Border around Menu

Hi I need some help with a code for a border around my menu.. would like it to stretch the page and be filled in black, im using the landscape theme. thank you!

/* =Menu
----------------------------------------------- */

.main-navigation {
	display: block;
	float: left;
	width: 100%;
	font-family: georgia, arial;
	text-transform:uppercase;
	background:#000;
	z-index: 99999;
	-moz-box-shadow: 0 1px 1px rgba(0,0,0,0.2);
	-webkit-box-shadow: 0 1px 1px rgba(0,0,0,0.2);
	box-shadow: 0 1px 1px rgba(0,0,0,0.2);
	clear:left;
	font-size:14px;
}

.main-navigation a{
	color:#fff;
}
.main-navigation ul {
	float: right;
    list-style: none;
    margin: 0;
    padding-left: 0;
    position: relative;
    right: 50%;
}
.main-navigation ul li {
	display: inline-block;
	position: relative;
	left: 50%;
}
.main-navigation ul li:after {
	color: #666;
	content: "|";
	display: inline;
	font-size: 12px;
	margin: 0 0 0 17px;
	font-style:italic;
}
.main-navigation ul li:last-child:after {
	content: normal;
	margin: 0;
	padding: 0;
}
.main-navigation ul ul li {
	float: left;
	left: auto;
	font-style:normal;
}
.main-navigation ul a {
	display: inline-block;
	text-decoration: none;
	padding: 10px 6px 10px 21px;
	font-style:normal;
}
.main-navigation ul ul a {
	color: #999;
}
.main-navigation ul ul {
	-moz-box-shadow: 0 1px 1px rgba(0,0,0,0.2);
	-webkit-box-shadow: 0 1px 1px rgba(0,0,0,0.2);
	box-shadow: 0 1px 1px rgba(0,0,0,0.2);
	background: #000;
	display: none;
	float: left;
	position: absolute;
		top: auto;
		left: 10px;
		right: auto;
	text-align: left;
	z-index: 99999;
}

.main-navigation ul ul ul {
	left: 100%;
	top: 0;
}
.main-navigation ul ul a {
	width: 150px;
	font-size: 15px;
	padding: 7px 15px;
}
.main-navigation ul ul li:after {
	content: normal;
	margin: 0;
	padding: 0;
}
.main-navigation li:hover > a {
	color: #999;
}
.main-navigation ul ul :hover > a {
	color: #fff;
}
.main-navigation ul ul a:hover {
}
.main-navigation ul li:hover > ul {
	display: block;
}
.main-navigation li.current_page_item a,
.main-navigation li.current-menu-item a {
	color: #999;
}

/* Small menu */
.main-small-navigation {
	background:#000;
	margin: 0;
	padding: 0.5em 0 0;
	z-index:99999;
	position:fixed;
	width:100%;
}
.menu-toggle {
	color: #fff;
	cursor: pointer;
	font-size: 20px;
	text-align: center;
}
.main-small-navigation .menu {
	display: none;
}
.main-small-navigation .menu,
.main-small-navigation .menu a {
	color: #fff;
}
.main-small-navigation ul{
	z-index:9999;
}
.main-small-navigation ul li{
	list-style-type:none;
}