//ページトップに戻るボタン
document.addEventListener('DOMContentLoaded', () => {
  const btn = document.querySelector('.pagetop');
  if (!btn) return;

  window.addEventListener('scroll', () => {
    btn.classList.toggle('is-show', window.scrollY > 300);
  });

  btn.addEventListener('click', (e) => {
    e.preventDefault();
    window.scrollTo({ top: 0, behavior: 'smooth' });
  });
});