@media only screen and (-webkit-min-device-pixel-ratio: 2), only screen and (min-device-pixel-ratio: 2) {.replace-2x {font-size: 1px;}.example {background-image: url(../images/example2x.png);-webkit-background-size:13px 13px;-moz-background-size:13px 13px;-o-background-size:13px 13px;background-size:13px 13px;}}