CodeIgniter HTAccess doesn't load CSS files

You may also wish to try the following:

# Checks to see if the user is attempting to access a valid file,# such as an image or css document, if this isn't true it sends the# request to index.phpRewriteCond %{REQUEST_FILENAME} !-fRewriteCond %{REQUEST_FILENAME} !-dRewriteRule ^(.*)$ main.php/$1 [L]

This will allow you create whatever folders you want in the web root (styles, images, scripts) without having to declare them in the htaccess file.

I use this. Is well commented, and obviously not written by me.

<IfModule mod_rewrite.c>    RewriteEngine On    RewriteBase /    #Removes access to the system folder by users.    #Additionally this will allow you to create a System.php controller,    #previously this would not have been possible.    #'system' can be replaced if you have renamed your system folder.    RewriteCond %{REQUEST_URI} ^system.*    RewriteRule ^(.*)$ /index.php?/$1 [L]    #When your application folder isn't in the system folder    #This snippet prevents user access to the application folder    #Submitted by: Fabdrol    #Rename 'application' to your applications folder name.    RewriteCond %{REQUEST_URI} ^application.*    RewriteRule ^(.*)$ /index.php?/$1 [L]    #Checks to see if the user is attempting to access a valid file,    #such as an image or css document, if this isn't true it sends the    #request to index.php    RewriteCond %{REQUEST_FILENAME} !-f    RewriteCond %{REQUEST_FILENAME} !-d    RewriteRule ^(.*)$ index.php?/$1 [L]</IfModule><IfModule !mod_rewrite.c>    # If we don't have mod_rewrite installed, all 404's    # can be sent to index.php, and everything works as normal.    # Submitted by: ElliotHaughin    ErrorDocument 404 /index.php</IfModule> 

your htaccess file is missing one line :)

RewriteEngine onRewriteCond $1 !^(main\.php|images|robots\.txt|styles)RewriteRule ^(.*)$ /main.php/$1 [L]

You can put your styles directory in the RewriteCond line. I added styles for example.

More info here