LESS CSS class for cross browser opacity

gistfile1.css

.opacity(@opacity) {
	@ieOpacity: @opacity * 100;
	// If you don't use this order, IE8-as-IE7 doesn't apply the opacity, although IE8 and a pure IE7 do.
	// http://www.quirksmode.org/css/opacity.html
	-ms-filter: ~"progid:DXImageTransform.Microsoft.Alpha(Opacity=@{ieOpacity})"; // IE 8
	filter: ~"alpha(opacity=@{ieOpacity})"; // IE 5-7
	opacity: @opacity;
}