Sections Not Collapsing Properly In Firefox

I've got a page that shows a number of packages available for sale. Each
package has a little description, and then a (sometimes long) list of
features for each package. I thought it would be a good idea to let
visitors hide the details for each package, so that they can see just
the summaries together. So I borrowed some code (can't remember from
where), which was designed for expandable/collapsible menu trees, and
used it to show/hide the details of the packages.

The code works fine, but the only problem is that when you hide a
section, the page doesn't resize itself. The text underneath moves up,
but below that a huge empty space is left. The scroll bars should change
to reflect the page's new (smaller) length, but instead they stay the
same, and let you scroll through all the empty nothing at the bottom of
the page.

I've tested the page is IE6 and Firefox 0.9 - I only have this problem
in Firefox, in IE the whole page shrinks and the scroll bars change
accordingly. Any suggestions? I though maybe I need to call some
javascript function to refresh/recalculate the page - I tried using
document.normalize() straight after the section got hidden, but it
didn't help. Any other such functions that might do the trick?

Here's the code: