JSFiddle - React, Tailwind, and code Playground

HTML

<div style="width:500px;">

  <table class="table">
    <tr>
      <td style="background:blue;width:60%;">Some text for 1st cell</td>
      <td style="width:40%;background:red;"></td>
    </tr>
    <tr>
      <td colspan="2" style="width:100%;background:yellow;"><div style="width:400px;">
      test
      </div></td>
    </tr>
  </table>
  </div>

CSS

.table {
  width:100%;
}