Fix Mobile Navigation Visibility

I run a React-based prediction platform and the one thing still holding us back is a stubborn navigation issue: the menu vanishes completely on mobile screens. Everything else works, but without an accessible menu the user flow stops cold.

I need you to dive into the current React codebase, trace why the navigation component fails to render below typical breakpoints, and implement a clean, future-proof fix. The stack is plain React with react-router; styling is a mix of CSS modules and a few inline styles—no heavy UI framework. Feel free to bring whatever modern front-end tooling you prefer (Chrome DevTools, React Developer Tools, mobile emulators) as long as the final result fits naturally into the existing repo.

Acceptance criteria:
• The navigation menu is fully visible and functional on phones and small tablets (≤768 px).
• All existing links and dropdowns behave exactly as they already do on desktop.
• No regression on larger viewports; Lighthouse and console stay error-free.

Push the patched component plus any supporting CSS, and I’ll test it right away. Let me know how soon you can start and roughly how long you expect the investigation and fix to take.