#myBtn {
  display: none;
  position: fixed;
  bottom: 20px;
  right: 5px;
  z-index: 99;
  outline: none;
  background-color: red;
  color: white;
  cursor: pointer;
  padding: 15px;
  border-radius: 10px;
}
#myBtn:hover {
  background-color: #555;
  color: yellow;
  border: 1px solid #008CBA;
}
#myBtn {
  box-shadow: 0 8px 16px 0 rgba(0,0,0,0.2), 0 6px 20px 0 rgba(0,0,0,0.19);
}