如何将Highchart的字体家族更改为Bootstrap CSS默认字体家族

我想将标题，数据标签和工具提示的字体更改为饼图中的Bootstrap默认默认字体（我正在使用Highchart库显示该图表）。我要如何更改这些？试图添加fontFamily，但是没有用。

var chart = new Highcharts.Chart({
                    chart: {
                        renderTo: $(element).attr('id'),
                        backgroundColor: '#F8F8F8'
                    },
                    title: {
                        text: "Space Used by Users",
                        fontFamily: 'Helvetica'
                    },
                    plotOptions: {
                        pie: {
                            allowPointSelect: true,
                            cursor: 'pointer',
                            dataLabels: {
                                enabled: true,
                                format: '{point.name}: {point.sizeText}',
                                style: {
                                    fontSize: '11px'
                                }
                            },
                            showInLegend: true
                        }
                    },
                    credits: {
                        enabled: false
                    },
                    tooltip: {
                        pointFormat: '{series.name}: <b>{point.sizeText}</b>'
                    },
                    series: [{
                        type: 'pie',
                        data: [
                            {
                                name: 'Personal Usage',
                                y: scope.item.personalUsage,
                                sizeText: scope.item.personalUsageSizeText
                            },
                            {
                                name: 'Shared Usage',
                                y: scope.item.sharedUsage,
                                sizeText: scope.item.sharedUsageSizeText
                            }
                        ]
                    }]
                });

如何将字体更改为默认引导程序？