This gem adds Respond.js to your rails assets.
Add the following to your Gemfile:
gem 'respond-js-rails', github: 'naninyang/respond-js-rails'
then run:
bundle install
Now you only need to add the following to your layout:
<!--[if lt IE 9]>
<%= javascript_include_tag 'respond' %>
<![endif]-->
Same as respond itself, this gem is licensed under the MIT license.