Add Minimalistic Styling in both light and Dark Mode as well as Fixed the issue of sidebar padding.

[Mitesh-V-Chauhan]

… the issue of sidebar padding when it was scrolled there was padding issue

Summary

Here is a summary of the frontend changes and fixes:

• New Design: The website has been completely redesigned with a modern, minimalistic, and
  professional look and feel. This includes a new color palette, typography, and layout.
• fixed the sidebar scrolling issue and padding issue , when scrolled sidebar the navbar was
  hiding but the sidebar was not moving up so fixed it as well.

Related Issue

Resolves: # (if applicable) No

Type of change

• Bug fix
• New feature
• Documentation update
• Other (please describe): Redesign and Add Fix Sidebar Scroll Issue

Checklist

• My code follows the repository style
• I have added necessary documentation (if appropriate)
• I have added tests (if appropriate)
• I have read the contributing guidelines

How to test

Steps to reproduce or verify this change. Include relevant commands and expected output.
You have to just start the frontend and the change will visually appear.

Screenshots (if applicable)

Add screenshots to demonstrate the change.

There were colour issue in gradient backgorund so fixed it :
Before:

After:

Before:

After:

Additional notes

Anything else the reviewer should know.