HTML5canvas绘图，怎么去掉阴影？

怎么把个%75，%25,去掉阴影。并且饼图要阴影。


<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>阴影饼图</title>
    <style>
        #mycanvas{
                border: 2px solid #7FFFD4;
            }
    </style>
    <script>
        function draw () {
        var mycanvas=document.getElementById("mycanvas");
        var ctx=mycanvas.getContext("2d");
        
         //阴影
        ctx.shadowOffsetX=7;
        ctx.shadowOffsetY=7;
        ctx.shadowBlur=5;
        ctx.shadowColor="#999999";
        
        //第一个圆
        ctx.fillStyle="#7FFFD4";
        ctx.moveTo(200,200);
        ctx.arc(200,200,100,0,1.5*Math.PI); 
        ctx.closePath()
        ctx.fill()
        //第二个圆
        ctx.fillStyle="#ADFF2F";      
        ctx.moveTo(220,180);
        ctx.arc(220,180,100,0,1.5*Math.PI,true); 
        ctx.closePath()
        ctx.fill()
        
        //文字渐变
        var gradient=ctx.createLinearGradient(0,0,0,250);
        gradient.addColorStop(0,"green");
        gradient.addColorStop(1,"yellow");
        ctx.fillStyle=gradient;
        ctx.font='italic 30px 微软雅黑';
        ctx.fillText('%75',140,240)
        ctx.fillText('%25',230,150)
    }    
      
        
    </script>
</head>
<body onload="draw()">
    <canvas id="mycanvas" width="500" height="500" ></canvas>
</body>
</html>