W3C CSS Snapshot of 2025: An Analysis of Specification Stability

The sources consist of **excerpts from the W3C’s latest CSS Snapshot (2025)**, along with supporting context from **prior snapshots and Working Group publications**, which provide an in-depth analysis of the current state of Cascading Style Sheets. The core purpose of the **Snapshot is to serve as a non-normative Group Note** that collates all stable and maturing CSS modules, dividing them into categories based on stability: **Official Definition, Reliable Candidate Recommendations, Fairly Stable Modules, and Modules with Rough Interoperability**. This extensive document functions as a **critical roadmap for browser implementers and test authors**, guiding their development efforts by explicitly listing which features are stable enough to be considered "official CSS" and identifying the next set of features that are nearly standard. The analysis also highlights significant **changes since the previous year's snapshot**, noting the advancement of key features like Cascade Layers (Level 5) and the inclusion of Web Platform APIs related to styling.