app中画一条细线

&:after{
content: '';
position: absolute;
background-color: #ddd;
display: block;
z-index: 1;
top: auto;
position: relative;
top: .1rem;
width: 100%;
height: 1PX;
-webkit-transform-origin: 50% 100%;
-ms-transform-origin: 50% 100%;
transform-origin: 50% 100%;
-webkit-transform: scaleY(0.33);
-ms-transform: scaleY(0.33);
transform: scaleY(0.33);
}