;
	margin:-1em 0 0 -1em;
}
#nav ul ul ul{
	top:0;
	left:100%;
}
div#nav li:hover{
	cursor:pointer;
	z-index:100;
}
div#nav li:hover ul ul,
div#nav li li:hover ul ul,
div#nav li li li:hover ul ul,
div#nav li li li li:hover ul ul
{display:none; }

div#nav li:hover ul,
div#nav li li:hover ul,
div#nav li li li:hover ul,
div#nav li li li li:hover ul
{display:block;}

Thoughts?