html, body {height: 100%; margin: 0; padding: 0;}
body {text-align: center;}
.spacer {min-height: 50%; margin-bottom: -384px;}
.spacer div {height: 384px; font-size: 1px; line-height: 1px;}
.block {width: 1004px; height: 768px; margin: 0 auto; text-align: center; background: url(../img/postcard.jpg) no-repeat;}