Switch to libsass from sass-ruby even though it is deprecated

The sass-ruby gem is even more deprecated than libsass which was
deprecated in sass/libsass#3123. The dart-sass is the reference
implementation now but there is no clear path for using it with
the asset pipeline[1] currently.

[1]: https://discuss.rubyonrails.org/t/transition-to-the-sass-npm-gem/76566/6

Gemfile

@@ -17,7 +17,7 @@ gem 'dynamic_form'
 gem 'faraday'
 gem 'faraday_middleware'
 gem 'net-http-persistent'
-gem 'sass-rails', '~> 5.0'
+gem 'sassc-rails'
 gem 'textacular'
 gem 'uglifier'
 gem 'bcrypt'

Gemfile.lock

@@ -336,17 +336,14 @@ GEM
     rspec-support (3.10.1)
     rubyzip (1.3.0)
     safe_yaml (1.0.5)
-    sass (3.7.4)
-      sass-listen (~> 4.0.0)
-    sass-listen (4.0.0)
-      rb-fsevent (~> 0.9, >= 0.9.4)
-      rb-inotify (~> 0.9, >= 0.9.7)
-    sass-rails (5.1.0)
-      railties (>= 5.2.0)
-      sass (~> 3.1)
-      sprockets (>= 2.8, < 4.0)
-      sprockets-rails (>= 2.0, < 4.0)
-      tilt (>= 1.1, < 3)
+    sassc (2.4.0)
+      ffi (~> 1.9)
+    sassc-rails (2.1.2)
+      railties (>= 4.0.0)
+      sassc (>= 2.0)
+      sprockets (> 3.0)
+      sprockets-rails
+      tilt
     scrypt (3.0.7)
       ffi-compiler (>= 1.0, < 2.0)
     selenium-webdriver (3.142.7)
@@ -448,7 +445,7 @@ DEPENDENCIES
   rake
   redcarpet
   rspec-rails
-  sass-rails (~> 5.0)
+  sassc-rails
   scrypt
   shoulda-matchers
   simplecov

config/application.rb

@@ -71,5 +71,10 @@ class Application < Rails::Application
     config.generators do |generator|
       generator.orm :active_record, primary_key_type: :serial
     end
+
+    # Using a sass css compressor causes a scss file to be processed twice (once
+    # to build, once to compress) which breaks the usage of "unquote" to use
+    # CSS that has same function names as SCSS such as max
+    config.assets.css_compressor = nil
   end
 end

config/environments/production.rb

@@ -30,7 +30,10 @@
 
   # Compress JavaScripts and CSS.
   config.assets.js_compressor = :uglifier
-  # config.assets.css_compressor = :sass
+
+  # Rather than use a CSS compressor, use the SASS style to perform compression
+  config.sass.style = :compressed
+  config.sass.line_comments = false
 
   # Do not fallback to assets pipeline if a precompiled asset is missed.
   config.assets.compile = false