.btn {
/* background-color: #4CAF50;*/
  background-color: gray;
  border: none;
  color: white;
  padding: 8px 15px;
  text-align: center;
  font-size: 16px;
  margin: 4px 2px;
  transition: 0.3s;
}

.btn:hover {
/*background-color: #4691A4;*/
  background-color: silver;
  color: white;
}