Applying programming principles to HTML, CSS and JS reveals these technologies as legitimate “players” and gives us the tools we need to build, scale and maintain—and a language to describe—the complex systems they (we) are capable of creating. OOCSS and SMACCS are applications of the object oriented paradigm to CSS. Here’s another tenet of OOP—the open/closed principle—as it applies to CSS, that Jonathan Snook just referenced from Harry Roberts’ post, open/closed principle applied to CSS.

In a nutshell –

“software entities (classes, modules, functions, etc.) should be open for extension, but closed for modification.”

Harry looks like he’s doing a series as evidenced by April’s The Single Responsibility Principle Applied to CSS