title: Can I tell Visual Studio how treat a file with a custom file extension?
body: <p>Can I tell Visual Studio how treat a file with a custom file extension? I want to be able to open a file with ".xxx" extension in Visual Studio and have CSS highlighting. </p>
  
  <p>I've tried to do it by going to VS -> Tools -> Options -> Text Editor -> File Extension but in the Editor drop down there is nothing to specify "treat it as CSS".</p>