// 1) Click-to-flip helper
    function flip(page) {
      page.classList.toggle('flipped');
    }

    // 2) Next/Restart logic
    const pages = Array.from(document.querySelectorAll('#flipbook .page'));
    let current = 0;

    document.getElementById('nextBtn').addEventListener('click', () => {
      if (current < pages.length) {
        pages[current].classList.add('flipped');
        current++;
      }
      if (current === pages.length) {
        document.getElementById('nextBtn').disabled = true;
      }
    });
    document.getElementById('restartBtn').addEventListener('click', () => {
      pages.forEach(p => p.classList.remove('flipped'));
      current = 0;
      document.getElementById('nextBtn').disabled = true;
    });</script></body></html>