title: Undefined mixin with Bourbon and Neat gems
body: <p>I am using <strong>bourbon</strong> and <strong>neat</strong> gems for create the design of a rails application. My application.css.scss contains this:</p>
  
  <pre><code> @import "bourbon";
   @import "neat";
   @import "main";
  </code></pre>
  
  <p>But if I run 'rake assets:precompile' then happens this error:</p>
  
  <pre><code>rake aborted!
  Undefined mixin 'outer-container'.
  (in /Users/anonymous/example/app/assets/stylesheets/admin/main.css.scss)
  /Users/anonymous/example/app/assets/stylesheets/admin/main.css.scss:5:in  `outer-container'
  /Users/anonymous/example/app/assets/stylesheets/admin/main.css.scss:5
  </code></pre>
  
  <p>The file main.css.scss contains this:</p>
  
  <pre><code>footer#page_footer { 
   @include outer-container;
   nav{
    @include span-columns(6);
    @include shift(3);
    section#about_me_footer, section#contact_footer, section#miscellaneous_footer {
    @include span-columns(2 of 6);
   }
  }
  p {
   @include span-columns(6);
   @include shift(3);
  }
  }
  </code></pre>
  
  <p>Someone can give me some suggestions?</p>