my website is index.php (layout/design), and multiple links to include through php content in the center (articles/downloads/etc)

Code:
			<div id="page_content">
			<?php $dc = $_GET['dc'];if(!empty($dc)){$dc .= '.php';include_once($dc);}else{include_once('articles.php');}?>
			</div>
i need to be able to change the height of page_content when the link is pressed for other page content

Code:
						<li><a href="index.php?dc=articles">articles</a></li>
						<li><a href="index.php?dc=clan99">clan 99</a></li>
						<li><a href="index.php?dc=downloads">downloads</a></li>