CSS is widely used in browsers, editors, and other applications. CSS is used not only for web design but also as the stylesheet specification for a wide range of printing applications as well as for electronic paged media delivered as PDF.

CSS (Cascading Style Sheets) Level 1 became a W3C Recommendation in 1996. CSS 2 became a W3C Recommendation in 1998, and CSS 2.1 (Cascading Style Sheets Level 2 Revision 1), in 2011. As of early 2018, CSS 2.2 is currently under development.

CSS post-Level 2 is popularly known as CSS 3, but there will not be a single, monolithic CSS Level 3 specification. CSS beyond CSS Level 2 has been broken into multiple modules that define separate parts of CSS. These modules are numbered individually. The first versions of modules that build on CSS Level 2 are denoted as Level 3, and each may be superseded by a Level 4 version. For example, CSS Color Level 3 replaces several sections of CSS Level 2, and CSS Color Level 4, which is currently in development, will eventually replace CSS Color Level 3. Modules that do not build on CSS Level 2 features start at Level 1: for example, CSS Multi-Column Layout Level 1. There will not be a CSS Level 4 or beyond.

Individual modules are in varying stages of development and varying levels of stability. The stability levels for all W3C specifications range from Working Draft to Recommendation. The CSS Working Group maintains a separate stability categorization for its specifications that ranges from Rewriting and Exploring through to Stable and Completed.

The CSS Working Group compiles yearly snapshots of the current state of CSS at that point in time. CSS Snapshot 2017[1] lists both Recommendation and Candidate Recommendation specifications as comprising the official 2017 definition of CSS (even though the document defines Candidate Recommendation as the test phase of a W3C specification).

CSS 2.1 (and CSS 2.2) provides only minimal support for paged media output, and its page layout features are not powerful enough. CSS 3, although still under development by the W3C, defines many of the features that are necessary for professional quality formatting, including: advanced page layouts; multiple columns; vertical writing; hyphenation; and multilingual character layout. Antenna House Formatter provides additional features for optimal formatting, including: custom-developed MathML 3, CGM, and SVG rendering; baseline grids; PANTONE® spot colours; and additional properties for controlling Japanese layout.

Using CSS in paged media design for XML and HTML is not yet common but its use is expected to increase as the development of CSS 3 progresses. This tutorial aims to make CSS for Paged Media easy to understand.