/**
* Opacity
* 
* Thanks to Chris Eppstein. Borrowed this one from Compass. 
* Takes a number from 0 to 1.
*/
=opacity(!opacity = 1)
{
	opacity: !opacity;
	-moz-opacity: !opacity;
	-khtml-opacity: !opacity;
	-ms-filter: "progid:DXImageTransform.Microsoft.Alpha(Opacity=#[!opacity*100])";
	filter: "alpha(opacity=#[!opacity*100])";
}