Opencar Current link active Problem

Hello Friends , I am using opencart for ecommerce site. In this site, i have one problem in header part i.e in header i have put some custom menu items like about us, testimonials, video, comparison. I want these can be active when particular page is opened. for example: When some opened about us page the about us menu item is active i.e showing some background on about us menu item.

I have put custome links in header part like :

<li class="item<?php echo ((empty($_GET['_route_']) && empty($_GET['route'])) || (isset($_GET['route']) && $_GET['route'] == 'common/home')) ? '' : '' ?>"><a href="http://site url/aboutus">About Us</a></li>
<li class="item<?php echo ((empty($_GET['_route_']) && empty($_GET['route'])) || (isset($_GET['route']) && $_GET['route'] == 'common/home')) ? '' : '' ?>"><a href="http://site url/testimonials">testimonials</a></li>
<li class="item<?php echo ((empty($_GET['_route_']) && empty($_GET['route'])) || (isset($_GET['route']) && $_GET['route'] == 'common/home')) ? '' : '' ?>"><a href="http://site url/Videos">Videos</a></li>

How it can be active?????????


Thanks in advance.........................