Glossary · Websites and content systems
Cascading Style Sheets (CSS)
A stylesheet language that controls how structured web documents are presented across screens, print, speech, and other media.
Also called: CSS, Cascading Style Sheets
Definition
Cascading Style Sheets define visual presentation such as layout, spacing, color, type, and responsive behavior for HTML or XML documents. The cascade, inheritance, selectors, and media rules determine which declarations a browser applies.
Why it matters
CSS separates much of a website's presentation from its document structure and is central to responsive, accessible, maintainable rendering.
Common misunderstanding
CSS is not the page's content or semantic structure, and a visually correct stylesheet does not prove that the underlying HTML or interactions are accessible.
Related terms
Related system family: Websites & Publishing
Sources
- CSS: Cascading Style Sheets (opens in a new tab) · MDN Web Docs
Last reviewed July 16, 2026