fix: better dark/light support on unauthenticated

[jpvalery]

Description

The toggle on (unauthenticated) layout was disappearing when switching—this change prevents that

Checklist

• My code follows the code style of this project.
• I have performed a self-review of my code.
• I have commented my code, particularly in hard-to-understand areas.
• I have updated the documentation, if necessary.
• I have added tests that prove my fix is effective or my feature works.
• New and existing tests pass locally with my changes.

Screenshots (if applicable)

Before

After

(do note that in my own version I have a different method for ModeToggle that switches between the theme rather than displaying a dropdown).

[vercel]

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[QuentinFrc]

Alternative is to override color for toggle on light theme but think your solution is the best