问如果日期值小于当前日期，如何更改水平条的背景色？

EN

var today = new Date().getTime(),
  day = 1000 * 60 * 60 * 24;
var options = {
    title: {
      text: 'Visual Planner Chart with Navigation',
    },
    xAxis: currentDateIndicator: true,
    min: today - 3 * day,
    max: today + 18 * day
  },
  yAxis: {
    uniqueNames: true

  },
  series: [{
    name: 'Visual Planner',
    data: [],
    dataLabels: {
      enabled: true,
      format: '{point.owner}'
    }
  }]
}

var ganttChart = Highcharts.ganttChart('container-ganttChart', options)

ganttChart.series[0].addPoint({
  start: Date.UTC(2019, 01, 30),
  end: Date.UTC(2019, 03, 01),
  name: 'crewRank',
  owner: 'crewName'
})