<style>
canvas {
    width: 10px;
    height: 10px;
}
</style>
<script>
function runTest() {
    // Step 1. Grab the WebGL canvas and render a solid color.

    const canvas = document.querySelector("canvas");
    canvas.width = 10;
    canvas.height = 10;

    const gl = canvas.getContext("webgl");

    // Clear to green

    gl.clearColor(0, 1, 0, 1);
    gl.clear(gl.COLOR_BUFFER_BIT);
}

window.addEventListener("load", runTest, false);
</script>
<div id="container1">
</div>
<div id="container2">
<canvas></canvas>
</div>