gistfile1.xsl

<IfModule mod_deflate.c>
  # Compress all content, manually excluding specified file types
  # place filter 'DEFLATE' on all outgoing content
  SetOutputFilter DEFLATE
  # exclude uncompressible content via file type
  SetEnvIfNoCase Request_URI \.(?:gif|jpe?g|png|rar|zip)$ no-gzip

  # properly handle requests coming from behind proxies
  <IfModule mod_headers.c>
      Header append Vary User-Agent env=!dont-vary
  </IfModule>
  # Properly handle old browsers that do not support compression
  BrowserMatch ^Mozilla/4 gzip-only-text/html
  BrowserMatch ^Mozilla/4\.0[678] no-gzip
  BrowserMatch \bMSIE !no-gzip !gzip-only-text/html
</IfModule>