//body {
//background-image: url(hal9000.jpg);
// background-repeat: no-repeat;
//    background-position: center;
//    background-size: cover;
//    width: 100%;
//    height: 100%;
//}

body { 
  background: url(hal9000.jpg) no-repeat center center fixed; 
  -webkit-background-size: cover;
  -moz-background-size: cover;
  -o-background-size: cover;
  background-size: cover;
}