message: Set focus to heading when scrollToHeading is called
diff: @@ -101,6 +101,8 @@ function scrollToHeading(hash){
  if(!heading) return null;
  + heading.setAttribute('tabindex','-1');
  + heading.focus();
  const marginTop = parseFloat(window.getComputedStyle(heading).marginTop, 10);
  window.scrollTo(0, (heading.offsetTop) - toc.getMobileNavbarHeight() - (marginTop - 2));
  }
  