Sinatra Stylesheet Expires

gistfile1.rb

# avoid path traversal attacks and speed up look-up
set :css_files, {}
Dir.glob("#{settings.public}/css/*.css") { |file| settings.css_files[File.basename(file, '.css')] = file }

get "/css/:name.css" do |name|
  expires 60*60*24*356*3
  send_file setting.css_files[name]
end

Thanks rkh and also cactus! :)