<body onload="draw();">
  <canvas id="canvas" width="500" height="300"></canvas>  
</body>
canvas {
	border: solid black 5px;
	border-radius: 16px;
}
function draw() {
	var canvas = document.getElementById("canvas");
	var ctx = canvas.getContext("2d");

  ctx.fillStyle = "black";
	ctx.beginPath();
	ctx.arc(250,130,100,0,Math.PI*2,true);
	ctx.fill();
}

External CSS

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External JavaScript

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