@media (device-height:480px) and (-webkit-min-device-pixel-ratio:2){/* 兼容iphone4/4s */
.class{}
}
@media (device-height:568px) and (-webkit-min-device-pixel-ratio:2){/* 兼容iphone5 */
.class{}
}
@media(min-device-375px)and(max-device-667px)and(-webkit-min-device-pixel-ratio:2){
/*iphone6*/
}
@media(min-device-414px)and(max-device-736px)and(-webkit-min-device-pixel-ratio:3){
/*iphone6plus*/
}
分享一个最全的css @media : https://css-tricks.com/snippets/css/media-queries-for-standard-devices/