diff --git a/docs/_static/css/custom.css b/docs/_static/css/custom.css
new file mode 100644
index 0000000..c3defb4
--- /dev/null
+++ b/docs/_static/css/custom.css
@@ -0,0 +1,9 @@
+@import 'theme.css';
+
+.toctree-l4 {
+    font-size: 1.2em !important
+}
+
+.toctree-l4>a {
+    padding: 0em 1.618em 0em 5.663em !important
+}
diff --git a/docs/conf.py b/docs/conf.py
index 9a8d130..da968d7 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -15,3 +15,18 @@
 
 sys.path.insert(0, os.path.abspath("../src"))  # noqa: PTH100
 config = SphinxConfig("../pyproject.toml", globalns=globals())
+
+
+# def setup(app) -> None:
+#     """Set up the Sphinx application.
+
+#     Args:
+#     ----
+#         app: The Sphinx application object.
+
+#     Returns:
+#     -------
+#         None
+
+#     """
+#     app.add_css_file("source/custom.css")
diff --git a/docs/source/custom.css b/docs/source/custom.css
deleted file mode 100644
index f195be8..0000000
--- a/docs/source/custom.css
+++ /dev/null
@@ -1,8 +0,0 @@
-@import '../_build/html/_static/css/theme.css';
-
-.toctree-l4{
-font-size: 1.2em !important
-}
-.toctree-l4>a{
-padding: 0em 1.618em 0em 5.663em !important
-}
diff --git a/pyproject.toml b/pyproject.toml
index d915e56..6e66c29 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -261,7 +261,7 @@ auto_doc_default_options = {'autosummary' = true}
 # -- Options for HTML output -------------------------------------------------
 # https://www.sphinx-doc.org/en/master/usage/configuration.html#options-for-html-output
 html_theme = "sphinx_rtd_theme"
-html_style = "../../../source/custom.css"
+html_style = "css/custom.css"
 html_static_path = ["_static"]
 html_theme_options = {'display_version' = true, 'sticky_navigation' = true, 'includehidden' = true, 'titles_only' = false}
 autosummary_generate = true