@media only screen and (-webkit-min-device-pixel-ratio: 2), only screen and (min-device-pixel-ratio: 2) {    
	.class .class-title a{
	background-image:url(../images/image@2x.png);
	-webkit-background-size:21px 50px;
	   -moz-background-size:21px 50px;
	     -o-background-size:21px 50px;
	        background-size:21px 50px;
	}
}