window.addEventListener("scroll", () => {
  var winScroll = document.body.scrollTop || document.documentElement.scrollTop;
  var height = document.documentElement.scrollHeight - document.documentElement.clientHeight;  
  var scrolled = (winScroll / height) * 100;
  document.getElementById('progress').style.width = scrolled + "%";

  const toTop = document.getElementById('totop');

  if ((window.scrollY > 0 && !toTop.classList.contains("show")) || (window.scrollY <= 0 && toTop.classList.contains("show"))) {
    toTop.classList.toggle("show");
  }
});