diff --git a/website/_harp.json b/website/_harp.json
index 82e82093e..bb0489e64 100644
--- a/website/_harp.json
+++ b/website/_harp.json
@@ -55,7 +55,7 @@
             }
         },
 
-        "V_CSS": "1.2",
+        "V_CSS": "1.3",
         "V_JS": "1.2",
         "DEFAULT_SYNTAX": "python",
         "ANALYTICS": "UA-58931649-1",