Stop using html_context as it breaks css on RTD. See readthedocs/read…

…thedocs.org#2116.

source/conf.py

@@ -127,12 +127,6 @@
 # so a file named "default.css" will overwrite the builtin "default.css".
 html_static_path = ['_static']
 
-html_context = {
-    'css_files': [
-        '_static/theme_overrides.css',  # overrides for wide tables in RTD theme
-    ],
-}
-
 # If not '', a 'Last updated on:' timestamp is inserted at every page bottom,
 # using the given strftime format.
 #html_last_updated_fmt = '%b %d, %Y'
@@ -254,3 +248,7 @@
 
 # If true, do not generate a @detailmenu in the "Top" node's menu.
 #texinfo_no_detailmenu = False
+
+
+def setup(app):
+    app.add_stylesheet('theme_overrides.css')