Explore the world of functional CSS in this conference talk from CSSconf EU 2019. Dive deep into the debate surrounding functional CSS, comparing it to other OOCSS methodologies and examining its history. Debunk or support various critiques of this approach as you follow along with a live refactoring of an application from a classic CSS model to one leveraging the tachyons.io library. Learn about the benefits and challenges of functional CSS, including its impact on performance, scalability, and development time. Discover how functional CSS relates to concepts like separation of concerns, design systems, and component scoping. Gain insights into rapid prototyping in the browser and practical tips for implementing functional CSS in your own projects.