elementui的表格加红色*号

<template>
	<el-table :header-cell-class-name="mustAdd"></el-table>
</template>

<script>
export default {
  methods: {
    // lable红色
    mustAdd({ row, column, rowIndex, columnIndex }) { //  columnIndex 列下标
      console.log(row, column, rowIndex, columnIndex);
      if (columnIndex == 10) {
        return 'must';
      }
    },
  }
}
<script>
<style>
	table th.must div:before{  // 伪类选择器 :before
	  content: '*';
	  color: red !important; 
	}
</style>