CSS - Drop down menu

gistfile1.css

<!--HTML Portion-->
<ul id="nav">
					<li class="current"><a href="#">Home</a></li>
					<li><a href="#">Sub Menu</a>
						<ul>
							<li><a href="#">Submenu Item</a>
								<ul>
									<li><a href="#">Level 3 menu</a></li>
									<li><a href="#">Level 3 menu</a></li>	
								</ul>
							</li>
							<li><a href="#">Submenu Item 2</a></li>
							<li><a href="#">Submenu Item 3</a></li>
						</ul>	
					</li>
				</ul>
 
/*CSS portion*/
 
/*Navigation Section*/
a {
	color: #333;
}
#nav {
	margin: 0;
	padding: 7px 6px 0;
	line-height: 100%;
}
#nav li {
	margin: 0 5px;
	padding: 0 0 8px;
	float: left;
	position: relative;
	list-style: none;
}
 
 
/* main level link */
#nav a {
	font-weight: bold;
	color: #e7e5e5;
	text-decoration: none;
	display: block;
	padding:  8px 20px;
	margin: 0;
	text-shadow: 0 1px 1px rgba(0,0,0, .3);
}
 
/*
#nav a:hover {
	background: #000;
	color: #fff;
}
*/
 
/* main level link hover */
#nav .current a, #nav li:hover > a {
	color: yellow;
	text-shadow: 0 1px 0 rgba(255,255,255, 1);
}
 
/* sub levels link hover */
 
#nav ul li:hover a, #nav li:hover li a {
	background: none;
	border: none;
	color: #666;
 
	-webkit-box-shadow: none;
	-moz-box-shadow: none;
}
 
#nav ul a:hover {
	background: #0078ff url(img/gradient.png) repeat-x 0 -100px !important;
	color: #fff !important;
	text-shadow: 0 1px 1px rgba(0,0,0, .1);
}
 
/* dropdown */
#nav li:hover > ul {
	display: block;
}
 
/* level 2 list */
#nav ul {
	display: none;
	margin: 0;
	padding: 0;
	width: 185px;
	position: absolute;
	top: 43px;
	left: 0;
	background: #ddd url(img/gradient.png) repeat-x 0 0;
	border: solid 1px #b4b4b4;
	-webkit-box-shadow: 0 1px 3px rgba(0,0,0, .3);
	-moz-box-shadow: 0 1px 3px rgba(0,0,0, .3);
	box-shadow: 0 1px 3px rgba(0,0,0, .3);
}
#nav ul li {
	float: none;
	margin: 0;
	padding: 0;
}
 
#nav ul a {
	font-weight: normal;
	text-shadow: 0 1px 0 #fff;
}
 
/* level 3+ list */
 
#nav ul ul {
	left: 179px;
	top: -3px;
}
 
 
/* clearfix */
 
#nav:after {
	content: ".";
	display: block;
	clear: both;
	visibility: hidden;
	line-height: 0;
	height: 0;
}
#nav {
	display: inline-block;
} 
html[xmlns] #nav {
	display: block;
}
 
* html #nav {
	height: 1%;
}