device-pixel-ratio：定义输入设备屏幕的可视宽度与可见高度比率。device-width：输入设备屏幕的可视宽度。
device-width：输入设备屏幕的可视宽度。
orientation ：屏幕横竖屏定向。landscape 是横向，portrait 是纵向【ipad 相反】
@media only screen and (-webkit-min-device-pixel-ratio : 1.5),only screen and (min-device-pixel-ratio : 1.5) {}
@media only screen and (min-device-width : 768px) and (max-device-width : 1024px) and (orientation : portrait) {}
@media only screen and (min-device-width : 320px) and (max-device-width : 480px) {
}
}
@media only screen and (max-width : 320px) {}
@media only screen and (min-device-width : 768px)and (max-device-width : 1024px) {
}
@media only screen and (min-device-width : 768px) and (max-device-width : 1024px)
and (orientation : landscape) {}
@media only screen and (min-device-width : 768px) and (max-device-width : 1024px)
and (orientation : portrait) {}
@media only screenand (min-width : 1224px) {}
@media only screen and (min-width : 1824px) {}
来自 “ ITPUB博客 ” ，链接：https://blog.itpub.net/2505/viewspace-2815599/ ，如需转载，请注明出处，否则将追究法律责任。
