text: window.onscroll = function() {
    scrollFunction();
  };
  
  function scrollFunction() {
    if (
      document.body.scrollTop > 500 ||
      document.documentElement.scrollTop > 500
    ) {
      document.getElementById("navbar").style.top = "0";
    } else {
      document.getElementById("navbar").style.top = "-75px";
    }
  }
  