Cascading Style Sheets, commonly referred to as CSS, is commonly used to style web pages written in HTML and XHTML, but can be used together with any kind of XML document. It is a style sheet language used to describe the look and formatting (presentation semantics) of a document written in a markup language.
The primary use of CSS is to separate document content from document presentation, such as layout, fonts and colors. This allows for tableless web design, gives the web designer more flexibility and control, and makes it possible for multiple pages to share the same formatting.
The CSS specifications are maintained by the World Wide Web Consortium (W3C).
CSS History – the beginning
Before CSS was developed, the presentational attributes of HTML documents were almost always contained within the HTML markup. The web designer had to explicitly describe all backgrounds, font colors, borders, element alignments, etcetera. The aim of CSS was to allow web designers to move most of this information to a separate style sheet.
Style sheets have been round since the early days of SGML (Standard Generalized Markup Language), i.e. since the 1970s. As HTML became more and more widely used, HTML came to encompass a wide variety of stylistic possibilities to meet the demands of increasingly complex web page designs. The designers’ gained more and more control, but in the process, HTML became more and more complicated to write and maintain.
Robert Cailliau, the Belgian informatics engineer who together with Tim Berners-Lee developed the World Wide Web, wanted to find a way to separate the structure from the presentation. He also wanted to give the user the option of choosing between three different kinds of style sheets: one for screen presentation, one suitable for printing and one for the editor.
Eventually, nine different style sheet languages was presented to the World Wide Web Consortium. Two of them was chosen: Cascading HTML Style Sheets (CHSS) and Stream-based Style Sheet Proposal (SSP). CHSS had been suggested by Norweigan web pioneer Håkon Wium Lie, while SSP was the brainchild of Dutch computer scientist Ber Bos. Lie teamed up with computer scientists Yves Lafon and Dave Raggett to make Raggett’s Arena browser support CSS, while Lie and Bos worked together to turn CHSS into the CSS standard. (The letter H was removed since their style sheets was to be applied to more than just HTML).
A later addition to the world of Cascading Style Sheets is the bootstrap framework. Bootstrap is a front end framework originally designed by Mark Otto and Jacob Thornton. It is a lightweight framework that allows you to build beautiful websites that works well on mobile devices. It is currently the leading standard for responsive web design although it is not as light weight or fast as Google AMP. Good examples of websites built using bootstrap includes this finance website as well as twitter and Daytrading.com.
CSS History – CSS level 1 and level 2 Recommendations
The Evolution of CSS: From Style Proposals to Modern Web Engines
The timeline of styling standards, layout breakthroughs & native browser features
While working alongside Tim Berners-Lee at CERN, Håkon Wium Lie publishes the initial proposal titled “Cascading HTML Style Sheets”, presenting a balance of author preferences, browser defaults, and reader accessibility.
The World Wide Web Consortium (W3C) officially recommends CSS Level 1. It introduces the fundamental Box Model, fonts, background colors, margins, text alignment, and inline/block display mechanics.
CSS2 introduces absolute, relative, and fixed positioning alongside z-index, media types (print vs. screen), bidirectional text, and table rendering rules. (Later stabilized in 2011 as CSS 2.1).
To avoid monolithic release bottlenecks, the W3C splits the spec into autonomous modules (Selectors, Color, Box Model, Text). Developers endure the era of vendor prefixes (-webkit-, -moz-, -ms-) and table-based hacks.
Hampton Catlin invents Sass (followed closely by Less and Stylus), filling native CSS capability gaps by introducing nesting, mixins, math functions, partial imports, and programmatic variables.
Ethan Marcotte publishes “Responsive Web Design” on A List Apart. Relying on CSS3 @media queries and fluid proportion grids, responsive layouts replace dedicated mobile redirect sites (m.dot).
The Flexible Box Layout (Flexbox) module achieves widespread cross-browser support, solving vertical centering and dynamic item distributions. Native var(--custom-property) support begins rolling out across major rendering engines.
In a historic coordinated rollout, Chrome, Firefox, Safari, and Edge ship CSS Grid Level 1 within weeks of each other, providing the web with native two-dimensional rows and columns without framework constraints.
CSS unlocks component-driven responsiveness via @container queries, architectural priority control with @layer, pseudo-class matching (:has(), :is()), and native hierarchy nesting without preprocessor compilers.
Wide baseline availability of CSS Subgrid, @scope boundaries for component isolation, scroll-driven animations, and the View Transitions API elevate native stylesheets to rival complex JavaScript layout frameworks.