window.onscroll = function() {scrollFunction()};  
   
function scrollFunction() {  
  let homeSection = document.getElementById("home"); 
  let scrollTopBtn = document.getElementById("scrollTopBtn"); 
  if (window.pageYOffset > 200) {  
    scrollTopBtn.style.display = "block";  
  } else {  
    scrollTopBtn.style.display = "none";  
  }  
}  
document.getElementById("scrollTopBtn").addEventListener('click', function() {  
  document.body.scrollTop = 0;  
  document.documentElement.scrollTop = 0;  
});