diff --git a/docs/requirements.txt b/docs/requirements.txt
index 11f4674..43e4251 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -10,3 +10,4 @@ jupytext==1.13.7
 ipython
 requests
 sphinxcontrib-spelling
+lxml_html_clean
\ No newline at end of file
diff --git a/docs/source/conf.py b/docs/source/conf.py
index 6532d94..a9d65fd 100644
--- a/docs/source/conf.py
+++ b/docs/source/conf.py
@@ -83,7 +83,7 @@
 # so a file named "default.css" will overwrite the builtin "default.css".
 html_static_path = ["_static"]
 
-html_css_files = ['zhinst-sphinx-theme/css/custom.css']
+html_css_files = ["zhinst-sphinx-theme/css/custom.css"]
 
 html_theme_options = {
     "logo": {
@@ -111,7 +111,13 @@
 
 # Spelling
 # sphinxcontrib.spelling configuration file
-spelling_word_list_filename='spelling_wordlist.txt'
+spelling_word_list_filename = "spelling_wordlist.txt"
 # Show suggestion in console output
-spelling_show_suggestions=False
-spelling_exclude_patterns=['examples/*.nblink', 'source/_static/zhinst-sphinx-theme/**/*']
+spelling_show_suggestions = False
+spelling_exclude_patterns = [
+    "examples/*.nblink",
+    "source/_static/zhinst-sphinx-theme/**/*",
+]
+
+# Warnings
+suppress_warnings = ["config.cache"]