(function () {
  var content = document.querySelector("main");
  if (!content) return;

  var headings = content.querySelectorAll("h2, h3, h4");
  if (!headings) return

  headings.forEach(function (h) {
      if (!h.id) return;
      var a = document.createElement('a');
      a.href = '#' + h.id;
      a.className = 'heading-anchor';
      a.setAttribute('aria-label', 'Link to this section');
      a.textContent = '#';
      h.insertBefore(a, h.firstChild);
  });
}());