JSFiddle - React, Tailwind, and code Playground

HTML

<table>
    <tr>
        <th colspan="3">Ячейка 1</th>
    </tr>
    <tr>
        <td><br/>Ячейка 2<br/><br/><br/><br/></td><td colspan="2">Ячейка 3</td>
    </tr>    
</table>

CSS

table {
    width:100%;
    border:1px solid black;
}

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

tr:last-child td:first-child {
    width:30%;
}