Background Size Cover (webapp + grunt + compass) crossbrowser

gistfile1.txt

@include background-size(cover);
	background-image: image_url('bg.jpg');
	background-position: center top;
	background-repeat: no-repeat;
	background-attachment: scroll;
	filter: progid:DXImageTransform.Microsoft.AlphaImageLoader(
	src="image_url('bg.jpg')",
	sizingMethod='scale');

	-ms-filter: "progid:DXImageTransform.Microsoft.AlphaImageLoader(
	src="image_url('bg.jpg')",
	sizingMethod='scale')";