.example {
  background-image: url(example.png);
  background-image:
    -webkit-image-set(url(example.png) 1x, url(example-2x.png) 2x);
  background-image:
    -moz-image-set(url(example.png) 1x, url(example-2x.png) 2x);
  background-image:
    -o-image-set(url(example.png) 1x, url(example-2x.png) 2x);
  background-image:
    -ms-image-set(url(example.png) 1x, url(example-2x.png) 2x);
  background-position: center center;
}