Add Black & White (Monochrome) Theme Option for Better Accessibility and Minimal Design

[Sarojadhi]

• PR for this issue must follow the PR template
• This is a bug
• This is a feature request

Description:

Currently, the website doesn’t provide a black and white (monochrome) theme option. Adding this feature could enhance the accessibility, readability, and minimal aesthetic of the site.

* Why this is needed:

• Improves visibility for users sensitive to bright or colored interfaces

• Provides a clean, distraction-free design option

• Enhances accessibility for visually impaired users

• Aligns with minimal design preferences

* Suggested Solution:

• Introduce a toggle to switch between default theme and black & white mode

• Use CSS variables or a theme management system for easy implementation

• Ensure all images, icons, and UI elements adapt properly in monochrome mode