Add a very basic custom_css property to a conference.

It is loaded on all pages for that conference.

app/controllers/admin/conferences_controller.rb

@@ -182,7 +182,7 @@ module Admin
                                          :vpositions_attributes, :use_volunteers, :color,
                                          :sponsorship_levels_attributes, :sponsors_attributes,
                                          :registration_limit, :organization_id, :ticket_layout,
-                                         :booth_limit)
+                                         :booth_limit, :custom_css)
     end
   end
 end

app/views/admin/conferences/edit.html.haml

@@ -17,6 +17,11 @@
         = image_tag @conference.picture.thumb.url
       = f.input :picture, label: false, hint: 'This will be displayed on the front page.'
       = f.hidden_field :picture_cache
+
+      = f.input :custom_css,
+        hint: "Add Custon CSS to the main page. You might find the class '.conference-#{@conference.short_title}' useful.",
+        input_html: { rows: 5 }
+
       = f.input :ticket_layout, as: :select, collection: Conference.ticket_layouts.keys, hint: "Layout type for tickets of the conference."
       = f.inputs name: 'Scheduling' do
         = f.input :timezone, as: :time_zone, hint: 'The conference time zone'

app/views/layouts/application.html.haml

@@ -21,6 +21,10 @@
       = javascript_include_tag "//cdn.transifex.com/live.js"
 
     = yield(:head)
+    - if @conference && @conference.custom_css?
+      %style{type: 'text/css'}
+        = @conference.custom_css
+
   %body{ class: ("conference-#{@conference.short_title}" if @conference) }
     = render 'layouts/navigation', conference: @conference
     -# Admin area

db/migrate/20200715001812_add_custom_css_to_confereneces.rb

@@ -0,0 +1,5 @@
+class AddCustomCssToConfereneces < ActiveRecord::Migration[5.2]
+  def change
+    add_column :conferences, :custom_css, :text
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2020_07_10_215300) do
+ActiveRecord::Schema.define(version: 2020_07_15_001812) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -107,6 +107,7 @@ ActiveRecord::Schema.define(version: 2020_07_10_215300) do
     t.integer "ticket_layout", default: 0
     t.string "custom_domain"
     t.integer "booth_limit", default: 0
+    t.text "custom_css"
     t.index ["organization_id"], name: "index_conferences_on_organization_id"
   end
 
@@ -406,7 +407,7 @@ ActiveRecord::Schema.define(version: 2020_07_10_215300) do
     t.string "name", null: false
     t.integer "size"
     t.integer "venue_id", null: false
-    t.string "url"
+    t.text "url"
   end
 
   create_table "schedules", force: :cascade do |t|