body, html {
  height: 100%;
}

.bg { 
  /* The image used */
  /*background-image: url("/rest/static/img/Draytek_2926Vac.jpg"); */

  /* Full height */
  height: 100%; 

  /* Center and scale the image nicely */
  background-position: center;
  background-repeat: no-repeat;
  background-size: cover;
}