Hide comment highlight controls under sublink

Nice job with this script.

I prefer to hide the highlight controls by default since they take some space, so here is code I added to achieve that. Replacing lines 464 to 466 with:

    var $timeTravelControl = $el('div', {style: {marginTop: '1em', display: 'none'},}, $range, ' ', $button);

    var $timeTravelControlReveal = $el('a', {
      onClick(e) {
        $timeTravelControl.style.display = 'initial';
        e.target.style.display = 'none';
      },
    }, 
      'highlight new comments');
    el.appendChild(document.createTextNode(' | '));
    el.appendChild($timeTravelControlReveal);
    el.appendChild($timeTravelControl);