Selectors Level 3 was the first major CSSCascading Style Sheets — the language for layout, color, and typography on web pages. module to reach Recommendation status after CSSCascading Style Sheets — the language for layout, color, and typography on web pages. 2.1 — adding structural pseudo-classes, UIUser interface — the parts of software people see and interact with. state selectors (`:checked`, `:disabled`), and combinators that jQuery had popularized in JavaScript. Every modern stylesheet uses its patterns for targeting DOM nodes without extra markup.

Selectors Level 3 was the first CSS3 module to ship as a finished standard.

It gave authors precise DOM targeting primitives that powered responsive and component-based CSSCascading Style Sheets — the language for layout, color, and typography on web pages..