Just use a background image of an upwards pointing arrow on the selected item. You would be able to use nested lists here, so you'll have something more like:
- Code: Select all
<div class="topmenu">
<ul>
<li>Tech</li>
<li class="showArrow">Sci</li>
</ul>
</div>
<div class="secnav">
<ul>
<li>This</li>
<li>And that</li>
</ul>
</div>