gistfile1.css

.logo {
	width: 204px;
	height: 100px;
	background: url('/img/logo.png');
}

@media
(-o-min-device-pixel-ratio: 5/4),
(-webkit-min-device-pixel-ratio: 1.25),
(min-resolution: 120dpi) {
	.logo {
		background: url('/img/logo@2x.png');
		background-size: 100%;
	}
}