gradient-from-bottom($from, $to)
  background: -moz-linear-gradient(bottom, $from, $to)
  background: -webkit-gradient(linear, left bottom, left top, from($from), to($to))
  background: -o-linear-gradient(bottom, $from, $to)

gradient-from-top($from, $to)
  background: -moz-linear-gradient(top, $from, $to)
  background: -webkit-gradient(linear, left top, left bottom, from($from), to($to))
  background: -o-linear-gradient(top, $from, $to)

unselectable()
  -moz-user-select: none
  -webkit-user-select: none
  -ms-user-select: none
  user-select: none

flex-box()
  display: -ms-flexbox
  display: -webkit-box
  display: -webkit-flex
  display: flex

flex()
  -ms-flex: 1 1 0.000000001px
  -webkit-box-flex: 1
  -webkit-flex: 1
  flex: 1
  -webkit-flex-basis: 0.000000001px
  flex-basis: 0.000000001px
  width: 1%

border-top-1px($color)
  &:before, &:after
    display: block
    position: absolute
    border-top: 1px solid $color
    left: 0
    width: 100%
    content: ' '
  &:before
    display: block
    top: 0
  &:after
    display: none
    bottom: 0

border-bottom-1px($color)
  &:before, &:after
    display: block
    position: absolute
    border-top: 1px solid $color
    left: 0
    width: 100%
    content: ' '
  &:before
    display: none
    top: 0
  &:after
    display: block
    bottom: 0