scroll tbody

HTML

<div>
  <div class="wrapper">
    <table>
      <thead>
        <tr>
          <th>head</th>
          <th>head</th>
          <th>head</th>
          <th>head</th>
          <th>head</th>
        </tr>
      </thead>
      <tbody>
        <tr>
          <td>body</td>
          <td>body</td>
          <td>body</td>
          <td>body</td>
          <td>body</td>
        </tr>
        <tr>
          <td>body</td>
          <td>body</td>
          <td>body</td>
          <td>body</td>
          <td>body</td>
        </tr>
        <tr>
          <td>body</td>
          <td>body</td>
          <td>body</td>
          <td>body</td>
          <td>body</td>
        </tr>
        <tr>
          <td>body</td>
          <td>body</td>
          <td>body</td>
          <td>body</td>
          <td>body</td>
        </tr>
        <tr>
          <td>body</td>
          <td>body</td>
          <td>body</td>
          <td>body</td>
          <td>body</td>
        </tr>
        <tr>
          <td>body</td>
          <td>body</td>
          <td>body</td>
          <td>body</td>
          <td>body</td>
        </tr>
      </tbody>
    </table>
  </div>
</div>

CSS

.wrapper{
  background:salmon;
}
thead, tbody{
 
  display:block;
}
tbody{
   background:yellow;
  overflow-y:auto;
   height:6em;
}
thead th,
tbody td{
/*   width:4em;
   */}