Media query – Retina displays

@media (min--moz-device-pixel-ratio: 1.5),
       (-o-min-device-pixel-ratio: 3/2),
       (-webkit-min-device-pixel-ratio: 1.5),
       (min-device-pixel-ratio: 1.5),
       (min-resolution: 144dpi),
       (min-resolution: 1.5dppx) {
 
/* Retina rules! */
 
}

#my-image {background-image : url(low.png);}
@media only screen and (min-device-pixel-ratio: 1.5) {
    #my-image {background-image : url(high.png);}
}