Compensate for scrollbar disappearing when media modal visible (#8100)

* Compensate for scrollbar disappearing when media modal visible

Make auth pages backgrounds lighter

* Fix typo

app/controllers/auth/confirmations_controller.rb

@@ -3,6 +3,7 @@
 class Auth::ConfirmationsController < Devise::ConfirmationsController
   layout 'auth'
 
+  before_action :set_body_classes
   before_action :set_user, only: [:finish_signup]
 
   # GET/PATCH /users/:id/finish_signup
@@ -23,6 +24,10 @@ class Auth::ConfirmationsController < Devise::ConfirmationsController
     @user = current_user
   end
 
+  def set_body_classes
+    @body_classes = 'lighter'
+  end
+
   def user_params
     params.require(:user).permit(:email)
   end