By Forrest Smith - Drempd.com
.banner{
background-image: url('image.jpg');
background-size: auto 100%;
}
@media
only screen and (-webkit-min-device-pixel-ratio: 1.5),
only screen and (min-device-pixel-ratio: 1.5) {
.banner{
background-image: url('image@2x.jpg');
}
}