diff --git a/Doc/conf.py b/Doc/conf.py
index b192354..b9d9ab5 100644
--- a/Doc/conf.py
+++ b/Doc/conf.py
@@ -66,6 +66,9 @@
 # Options for HTML output
 # -----------------------
 
+html_theme = 'default'
+html_theme_options = {'collapsiblesidebar': True}
+
 # If not '', a 'Last updated on:' timestamp is inserted at every page bottom,
 # using the given strftime format.
 html_last_updated_fmt = '%b %d, %Y'