Retina background images. Note: The super weird min--moz-device-pixel-ratio is probably a bug, might wanna put in -moz-min-device-pixel-ratio also in case they fix it but leave it prefixed.
@media
only screen and (-webkit-min-device-pixel-ratio: 2),
only screen and ( min--moz-device-pixel-ratio: 2), /* Looks like a bug, so may want to add: */
only screen and ( -moz-min-device-pixel-ratio: 2),
only screen and ( -o-min-device-pixel-ratio: 2/1),
only screen and ( min-device-pixel-ratio: 2),
only screen and ( min-resolution: 192dpi),
only screen and ( min-resolution: 2dppx) {
/* Your retina specific stuff here */
}
/* This one considers resolution too */
@media (-webkit-min-device-pixel-ratio: 2), (min-resolution: 192dpi) {
.hero {
background-image: url('../img/hero-bg-2x.png');
}
}