code: function scrollToHash() {
      var hash = window.location.hash.substring(1);
      if (hash) {
        var el = document.getElementById(hash);
        var delta = document.body.classList.contains('scrolled') ? 72 : 128;
        document.body.scrollTop = el.offsetTop - delta;
      }
    }
docs: Scrolls to the window's current hash.  Note: this is required
  because of the {position: fixed} banner at the top, which will
  cover the heading if we let the browser scroll on its own.
  Instead, we add a delta to ensure that the heading ends up
  below the banner.