This post absolutely nails what’s special about CSS …and why supersmart programmers might have trouble wrapping their head around it:
Other programming languages often work in controlled environments, like servers. They expect certain conditions to be true at all times, and can therefore be understood as concrete instructions as to how a program should execute.
CSS on the other hand works in a place that can never be fully controlled, so it has to be flexible by default.
Max goes on to encapsulate years of valuable CSS learnings into some short and snappy pieces of advices:
No matter what your level of CSS knowledge, this post has something for you—highly recommended!