[eluser]InsiteFX[/eluser]
You can not use base_url() in a style sheet!
First off you should put your css in a separate file.css
Create a assets directory where the index.php file is.
assets
-- css
-- img or images
-- js
Your css image links will now be:
../images/yourimag.ext
Enjoy
InsiteFX
P.S.
If you search these forums you can find asset libraries.