SASS/SCSS Internet Explorer Compatible Opacity Mixin

opacity_mixin.css.scss

@mixin opacity($alpha) {
  // IE 8
  -ms-filter:"progid:DXImageTransform.Microsoft.Alpha(Opacity=$alpha*100)";
  // IE 5-7
  filter: alpha(opacity=$alpha*100);
  // Real Browsers
  -webkit-opacity: $alpha;
  -moz-opacity: $alpha;
  -khtml-opacity: $alpha;
  opacity: $alpha;
}

// 50% transparency
@include opacity(.5);

// no transparency
@include opacity(1);