List the gems in your application's Gemfile:
gem "less-rails-bootstrap"
gem "less-rails-bootstrap-devise", :git => 'git://github.com/bigbento/less-rails-bootstrap-devise.git'
Bundle your application
bundle install
Require the styles in your stylesheet (e.g. app/assets/stylesheets/application.css):
//= require 'bootstrap-devise-rails'
Replace your yield statement in application.html.erb with:
<%= content_for?(:content) ? yield(:content) : yield %>