el-tree组件如何添加虚线指示

<el-tree
  class="tree-line"
  :data="treeOption"
  :props="defaultProps"
  @node-click="getCurrentNode"
>

利用样式添加虚线指示

.el-tree-style{
  /deep/ .el-tree-node {
    position: relative;
  }
  /deep/ .el-tree-node__children {
    padding-left: 16px; 
  }

  /deep/ .el-tree-node::before {
    content: '';
    height: 100%;
    width: 1px;
    position: absolute;
    left: 30px;
    top: 0;
    border-width: 1px;
    border-left: 1px dashed #ddd;
  }
  /deep/ .el-tree-node:last-child::before {
    height: 38px; 
  }

  /deep/ .el-tree-node::after {
    content: '';
    width: 15px;
    height: 20px;
    position: absolute;
    left: 30px;
    top: 12px;
    border-width: 1px;
    border-top: 1px dashed #ddd;
  }

  & > .el-tree-node::after {
    border-top: none;
  }
  & > .el-tree-node::before {
    border-left: none;
  }

  .el-tree-node__expand-icon {
    font-size: 16px;
    &.is-leaf {
      color: transparent;
    }
  }
}