showdownjs/test/functional/makehtml/cases/features/tables/gh-style-tables.html

<table>
    <thead>
        <tr>
            <th>First Header</th>
            <th>Second Header</th>
            <th>Third Header</th>
        </tr>
    </thead>
    <tbody>
        <tr>
            <td>Content Cell</td>
            <td>Content Cell</td>
            <td>C</td>
        </tr>
        <tr>
            <td>Content Cell</td>
            <td>Content Cell</td>
            <td>C</td>
        </tr>
    </tbody>
</table>