JSFiddle - React, Tailwind, and code Playground

HTML

<script src="//cdn.rawgit.com/mrdoob/three.js/master/build/three.min.js"></script>

CSS

body {
	  margin: 0;
}

JavaScript

var camera, scene, renderer;
var geometry, material, mesh;
var hemiLight, dirLight;

init();
animate();

function init() {

    camera = new THREE.PerspectiveCamera( 70, window.innerWidth / window.innerHeight, 0.01, 10 );
    camera.position.z = 1;

    scene = new THREE.Scene();
		scene.background = new  THREE.Color( 0xcccccc );

    geometry = new THREE.BoxGeometry( 0.2, 0.2, 0.2 );
    material = new THREE.MeshBasicMaterial( { color: 0xcccccc } );

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

    renderer = new THREE.WebGLRenderer( { antialias: true } );
    renderer.setSize( window.innerWidth, window.innerHeight );
    renderer.setPixelRatio(window.devicePixelRatio);
    renderer.setSize(window.innerWidth, window.innerHeight);
    renderer.gammaInput = true;
    renderer.gammaOutput = true; // <- if this option is true, it shows the problem I'm talking about.
    renderer.shadowMap.enabled = true;
    renderer.shadowMap.type = THREE.PCFSoftShadowMap;
    document.body.appendChild( renderer.domElement );
    
    // lights
    var hemiLight = new THREE.HemisphereLight( 0xffffff, 0xffffff, 0.6 );
    hemiLight.color.setHSL( 0.6, 1, 0.6 );
    hemiLight.groundColor.setHSL( 0.095, 1, 0.75 );
    hemiLight.position.set( 0, 50, 0 );
    scene.add( hemiLight );

    dirLight = new THREE.DirectionalLight( 0xffffff, 0.6 );
    dirLight.color.setHSL( 0.1, 1, 0.95 );
    dirLight.position.set( 1, 1.75, -1 );
    dirLight.position.multiplyScalar( 30 );
    scene.add( dirLight );

    // setup directional shadow
    var shadowMapDist = 100;
    dirLight.castShadow = true;
    dirLight.shadow.mapSize.width = 1024;
    dirLight.shadow.mapSize.height = 1024;
    dirLight.shadow.camera.left = -shadowMapDist;
    dirLight.shadow.camera.right = shadowMapDist;
    dirLight.shadow.camera.top = shadowMapDist;
    dirLight.shadow.camera.bottom = -shadowMapDist;
    dirLight.shadow.camera.far = 3500;
    dirLight.shadow.bias = -0.00001;

}

function...