feat(sidebar): add elastic drawer panel animation

[SreeyaKumari]

Pull Request Description

Implemented an elastic drawer panel animation for the sidebar component on mobile devices.

Changes

• Added spring-like drawer slide-in animation using cubic-bezier easing
• Added shadow effect for visual depth when the drawer is active
• Added main content translate + scale-down effect when the sidebar opens
• Improved transition behavior for smoother user interactions
• Preserved reduced-motion accessibility support

This addresses the feature request described in Issue #426.

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Type of Change

• ✨ New animation / hover effect
• 🧩 New component
• 📝 Documentation improvement
• 🐛 Bug fix in an existing submission
• Other (describe below)

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Submission Checklist

• All changes are inside submissions/examples/your-feature-name/
• Includes demo.html — self-contained, opens in browser with no server
• Includes style.css — raw CSS for the proposed feature
• Includes README.md — what it does, how to use it, why it fits EaseMotion CSS
• No changes to core/
• No changes to components/
• One feature per PR (no bundled unrelated changes)

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fixes #426

Feature Description

Added an elastic drawer panel animation and main body scale-down effect for the sidebar component on mobile devices.

How does a developer use it?

<div class="ease-sidebar-layout ease-sidebar-open">
     <aside class="ease-sidebar">
         Sidebar Content 
     </aside>

     <main class="ease-sidebar-main">
          Main Content 
     </main>
</div>

Why does it fit EaseMotion CSS?
This enhancement aligns with EaseMotion CSS's animation-first philosophy by providing a smooth, natural drawer interaction using spring-like easing, depth effects, and coordinated motion between the sidebar and main content.

Demo

• Demo added (demo.html works by opening directly in a browser)

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Browser Testing

• Chrome
• Firefox
• Edge
• Safari (optional but appreciated)

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Notes for Maintainer

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Reminder: Only the repository maintainer may merge pull requests.
Do not self-merge, even if you have write access.
Maximum 2 active assigned issues per contributor — unassign extras before opening a PR.

[github-actions]

📊 CSS Bundle Size Benchmark

No change in CSS bundle size. ✨