The CSS Working Group invites implementations of a Candidate Recommendation Snapshot of CSS Custom Properties for Cascading Variables Module Level 1. This module introduces cascading variables as a new primitive value type that is accepted by all CSS properties, and custom properties for defining them.

CSS is a language for describing the rendering of structured documents (such as HTML and XML) on screen, on paper, etc.

Original source: https://www.w3.org/blog/news/archives/9580