CSS Media Queries
#element { background-image: url(‘hires.png‘); }
@media only screen and (min-device-pixel-ratio: 2) {
#element { background-image: url(‘hires@2x.png‘); }
}
@media only screen and (min-device-pixel-ratio: 3) {
#element { background-image: url(‘hires@3x.png‘); }
}
#element { background-image: url(‘hires.png‘); }
@media only screen and (min-device-pixel-ratio: 2) {
#element { background-image: url(‘hires@2x.png‘); }
}
@media only screen and (min-device-pixel-ratio: 3) {
#element { background-image: url(‘hires@3x.png‘); }
}
https://css-tricks.com/snippets/css/retina-display-media-query/