document.addEventListener('DOMContentLoaded', () => {

  function updateFooterPosition() {
    const footer = document.querySelector('.footer');
    const containerHeight = document.querySelector('.main').offsetHeight + footer.offsetHeight;
    footer.classList.toggle('footer-fixed', containerHeight <= window.innerHeight);
  }

  updateFooterPosition();
  window.addEventListener('resize', updateFooterPosition);
  window.addEventListener('scroll', updateFooterPosition, { passive: true });
});