Modern Website Redesign with User Login

I need a skilled web developer to update the design of my existing website. The new design should be modern and sleek, and include a user login system as a new feature.

Requirements:
- Aesthetic update for a modern and sleek look
- Implement a user login system
- Experience in website design and development
- Proficiency in creating intuitive user interfaces

Ideal Skills and Experience:
- Strong portfolio showcasing modern website designs
- Experience with user authentication systems
- Familiarity with responsive design principles
- Knowledge of SEO best practices

Please provide samples of your previous work and a brief outline of your approach.