CSS :first-child and :last-child

#third_container > nav:first-child {	height: 31px;	padding-right: 2px;	margin: 0;	list-style: none;}#third_container > nav:first-child li {	float: right;	display: block;	width: 82px;	height: 31px;}#third_container > nav:first-child a {	display: block;	width: 82px;	height: 31px;	background-color: inherit;	text-decoration: none;	line-height: 31px;	text-align: center;}#third_container > nav:first-child a:link,#third_container > nav:first-child a:visited {	color: #749942;	background-color: #D3E2C3;}#third_container > nav:first-child a:hover,#third_container > nav:first-child a:active {	background-image: url('../img/taba2.jpg');	color: #ffffff;}#third_container > nav:last-child {	float: left;	height: 31px;	width: 300px;	padding-left: 10px;	margin: 0;	list-style: none;}#third_container > nav:last-child li {	float: left;	display: block;	width: 82px;	height: 31px;}#third_container > nav:last-child a {	display: block;	width: 82px;	height: 31px;	background-color: inherit;	text-decoration: none;	line-height: 25px;	text-align: center;}#third_container > nav:last-child a:link,#third_container > nav:last-child a:visited {	color: #749942;	background-color: #D3E2C3;}#third_container > nav:last-child a:hover,#third_container > nav:last-child a:active {	background-image: url('../img/tabb2.jpg');	color: #ffffff;}