title: app_themes css files and version number
body: <p>I would like to be able to have a version number appended to a css file located in my app_themes folder in my asp.net website so that modification to the file would force the browser to get the file from the server instead of using the one in the cache.</p>
  
  <p>the css output path would look like ~/app_themes/blue/blue.css?v=1234 </p>
  
  <p>Any idea how it can be done without having to manually edit the filename?</p>