#centeredDiv {
	position:absolute;
	left: 50%;
	top: 50%;
	width:450px;
	height:100px;
	margin-top: -50px; /*set to a negative number 1/2 of your height*/
	margin-left: -425px; /*set to a negative number 1/2 of your width*/
	border: 1px solid #ccc;
	background-color: #f3f3f3;
}