To add themes to a rails app

• Drop respective css and javascript files into appropriate directory under vendor/assets/.
  Note: Files should have unique name (I name them after the theme so flatty-theme/css/style.css simply becomes flatty.css.
• Add the following code to your config/application.rb under # add custom validators path in the Application class
  
config.assets.paths << "#{Rails.root}/vendor/assets/*"
config.assets.paths << "#{Rails.root}/vendor/assets/fonts"
config.assets.paths << "#{Rails.root}/vendor/assets/stylesheets"

• Adjust whatever views you’re using to use the appropriate classes in your theme

…And that’s it!