<style>
table, th, td {
  border: 1px solid black;
}
</style>
<table>   
  <tr>
     <th>Firstname</th>
     <th rowspan="2">Surname</th>
  </tr>
  <tr>
     <td>John</td>
  </tr>
  <tr>
     <td>Susan</td>
     <td>Smith</td>
  </tr>
</table>

External CSS

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External JavaScript

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