docs: function hasMathMLSupport() {
    var div = document.createElement("div"), box;
    div.innerHTML = "<math><mspace height='23px' width='77px'/></math>";
    document.body.appendChild(div);
    box = div.firstChild.firstChild.getBoundingClientRect();
    document.body.removeChild(div);
    return Math.abs(box.height - 23) <= 1  && Math.abs(box.width - 77) <= 1;
  }