On slide-event height issues multiple menu-items

Dear Sitepoint-users

Thanks to your help I made this site a while ago. I’m currently adapting the site, but I’m encountering some problems.
Because it’s a horizontal side, I made the text appear through an on-click slide-event. However, the calculations for this slide-event are based on 3 or less menu-items (image: ). When I add menu-items, the sliding continues and slides larger than the height of our central container (image: ). It should be no higher than 450px (height of left image). With 2 it’s perfect, with 3menu-items it goes a little bit too high aswell (image: )

Since I’m not a jquery-hero, I can’t seem to find how to adjust this so that this will work with even 6 menu-items.

If there is a lot of text under the menu-item, that makes that you can’t read it all because of the height with the menu-items OF because you window the site which makes the textarea smaller, how can we resolve this issue (image: )? If we add overflow- scroll, there’s an ugly scrollbar right from the beginning, which makes the entire page look ugly. Are there any other options?
Here is how a title is being made up in source code:

<div id="DIV1" style=" overflow:hidden; position: relative; height: 30px;" onclick="start_slide(this.id);"> 
<div id="DIV1_title" style="top:0px; left:0px;">Title</div>
<div id="DIV1_content">Content </div></div>

In attachment also my css .

Thanks a lot for the help.

Kind regards