config: fix contentui css

The contentui sets the page with to be infinite in order to add a second column.

We do not use this feature, so we set the width back to normal.  Also make sure our theme_overrides are last in conf.py to make sure they override the contentui css.

doc/common/_static/css/theme_overrides.css

@@ -25,3 +25,14 @@ span.caption-number:after {
     font-family: "Roboto Slab","ff-tisa-web-pro","Georgia",Arial,sans-serif;
     margin-bottom: 24px !important;
 }
+
+/* 
+    sphinx-contrib contentui sets max-width to none,
+    giving a very wide page which makes text hard to
+    read. This sets it to a finite value.
+*/
+@media screen and (min-width: 1300px) {
+    .wy-nav-content {
+        max-width: 800px;
+    }
+}

doc/common/conf.py

@@ -139,8 +139,8 @@ else:
     html_theme_path = [sphinx_rtd_theme.get_html_theme_path()]
     html_context = {
         'css_files': [
-            '_static/css/theme_overrides.css',
             '_static/contentui.css',
+            '_static/css/theme_overrides.css',
         ],
         'disclaimer': _DISCLAIMER,
     }