Is CSS a real programming language

While CSS and HTML aren't Turing-complete in that they lack features such as the ability to perform arbitrary computations or to express logic and control flow, they are intentionally designed with a limited set of capabilities focused on their usecases. Making them an ideal choice for their domain.
In this context, the Rule of Least Power supports the notion that HTML and CSS are perfectly suited for their intended tasks—structuring and styling web content, respectively—without the need for the more complex capabilities of Turing-complete programming languages. This principle suggests that the value of a language should not solely be measured by its computational power but also by its appropriateness and efficiency in solving specific problems.