style.css.scss

@mixin background-image-retina($file, $type, $width, $height) {
	background-image: url($file + '.' + $type);

	@media (-webkit-min-device-pixel-ratio: 2), (-moz-min-device-pixel-ratio: 2) {
		& {
		background-image: url($file + '@2x.' + $type);
		-webkit-background-size: $width $height;
		}
	}
}

.logo{
@include background-image-retina('../images/logo', 'png', 80px, 79px);
}