怎样设置阴影指示器宽度echarts 柱状配置项内容和展示

      option = {
    tooltip: {
        trigger: 'axis',
        axisPointer: {
            type: 'shadow'
        }
    },
    xAxis: {
        type: 'category',
        data: ['Mon']
    },
    yAxis: {
        type: 'value'
    },
    series: [{
        data: [120],
        type: 'bar',
        barWidth: 30
    }]
};