scroll dropdown bootstrap

1       <ul class="dropdown-menu scrollable-menu" role="menu">
2          <li><a href="#">Action</a></li>
3          <li><a href="#">Another action</a></li>
4          <li><a href="#">Something else here</a></li>
5          <li><a href="#">Action</a></li>
6            ..
7          <li><a href="#">Action</a></li>
8          <li><a href="#">Another action</a></li>
9       </ul>
10

1.scrollable-menu {
2    height: auto;
3    max-height: 200px;
4    overflow-x: hidden;
5}
6