hey silviog,
i have exactly the same problem.
Even if i put it it in a table like this
<table border="1">
<tbody>
<tr>
<td><strong>Artikelnr.:</strong> [custom_field name="artikelnummer_intern" filter="wrapper"]<span class="my_class">[+content+]</span>[/custom_field]</td>
</tr>
</tbody>
</table>
its still stays on top of the content.
Did you already sort this problem out?
cheers
instant