series: [
   {
       type: 'line',
       areaStyle: {
            color: {
              type: 'linear',
              x: 0,
              y: 0,
              x2: 0,
              y2: 1,
              colorStops: [{
                offset: 0, color: 'rgba(125,72,255,0.5)'
              }, {
                offset: 1, color: 'rgba(0,180,255,0.3)'
              } ],
              global: false
            }
      },

    }       
]