#Settings: Settings sub-pages are missing navigation button on mobile

[gtandersen]

Describe the bug
On the sub-pages of Settings there is no navigation button (burger icon), which means that on mobile the user is stuck on e.g. the Identities or Aliases page.

To Reproduce
Steps to reproduce the behavior:

1. Go to e.g. https://runbox.com/app/account/identities with a mobile viewport.
2. Observe that there is no visible navigational button.

Expected behavior
There should be a navigation button (burger icon) similar to the Settings page.

Screenshots