#topBtn{
  position: fixed;
  bottom: 40px;
  right: 40px;
  font-size: 22px;
  width: 50px;
  height: 50px;
  background: #3498db;
  color: white;
  border: none;
  cursor: pointer;
  display: none;
  background-size: cover;
}
#topBtn:hover{
  background: white;
  color: #3498db;
}