@boutinb Could you have a look?

Great! I still see an issue in this case:

But this is already must better than before!

Good find, I will have a look. did you tried vertical alignment of exponential numbers?

Good find, I will have a look. did you tried vertical alignment of exponential numbers?

As far as I can see, alignment works well now.

Good find, I will have a look. did you tried vertical alignment of exponential numbers?

As far as I can see, alignment works well now.

Hummm, I cannot reproduce it works well on my PC (libreOffice and WPS):

What happend if you paste this table below in your spreadsheet software?

<table wicket:id="simpleTable">
	<thead>
		<tr>
			<th rowspan="2"><div class="over-title-space">1<div></th>
			<th rowspan="2">2</th>
			<th colspan="3"><div class="over-title-space">3<div></th>
		</tr>
		<tr>
			<th>3-1</th>
			<th>3-2</th>
			<th>3-3</th>
		</tr>
	</thead>
	<tbody>
		<tr>
			<td>a</td>
			<td>b</td>
			<td>c</td>
			<td>d</td>
			<td>e</td>
		</tr>
		<tr>
			<td>f</td>
			<td>g</td>
			<td>h</td>
			<td>i</td>
			<td>j</td>
		</tr>
	</tbody>
</table>