Fix: Add proper z-index layer priority context for dropdown nav elements

[janievinod]

Pull Request Description

This PR introduces a layout stacking priority patch inside the submissions directory to resolve issue #1239. It configures an explicit stacking context boundary on the animated mobile navigation headers, ensuring expanding layout elements overlap surrounding page items cleanly instead of clipping beneath adjacent blocks.

---

Type of Change

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

---

Submission Checklist

⚠️ PRs that fail this checklist will be closed without review.

• 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)

---

Feature Description

What does this add?
Establishes clear vertical depth hierarchy guidelines using explicit stacking properties on responsive layout bars.

How does a developer use it?

<nav class="ease-nav-menu">
  </nav>

Why does it fit EaseMotion CSS?
It addresses a vital interface overlap bug, allowing drop and slide disclosure menus to expand cleanly without unexpected visual breaks across core pages.

Demo
[x] Demo added (demo.html works by opening directly in a browser)

Browser Testing
[x] Chrome

[x] Edge

[ ] Firefox

[ ] Safari (optional but appreciated)

Notes for Maintainer
Closes #1239. Viewport layer priorities evaluated across local dark-theme structural variations.

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]

✅ Submission Validation Passed!

Great job! All required files are present.

📁 Folder: submissions/examples/nav-clipping-fix

Files found:

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

🚀 Next Steps:

• The 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! 🎉