feat: added tab-pill-switcher

[cyber-scribe]

Summary

Adds the Tab Pill Switcher component. The component provides a bordered tab strip with a sliding active
background and an underline accent using only HTML and CSS.

What's Included

demo.html

• Three interactive tabs.
• CSS-only state switching.
• Native radio controls.
• Responsive content layout.
• No JavaScript dependencies.

style.css

• Sliding active pill.
• Gradient accent underline.
• Smooth transitions.
• Active-state content animation.
• Responsive mobile styling.
• EaseMotion-style CSS custom properties.
• Keyboard focus states.
• prefers-reduced-motion support.

README.md

Includes:

• Component overview.
• Usage instructions.
• Customization tokens.
• Accessibility notes.
• Browser requirements.

Accessibility

• Uses native form controls for interaction.
• Keyboard focus is visible.
• Reduced-motion preferences are respected.
• No JavaScript is required.

The demo keeps the implementation dependency-free. A production ARIA
tab system may require additional keyboard behavior such as arrow-key
navigation and programmatic tab selection.

Closes #86823

[SAPTARSHI-coder]

✅ Submission Validation Passed!

Great job! All required files are present and valid.

📁 Folder: submissions/examples/tab-pill-switcher

Files found:

• ✅ demo.html
• ✅ style.css
• ✅ README.md

🚀 Next Steps:

• A maintainer will review your PR
• Respond to any feedback if requested
• Once approved, your contribution will be merged!

Thank you for contributing to EaseMotion CSS! 🎉

[github-actions]

🎉 Congratulations on your PR merge, @cyber-scribe! 🚀

Thank you so much for your valuable contribution to EaseMotion CSS! Your code is now merged into the main branch.

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[github-actions]

🎉 PR Merged! Thanks @cyber-scribe! You have submitted 1/250 PRs today (resets in 10h). GSSoC labels assigned. Discord