html { 
  background: url(images/bg.jpg) no-repeat center center fixed; 
  -webkit-background-size: cover;
  -moz-background-size: cover;
  -o-background-size: cover;
  background-size: cover;
}

html, body, #wrapper {
   height:100%;
   width: 100%;
   margin: 0;
   padding: 0;
   border: 0;
}
#wrapper td {
   vertical-align: middle;
   text-align: center;
}