body {
 background-color: #000;
 background-position: center center;
 background-repeat: no-repeat;
 background-attachment: fixed;
}
body.E403 { background-image: url('http://errors.x2.cz/403.gif');}
body.E404 { background-image: url('http://errors.x2.cz/404.jpg');}
h1,p {visibility: hidden;}
div { margin: 25%;}