Highcharts。热图严重着色

Question

我想让一些细胞像我这样半空：

http://jsfiddle.net/fuw65g95/3/

但是当一半上面没有一个单元格时，它只显示一种颜色：http://jsfiddle.net/fuw65g95/6/

series: [{
        name: 'Sales per employee',
        borderWidth: 1,
        data: [  {
 x: 0,
 y: 0,
 value: 90,
 color: {
     linearGradient: {
         x1: 0,
         x2: 0,
         y1: 0,
         y2: 1
     },
     stops: [
         [0, '#000000'],
         [0.49999999, '#000000'],
         [0.5, '#007340'],
         [1, '#007340']
     ]
 }
        }],

如果有一个在顶部，它可以正常工作http://jsfiddle.net/fuw65g95/7/

 series: [{
        name: 'Sales per employee',
        borderWidth: 1,
        data: [  { ... }, [0,1,2]],