responsive

index.html

<div id="editor">
      <div id="view"><canvas id="c"></canvas></div>
      <div id="controls">
        <div>
          <p>various controls
             would appear here</p>
           <div>Drag this bar</div>
           <div>⇐</div>
        </div>
      </div>
    </div>
  <script  type="importmap">{
	"imports": {
		"three": "https://threejs.org/build/three.module.js"
	}
}</script><script type="module" src="https://threejs.org/manual/examples/threejs-responsive.js"></script>
<script src="https://threejs.org/manual/3rdparty/split.min.js"></script>

styles.css

html, body {
  margin: 0;
  height: 100%;
}
#c {
  width: 100%;
  height: 100%;
  display: block;
}

three.js

import * as THREE from 'three';

function main() {

	const canvas = document.querySelector( '#c' );
	const renderer = new THREE.WebGLRenderer( { antialias: true, canvas } );

	const fov = 75;
	const aspect = 2; // the canvas default
	const near = 0.1;
	const far = 5;
	const camera = new THREE.PerspectiveCamera( fov, aspect, near, far );
	camera.position.z = 2;

	const scene = new THREE.Scene();

	{

		const color = 0xFFFFFF;
		const intensity = 3;
		const light = new THREE.DirectionalLight( color, intensity );
		light.position.set( - 1, 2, 4 );
		scene.add( light );

	}

	const boxWidth = 1;
	const boxHeight = 1;
	const boxDepth = 1;
	const geometry = new THREE.BoxGeometry( boxWidth, boxHeight, boxDepth );

	function makeInstance( geometry, color, x ) {

		const material = new THREE.MeshPhongMaterial( { color } );

		const cube = new THREE.Mesh( geometry, material );
		scene.add( cube );

		cube.position.x = x;

		return cube;

	}

	const cubes = [
		makeInstance( geometry, 0x44aa88, 0 ),
		makeInstance( geometry, 0x8844aa, - 2 ),
		makeInstance( geometry, 0xaa8844, 2 ),
	];

	function resizeRendererToDisplaySize( renderer ) {

		const canvas = renderer.domElement;
		const pixelRatio = window.devicePixelRatio;
		const width = Math.floor( canvas.clientWidth * pixelRatio );
		const height = Math.floor( canvas.clientHeight * pixelRatio );
		const needResize = canvas.width !== width || canvas.height !== height;
		if ( needResize ) {

			renderer.setSize( width, height, false );

		}

		return needResize;

	}

	function render( time ) {

		time *= 0.001;

		if ( resizeRendererToDisplaySize( renderer ) ) {

			const canvas = renderer.domElement;
			camera.aspect = canvas.clientWidth / canvas.clientHeight;
			camera.updateProjectionMatrix();

		}

		cubes.forEach( ( cube, ndx ) => {

			const speed = 1 + ndx * .1;
			const rot = time * speed;
			cube.rotation.x = rot;
			cube.rotation.y = rot;

		} );

		renderer.render( scene, camera );

		requestAnimationFrame( render );

	}

	requestAnimationFrame( render );

}

main();