doc/bootstrap/mixins/opacity.less - platform/external/fmtlib - Git at Google

 // Opacity

 .opacity(@opacity) {
   opacity: @opacity;
   // IE8 filter
   @opacity-ie: (@opacity * 100);
   filter: ~"alpha(opacity=@{opacity-ie})";
 }
	// Opacity

	.opacity(@opacity) {
	opacity: @opacity;
	// IE8 filter
	@opacity-ie: (@opacity * 100);
	filter: ~"alpha(opacity=@{opacity-ie})";
	}