Creating a collapsible box

[MrEyes]

Hello all,

I am working on a mod that requires a collapsible section, so I have the following template markup

<div>
	<div class="threadlisthead table collapse">
		<span class="threadinfo">
			<div>Sticky Threads
				<a class="collapse" style="top:3px" id="collapse_sticky_threads" href="forum.php#top"><img src="images/buttons/collapse_40b.png" alt="" title="Collapse this Category" /></a>
			</div>
		</span>
	</div>

	<ol id="sticky_threads" class="threads">
		{vb:raw sticky_bits}
	</ol>
</div>

Now, heres the problem:

When I click the collapse button the order list element disappears, however the page does not roll up to take up the space. Which obviously defeats the point of collapsing and isn't the normal behaviour.

For the life of me I cannot see what I am missing here.