xiaoshi-wx/myComponents/popover/popover.wxss

.popover-view {
  position: absolute;
  background-color: white;
  box-shadow: 0 0 2px 2px #ddd;
  border-radius: 6rpx;
}
/* 实现三角形 */
.popover-view::before {
  position: absolute;
  display: inline-block;
  width: 0;
  height: 0px;
  content: '';
  border-style: solid;
  border-width: 6px;
  border-color: #fff #fff transparent transparent;
  box-shadow: 2px -2px 2px #ddd;
}
/* 上 */
.popover-view.top::before {
  bottom: -6px;
  transform: rotate(135deg);
}
/* 下 */
.popover-view.bottom::before {
  top: -6px;
  transform: rotate(-45deg);
}
/* 左 */
.popover-view.left::before {
  right: 20px;
}
/* 中 */
.popover-view.center::before {
  left: 47px;
}
/* 右 */
.popover-view.right::before {
  left: 20px;
}