#myBtn {
  display: none;
  position: fixed;
  bottom: 20px;
  left: 3%;
  z-index: 99;
  font-size: 14px;
  border: none;
  outline: none;
  background-color: blue;
  color: white;
  cursor: pointer;
  padding: 5px;
  border-radius: 4px;
}

#myBtn:hover {
  background-color: #555;
}