Como no tienes el foro en línea no podemos ver tu código. Te pasaré las modificaciones que hice para que tuviese ese resultado.
forumbit_depth1_cat:
<table border="0" cellspacing="{$theme['borderwidth']}" cellpadding="{$theme['tablespace']}" class="tborder">
<thead>
<tr>
<td class="thead" colspan="5">
<div class="expcolimage"><img src="{$theme['imgdir']}/{$expcolimage}" id="cat_{$forum['fid']}_img" class="expander" alt="{$expaltext}" title="{$expaltext}" /></div>
<div><strong><a href="{$forum_url}">{$forum['name']}</a></strong><br /><div class="smalltext">{$forum['description']}</div></div>
</td>
</tr>
</thead>
<tbody style="{$expdisplay}" id="cat_{$forum['fid']}_e">
{$sub_forums}
</tbody>
</table>
<br />
forumbit_depth2_cat y
forumbit_depth2_forum:
<tr>
<td class="trow1" align="center" valign="middle" width="1"><img src="{$theme['imgdir']}/{$lightbulb['folder']}.gif" alt="{$lightbulb['altonoff']}" title="{$lightbulb['altonoff']}" class="ajax_mark_read" id="mark_read_{$forum['fid']}" /></td>
<td class="trow2" valign="middle">
<strong><a href="{$forum_url}">{$forum['name']}</a></strong>{$forum_viewers_text}<div class="smalltext">{$forum['description']}{$modlist}{$subforums}</div>
</td>
<td class="trow1" valign="middle" align="center" style="white-space: nowrap" width="50"><span class="largetext">{$threads}{$unapproved['unapproved_threads']}</span><br /><span class="smalltext">{$lang->forumbit_threads}</span></td>
<td class="trow1" valign="middle" align="center" style="white-space: nowrap" width="50"><span class="largetext">{$posts}{$unapproved['unapproved_posts']}</span><br /><span class="smalltext">{$lang->forumbit_posts}</span></td>
<td class="trow2" valign="middle" align="left" style="white-space: nowrap" width="220">{$lastpost}</td>
</tr>