revert: Revert "feat: Add bottom border to top navigation (#3192)"

[cansuaa]

This reverts commit 13ff9d4.

Description

Related links, issue #, if available: n/a

How has this been tested?

Review checklist

The following items are to be evaluated by the author(s) and the reviewer(s).

Correctness

• Changes include appropriate documentation updates.
• Changes are backward-compatible if not indicated, see CONTRIBUTING.md.
• Changes do not include unsupported browser features, see CONTRIBUTING.md.
• Changes were manually tested for accessibility, see accessibility guidelines.

Security

• If the code handles URLs: all URLs are validated through the checkSafeUrl function.

Testing

• Changes are covered with new/existing unit tests?
• Changes are covered with new/existing integration tests?

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.44%. Comparing base (e1c488b) to head (c06bff8).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff            @@
##             main    #3216    +/-   ##
========================================
  Coverage   96.44%   96.44%            
========================================
  Files         790      790            
  Lines       22246    22246            
  Branches     7644     7229   -415     
========================================
  Hits        21455    21455            
- Misses        739      784    +45     
+ Partials       52        7    -45     

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[purplepenguin2]

Was there any info on why this was reverted?