Specifications. Validaton. Cascading Style Sheets Level 2 Revision 1 (CSS 2.1) Specification. This specification defines Cascading Style Sheets, level 2 revision 1 (CSS 2.1).
CSS 2.1 is a style sheet language that allows authors and users to attach style (e.g., fonts and spacing) to structured documents (e.g., HTML documents and XML applications). By separating the presentation style of documents from the content of documents, CSS 2.1 simplifies Web authoring and site maintenance. All Standards and Drafts.