According to this issue https://github.com/rails/sass-rails/pull/192 sass-rails hasn\'t support for Sass 3.3 yet.
But it seems that sass-rails-sou
There is a great new drop in replacement for sass-rails, which is not only faster, but also has the option to use inline source-maps.
Just add it to your Gemfile
#gem 'sass-rails', '~> 5.0'
gem 'sassc-rails'
and add the configuration
# config/environments/development.rb
config.sass.inline_source_maps = true
Don't forget to restart your server, then you should see it working in the inspector:
You can find the repo here: https://github.com/sass/sassc-rails