Julie

  function gro() {
    var scrolly = document.getElementById('scrolly');

    var mass = Math.min(20, 1+0.005*document.scrollTop);
    
    scrolly.style.transform = 'scale(' + mass + ')';
    
    //$('#scrolly').css('transform', 'scale(' + mass + ')');
    
  };

  window.addEventListener('scroll', gro);