element ui tree组件怎么设置滚动条

   <el-tree class="el-scrollbar tree" :data="areaList" node-key="id" default-expand-all
            :expand-on-click-node="false" @current-change="currentChange">
            <span class="custom-tree-node" slot-scope="{ node, data }">
                <span>{{ node.label }}</span>
                <span class="butotn">
                    <slot name="operate" :treeData="data"></slot>
                </span>
            </span>
    </el-tree>

//css样式
.tree {
    display: inline-block;
}

给tree元素添加el-scrollbar 和自定义class类名，并给el-tree的父元素设置overflow:auto

//全局样式
.Tree[data-v-610b47e2]::-webkit-scrollbar {
    width: 5px;
    height: 5px;
}
//内嵌滚动条样式
.Tree[data-v-610b47e2]::-webkit-scrollbar-thumb {
    border-radius: 1px;
    background-color: #40a0ff65;
}
//外部样式
.Tree[data-v-610b47e2]::-webkit-scrollbar-track {
    background-color: #f3f3f3;
}