Expert Wordpress Website Development with Responsive Mobile-First Design

I am looking for a skilled freelancer to develop a new website using WordPress. The project requires a strong focus on mobile-first design principles to ensure an optimal user experience across all devices, from smartphones to desktops. The ideal candidate will be proficient in WordPress development, including custom theme implementation or modification, plugin integration, and ensuring the site is fully responsive. Key aspects include creating a user-friendly interface, optimizing for performance and SEO, and implementing robust security measures. Please provide examples of previous WordPress projects with strong mobile responsiveness.