I need help on why my three.js code isn’t working – Blancer.com Tutorials and projects

I want to learn three.js and tried following the getting started code on the three.js documentation, but the scene isn’t rendering, and I am completely stumped.

index.html:

<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="utf-8">
        <h1>My first three.js app</h1>
        <style>
            body { 
                margin: 0; 
            }
        </style>
        <script type="importmap">
            {
              "imports": {
                "three": "https://cdn.jsdelivr.net/npm/three@<v0.167.1>/build/three.module.js",
                "three/addons/": "https://cdn.jsdelivr.net/npm/three@<v0.167.1>/examples/jsm/"
              }
            }
          </script>
    </head>
    <body>
        <script  type="module" src="/main.js"></script>
    </body>
</html>

main.js:

import * as THREE from 'three';

const scene = new THREE.Scene();
const camera = new THREE.PerspectiveCamera( 75, window.innerWidth / window.innerHeight, 0.1, 1000 );

const renderer = new THREE.WebGLRenderer();
renderer.setSize( window.innerWidth, window.innerHeight );
document.body.appendChild( renderer.domElement );

const geometry = new THREE.BoxGeometry( 1, 1, 1 );
const material = new THREE.MeshBasicMaterial( { color: 0x00ff00 } );
const cube = new THREE.Mesh( geometry, material );
scene.add( cube );

camera.position.z = 5;

function animate() {
    cube.rotation.x += 0.01;
    cube.rotation.y += 0.01;
    renderer.render( scene, camera );
}
renderer.setAnimationLoop( animate );

I have no idea what is wrong, but the only thing showing up is the header. Please help!