title: Change Graph Series Fillcolor in highcharts
body: <p>AS shown in image, i want to change Fill color by point (referring project state in my case so),
  <a href="http://i.stack.imgur.com/xGhPQ.png" rel="nofollow">visual for my chart</a></p>
  
  <p>code i have used so far to achieve this is below,</p>
  
  <pre><code>    $(function () {
      $('#ao-projectssummry-chart').highcharts({
          type: "spline",
          title: null,
          borderRadius : null,
          xAxis: {
              categories: ['May2016', 'June2016', 'July2016', 'August2016', 'september2016', 'November2016'],
              opposite: true
              //type: 'datetime',
              //min: Date.UTC(2011, 4, 31),
              //max: Date.UTC(2012, 11, 6)
          },
          yAxis: {
              min: 0,
              max: 5,
              title : null
          },
          plotOptions: {
              series: {
                  lineWidth: 20,
                  borderRadius: null,
                  radius: 0
              },
              marker: {
                  radius : 0
              }
  
          },
          credits : {
              enabled : false
          },
          legend: {
              enabled : false
          },
  
          series: [{
              name: "Project 1",
              data: [1, 1, {
                  y: 1,
                              marker: {
                                  symbol: 'url(https://www.highcharts.com/samples/graphics/sun.png)',
                                  overlapping: true
                              }
                  }, {
                      y: 1,
                              marker: {
                                  symbol: 'url(https://www.highcharts.com/samples/graphics/sun.png)'
                              }
                  }, {
                      y: 1,
                      marker: {
                          symbol: 'url(https://www.highcharts.com/samples/graphics/sun.png)'
                      }
                  }
                  ]
          },
          {
              name: "Project 2",
  
              data: [2, {
                  y: 2,
                  marker: {
                      symbol: 'url(https://www.highcharts.com/samples/graphics/sun.png)',
                      overlapping : true
                  }
              }, 2, 2, 2, {
                  y:2,
                  marker: {
                      symbol: 'url(https://www.highcharts.com/samples/graphics/sun.png)',
                      overlapping: true
                  }
              },
              ]
          }]
      });
  });
  </code></pre>
  
  <p>so, how can i change the plotoption color by point? also how can i achieve background lines shown in the picture?</p>
  
  <p>Any help would be appreciated! thanks in advance.</p>