diff --git a/docs/conf.py b/docs/conf.py
index 5179d34..36b4c8a 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -141,6 +141,10 @@
 # so a file named "default.css" will overwrite the builtin "default.css".
 html_static_path = ["_static"]
 
+html_css_files = [
+    "custom.css",
+]
+
 html_context = {
     # ...
     "default_mode": "light"
@@ -148,4 +152,5 @@
 
 
 def setup(app):
-    app.add_css_file("custom.css")
+    ...
+    # app.add_css_file("custom.css")