#GoToTopBtn {
  display: none;
  position: fixed;
  bottom: 20px;
  right: 30px;
  z-index: 99;
  font-size: 18px;
  cursor: pointer;
  padding: 10px;
  border-radius: 4px;
  box-shadow: 1px 1px 5px lightgrey;
  color: grey;
}

#GoToTopBtn:hover {
  background-color: #fafafa;
}