=respond-to($media)
  @if $media == handheld
    @media only screen and (max-width: 640px)
      @content

  @else if $media == small-screen
    @media only screen and (max-width: 1023px)
      @content

  @else if $media == medium-screen
    @media only screen and (min-width: 1024px)
      @content