//iphoneX、iphoneXs

@media only screen and (device-width: 375px) and (device-height: 812px) and (-webkit-device-pixel-ratio: 3) {
}

即: 设备屏幕可见宽度为375px， 可见高度为812px及设备像素比为3

//iphone Xs Max
@media only screen and (device-width: 414px) and (device-height: 896px) and (-webkit-device-pixel-ratio:3) {
}

//iphone XR
@media only screen and (device-width: 414px) and (device-height: 896px) and (-webkit-device-pixel-ratio:2) {
}