#container {
	position:absolute;
	top:50%; left:50%;
	margin:-200px 0 0 -350px;
	width:700px;
	height:400px;
	border:1px solid #000;
	background:url(../images/404.jpg) center top no-repeat;}
#btn {
	position:absolute;
	left:236px;
	top:319px;
	width:229px;
	height:30px;
	display:block;
	background:url(../images/404.png) no-repeat;}
#btn:hover {
	background-position:left bottom;}