The importance of writing maintainable code is well established in the software industry but it is often ignored in CSS codebases. Web applications are becoming larger than ever and a poorly maintained CSS codebase can become a major drag on a team and company’s performance. John Craddock is a UI developer in Adaptemy, an educational software company in Dublin. For the past 2 years, Adaptemy has been building and maintaining a web app used in schools across Europe. John will describe the challenges Adaptemy has faced in maintaining and expanding their CSS codebase. In 2015 John gave a talk (https://www.youtube.com/watch?v=ZIFHG9ffPM0) on Adaptemy’s experiences setting up a new CSS architecture. This talk will focus on the learnings they’ve acquired since then. What mistakes they made and how they recovered from them. Which of the industry best practices they adopted (or rejected). And what John’s opinions are on the state of the industry overall. In common with other development languages, CSS must be predictable, re-usable, scalable and maintainable. There are also challenges which are particular to UI development. UI teams build the user facing part of a product and all stakeholders will have a view on the product’s UI. As a result, your UI must be able to adapt quickly. Your CSS codebase must be robust to frequent changes without any degradation in quality. John will discuss the coding and work practices which have evolved in Adaptemy to face the challenges specific to UI teams. He will discuss the pitfalls of agile methodologies which can result in poor quality code and how to manage them.