Apparently we now need to specify the theme also for rtd.org

https://sphinx-rtd-theme.readthedocs.io/en/1.1.0/installing.html#how-to-install-and-use-the-theme

source/conf.py

@@ -20,6 +20,7 @@
 import os
 # import sys
 # sys.path.insert(0, os.path.abspath('.'))
+import sphinx_rtd_theme
 
 
 # -- General configuration ------------------------------------------------
@@ -31,7 +32,9 @@
 # Add any Sphinx extension module names here, as strings. They can be
 # extensions coming with Sphinx (named 'sphinx.ext.*') or your custom
 # ones.
-extensions = []
+extensions = [
+    'sphinx_rtd_theme',
+]
 
 # Add any paths that contain templates here, relative to this directory.
 templates_path = ['_templates']
@@ -88,15 +91,8 @@
 # The theme to use for HTML and HTML Help pages.  See the documentation for
 # a list of builtin themes.
 #
-html_theme = 'default'
-
-# on_rtd is whether we are on readthedocs.org, this line of code grabbed from docs.readthedocs.org
-on_rtd = os.environ.get('READTHEDOCS', None) == 'True'
-
-if not on_rtd:  # only import and set the theme if we're building docs locally
-    import sphinx_rtd_theme
-    html_theme = 'sphinx_rtd_theme'
-    html_theme_path = [sphinx_rtd_theme.get_html_theme_path()]
+html_theme = 'sphinx_rtd_theme'
+html_theme_path = [sphinx_rtd_theme.get_html_theme_path()]