Lets take a step back. Are you sure your current HTML markup is the only way to produce those tabs with the certain look? Right now you're using two empty LI elements to achieve this effect, which for one is semantically invalid:
Code:
<ul id="AttributeTabs" class="shadetabs">
<li id="DescriptionStart" class="SelectedStart"></li>
<li><a href="#" rel="Description" class="selected">Description</a></li>
<li id="DescriptionEnd" class="SelectedEnd"></li>
<li id="New FeaturesStart" class="NonSelectedStart"></li>
<li><a href="#" rel="New Features">New Features</a></li>
<li id="New FeaturesStart" class="NonSelectedEnd"></li>
<li id="FeaturesStart" class="NonSelectedStart"></li>
<li><a href="#" rel="Features">Features</a></li>
<li id="FeaturesEnd" class="NonSelectedEnd"></li>
<li id="VariantStart" class="NonSelectedStart"></li>
<li><a href="#" rel="Variant">Variant</a></li>
<li id="VariantEnd" class="NonSelectedEnd"></li>
</ul>
The more important issue of course is that it complicates getting the script to correctly apply the "selected" effect to the selected tab. I could take a stab, but in the long run, you'd be a lot better off if you can somehow create the look you want within the single <LI> element in which the tab is contained in. That way, applying the selected effect is as simple as modifying the ".selected" class within the CSS file.
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