The History of CSS

Origins at CERN (1994-1995)

Cascading Style Sheets (CSS) is a language for styling documents written in HTML or XML, including XML-based formats such as SVG and XHTML. It specifies how elements should appear across different media, such as screens, print, or speech, and is essential for designing and developing web pages [29]. CSS was created to address the growing need for separating content from presentation on the web. In the early 1990s, websites were largely structured with HTML alone, which combined content and presentation, leading to inconsistent styling and difficulties in maintaining large sites. In 1994, Håkon Wium Lie, then working at CERN, proposed CSS as a solution to these challenges. Shortly afterward, Bert Bos joined the project, collaborating with Wium Lie to develop the first CSS specifications [29], allowing authors to define the visual presentation of HTML documents independently of the content.

CSS1: The First Standard (1996)

The first official specification, CSS1, was published by the World Wide Web Consortium (W3C) in 1996. CSS1 provided basic styling capabilities such as fonts, colors, text alignment, margins, borders, and the box model [29], enabling web designers to standardize the look of web pages across different browsers.

CSS2: Expanding Capabilities (1998)

CSS2 was introduced in 1998 [30], adding features like absolute, relative, and fixed positioning, z-index layering, media types, and support for aural styles for accessibility. This allowed more complex layouts and increased control over how content was displayed on different devices.

CSS 2.1: Stabilizing the Standard (2011)

CSS 2.1, finalized in June 2011, was a revision of CSS2 that addressed errors, ambiguities, and inconsistencies, creating a more stable and widely supported standard [29]. Notably, the development of CSS3 had already begun in the early 2000s as a modular approach to extending styling capabilities. While browsers adopted CSS2.1 as the baseline, CSS3 modules were developed and implemented incrementally alongside CSS2.1 stabilization.

CSS3: Modular Approach and Modern Features (2000s-2010s)

Work on CSS3 began in the early 2000s, but unlike earlier versions, CSS3 was modularized: each module, such as selectors, backgrounds, transitions, or animations, was developed independently. Some modules were finalized at different times, allowing browser vendors to implement and support new features incrementally. CSS3 introduced powerful modern styling capabilities, including flexible layouts, advanced selectors, transitions, animations, and media queries, enabling responsive design and richer user experiences across devices [29].

Ongoing Evolution of CSS

As of 17 December 2016, CSS marked its 20th anniversary since the release of CSS1 [31], reflecting on two decades of growth and transformation. While the term CSS3 was widely used in the 2000s-2010s to describe modular updates, today that distinction is no longer made [29]. Today, the features once grouped under CSS3 are considered part of the continuously evolving CSS, which is maintained as a living standard by the W3C CSS Working Group. This means CSS evolves continuously, with new capabilities being added independently rather than waiting for versioned releases.

Recent developments introduced features beyond the original CSS3 wave, including custom properties (CSS variables) for reusability, Grid Layout for powerful two-dimensional design, and container queries for more adaptive layouts. In addition, new pseudo-classes and pseudo-elements continue to expand the ability to style specific states and portions of content, offering greater precision and flexibility for designers [29]. These advancements further strengthen CSS as an essential tool for responsive and modern web design.

Final Thoughts

CSS has grown from a simple styling language into a dynamic and evolving standard, enabling consistency, accessibility, and creativity in web development. Its role as one of the three core technologies of the web ensures that it will remain vital for shaping user experiences across platforms well into the future. Today, CSS is used on nearly all websites, making it an essential and universally adopted technology for web design.