Enhance UI & Fix Sync Issues

Project Title: Fix Authentication Sync & Improve Web App Performance

Project Description:

I am looking for an experienced full-stack developer to fix issues with the user authentication system and improve overall performance and UI smoothness of my web application. The main goal is to implement a single account login system per email that synchronizes user progress and data across any device seamlessly.

Key Requirements:

Ensure single account per email with cross-device access and data sync.

Fix inaccurate progress tracking issues.

Debug and stabilize all existing core features to work correctly.

Optimize app speed, responsiveness, and smooth UI transitions.

Add a light/dark theme toggle.

Preserve all existing app functionalities without removing or changing features.

The project is small-scale; therefore, budget is limited to INR 1,000.

Skills Required:

Strong experience in React/Next.js or similar frameworks.

Knowledge of cloud-based authentication and session management.

Ability to debug complex front-end and back-end issues.

UI/UX performance optimization skills.

Please provide your approach, relevant experience, timeline, and fixed cost no more than INR 1,000.