Firefox2 and css caching issue - part 2

I have tried out to change settings for expire headers, and figured it that application adds its own headers to dynamic generated css files. Then apache2 mod-expire tries to add own settings.
After tweaking application settings there are resulting headers:

Date: Mon, 1 Mar 2008 06:46:02 GMT
Server: Apache/2
Cache-Control: max-age=600, max-age=604800
Expires: Mon, 6 Mar 2008 06:46:02 GMT
Vary: Accept-Encoding
Content-Encoding: gzip
Content-Length: 18128
Content-Type: text/css


Expire times:

• max-age=600 - given by apache2 global settings


• max-age=604800 - given by applications itself

It's ugly - but surprisingly caching works under Firefox with these headers. I haven't checked yet which expiration time is taken by Firefox. I need to clean it and remove one of extra headers anyway.

Below are old headers for the same resource fort comparison - when Firefox caching was not working:


Date: Sat, 01 Mar 2008 07:28:31 GMT
Last-Modified: Sat, 01 Mar 2008 07:26:56 GMT
Expires: Sat, 01 Mar 2008 07:36:56 GMT
Cache-Control: max-age=600
Vary: Accept-Encoding
Content-Encoding: gzip
Content-Length: 18128
Keep-Alive: timeout=10, max=98
Connection: Keep-Alive
Content-Type: text/css


There are removed last-modified and keep-alive headers, but it's hard to understand how it can change Firefox caching.
I have to check difference between 600 and 604800 expire age, that may be solution.

Probably all headers should look like those added by apache mod-expire for static files:


Date: Mon, 1 Mar 2008 06:46:04 GMT
Server: Apache/2
Last-Modified: Thu, 6 May 2007 02:52:18 GMT
Accept-Ranges: bytes
Cache-Control: max-age=604800
Expires: Mon, 6 Mar 2008 06:46:04 GMT
Vary: Accept-Encoding
Content-Encoding: gzip
Content-Length: 3588
Content-Type: application/x-javascript