el-table表头文字换行或者修改字体颜色样式

例如

 <el-table
      :data="tableData"
      :header-cell-style="headClass" 
      style="width: 100%;" border >
      <el-table-column
        prop="address"
        label="生产工序"
         align="center">
      </el-table-column>
//重点看这里
       <el-table-column
         align="center">
          <template slot="header" slot-scope="slot">
          <div>方数㎡</div>
          <div class="greyColor">工件展开面积</div>
        </template>
        <template slot-scope="scope">
          <span>{{ scope.row.toolName }}</span>
        </template>
      </el-table-column>

       <el-table-column
        prop="address"
        label="子单数"
         align="center">
      </el-table-column>
       <el-table-column
        prop="address"
        label="工件数"
         align="center">
      </el-table-column>
 </el-table>