Highcharts - Compare two months (line chart)

using twin xaxis with adjustable offset between series

HTML

<script src="https://code.highcharts.com/highcharts.js"></script>
<script src="https://code.highcharts.com/modules/exporting.js"></script>

<div id="container" style="min-width: 400px; height: 400px; margin: 0 auto"></div>
<button id="button1" class="autocompare">Reset Extremes xAxis 1</button>
<button id="button2" class="autocompare">&lt;</button>
<button id="button3" class="autocompare">&gt;</button>

JavaScript

$(function() {
  $('#container').highcharts({
   /*  chart: {
      zoomType: 'x'
    }, */
    title: {
      text: 'Month Compare'
    },
/*     legend: {
      'align': 'centre'
    }, */
    xAxis: [{
      type: "datetime",
      dateTimeLabelFormats: {
        day: '%e %b (%w)'
      },
      title: {
        text: 'March'
      }
    }, {
      type: "datetime",
      dateTimeLabelFormats: {
        day: '%e %b (%w)'
      },
      title: {
        text: 'Compare Feb'
      }
    }], 
   /*  yAxis: [{ // Primary yAxis
      labels: {
        style: {
          color: Highcharts.getOptions().colors[2]
        }
      },
      title: {
        text: 'Sales',
        style: {
          color: Highcharts.getOptions().colors[2]
        }
      },
    
    }], */
    tooltip: {
     /* shared: true,
      formatter: function() {
        var s = "";
        s += "x0=" + Highcharts.dateFormat("%e %b", this.points[0].x) + "<br/>";
        s += "x1=" + Highcharts.dateFormat("%e %b", this.points[1].x) + "<br/>";
        s += "y0=" + this.points[0].y + "<br/>";
        s += "y1=" + this.points[1].y + "<br/>";
        s += "change="+format_change(this.points[1].y, this.points[0].y) + "<br/>";
      
        return s;
      },  */
    },
/*     legend: {
      enable: false
    }, */
    series: [{
      name: 'March Sales',
      xAxis: 0,
      dashStyle: 'shortdot',
      data: [
        [Date.UTC(2016, 2, 1, 00, 00, 00), 50.9],
        [Date.UTC(2016, 2, 2, 00, 00, 00), 45.9],
        [Date.UTC(2016, 2, 3, 00, 00, 00), 41.9],
        [Date.UTC(2016, 2, 4, 00, 00, 00), 48],
        [Date.UTC(2016, 2, 5, 00, 00, 00), 51],
        [Date.UTC(2016, 2, 6, 00, 00, 00), 56],
        [Date.UTC(2016, 2, 7, 00, 00, 00), 53.2],
        [Date.UTC(2016, 2, 8, 00, 00, 00), 52],
        [Date.UTC(2016, 2, 9, 00, 00, 00), 48],
        [Date.UTC(2016, 2, 10, 00, 00, 00), 38],
        [Date.UTC(2016, 2, 11, 00, 00, 00), 50],
        [Date.UTC(2016, 2, 12, 00, 00, 00), 51],
       ...