JSFiddle - React, Tailwind, and code Playground

HTML

<table><tr class="one"><td>start grouped row 1 column 1 row 1<td>column 2 row 1</td></tr><tr><td>column 1 row 2<td>column 2 row 2</td></tr>
    
    <tr class="two"><td>start grouped row 2 column 1 row 1<td>column 2 row 1</td></tr><tr><td>column 1 row 2<td>column 2 row 2</td></tr>
        
        <tr class="three"><td>start grouped row 3 column 1 row 1<td>column 2 row 1</td></tr><tr><td>column 1 row 2<td>column 2 row 2</td></tr>
    </table>

CSS

tr.one  { background-color: #e2e2e2; }

tr.two { background-color: #a6a6a6; }

tr.three { background-color: #999; }