angular2-csv如何添加标题粗体？

Question

this.personList有一些元素数组。我想添加标题行Firstname，Lastname和Email是粗体。 我使用Angular2Csv模块下载csv

import { Angular2Csv } from 'angular2-csv/Angular2-csv';

downloadCSV() {
            let options = {
                fieldSeparator: ',',
                quoteStrings: '"',
                decimalseparator: '.',
                showLabels: true,
                showTitle: true,
                useBom: true,
                headers: ['Firstname', 'Lastname', 'Email']
            };

            new Angular2Csv(this.personList, 'Person List', options);
        }