docs dark mode

docs/source/conf.py

@@ -52,7 +52,10 @@ needs_sphinx = '5.3'
 # Add any Sphinx extension module names here, as strings. They can be
 # extensions coming with Sphinx (named 'sphinx.ext.*') or your custom
 # ones.
-extensions = [ 'sphinxcontrib.jquery']
+extensions = [ 'sphinxcontrib.jquery', 'sphinx_rtd_dark_mode']
+
+# user starts in light mode
+default_dark_mode = False
 
 # Add any paths that contain templates here, relative to this directory.
 templates_path = ['_templates']