body {
  background: url('http://shorty.koeln/img/shorty-berlin.jpg') no-repeat center center fixed;
  -webkit-background-size: cover;
  -moz-background-size: cover;
  background-size: cover;
  -o-background-size: cover;
  color: white;
  text-shadow: 1px 1px 5px #000;
}

a, a:hover, a:visited, pre {
  color: white !important; 
}

body::before {
  content: "";
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.5); /* black with 50% opacity */
  z-index: -1;
}