// ── Nav: scroll state & active link ───────────────────────────
(function () {
  const header    = document.getElementById('header');
  const links     = document.querySelectorAll('.nav-link');
  const sections  = document.querySelectorAll('section[id]');
  const burger    = document.getElementById('burger');
  if (!header || !burger) return;

  window.addEventListener('scroll', () => {
    header.classList.toggle('scrolled', window.scrollY > 24 || burger.classList.contains('open'));

    let current = '';
    sections.forEach(s => {
      if (window.scrollY >= s.offsetTop - 100) current = s.id;
    });
    links.forEach(l => {
      l.classList.toggle('active', l.getAttribute('href') === '#' + current);
    });
  }, { passive: true });
})();
