element 树形控件，父节点不显示复选框，子节点显示复选框，需增加特定样式
代码复用参考：
/deep/ .stafftree .el-tree .el-tree-node .is-leaf + .el-checkbox .el-checkbox__inner { display: inline-block; } /deep/ .stafftree .el-tree .el-tree-node .el-checkbox .el-checkbox__inner { display: none; } ::v-deep.el-tree-node.is-current > .el-tree-node__content { background-color: #041a21 !important; }