Use default sphinx_rtd_theme

Closes #397, closes #398.

docs/conf.py

@@ -13,6 +13,7 @@
 
 import sys
 import os
+on_rtd = os.environ.get('READTHEDOCS', None) == 'True'
 
 # If extensions (or modules to document with autodoc) are in another directory,
 # add these directories to sys.path here. If the directory is relative to the
@@ -109,18 +110,16 @@
 # The theme to use for HTML and HTML Help pages.  Major themes that come with
 # Sphinx are currently 'default' and 'sphinxdoc'.
 #html_theme = 'default'
-# Theme URL: https://github.com/coordt/ADCtheme/
-RTD_NEW_THEME = True
-html_theme = 'rtd_theme'
+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()]
 
 # Theme options are theme-specific and customize the look and feel of a theme
 # further.  For a list of options available for each theme, see the
 # documentation.
 #html_theme_options = {}
 
-# Add any paths that contain custom themes here, relative to this directory.
-html_theme_path = ['theme']
-
 # The name for this set of Sphinx documents.  If None, it defaults to
 # "<project> v<release> documentation".
 #html_title = None