Responsive Event Website Design Needed

I’m planning a new website and the core requirement is a clean, modern event page that looks and works perfectly on both iOS and Android devices. The project is strictly web-based—no native app—so please focus on responsive front-end techniques (HTML5, CSS3, JavaScript or a framework you prefer)... (Budget: $250 - $750 USD, Jobs: CSS, HTML, JavaScript, Mobile Development, PHP, Web Design, Web Development, WordPress)