Progress does not stand still, and, following the CSS3, the new CSS4 comes to us, which is developing by the W3C editing team. Historically, the process of development of CSS is independent from the process of development of web-browsers – both are developed in parallel. This has led to the fact that different browsers support different sets of CSS specifications. But back to CSS4. W3C periodically update a working (draft) specification CSS4 and I want to give you first and basic information about what is already included in the specification of CSS selectors level 4.
CSS is a language for describing the rendering of structured documents (such as HTML and XML) on screen, on paper, in speech, etc.