Added styling to the PopOver and Cogwheel. Fixed typo in highlight

[BartvanEijkelenburg]

Description

A few sentences describing the overall goals of the pull request's commits.

Type of change

• [ x ] Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Checklist

• [ x ] My code follows the style guidelines of this project
• [ x ] I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• I updated the changelog with an end-user readable description
• I assigned this pull request to the correct project board to update the sprint board

Steps to Test or Reproduce

Click on the cogwheel on the project modal page.
Changed styling will now show up.

Closes: #461

[HansenSven]

Looks good