body, html {
  height: 100%;
  margin: 0;
}

div {
  background-image: url(images/ladyslippers.jpg);
  height: 100%;
  /* Center and scale the image nicely */
  background-position: center;
  background-repeat: no-repeat;
  background-size: cover;
 }


@media only screen and (max-width: 400px) {
  body {
    background-image: url(images/ladyslippers_temp.jpg);
  }
}