Enhanced the UI of the Navbar (#192)

[feature Request]: ENHANCING THE UI OF HEADER PORTION IN THE ONLINE
DELIVERY SECTION

## Description
I would love to enhance the appearance of the header section by
incorporating CSS to style the navigation bar, adding a visually
appealing and polished look. My goal is to modify and refine the design,
making it more attractive and user-friendly while maintaining
functionality.


## Related Issues

<!--Cite any related issue(s) this pull request addresses. If none,
simply state “None”-->
- Closes #187 

## Type of PR
<!-- Mention PR Type according to the issue in brackets below and check
the below box -->
- [ ] ()

## Screenshots / videos (if applicable)
![Screenshot 2024-10-04
204451](https://github.com/user-attachments/assets/7cd40e1b-7415-40ee-b680-464bb58bde6a)


## Checklist
<!-- [X] - put a cross/X inside [] to check the box -->
- [ x] I have gone through the [contributing
guide](https://github.com/Anjaliavv51/Retro)
- [ x] I have updated my branch and synced it with project `main` branch
before making this PR
- [x ] I have performed a self-review of my code
- [x ] I have tested the changes thoroughly before submitting this pull
request.
- [ x] I have provided relevant issue numbers, screenshots, and videos
after making the changes.
- [ x] I have commented my code, particularly in hard-to-understand
areas.


## Additional context:
<!--Include any additional information or context that might be helpful
for reviewers.-->
Initially the nav bar didnot have any much UI but I have changed the
style of the navbar and when the mouse hovers over it the colour changes
to blue.

Css-files/about.css

@@ -561,4 +561,4 @@
     margin-top: 5px;
   }
 
-
+