@mixin barber_pole($bg: black, $color:white, $speed:.7s)
  background-size  : 30px 30px
  @include animation(barber_pole $speed linear infinite)
  @include background-image(linear-gradient(-45deg,  $color 25%,transparent 25%,transparent 50%, $color 50%, $color 75%,transparent 75%))
  background-color : $bg