On smaller screens the bootstrap family of themes displays a button in the upper right that is meant to reveal custom menu items and / or the language menu. If both of those are empty, however, the button still appears. Clicking it does nothing but reveal the border of a collapsed box.

To reproduce:

1. Turn off the option to display the language menu under Site administration > Language > Language settings.
2. Make sure that the custom menu under Site administration > Appearance > Themes > Theme settings is empty.
3. View your site in Clean using a narrow window

Expected: There should be no navbar button.
Actually: The navbar button is there but it has nothing to reveal