RewriteEngine on
RewriteBase /
RewriteCond $1 !^(admin\/(.*)|$)
RewriteCond $1 !^(user\/(.*)|$)
RewriteCond $1 !^(index.php(.*)|$)
RewriteCond $1 !^(config.php(.*)|$)
RewriteCond $1 !^(cs.php(.*)|$)
RewriteRule ^(.*)$ / [L,QSA]
RewriteRule ^([uU]ser)([/]*)$ cs.php