<html>
<body>
<h1>HTML5 Canvas</h1>
<canvas id="myCanvas" width="300" height="150" style="border:1px solid grey"></canvas>
<script>
const myCanvas = document.getElementById("myCanvas");
const ctx = myCanvas.getContext("2d");
ctx.fillStyle = "red";
ctx.fillRect(20, 20, 150, 100);
</script>
</body>
</html>