@mixin gradient($start-color: rgba(255, 255, 255, 0.3), $end-color: transparent) {
  background: $start-color; /* for non-css3 browsers */
  filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#{$start-color}', endColorstr='#{$end-color}'); /* ie */
  background: -webkit-gradient(linear, left top, left bottom, from($start-color), to($end-color)); /* webkit */
  background: -moz-linear-gradient(top,  $start-color,  $end-color); /* ff */
}