vant/packages/vant-css/src/uploader.css

@component-namespace van {
  @b uploader {
    position: relative;
    display: inline-block;

    @e input {
      position: absolute;
      top: 0;
      right: 0;
      bottom: 0;
      left: 0;
      display: block;
      width: 100%;
      height: 100%;
      opacity: 0;
      cursor:pointer;
    }

    input[type="file" i]::-webkit-file-upload-button {
      cursor:pointer;
    }
  }
}