export const Header = () => {
  const header = document.querySelector('.header');

  if (!header) return false;

  const active = () => {
    if (window.pageYOffset || document.documentElement.scrollTop <= 0) {
      header.classList.remove('active');
    }

    if (window.pageYOffset || document.documentElement.scrollTop > 20) {
      header.classList.add('active');
    }
  };

  active();

  window.addEventListener('scroll', active, false);
}