diff --git a/src/sphinx_argparse_cli/__init__.py b/src/sphinx_argparse_cli/__init__.py
index 100b38c..fcf631f 100644
--- a/src/sphinx_argparse_cli/__init__.py
+++ b/src/sphinx_argparse_cli/__init__.py
@@ -11,8 +11,6 @@
 
 
 def setup(app: Sphinx) -> dict[str, Any]:
-    app.add_css_file("custom.css")
-
     from ._logic import SphinxArgparseCli  # noqa: PLC0415
 
     app.add_directive(SphinxArgparseCli.name, SphinxArgparseCli)
diff --git a/tests/test_logic.py b/tests/test_logic.py
index b0f46c9..1017ff6 100644
--- a/tests/test_logic.py
+++ b/tests/test_logic.py
@@ -49,6 +49,7 @@ def build_outcome(app: SphinxTestApp, request: SubRequest, monkeypatch: pytest.M
 @pytest.mark.sphinx(buildername="html", testroot="basic")
 def test_basic_as_html(build_outcome: str) -> None:
     assert build_outcome
+    assert "custom.css" not in build_outcome
 
 
 @pytest.mark.sphinx(buildername="text", testroot="complex")