[Style] Enhance the hover effect of navbar

[heli0707]

Description

Update the footer hover effect by changing the background color to a lighter shade and adding a subtle text shadow. This enhancement provides clear visual feedback, making footer links more engaging and easier to interact with.

Screenshots

https://github.com/user-attachments/assets/9d60d7ef-833b-45ce-88dd-b2dde5b19b69

Checklist

• [X] I have checked the existing issues.
• [X] I follow Contributing Guidelines of this project.
• [X] I am a GSSOC'24 contributor.
• [ ] I am a IWOC'24 contributor.
• [ ] I am a JWOC'24 contributor.
• [ ] I am a SWOC'24 contributor.

Code of Conduct

• [X] I agree to follow this project's "Code of Conduct".