_compass-retina-sprites.scss

@import "compass/css3/background-size";

$map: sprite-map("sprites/*.png", $layout:smart);
$map-img: sprite-url($map);

@mixin sprite-background($name) {
  display: inline-block;
  width: image-width(sprite-file($map, $name)) / 2;
  height: image-height(sprite-file($map, $name)) / 2;
  background-image: $map-img;
  background-repeat: no-repeat;
  $pos: sprite-position($map, $name);
  background-position: ceil(nth($pos, 1) / 2) ceil(nth($pos, 2) / 2);
  @include background-size(ceil(image-width(sprite-path($map)) / 2) auto);
}