<style>
  table {
    border-collapse: collapse;
  }

  td,
  th {
    border: 1px solid black;
    padding: 10px 20px;
  }

  .thick-border {
    border: 5px solid black;
  }
</style>

<table>
  <thead>
    <td>0</td>
    <td>1</td>
  </thead>
  <tbody class="thick-border">
    <tr>
      <td>A</td>
      <td>B</td>
    </tr>
    <tr>
      <td>C</td>
      <td>D</td>
    </tr>
  </tbody>
</table>