structure.css -> default.css

Themes are optional, a theme overrides style in default.css

app/models/design/design.rb

@@ -15,7 +15,7 @@ class Design
   has_many :pages
 
   embeds_one :layout
-  mount_uploader :structure_css, AssetUploader
+  mount_uploader :default_css, AssetUploader
 
   embeds_many :themes
   embeds_many :javascripts

app/models/page.rb

@@ -1,7 +1,7 @@
 class Page < Item
   
   field :content
-  field :theme_id, :type => BSON::ObjectId
+  field :theme_id, :type => BSON::ObjectId, :default => nil
   
   belongs_to :design
   has_many :page_parts