CSS - Css Style Switching Issue

a:link, a:visited, a:active {
	font-weight: bold;
	color: #000099;
	text-decoration: none;
	background-color: #C4E4F7;
	border: 1px solid #000066;
}
a:hover {
	font-weight: bold;
	color: #FC6103;
	text-decoration: none;
	background-color: #FFEAD5;
	border: 1px solid #974B00;
}

#centerCol p, #centerCol select, #centerCol textarea, #centerCol form, #centerCol td, #centerCol th, #centerCol input, #centerColTop p, #centerColSecondaryTop p {
	color: #333;
	font-size: 1em;
	font-family: Verdana, Arial, Helvetica, sans-serif;
}

<div id="content_test">
	<div id="rollovercontentwrapper">

		<div id="tabwrapper">
			<ul id="tabmenu">
				<li><p><a href="#" onClick="javascript:showTabContentOne('TabContentOne')">Summary</p></a></li>
				<li><p><a href="#" onClick="javascript:showTabContentTwo('TabContentTwo')">Benefits</p></a></li>
			</ul><!--TABMENU-->
		</div><!--TABWRAPPER-->

		<div id="TabContentOne" class="TabContentOne" style="visibility: hidden">
						<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer lacus risus, 
						porttitor non aliquam non, scelerisque vitae turpis. Duis venenatis nisl lectus, 
						et aliquam eros. Nam commodo, ligula sed ultrices vehicula, justo augue ultricies 
						urna, sed rhoncus nisi dui sed risus. Nullam commodo risus nec justo sagittis eu 
						cursus nisi interdum.</p>
						<br>
						<p>In hac habitasse platea dictumst. Sed vulputate auctor cursus. Morbi ac 
						ullamcorper dui. In sem velit, pulvinar sit amet cursus id, vulputate fringilla 
						erat. Vestibulum ante ipsum primis in faucibus orci luctus et ultrices posuere 
						cubilia Curae; Sed lorem urna, imperdiet eget fringilla eget, molestie nec justo. 
						Fusce diam nulla, fringilla a sodales at, rhoncus vitae massa. Donec tincidunt, 
						leo quis fermentum venenatis, purus elit tincidunt ipsum, vitae sollicitudin nulla 
						orci nec arcu. Sed non neque neque, ac pharetra lectus. Donec a massa mauris. Sed 
						vel magna eget tellus commodo placerat in quis risus. Aenean velit lectus, aliquam 
						quis dictum ac, pellentesque sed diam.</p>
		</div><!--TabContentOne-->
		<div id="TabContentTwo" class="TabContentTwo" style="visibility: hidden">
						<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer lacus risus, 
						porttitor non aliquam non, scelerisque vitae turpis. Duis venenatis nisl lectus, 
						et aliquam eros. Nam commodo, ligula sed ultrices vehicula, justo augue ultricies 
						urna, sed rhoncus nisi dui sed risus. Nullam commodo risus nec justo sagittis eu 
						cursus nisi interdum.</p>
		</div><!--TabContentTwo-->

	</div><!--ROLLOVERCONTENTWRAPPER-->
</div>	<!----CONTENT_TEST---->

<div id="onebyone" style="visibility:hidden;">
<img src="onebyonepixel.gif" onLoad="javascript:showTabContentOne('TabContentOne')" width="1" height="1">
</div>

div#rollovercontentwrapper {
	float: left;
	width: 630px;
	background-color: #E9E9E8
}

div#tabwrapper {
	width: 630px;
}

ul#tabmenu {
	display: block;
	float: left;
	width: 630px;
	list-style-type: none;
	border-bottom: 1px solid #0048A7;
}

ul#tabmenu li {
	display: block;
	float: left;
	background-color: #E9E9E8;
}

ul#tabmenu li a {
	display: block;
	float: left;
	padding: 10px;
	background-color: #E9E9E8;
	border-top: 1px dashed #0048A7;
	border-right: 1px dashed #0048A7;
}

ul#tabmenu li a:focus {
	display: block;
	float: left;
	padding: 10px;
	background-color: #3383CD;
	border-top: 1px dashed #0048A7;
	border-right: 1px dashed #0048A7;
}

#TabContentOne {
	float: left;
	position: absolute;
	top: 350px;
	width: 628px;
	z-index: 1;
	padding-top: 10px;
	padding-bottom: 10px;
}

#TabContentTwo {
	float: left;
	position: absolute;
	top: 350px;
	width: 628px;
	z-index: 1;
	padding-top: 10px;
	padding-bottom: 10px;
}

div#onebyone {
	float: left;
}

div#content_test {
	float: left;
	width: 900px;
	padding: 20px;
	background-color: #CCCCCC;
}