JSFiddle - React, Tailwind, and code Playground

HTML

<script type="module">

import * as THREE from '//raw.githack.com/mrdoob/three.js/dev/build/three.module.js';

import Stats from '//raw.githack.com/mrdoob/three.js/dev/examples/jsm/libs/stats.module.js';

var camera, scene, renderer, stats;

var mesh;
var amount = 10;
var count = Math.pow( amount, 3 );
var dummy = new THREE.Object3D();

init();
animate();

function init() {

  camera = new THREE.PerspectiveCamera( 60, window.innerWidth / window.innerHeight, 0.1, 1000 );
  camera.position.set( 9, 9, 9 );
  camera.lookAt( 0, 0, 0 );

  scene = new THREE.Scene();

	var geometry = new THREE.BoxBufferGeometry();

var urls = [ "posx.jpg", "negx.jpg", "posy.jpg", "negy.jpg", "posz.jpg", "negz.jpg" ];
	var texture = new THREE.CubeTextureLoader().setPath( 'https://raw.githubusercontent.com/mrdoob/three.js/dev/examples/textures/cube/Bridge2/' ).load( urls );
	texture.format = THREE.RGBFormat;
	texture.mapping = THREE.CubeReflectionMapping;
	texture.encoding = THREE.sRGBEncoding;
  
  var material = new THREE.MeshStandardMaterial( { roughness: 0, envMap: texture });
  // check overdraw
  // var material = new THREE.MeshBasicMaterial( { color: 0xff0000, opacity: 0.1, transparent: true } );

  mesh = new THREE.InstancedMesh( geometry, material, count );
  scene.add( mesh );
  
  var light = new THREE.DirectionalLight();
  light.position.set( 0, 1, 0 );
  scene.add( light );

  //

  renderer = new THREE.WebGLRenderer( { antialias: true } );
  renderer.setPixelRatio( window.devicePixelRatio );
  renderer.setSize( window.innerWidth, window.innerHeight );
  document.body.appendChild( renderer.domElement );

  //

  stats = new Stats();
  document.body.appendChild( stats.dom );

  //

  window.addEventListener( 'resize', onWindowResize, false );

}

function onWindowResize() {

  camera.aspect = window.innerWidth / window.innerHeight;
  camera.updateProjectionMatrix();

  renderer.setSize( window.innerWidth, window.innerHeight );

}

//

function animate() {

 ...

CSS

body { margin: 0 }