React is a wonderful tool to write reusable components but there is no clear definition on how a good API for theming and customization should look like. There are too many approaches when it comes to styling, and choosing one of those is a crucial decision, specially for vendor component libraries like http://react-toolbox.com/ In this talk we will go through some of the most important styling libraries, analyzing what should they cover from the point of view of a library of components, and using React Toolbox as study case. We will explore how customization and theming can be modeled for UI Kit projects with different tools. Finally, we will see a simple technique that allows one to write components that are agnostic from styling, without committing to an specific tool. This makes possible to switch between styling strategies over time and experiment with them while keeping the same component implementation.