title: Highcharts - areaspline with negative values, area should be always at the bottom
body: <p>I would like to create a chart with Highcharts, with negative values, like this:  </p>
  
  <p><a href="http://jsfiddle.net/vargapeti/LjL03o8h/3/" rel="nofollow">http://jsfiddle.net/vargapeti/LjL03o8h/3/</a></p>
  
  <pre><code>$(function () {
      $('#container').highcharts({
          chart: {
              type: 'areaspline'
          },
          title: {
              text: 'Area chart with negative values'
          },
          yAxis: {
              title: {
                  text: 'value'
              }
          },
          plotOptions: {
              area: {
                  dataLabels: {
                      enabled: true
                  },
                  stacked: 'normal'
              }
          },
          series: [{
              name: 'Area with negative values',
              data: [[0, -7.0], [1, 6.9], [1.5, 9.5], [3, -6]],
              fillColor : {
                linearGradient : [0, 0, 0, 300],
                stops : [
                    [ 0, Highcharts.Color('#FFA500').setOpacity(1).get('rgba') ],
                    [ 1, Highcharts.Color('#ffffff').setOpacity(0.3).get('rgba') ]
                ]
          }
          },
          {
              name: 'Area with positive values',
              data: [[0, 13.0], [1, 26.9], [1.5, 29.5], [3, 14]],
              fillColor : {
                linearGradient : [0, 0, 0, 300],
                stops : [
                    [ 0, Highcharts.Color('#d2d8df').setOpacity(1).get('rgba') ],
                    [ 1, Highcharts.Color('#ffffff').setOpacity(0.3).get('rgba') ]
                ]
          }
          }        
  
                  ],
  
      });
  });
  </code></pre>
  
  <p>I need however, the orange area to be always between the X-axis and the curve, regardless of the negative values. So basically I want to shift the curve "Area with positive values" under zero, but keep the filled up area under the curve.  </p>
  
  <p>Is it possible with Highcharts anyhow?</p>
  
  <p>Thank you.</p>