+ background-position -(@width) y
+// see sprites-rollover
+sprites(image, height, count, h-offset = 0)
+ height: unit(height, px)
+ background-image: url(image)
+ background-position: top left
+ background-repeat: no-repeat;
+ for n in (0...count)
+ &.n{n}
+ y = - (@height * n) - h-offset
+ background-position 0 y