HTMLify

document.getElementById('btn').addEventListener('click', () => {
  const boxes = document.querySelectorAll('.box'); 
  const container = document.querySelector('.container');
  const section = document.querySelector('.section');
  boxes.forEach((box, index) => {
      setTimeout(() => {
          box.style.transition = 'opacity 0.8s ease-out'; 
          box.style.opacity = '0'; 
          setTimeout(() => {
                box.style.display = 'none'; 
                const allBoxesHidden = Array.from(boxes).every(b => b.style.display === 'none');
                if (allBoxesHidden) {
                    section.style.display = 'none';
                    container.style.display = 'block';
                }
          }, 500); 
      }, index * 500); 
  });
});