JSFiddle - React, Tailwind, and code Playground

HTML

<table>
    <tr>
        <td rowspan="2" colspan="2" style="background-color:#03C">1,2
            <br/>4,5</td>
        <td style="background-color:#699">3</td>
        <td>&nbsp;</td>
    </tr>
    <tr>
        <td rowspan="2" style="background-color:#F96">6
            <br/>9</td>
        <td>&nbsp;</td>
    </tr>
    <tr>
        <td style="background-color:#F3C">7</td>
        <td style="background-color:#FC9">8</td>
        <td>&nbsp;</td>
    </tr>
    <tr>
        <td colspan="3" style="background-color:#CF3">10,11,12</td>
        <td>&nbsp;</td>
    </tr>
</table>

CSS

td {
    height: 45px;
}