Upgrade to Bootstrap 4 with mobile-first approach

.editorconfig

@@ -0,0 +1,33 @@
+root = true
+
+[*]
+trim_trailing_whitespace = true
+insert_final_newline     = true
+end_of_line              = lf
+charset                  = utf-8
+tab_width                = 2
+
+[*.md]
+indent_style             = space
+max_line_length          = 80
+
+[**.js]
+indent_style = space
+indent_size = 2
+
+# 2 spaces in scss
+[**.scss]
+indent_style = space
+indent_size = 2
+
+[**.css]
+indent_style = space
+indent_size = 2
+
+[**.php]
+indent_style = space
+indent_size = 4
+
+[**.html]
+indent_style = space
+indent_size = 2

.gitignore

@@ -20,3 +20,5 @@ config/database.yml
 .env
 .generators
 .byebug_history
+
+public/assets/**/*

Gemfile

@@ -1,11 +1,13 @@
+# frozen_string_literal: true
+
 source 'https://rubygems.org'
-ruby "2.4.0"
+ruby '2.4.0'
 
 gem 'rails', '5.2.3'
 
 gem 'dotenv-rails', '~> 2.7', '>= 2.7.4'
-gem 'pg'#, group: 'production'
-#gem 'mysql2', group: 'development'
+gem 'pg' # , group: 'production'
+# gem 'mysql2', group: 'development'
 gem 'bootsnap', '~> 1.4', '>= 1.4.4'
 gem 'listen', '~> 3.1', '>= 3.1.5'
 
@@ -14,31 +16,32 @@ gem 'listen', '~> 3.1', '>= 3.1.5'
 
 # Gems used only for assets and not required
 # in production environments by default.
-#group :assets do
-  #gem 'sass-rails',   '~> 3.2.3'
-  #gem 'coffee-rails', '~> 3.2.1'
+# group :assets do
+# gem 'sass-rails',   '~> 3.2.3'
+# gem 'coffee-rails', '~> 3.2.1'
 
-  # See https://github.com/sstephenson/execjs#readme for more supported runtimes
-  # gem 'therubyracer'
+# See https://github.com/sstephenson/execjs#readme for more supported runtimes
+# gem 'therubyracer'
 
 gem 'uglifier', '>= 1.0.3'
-#end
+# end
 
 gem 'byebug', '~>11.0.1'
 gem 'puma', '~> 4.0.1'
-gem 'twitter', '~> 6.2.0'
 gem 'sentry-raven', '~> 2.11'
-#gem 'jquery-rails'
-gem "devise", "~> 4.6.2"
-gem "omniauth", "~>1.9.0"
-gem "omniauth-twitter", "~> 1.4.0"
-gem "haml-rails", "~> 2.0.1"
-gem "twitter-bootstrap-rails", "~> 4.0.0"
-gem "redcarpet", "~> 1.17.2"
-gem "nokogiri", "~> 1.10.3"
-gem "pygmentize", "~> 0.0.3"
-#gem "exception_notification", "~> 2.5.2"
+gem 'twitter', '~> 6.2.0'
+gem 'jquery-rails'
+gem 'devise', '~> 4.6.2'
+gem 'haml-rails', '~> 2.0.1'
+gem 'nokogiri', '~> 1.10.3'
+gem 'omniauth', '~>1.9.0'
+gem 'omniauth-twitter', '~> 1.4.0'
+gem 'pygmentize', '~> 0.0.3'
+gem 'redcarpet', '~> 1.17.2'
+# gem "exception_notification", "~> 2.5.2"
+gem 'activeadmin', '~> 2.2.0'
 gem 'newrelic_rpm'
-gem "activeadmin", "~> 2.2.0"
-#gem "meta_search",    '>= 1.1.0.pre'
-#gem "therubyracer", "~> 0.11.2"
+# gem "meta_search",    '>= 1.1.0.pre'
+# gem "therubyracer", "~> 0.11.2"
+gem 'bootstrap', '~> 4.3.1'
+gem 'sprockets-rails', require: 'sprockets/railtie'

Gemfile.lock

@@ -59,17 +59,22 @@ GEM
     arbre (1.2.1)
       activesupport (>= 3.0.0)
     arel (9.0.0)
+    autoprefixer-rails (9.6.1.1)
+      execjs
     babel-source (5.8.35)
     babel-transpiler (0.7.0)
       babel-source (>= 4.0, < 6)
       execjs (~> 2.0)
     bcrypt (3.1.13)
     bootsnap (1.4.4)
       msgpack (~> 1.0)
+    bootstrap (4.3.1)
+      autoprefixer-rails (>= 9.1.0)
+      popper_js (>= 1.14.3, < 2)
+      sassc-rails (>= 2.0.0)
     buftok (0.2.0)
     builder (3.2.3)
     byebug (11.0.1)
-    commonjs (0.2.7)
     concurrent-ruby (1.1.5)
     crass (1.0.4)
     devise (4.6.2)
@@ -146,13 +151,6 @@ GEM
       activerecord
       kaminari-core (= 1.1.1)
     kaminari-core (1.1.1)
-    less (2.6.0)
-      commonjs (~> 0.2.7)
-    less-rails (2.8.0)
-      actionpack (>= 4.0)
-      less (~> 2.6.0)
-      sprockets (> 2, < 4)
-      tilt
     listen (3.1.5)
       rb-fsevent (~> 0.9, >= 0.9.4)
       rb-inotify (~> 0.9, >= 0.9.7)
@@ -190,6 +188,7 @@ GEM
       rack
     orm_adapter (0.5.0)
     pg (1.1.4)
+    popper_js (1.14.5)
     public_suffix (3.1.1)
     puma (4.0.1)
       nio4r (~> 2.0)
@@ -276,11 +275,6 @@ GEM
       multipart-post (~> 2.0)
       naught (~> 1.0)
       simple_oauth (~> 0.3.0)
-    twitter-bootstrap-rails (4.0.0)
-      actionpack (~> 5.0, >= 5.0.1)
-      execjs (~> 2.7)
-      less-rails (~> 2.8, >= 2.8.0)
-      railties (~> 5.0, >= 5.0.1)
     tzinfo (1.2.5)
       thread_safe (~> 0.1)
     uglifier (4.1.20)
@@ -300,10 +294,12 @@ PLATFORMS
 DEPENDENCIES
   activeadmin (~> 2.2.0)
   bootsnap (~> 1.4, >= 1.4.4)
+  bootstrap (~> 4.3.1)
   byebug (~> 11.0.1)
   devise (~> 4.6.2)
   dotenv-rails (~> 2.7, >= 2.7.4)
   haml-rails (~> 2.0.1)
+  jquery-rails
   listen (~> 3.1, >= 3.1.5)
   newrelic_rpm
   nokogiri (~> 1.10.3)
@@ -315,8 +311,8 @@ DEPENDENCIES
   rails (= 5.2.3)
   redcarpet (~> 1.17.2)
   sentry-raven (~> 2.11)
+  sprockets-rails
   twitter (~> 6.2.0)
-  twitter-bootstrap-rails (~> 4.0.0)
   uglifier (>= 1.0.3)
 
 RUBY VERSION

app/admin/letter.rb

@@ -1,6 +1,8 @@
 ActiveAdmin.register Letter do
 
-  index do 
+  permit_params :description
+
+  index do
     column :id
     column :description do |l|
       l.description.truncate(200)

app/assets/javascripts/application.js

@@ -10,7 +10,8 @@
 // WARNING: THE FIRST BLANK LINE MARKS THE END OF WHAT'S TO BE PROCESSED, ANY BLANK LINE SHOULD
 // GO AFTER THE REQUIRES BELOW.
 //
-//= require jquery
+//= require jquery3
 //= require jquery_ujs
-//= require twitter/bootstrap
+//= require popper
+//= require bootstrap
 //= require_tree .