Fix / Remove focus outline around main element

[MelissaDTH]

Description

This PR contains a small adjustment that prevents an unwanted focus outline from appearing in certain situations. See the example for the visual bug that was found (on mobile):

Steps completed:

According to our definition of done, I have completed the following steps:

• [x] Acceptance criteria met
• [ ] Unit tests added
• [ ] Docs updated (including config and env variables)
• [ ] Translations added
• [x] UX tested
• [x] Browsers / platforms tested
• [x] Rebased & ready to merge without conflicts
• [x] Reviewed own code

[github-actions[bot]]

Visit the preview URL for this PR (updated for commit bf4f9be):

https://ottwebapp--pr540-fix-app-outline-o4x1rzpu.web.app

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