JSFiddle - React, Tailwind, and code Playground

HTML

<table>
  <colgroup>
    <col class="highlight">
    <col>
  </colgroup>
  <thead>
    <tr>
      <th colspan="2">1</th>
    </tr>
  </thead>
  <tbody>
    <tr>
      <td>1.1</td>
      <td>1.2</td>
    </tr>
  </tbody>
</table>

<br>

<table>
  <colgroup>
    <col>
    <col class="highlight">
  </colgroup>
  <thead>
    <tr>
      <th colspan="2">1</th>
    </tr>
  </thead>
  <tbody>
    <tr>
      <td>1.1</td>
      <td>1.2</td>
    </tr>
  </tbody>
</table>

CSS

.highlight {
  background-color: red;
}
th, td {
  border: 1px solid;
}