Authoring performant, scalable & accessible CSS is difficult and requires specialist knowledge. Emily covers why design systems can help enable organizations to ship well-written CSS. She also covers what design systems are, the history of design systems at GitHub, and why we decided to abstract styles into reusable React components. You will walk away with a deeper knowledge of how to design a public API for components, how theming works, and common pitfalls one might come across when trying to scale a design system across an organization.