/* 如果设备像素大于等于2,则用2倍图 */ @media screen and (-webkit-min-device-pixel-ratio: 2), screen and (min--moz-device-pixel-ratio: 2) { .img { background-image: url(../images/arrow@2x.png); background-size: 30px 30px; 30px; height: 30px; background-repeat: no-repeat; } } /* 如果设备像素大于等于3,则用3倍图 */ @media screen and (-webkit-min-device-pixel-ratio: 3), screen and (min--moz-device-pixel-ratio: 3) { .img { background-image: url(../images/arrow@3x.png); background-size: 30px 30px; 30px; height: 30px; background-repeat: no-repeat; } }