JavaScript Web App Enhancement & Fixes

I have a production web application built around JavaScript and Node.js that needs a focused round of improvements. My priorities are:

• Revamp the user interface, specifically the overall design and layout, so navigation feels intuitive and flows logically from page to page.
• Resolve several outstanding Node.js issues that affect stability and prevent smoother performance behind the scenes.

For the front-end, I want the menu structure, page hierarchy, and interaction cues rethought so users can reach any key feature within two clicks. You’re free to suggest modern UI patterns, but the look and feel must remain consistent with our current brand palette.

On the back-end, you’ll audit the existing Node.js codebase, isolate bottlenecks or error-prone modules, and implement clean, well-commented fixes. Error handling should be centralized; any significant refactor must include unit tests so future upgrades are safer.

Deliverables
1. Interactive mock-up or prototype that demonstrates the proposed navigation flow.
2. Updated front-end code (HTML, CSS, JavaScript) ready to merge, with clear commit messages.
3. Patched Node.js modules with accompanying test cases.
4. A brief handover document summarizing changes, dependencies, and steps to reproduce the build.

I provide full repo access, staging credentials, and a list of current pain points. If you have solid experience in JavaScript, responsive UI design, and Node.js debugging, I’m ready to start immediately and iterate quickly on feedback.