[FEATURE REQUEST] Implement Transparent Navbar with Scroll Effect

## Description

This issue proposes implementing a navbar that is transparent at the top of the page and gradually transitions to a solid background color as the user scrolls down. This will improve the user experience by:

Enhancing the visual appeal of the website.
Providing a clearer distinction between the navbar and content when scrolled.

There are two possible approaches to achieve this effect:
CSS with JavaScript: This method offers more flexibility but requires some JavaScript knowledge.
CSS with Placeholder Element: This is a simpler method but might not be suitable for all layouts.