body {
  background-image: url('raven.gif');
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
  background-attachment: fixed;
  }
  
  #wrapper {position: absolute; left: 30px; top: 30px; width: calc(100vw - 60px); height: calc(100vh - 60px); border: 1px solid black;}