Adding CSS-Only Accordion / Collapsible Sections

[kavana185]

Description

This PR adds a fully functional accordion (collapsible sections) built using only HTML and CSS.
No JavaScript is required.

Features

• Expand/collapse multiple sections
• Smooth CSS transitions
• Only one section open at a time (radio button version)
• Responsive design for mobile and desktop
• Customizable colors and styles
• Accessible (keyboard-friendly)
• Rotating arrow icon for open sections

Files Added

• css-accordion/index.html
• css-accordion/style.css
• css-accordion/README.md

Usage

1. Open index.html in any modern browser.
2. Click on section headers to expand/collapse content.

Related Issue

Closes #866

[aayush105]

can you attach the full video demo showcasing the proper responsive across all screen sizes? And also like add you project under the Accordion folder, there you can copy and paste your project folder.

In this main folder you can add yours project.