[eluser]WanWizard[/eluser]
Have you checked the URI class (see the user guide )?
You shouldn't make a css file (or any asset) dependent on the page URI. It is best practice to have all assets in a folder called 'assets' in the root of your website (and then sub folders per type).
Assets are then references using
Code:
<link rel="stylesheet" href="<?php echo base_url();?>assets/css/mycssfile.css" type="text/css" media="screen"/>
Don't forget to configure your base_url and index file in config/config.php.