title: Can not manage to launch the site with sinatra
body: <p>I have a small problem with sinatra.</p>
  
  <p>I recovered a project made ​​Sinatra, and I made a bundle install just that all goes well but when I made ​​a </p>
  
  <blockquote>
    <p>ruby app.rb</p>
  </blockquote>
  
  <p>well, he told me</p>
  
  <blockquote>
    <p>kernel_require.rb:110:in `require': cannot load such file -- sass (LoadError)</p>
  </blockquote>
  
  <p>I do not understand the problem or just because it is well require 'sass'</p>
  
  <p>thanks you</p>