ResponsivePreview

Rack Middleware gem that injects an iframe around the response for the purpose of testing responsive css at different breakpoints.

Define when the responsive preview is shown

class MyController < ApplicationController
  def wants_responsive_preview?
    # some condition to decide when to view the page in the responsive preview layout
  end
end

Provide a responsive preview layout

<!-- app/views/layouts/responsive_preview.html.erb -->

<!-- Add some other chrome for switching devices/iframe dimensions -->
<%= content_tag :iframe, '', srcdoc: yield %>
<%= responsive_preview_js %>