<!DOCTYPE html>
<html>
<head>
<title>Title of the document</title>
</head>
<body>
<canvas id="canvas" width="300" height="100"></canvas>
<script>
var canvas=document.getElementById('canvas');
var context=canvas.getContext('2d');
var centerX=canvas.width / 2;
var centerY=canvas.height / 2;
var radius=40;
context.beginPath();
context.arc(centerX, centerY, radius, 0, 2 * Math.PI, false);
context.fillStyle='lightgreen';
context.fill();
context.lineWidth=2;
context.strokeStyle="green";
context.stroke();
</script>
</body>
</html>