fix startup

config.ru

@@ -1,17 +1,16 @@
 require 'bundler'
 Bundler.require
 require 'tilt/erb'
-
 require "opal"
-require 'opal-browser'
+require 'opal-sprockets'
 
 Opal.use_gem("rubyx")
 
-run Opal::Sprockets::Server.new do |s|
+run Opal::Sprockets::Server.new { |s|
   s.main = 'debugger.js.rb'
   s.append_path 'lib'
   s.append_path 'assets'
   s.debug = !ENV["DEBUG"].nil?
   s.index_path = "index.html.erb"
   s.sprockets.cache = Sprockets::Cache::MemoryStore.new(10000)
-end
+}