#header {
	left: 50%; 
top: 50%;

	text-align: left; 
	position: absolute; 
	margin-left : -475px;
	margin-top: -285px;
	}
#header h1 {
	float: center;
	left: 50%;
	width: 950px;
height: 570px;
}
#header h1 a {

	width: 950px;
	height: 570px;
	display: block;
	background: url(voorgrond.jpg) no-repeat top left;
	}
#header h1 a span { display: none; }