LESS legacy IE transparent background colour

transparent-bg.less

.ms-compatible-rgba-bg(@color, @alpha) {

	// Lacking Sass' 'transparentize' function here =(
	background-color:rgba( red(@color), green(@color), blue(@color), @alpha);

	// Less can be very ugly, but using JS parsing is pretty useful
	@alpha_rgb: 255 * @alpha;
	@alpha_hex: ~`( parseInt("@{alpha_rgb}", 10)).toString(16)`;
	@color_str: ~`"@{color}".replace('#', '')`;

	*zoom:1;
	-ms-filter: "progid:DXImageTransform.Microsoft.gradient(startColorstr=#@{alpha_hex}@{color_str}, endColorstr=#@{alpha_hex}@{color_str})";
	*filter:   ~"progid:DXImageTransform.Microsoft.gradient(startColorstr=#@{alpha_hex}@{color_str}, endColorstr=#@{alpha_hex}@{color_str})";
}

.omg-this-works-in-ie {
  .ms-compatible-rgba-bg(#499EBB, .75);
}