/*retina屏物理像素比例*/

/*边框*/
.border { border: 1px solid #999 }
@media screen and (-webkit-min-device-pixel-ratio: 2) {
    .border{
        border: 0.5px solid #999;
    }
}
@media screen and (-webkit-min-device-pixel-ratio: 3) {
    .border{
        border: 0.333333px solid #999;
    }
}