Hi. How can i cancel the uri style of Code Igniter system?

[eluser]agresif[/eluser]
I tried these.

RewriteEngine on
----
RewriteCond $1 !^(index\.php|images|robots\.txt|stats)
-or-
RewriteCond $1 !^(index\.php|robots\.txt|stats)
-or-
RewriteCond $1 !^(index\.php|stats)
----
RewriteRule ^(.*)$ /index.php/$1 [L]

But result same.

http://site.com/stats/ => "404 Page Not Found"
http://site.com/ => css's doesn't load. site was broken down.