Developing rails engines and using the asset pipeline

Question

So I've started building a gem, which is difficult, but it seems to be working out so far.. Except for one little thing, the assets. I've tried putting them in my lib/assets, app/assets and vendor/assets. But they don't seem to load.

I have a test-app which loads my gem to test it, but nothing seems to work. I have an engine in my gem which I'm sure is being loaded.

What more do I need to know for this to start working?

EDIT:

here is my engine (located in lib/baco/engine.rb):

require 'rails'

module Baco

  class Engine < Rails::Engine

  end

end

EDIT 2:

This is my css file (located in vendor/assets/stylesheets/application.css.scss):

/*
     * 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 baco
*/

input {
    padding:10px;
}