Semantic-mixins use case

gistfile1

#site_overview
  background-color: $aqua
  padding: 2*$base-margin 0
  +decorative-content
    $name: "star"
    +sprite-replace($name)
    +absolute-centering(sprites-sprite-width($name))
    bottom: - sprites-sprite-height($name)/2

  .post_overview
    +apply-to(less-than, ipad-portrait)
      width: 50%