移动端实现1px像素边框

		<div class="box"></div>
 		.box{
            width: 100px;
            height: 100px;
            position: relative;
        }
        .box::after{
            position: absolute;
            left: -50%;
            top: -50%;
            width: 200%;
            height: 200%;
            transform: scale(.5);
            border: 1px solid #000000;
            display: block;
            content: '';
        }