config.ru

class RackPathInfoFix
  def initialize(app)
    @app = app
  end

  def call(env)
    env['PATH_INFO'] = File.join(env['SCRIPT_NAME'], env['PATH_INFO'])

    @app.call env
  end
end

use RackPathInfoFix

map '/assets' do
  run IPTApp.sprockets
end

map '/' do
  run IPTApp
end