[Rails] TwitterBootstrapとSassとAssetPipeline ref: http://qiita.com/kidachi_/items/4c47b28b2a74c723d835

application.css

/*
 * This is a manifest file that'll automatically include all the stylesheets
 * available in this directory and any sub-directories. You're free to add
 * application-wide styles to this file and they'll appear at the top of the
 * compiled file, but it's generally better to create a new file per style
 * scope.
 *= require_self
 *= require_tree .
*/

application.rb

#Asset Pipeline互換の行を追加
require File.expand_path('../boot', __FILE__)
~
module SampleApp
  class Application < Rails::Application
    ~
    #AssetPipelineによるコンパイル対象を増やす
    config.assets.precompile += %w(*.png *.jpg *.jpeg *.gif)
  end
end

custom.css.scss

$lightGray: #999;

h2 {
  ~
  color: $lightGray;
}
~
footer {
  ~
  color: $lightGray;
}

file1.sh

bundle install

file6.txt

*= require_tree .

file7.txt

*= require_self

Gemfile

source 'https://rubygems.org'
ruby '2.0.0'
#ruby-gemset=railstutorial_rails_4_0

gem 'rails', '4.0.1'
gem 'bootstrap-sass', '2.3.2.0'