I don't know how to merge rows and columns inside HTML tables.
Can you please help me with making such a table in HTML?
I'd suggest:
table {
empty-cells: show;
border: 1px solid #000;
}
table td,
table th {
min-width: 2em;
min-height: 2em;
border: 1px solid #000;
}
<table>
<thead>
<tr>
<th rowspan="2"></th>
<th colspan="4"> </th>
</tr>
<tr>
<th>I</th>
<th>II</th>
<th>III</th>
<th>IIII</th>
</tr>
</thead>
<tbody>
<tr>
<td></td>
<td>1</td>
<td>2</td>
<td>3</td>
<td>4</td>
</tr>
</tbody>
</table>
References: