img {
  display: block;
  width: 100%; }

html, body {
  height: 100%; }

#bg-1, #bg-2, #bg-3 {
  background-size: cover;
  background-position: 50%;
  background-color: #999; }

#bg-1 {
  background-image: url("../img/1.jpg"); }

#bg-2 {
  background-image: url("../img/2.jpg"); }

#bg-3 {
  background-image: url("../img/3.jpg"); }