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/* iphone 3 */
@media only screen and (min-device-width: 320px) and (max-device-height: 480px) and (-webkit-device-pixel-ratio: 1) { }

/* iphone 4 */
@media only screen and (min-device-width: 320px) and (max-device-height: 480px) and (-webkit-device-pixel-ratio: 2) { }

/* iphone 5 */
@media only screen and (min-device-width: 320px) and (max-device-height: 568px) and (-webkit-device-pixel-ratio: 2) { }

/* iphone 6, 6s */
@media only screen and (min-device-width: 375px) and (max-device-height: 667px) and (-webkit-device-pixel-ratio: 2) { }

/* iphone 7, 8 */
@media only screen and (min-device-width: 375px) and (max-device-height: 667px) and (-webkit-device-pixel-ratio: 2) { }

/* iphone 6+, 6s+, 7+, 8+ */
@media only screen and (min-device-width: 414px) and (max-device-height: 736px) and (-webkit-device-pixel-ratio: 3) { }

/* iphone X */
@media only screen and (min-device-width: 375px) and (max-device-height: 812px) and (-webkit-device-pixel-ratio: 3) { }

转自链接：https://www.jianshu.com/p/ac4fb710ed44