修改element ui 小三角 dropdown

<style scoped>

  .el-popper /deep/ .popper__arrow {
    border-bottom-color: #1EBEF4 !important;
    left: 50% !important;
    visibility: hidden;
  }

因为style在scoped内部需要用/deep/进行穿透
visibility：hidden，使其不显示

参考
https://blog.csdn.net/xuhua32100/article/details/107494873?utm_medium=distribute.pc_aggpage_search_result.none-task-blog-2_allfirst_rank_v2~rank_v25-4-107494873.nonecase&utm_term=element%20ui%20%E5%8E%BB%E6%8E%89%E5%B0%8F%E4%B8%89%E8%A7%92

https://blog.csdn.net/weixin_42304808/article/details/106118025?utm_medium=distribute.pc_aggpage_search_result.none-task-blog-2_allfirst_rank_v2~rank_v25-1-106118025.nonecase&utm_term=element%20ui%20%E5%8E%BB%E6%8E%89%E5%B0%8F%E4%B8%89%E8%A7%92