Make Chrome splash screen same color as web UI's background color (#5169)

app/controllers/manifests_controller.rb

@@ -1,11 +1,7 @@
 # frozen_string_literal: true
 
 class ManifestsController < ApplicationController
-  before_action :set_instance_presenter
-
-  def show; end
-
-  def set_instance_presenter
-    @instance_presenter = InstancePresenter.new
+  def show
+    render json: InstancePresenter.new, serializer: ManifestSerializer
   end
 end