+++ b/core/themes/seven/css/theme/maintenance-page.css
@@ -142,7 +142,7 @@
- max-width: 770px;This change affects install page as well.
Screenshots before: https://www.drupal.org/files/issues/install-screen-before.png
Screenshot, after: https://www.drupal.org/files/issues/install-screen-after.png