Web form having expanding divs inside a tab container

What I would like to achieve is to have two divs on either side of my tab container, one on the left and one on the right both touching the far sides. Then information in the page will need to go inbetween the two divs in the middle.

They also need to automatically expand in height when the tab container expands as more information could be added to the form dynamically thus lengthening the height. Here is my code up to now:


<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title>Untitled Page</title>
<link href="StyleSheet.css" rel="stylesheet" type="text/css" />
 
<script type="text/javascript">
 
function ShowDiv(divid)
{
    if(document.getElementById(divid).style.display == 'none')
   ...