[Victor D]

try to change

{foreach from=$altcategories item=v}
<tr>
    <td valign="top" style="padding-left:15px;"><img src="{$ImagesDir}/category_bullet.gif" width="10" height="13" alt="" /></td>
    <td><a href="home.php?cat={$v.categoryid}" class="VertMenuItems"><font class="CategoriesList"  style="font-size:10px;">{$v.category}</font></a></td>
</tr>
{/foreach}

to

{foreach from=$altcategories item=v}
<tr>
    <td valign="top" style="padding-left:15px;"><img src="{$ImagesDir}/category_bullet.gif" width="10" height="13" alt="" /></td>
    <td>{if $v.categoryid ne $current_category.categoryid }<a href="home.php?cat={$v.categoryid}" class="VertMenuItems"><font class="CategoriesList"  style="font-size:10px;">{$v.category}</font></a>{else} <font class="myactivecategory">$v.category</font>
{/if}</td>
</tr>
{/foreach}

And put myactivecategory class description in skin1.css