This document provides an overview of Cascading Style Sheets (CSS) in 3 paragraphs: CSS contains rules for presenting HTML content separately from the HTML markup. It was introduced to separate presentation from content. Before CSS, designers used HTML presentation tags and images to control design, which made modifications difficult and supporting multiple browsers a challenge. CSS history includes style sheets existing since the 1970s, with CSS level 1 published in 1996 and level 2 in 1998. CSS level 3 remains in development.