diff --git a/releasenotes/notes/fix-css-handling-e17f37c98d80b76e.yaml b/releasenotes/notes/fix-css-handling-e17f37c98d80b76e.yaml
new file mode 100644
index 0000000..9108a66
--- /dev/null
+++ b/releasenotes/notes/fix-css-handling-e17f37c98d80b76e.yaml
@@ -0,0 +1,4 @@
+---
+fixes:
+  - |
+    Updated the CSS handling to use add_css_file instead of add_stylesheet.
diff --git a/sphinx_feature_classification/support_matrix.py b/sphinx_feature_classification/support_matrix.py
index aaab7fa..0d4c8b4 100644
--- a/sphinx_feature_classification/support_matrix.py
+++ b/sphinx_feature_classification/support_matrix.py
@@ -465,4 +465,4 @@ class Directive(rst.Directive):
 
 def setup(app):
     app.add_directive('support_matrix', Directive)
-    app.add_stylesheet('support-matrix.css')
+    app.add_css_file('support-matrix.css')