(function() {
  document.addEventListener('DOMContentLoaded', function() {
    // Skip-nav link for keyboard/screen reader accessibility
    var main = document.querySelector('main') || document.querySelector('.main') || document.querySelector('#main');
    if (main) {
      if (!main.id) main.id = 'main-content';
      var skipLink = document.createElement('a');
      skipLink.href = '#' + main.id;
      skipLink.className = 'skip-nav';
      skipLink.textContent = 'Skip to main content';
      skipLink.setAttribute('tabindex', '0');
      document.body.insertBefore(skipLink, document.body.firstChild);
    }

    // Fix back-to-top buttons without aria-label
    var btt = document.getElementById('back-to-top');
    if (btt && !btt.getAttribute('aria-label')) {
      btt.setAttribute('aria-label', 'Back to top');
    }

    var sidebar = document.querySelector('.sidebar');
    if (!sidebar) return;

    var body = document.body;
    var toggle = document.createElement('button');
    toggle.className = 'hamburger sidebar-toggle';
    toggle.setAttribute('type', 'button');
    toggle.setAttribute('aria-label', 'Open navigation');
    toggle.setAttribute('aria-expanded', 'false');
    toggle.innerHTML = '☰';
    body.prepend(toggle);

    var overlay = document.createElement('div');
    overlay.className = 'sidebar-overlay';
    body.appendChild(overlay);

    function setOpen(isOpen) {
      body.classList.toggle('mobile-drawer-open', isOpen);
      sidebar.classList.toggle('open', isOpen);
      overlay.classList.toggle('open', isOpen);
      toggle.innerHTML = isOpen ? '✕' : '☰';
      toggle.setAttribute('aria-label', isOpen ? 'Close navigation' : 'Open navigation');
      toggle.setAttribute('aria-expanded', String(isOpen));
    }

    toggle.addEventListener('click', function() {
      setOpen(!body.classList.contains('mobile-drawer-open'));
    });

    overlay.addEventListener('click', function() {
      setOpen(false);
    });

    sidebar.querySelectorAll('a').forEach(function(a) {
      a.addEventListener('click', function() {
        setOpen(false);
      });
    });

    window.addEventListener('resize', function() {
      if (window.innerWidth > 1080) setOpen(false);
    });

    document.addEventListener('keydown', function(event) {
      if (event.key === 'Escape') setOpen(false);
    });
  });
})();