Edit in JSFiddle

window.onload = function() {

    $("canvas").attr({height:$("#wrapper").height()});
    $("canvas").attr({width:$("#wrapper").width()});

    var stage = new Stage($("canvas")[0]);
    var g = new Graphics();
    
    //塗りを指定する
    g.beginLinearGradientFill(["#9ef","#9e2"],[0.1,1.0],0,-100,50,100);
    g.drawCircle(0,0,100);
  
    g.setStrokeStyle(5);
    g.beginFill(Graphics.getHSL(0,0,0,0));
    g.beginLinearGradientStroke(["#9e2","#000","#9ef"],[0.1,0.3,1.0],0,-100,50,100);
    g.drawCircle(0,0,130);
    
    var s = new Shape(g);
    s.x = $(window).width()/2;
    s.y = $(window).height()/2;
    
    
    
    stage.addChild(s);   
    stage.update();

}

<div id="wrapper">
<canvas></canvas>
</div>

html{
    min-height: 100%;
    overflow: auto;
    position:relative;
    z-index: 1;
}

body{
    min-height: 100%;
    margin: 0;
    padding: 0;
    overflow: auto;
    position: relative;
    z-index: 1;
}

#wrapper{
    height: auto;
    overflow: auto;
    position: fixed;
    z-index: 1;
    width: 100%;
    height:100%;
    min-height:100%;
}

canvas{
    position: fixed;
}