CSS, or Cascading Style Sheets, is a style sheet language used for describing the presentation of a document written in HTML or XML. Here is a brief history of CSS:

1. 1994 – Proposal by Håkon Wium Lie:
   • The concept of separating the structure and style of web documents was proposed by Håkon Wium Lie in 1994 while working with Tim Berners-Lee at CERN. The idea was to have a separate style language to control the appearance of documents.
2. 1996 – CSS Level 1 Specification:
   • The World Wide Web Consortium (W3C) published the first CSS specification, CSS Level 1, in December 1996. This specification introduced the basic styling properties, such as font, color, and text alignment.
3. 1998 – CSS Level 2 Specification:
   • CSS Level 2, published in May 1998, brought significant enhancements, including positioning and floating elements, media types, and support for internationalization. This version improved the capabilities for layout and presentation.
4. 2005 – CSS Level 2 Revision 1:
   • A revised version of CSS Level 2, known as CSS 2.1, was introduced in 2005. It corrected errors and clarified ambiguities from the previous version.
5. 2011 – CSS Level 3 Modules:
   • Instead of releasing a monolithic specification, CSS Level 3 is developed as a modular system with different modules covering various aspects of styling. This approach allows for more flexible updates.
6. 2012 – CSS4 Discussions:
   • There were discussions about the possibility of CSS4, which would be the next major version. However, the modular approach continued, and the term “CSS4” is not widely used in the development community.
7. Present – Ongoing Development (CSS4?):
   • CSS development continues with ongoing work on individual modules. New features and improvements are introduced regularly. Flexbox, Grid Layout, and Variables are some notable additions enhancing the capabilities of CSS.
8. Living Standard – Continuous Evolution:
   • Similar to HTML, CSS is considered a “living standard” by the WHATWG (Web Hypertext Application Technology Working Group). This means ongoing updates and refinements to meet evolving needs and technology advancements.

CSS plays a critical role in web development by providing a means to control the layout, design, and presentation of web documents. Its evolution reflects the need for a flexible and powerful styling language to support the diverse and dynamic nature of the internet.