<style>
#floater{
	height:50%;
	margin-bottom:-207px;
}
#content{
	height:415px;
	position:relative;
	border:solid 1px red;
}
</style>

<div id="floater"></div>
 <div id="content">here content</div>

pokrvsiii.com

Vertical align centering

css

XHTML