iPhone < 5:
@media screen and (device-aspect-ratio: 2/3) {}

iPhone 5:
@media screen and (device-aspect-ratio: 40/71) {}

iPhone 6:
@media screen and (device-aspect-ratio: 375/667) {}

iPhone 6 Plus:
@media screen and (device-aspect-ratio: 16/9) {}

iPad:
@media screen and (device-aspect-ratio: 3/4) {}

苹果手机css