For stylesheets, once you’ve copied a file into $RAILS_ROOT/vendor/assets/stylesheets you need to also add a couple of lines to use the stylesheet. First create a link in the app/views/layouts/application.html.erb file. For example:
<%= stylesheet_link_tag ‘clockpicker’, media: ‘all’ %>
Then inside the config/initializers/assets.rb file add:
Rails.application.config.assets.precompile += %w( clockpicker.css )
With these two file changes you can use the styles from additional stylesheets. Oh ya, one more thing you’ll need to do is restart your Rails server if you have it running. The running server won’t know about the change to the assets configuration until you restart it.
Note: If you have more than one vendor CSS file, you can simply add the file name inside the %w() separated from the other names by a space.
//= require clockpicker