diff --git a/atlas.json b/atlas.json
index c578b9c9..44295243 100644
--- a/atlas.json
+++ b/atlas.json
@@ -53,7 +53,7 @@
       "show_comments": false
     }
   },
-  "theme": "oreillymedia/animal_theme",
+  "theme": "oreillymedia/animal_theme_sass",
   "title": "Mastering Bitcoin",
   "print_isbn13": "9781449374044",
   "templating": false,