Untitled

<!-- pure CSS hover example -->
<html>
      <head>
      <style>
             #my-container {
                height: 30px;
                overflow: hidden;

                border: 1px black solid;
                cursor: pointer;
             }
             #my-button {
                height: 30px;
             }
             #my-container:hover {
                height: auto;
             }
      </style>
      </head>
      <body>
            <div id="my-container">
                 <div id="my-button">
                      Hover over me
                 </div>
                 <ul>
                     <li>Option 1</li>
                     <li>Option 2</li>
                     <li>Option 3</li>
                 </ul>
            </div>
      </body>
</html>