message: remove the green hover
diff: .btn {
  - color: rgba(0, 0, 0, 0.87);
  + color: #656565;
  background-color: #F5F5F5;
  padding: 10px 20px;
  margin: 5px 8px;
  }
  .btn:hover {
  - color: #00c5b4;
  + color: #333;
  }
  .btn:focus {
  