File is locked

// document.getElementById('btn').addEventListener('click', () => {
// const boxes = document.querySelectorAll('.box');
// const beepSound = document.getElementById('beepSound');

// boxes.forEach((box, index) => {
// setTimeout(() => {
// box.style.transition = 'opacity 0.8s ease-out';
// box.style.opacity = '0';

body {
margin: 0;
padding: 30px;
/* padding: 0px; */
/* display: none; */
justify-content: center;
align-items: center;
width: 100%;