title: Concatenating CSS with cache control
body: <p>Ok, here's a tough one:</p>
  
  <p>I have these website with several CSS files that uses cache busting and it worked fine. i was getting 403 Not Modified with every call.</p>
  
  <p>But now Im using this rule in my htaccess to concatenate all my files</p>
  
  <pre><code>
  &lt;FilesMatch "\.combined\.css$"&gt;
    Options +Includes
    AddOutputFilterByType INCLUDES text/css
    SetOutputFilter INCLUDES
  &lt;/FilesMatch&gt;
  </code></pre>
  
  <p>Inside script.combined.css you can find this:</p>
  
  <pre><code>
  &lt;!--#include file="file1.css" --&gt;
  &lt;!--#include file="file2.css" --&gt;
  </code></pre>
  
  <p>The problem comes that even though my file "script.combined.css" uses cache busting. it's always returning "200 Ok". These are the headers of script.combined.css:</p>
  
  <pre><code>
  Request
  
  URL:http://XXX/css/script.combined.css
  Request Method:GET
  Status Code:200 OK
  
  Request Headers
  
  Accept:text/css,*/*;q=0.1
  Accept-Charset:ISO-8859-1,utf-8;q=0.7,*;q=0.3
  Accept-Encoding:gzip,deflate,sdch
  Accept-Language:en-US,en;q=0.8
  Cache-Control:max-age=0
  Connection:keep-alive
  Cookie:typo3-login-cookiecheck=true; PHPSESSID=2evc53ngjjobateti38gpahtt7; tx_phpmyadmin=quf4sgevagubd1snd9eoq4g4d0; be_typo_user=0f4c7e291b6d7673310d6f15da687910; Typo3InstallTool=62erpih8fmqbbl3pe75pcenuu0; fe_typo_user=a7e5de71521603161fa598ed523b024b
  Host:XXX
  Referer:http://XXX/
  User-Agent:Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/534.30 (KHTML, like Gecko) Ubuntu/11.04 Chromium/12.0.742.112 Chrome/12.0.742.112 Safari/534.30
  
  Response Headers
  
  Accept-Ranges:bytes
  Cache-Control:max-age=31536000, public
  Connection:Keep-Alive
  Content-Type:text/css
  Date:Wed, 17 Aug 2011 13:56:42 GMT
  Expires:Thu, 16 Aug 2012 13:56:42 GMT
  Keep-Alive:timeout=5, max=99
  Server:HTTPD
  Transfer-Encoding:chunked
  </code></pre>
  
  <p>...while these are the headers for another simple css file:</p>
  
  <pre><code>
  Request URL:http://XXX/css/style.css
  Request Method:GET
  Status Code:304 Not Modified
  
  Request Headers
  
  Accept:text/css,*/*;q=0.1
  Accept-Charset:ISO-8859-1,utf-8;q=0.7,*;q=0.3
  Accept-Encoding:gzip,deflate,sdch
  Accept-Language:en-US,en;q=0.8
  Cache-Control:max-age=0
  Connection:keep-alive
  Cookie:typo3-login-cookiecheck=true; PHPSESSID=2evc53ngjjobateti38gpahtt7; tx_phpmyadmin=quf4sgevagubd1snd9eoq4g4d0; be_typo_user=0f4c7e291b6d7673310d6f15da687910; Typo3InstallTool=62erpih8fmqbbl3pe75pcenuu0; fe_typo_user=a7e5de71521603161fa598ed523b024b
  Host:XXX
  If-Modified-Since:Wed, 17 Aug 2011 11:45:17 GMT
  Referer:http://XXX/
  User-Agent:Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/534.30 (KHTML, like Gecko) Ubuntu/11.04 Chromium/12.0.742.112 Chrome/12.0.742.112 Safari/534.30
  
  Response Headers
  
  Cache-Control:max-age=31536000, public
  Connection:Keep-Alive
  Date:Wed, 17 Aug 2011 13:56:42 GMT
  Expires:Thu, 16 Aug 2012 13:56:42 GMT
  Keep-Alive:timeout=5, max=97
  Server:HTTPD
  </code></pre>
  
  <p>I used an extension to measure Page Speed from google and I got this message:</p>
  
  <blockquote>
    <p>Specify a cache validator</p>
    
    <p>The following resources are missing a cache validator. Resources that
    do not specify a cache validator cannot be refreshed efficiently.
    Specify a Last-Modified or ETag header to enable cache validation for
    the following resources:</p>
    
    <p><a href="http://XXX/css/script.combined.css?1313583214" rel="nofollow">http://XXX/css/script.combined.css?1313583214</a></p>
  </blockquote>
  
  <p>What should I do??</p>