Check out a free preview of the full Scalable Modular Architecture for CSS (SMACSS) course:
The "Extending Classes" Lesson is part of the full, Scalable Modular Architecture for CSS (SMACSS) course featured in this preview video. Here's what you'd learn in this lesson:
Preprocessors allow for CSS classes to be based on another class. Extending CSS classes is nice for code reuse but can lead to side effects. The generated CSS can become quite large and difficult to work with.