SUIT CSS
I was a core maintainer of SUIT CSS, an open source methodology and set of tools for building component-based interfaces. Teams including Twitter used the project.
Components and Styles
SUIT CSS uses structured class names to make the relationship between a component, its parts and its states clear. Its packages provide base styles, utilities and reusable components that teams can install individually. A preprocessor brings the pieces together and supports checks against the naming conventions.
I also built SUIT CSS Toolkit, a collection of components and utilities following those principles.