+gradient(!color1, !percent1, !color2, !percent2)
  background: -webkit-gradient(linear,left bottom,left top,color-stop(#{!percent2 / 100.0}%, #{!color2}),color-stop(#{!percent1 / 100.0}%, #{!color1}))
  background: -moz-linear-gradient(center bottom,#{!color2} #{!percent2}%,#{!color1} #{!percent1}%)