Shopify Store Customization Expert Needed

I'm looking for an experienced Shopify developer to customize my store according to my needs. I already have the theme but need help with both design and functionality.

Design Customization:
- Change layout and colors
- Add custom graphics and banners
- Improve mobile responsiveness

Functionality Improvements:
- Advanced search and filtering
- Customer reviews and ratings
- Integration with third-party apps

Ideally, you should have:
- Proven Shopify development experience
- Strong design skills for a professional look
- Familiarity with app integrations and improving store functionality
- Responsive communication and project management skills

Please provide examples of your past work and any relevant certifications.