微信小程序1px边框

.border-b:after {

  position: absolute; 

  content: '';

  width: 100%;

  left: 0;

  bottom: 0;

  height: 1px;

  background-color: #e3e5e9;

  -webkit-transform: scale(1, 0.5);

  transform: scale(1, 0.5);

  -webkit-transform-origin: center bottom;

  transform-origin: center bottom;

}