JSFiddle - React, Tailwind, and code Playground

HTML

<table>
<colgroup>
<col width="120x">
<col width="200px">
<col width="50px">
<col class="foo" width="40px">
<col width="75px">
</colgroup>
<tr><td>1</td><td>2</td><td>3</td><td>4</td><td>5</td></tr>
<tr><td colspan=2>1+2</td><td>3</td><td>4</td><td>5</td></tr>
<tr><td>1</td><td>2</td><td>3</td><td>4</td><td>5</td></tr>
</table>

CSS

td {
  border: 1px solid black;
}
col.foo {
  background-color: red;
  font-weight: bold;
  text-align: center;
}