Have you ever tried to implement a PostCSS plugin which does something special on your project and fits your needs the best? It’s not so hard, really. In this talk you will find out the basics of traversing Abstract Syntax Tree, manipulating its nodes, and get some ideas of how PostCSS and CSSTree can work together. The talk is based on two real-life examples. One of them is an educational assignment for a junior developer. The plugin should replace one color with another. Another one is a color theme generator. The plugin produces a set of color variations based on source styles.