Understanding where CSS came from puts today's features in context and explains why some things work the way they do — including some of the quirks and limitations you'll encounter. The history of CSS is really the history of the web itself trying to grow up.

In the early 1990s, the web had no CSS. HTML was intended to be purely structural — <h1> meant "this is a top-level heading", not "make this big and bold". But as the web grew, people wanted to make pages look good. Without a styling language, browsers started adding presentational HTML tags: <font> to change typeface and colour, <center> to centre content, <b> for bold, <i> for italic. Web pages became littered with markup like <font color="red" size="3" face="Arial">, which had to be repeated on every paragraph. It was messy, repetitive, and impossible to maintain.

In 1994, Norwegian computer scientist Håkon Wium Lie (then working at CERN) published the first proposal for a style sheet language for the web. Bert Bos, who was working on a browser project, collaborated with him, and together they presented the idea to the W3C (World Wide Web Consortium). After two years of debate and refinement, CSS Level 1 became a W3C recommendation in December 1996.

CSS1 introduced the fundamental model that still exists today: selectors, properties, values, the cascade, and inheritance. It defined properties for colours, fonts, margins, padding, and basic positioning. It was a huge step forward — but browser adoption was patchy. Internet Explorer 3 and Netscape 4 both implemented CSS, but inconsistently and with bugs. Developers spent years writing workarounds for browser differences.

CSS Level 2 was released in 1998, adding positioning (absolute, fixed), z-index, media types (print vs screen), and more powerful selectors. But the real story of this era was the browser war between Internet Explorer and Netscape. Both browsers implemented CSS differently, invented non-standard features, and the resulting inconsistencies made web development genuinely painful.

The period from roughly 2000–2008 was the dark ages of CSS. Internet Explorer 6 — which dominated the market for years — had notorious bugs like the double margin float bug, the IE box model bug (where border and padding were included in width rather than added to it), and missing support for features like :hover on anything other than links. Developers wrote elaborate CSS hacks, conditional comments, and browser-detection scripts just to get layouts to look the same in every browser.

CSS2.1 was not a new version so much as a corrected and clarified version of CSS2, published in 2011 after years of work. But the more important development of this era was the Web Standards Project — a group of developers who campaigned loudly for browsers to implement CSS properly. Firefox emerged as a standards-compliant alternative to IE, and the pressure on Microsoft eventually paid off. By 2008 IE7 and IE8 had dramatically improved CSS support.

The W3C learned a lesson from CSS2: releasing a monolithic specification that took 10 years to finalize was too slow. CSS Level 3 split into independent modules — Selectors, Backgrounds, Borders, Color, Flexbox, Grid, Animations, and so on — each with its own specification that could be developed and shipped independently. This is why you'll hear phrases like "the Flexbox module" or "the Grid specification".

This modular approach accelerated the pace dramatically. The period from 2009 to today has seen an explosion of powerful CSS features:

A few things you'll understand better with this context: