移动端中一像素的解决方案

.border::after {
content: " ";
width: 200%;
height: 200%;
position: absolute;
top: 0;
left: 0;
border: 1px solid #888;
-webkit-transform: scale(0.5);
transform: scale(0.5);
-webkit-transform-origin: 0 0;
transform-origin: 0 0;
box-sizing: border-box;
}

.borderBottom::after{
content:"";
position:absolute;
bottom: -1px;
left:0;
border-bottom:1px solid #e5e5e5;
width: 200%;
display: block;
-webkit-transform:scale(0.5);
transform:scale(0.5);
-webkit-transform-origin:0 0;
transform-origin:0 0;
right: 0;
box-sizing: border-box;
}