悬浮框文字信息显示echarts 折线配置项内容和展示

怎么使提示框中的字左对齐，现在居中对齐

      option = {
    title: {
        text: 'Awesome Chart'
    },
    tooltip: {

    },
    xAxis: {
        data: ['Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat']
    },
    yAxis: {},
    series: [{
        type: 'line',
        data: [220, 182, 191, 234, 290, 330, 210]

    }]
};