_utilities.sass

@mixin sprite($url, $height: 100, $width: 100, $x: 0, $y: 0)
  display: block
  height: $height
  width: $width
  background: url($url)
  background-position: ($x * $width) ($y * $height)


// used like so
// @include sprite($url: "images/sprite.png", $x: -3, $y: -1)
//
// The $x & $y values act like unit measurement offsets. In the example above
// the sprite image is offset by -300px on the x-axis and
// by -100px on the y-axis. A "unit" is defined by the $width and $height values.