Allow additional stylesheets to be included in the admin UI

app/views/layouts/alchemy/admin.html.erb

@@ -13,7 +13,9 @@
     <%= stylesheet_link_tag('alchemy/custom-properties', media: 'screen', 'data-turbo-track' => true) %>
     <%= stylesheet_link_tag('alchemy/admin', media: 'screen', 'data-turbo-track' => true) %>
     <%= stylesheet_link_tag('alchemy/admin/print', media: 'print', 'data-turbo-track' => true) %>
-    <%= stylesheet_link_tag('alchemy/admin/custom', 'data-turbo-track' => true) %>
+    <% Alchemy.admin_stylesheets.each do |stylesheet| %>
+      <%= stylesheet_link_tag(stylesheet, 'data-turbo-track' => true) %>
+    <% end %>
     <%= yield :stylesheets %>
     <script>
       // Global Alchemy JavaScript object.

lib/alchemy.rb

@@ -98,6 +98,20 @@ def self.admin_importmaps
     }])
   end
 
+  # Additional stylesheets to be included in the Alchemy admin UI
+  #
+  # == Example
+  #
+  #    # lib/alchemy/devise/engine.rb
+  #    initializer "alchemy.devise.stylesheets", before: "alchemy.admin_stylesheets" do
+  #      Alchemy.admin_stylesheets << "alchemy/devise/admin"
+  #    end
+  #
+  # @return [Set<String>]
+  def self.admin_stylesheets
+    @_admin_stylesheets ||= Set.new(["alchemy/admin/custom"])
+  end
+
   # Define page publish targets
   #
   # A publish target is a ActiveJob that gets performed

lib/alchemy/engine.rb

@@ -16,11 +16,14 @@
       end
     end
 
-    initializer "alchemy.assets" do
+    initializer "alchemy.assets" do |app|
       if defined?(Sprockets)
         require_relative "../non_stupid_digest_assets"
         NonStupidDigestAssets.whitelist += [/^tinymce\//]
-        Rails.application.config.assets.precompile << "alchemy_manifest.js"
+        app.config.assets.precompile << "alchemy_manifest.js"
+        Alchemy.admin_stylesheets.each do |stylesheet|
+          app.config.assets.precompile << stylesheet
+        end
       end
     end
 

spec/dummy/app/assets/config/manifest.js

@@ -4,4 +4,3 @@
 //= link_tree ../images
 //= link tinymce/langs/de.js
 //= link_tree ../builds
-//= link alchemy/admin/custom.css