This is /skin1/customer/tab.tpl
This template contains one tan from menu.
You can edit this template and design tabs as you want.
For example, try to use this code.
Code:
<table cellpadding="0" cellspacing="0" dir="ltr">
<tr>
<td class="TabLeftSide"><img src="{$ImagesDir}/spacer.gif" class="TabSide" alt="" /></td>
<td style="background-color:#FFD44C; font-weight: bold;" {$reading_direction_tag}>{$tab_title}</td>
<td class="TabRightSide"><img src="{$ImagesDir}/spacer.gif" class="TabSide" alt="" /></td>
</tr>
<tr>
<td class="TabLeftCorner"><img src="{$ImagesDir}/spacer.gif" class="TabCorner" alt="" /></td>
<td class="TabCenter"><img src="{$ImagesDir}/spacer.gif" class="TabCorner" alt="" /></td>
<td class="TabRightCorner"><img src="{$ImagesDir}/spacer.gif" class="TabCorner" alt="" /></td>
</tr>
</table>