vant-weapp/dist/common/style/hairline.wxss

.van-hairline,.van-hairline--bottom,.van-hairline--left,.van-hairline--right,.van-hairline--surround,.van-hairline--top,.van-hairline--top-bottom{position:relative}.van-hairline--bottom::after,.van-hairline--left::after,.van-hairline--right::after,.van-hairline--surround::after,.van-hairline--top-bottom::after,.van-hairline--top::after,.van-hairline::after{content:'';position:absolute;top:0;left:0;width:200%;height:200%;-webkit-transform:scale(.5);transform:scale(.5);-webkit-transform-origin:0 0;transform-origin:0 0;pointer-events:none;box-sizing:border-box;border:0 solid #e5e5e5}.van-hairline--top::after{border-top-width:1px}.van-hairline--left::after{border-left-width:1px}.van-hairline--right::after{border-right-width:1px}.van-hairline--bottom::after{border-bottom-width:1px}.van-hairline--top-bottom::after{border-width:1px 0}.van-hairline--surround::after{border-width:1px}