mod_rewrite not fully working.

This is the bit of my .htaccess which matters, in the root directory:

RewriteEngine on

RewriteCond %{SCRIPT_FILENAME} !-d
RewriteCond %{SCRIPT_FILENAME} !-f

RewriteRule ^(.*) /thatDirectory/index.php?invalidDir=$1

If somebody goes to www.example.com/images, it goes to images okey.

If somebody goes to www.example.com/thisDirectory/, while "thisDirectory" does not exist, it should forward to "www.example.com/thatDirectory". The name of the directory that doesnt exist should be passed to the page via a HTTP_GET_VARS variable.

At the moment, it forwards and reads files in "thatDirectory", which exist, but when it needs to reference things like style.css and images, they dont work.

I think, this is because the script is coming from "www.example.com/thatDirectory", I think that reqresite files, like .css, images and etc, are being referenced by "www.example.com/thisDirectory" (which does not exist).

Hope that all makes sense. Thanks.