[BUG]: TopNavbar scrolls out of view on page scroll

[ankitkr104]

Bug Description

The navbar had no sticky/fixed positioning, so it scrolled away with the page content — making nav links, the wallet connector, and theme toggle completely inaccessible mid-page.

Steps to Reproduce

1. Open the app at any route (e.g., /reactor)
2. Scroll down the page past the navbar height
3. Expected: Navbar remains pinned at the top of the viewport
4. Actual: Navbar scrolls off-screen with the page content

Logs and Screenshots

No response

Environment Details

No response

Impact

Medium - Feature works but has issues

Code of Conduct

• I have joined the Discord server and will post updates there
• I have searched existing issues to avoid duplicates