Modern UI/UX Design for Web App

I'm looking for a UI/UX designer to enhance the user experience of my web application, with a particular focus on the visual design. The goal is to create a modern and sleek visual style.

Key Requirements:
- Expert in UI/UX design with a strong portfolio of web applications
- Proficient in modern and sleek visual design
- Able to improve user experience with a focus on visual design
- Experience with user engagement strategies is a plus