响应式布局宽度
@media (min-width:480px) and (max-width: 767px)@media (min-width:768px) and (max-width: 992px)@media (max-width: 479px)@media all and (-webkit-min-device-pixel-ratio: 2), all and (-moz-min-device-pixel-ratio: 1.5), all and (min-device-pixel-ratio: 2), all and (-o-min-device-pixel-ratio: 2/1)@media (
