【retina】手机上 1PX 边框

1像素边框，在2倍屏幕上为2“占位”，3倍屏上为3“占位”，但设计师就要1“占位”

 .content h1:after,
 .content h2:after {
     border-top: 1px solid #bfbfbf;
     content: ' ';
     display: block;
     width: 100%;
     position: absolute;
     left: 0;
     bottom: 0;
     -webkit-transform-origin: left bottom;
 }
 /* Retina 适配 */
 @media only screen and (-webkit-min-device-pixel-ratio: 2.0),
 only screen and (min--moz-device-pixel-ratio: 2.0),
 only screen and (-o-min-device-pixel-ratio: 200/100),
 only screen and (min-device-pixel-ratio: 2.0) {
     .content h1:after,
     .content h2:after {
         -webkit-transform: scaleY(0.5);
         transform: scaleY(0.5);
     }
 }

 /* 三倍屏 适配 */
 @media only screen and (-webkit-min-device-pixel-ratio: 2.5),
 only screen and (min--moz-device-pixel-ratio: 2.5),
 only screen and (-o-min-device-pixel-ratio: 250/100),
 only screen and (min-device-pixel-ratio: 2.5) {
     .content h1:after,
     .content h2:after {
         -webkit-transform: scaleY(0.33333334);
         transform: scaleY(0.33333334);
     }
 }