body, html {
  height: 100%;
}
.bg {
  /* The image used */
  background-image: url("ws_Sweet_Horses_Pair_Lilac_Cherry_1920x1200.jpg");

  /* Half height */
  height: 50%;

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