CSS, short for Cascading Style Sheets, is the style sheet language for web pages. It sets colors, fonts, spacing and layout. It works with HyperText Markup Language (HTML) and with XML. A style sheet holds rules. Each rule links selectors to declarations.
History of CSS
Creator: Håkon Wium Lie and Bert Bos. Year: 1994.
CSS was first proposed by Håkon Wium Lie on 10 October 1994. At that time Lie worked with Tim Berners-Lee at CERN, the European Organization for Nuclear Research. A proposal by Bert Bos was also influential. He became co-author of CSS level 1, so he is regarded as a co-creator.
Before CSS, the web had no shared way to style a page. The style sheets were hard-coded into the browser program. They could not be linked to documents on the web. Robert Cailliau at CERN wanted presentation kept apart from structure. The www-style mailing list received nine proposals. Two of them shaped CSS: Cascading HTML Style Sheets and the Stream-based Style Sheet Proposal.
The World Wide Web Consortium (W3C) took an interest in CSS and held a workshop toward that end. In early 1997 its review board split into three groups. Chris Lilley of the W3C chaired the CSS Working Group. The first CSS Recommendation, CSS level 1, came out in December 1996. CSS level 2 became a W3C Recommendation on 12 May 1998. CSS level 3 began in 1998 and is split into modules.
Browser support came slowly. Microsoft Internet Explorer 3 shipped in 1996 with limited CSS. Internet Explorer 5.0 for the Macintosh came out in March 2000. It was the first browser with better than 99 percent CSS level 1 support. Internet Explorer 6 added a quirks mode for old pages and a standards mode for correct ones.
Changelog and latest update
In 2005 the CSS Working Group enforced its standards rules more strictly. CSS 2.1, CSS 3 Selectors and CSS 3 Text went back to Working Draft. Today CSS is split into modules. Each module has its own level and status. The W3C lists modules such as CSS Grid Layout Level 1 and Media Queries Level 4 as current work.
The W3C publishes a CSS Snapshot once a year. A snapshot is a Group Note. It lists the modules that are stable on that date. The W3C current work page lists snapshots from 2007 to 2026. The newest snapshot is the stable reference for CSS.
The first snapshot on the list is from 2007. Each entry is a separate Group Note with its own date. Older snapshots stay online, so a reader can compare the stable modules from one year to the next.
Latest update: CSS Snapshot 2026, 2026-06-22
The W3C published CSS Snapshot 2026 as a Group Note on 22 June 2026. The note lists the CSS specifications that are stable in 2026. It is written for implementers. The W3C current work page calls it the latest stable CSS. The live specifications remain on the W3C site.
Usage examples
CSS works through rules. Each rule has a selector and a declaration block. The selector picks elements in the HTML tree. The block sets properties such as color or display. A link element loads a file. The browser applies its rules to every match. The five examples show a link, a hover state, a media query, a row layout and a custom property.
<head>
<meta charset="utf-8">
<link rel="stylesheet"
href="/css/site.css">
</head>The link element with rel set to stylesheet loads the file /css/site.css into the page. The browser then applies every rule in that file. A single file lets many pages share the same styles, and the browser can cache the file between page loads.
.button {
background: #0b5ed7;
color: #ffffff;
padding: 12px 24px;
border-radius: 6px;
}
.button:hover {
background: #084298;
}The .button selector matches every element that has class button. The :hover pseudo-class changes the background when the mouse pointer is over the element. The border-radius property rounds the corners of the box by six pixels.
@media (max-width: 600px) {
.sidebar {
display: none;
}
body {
font-size: 16px;
}
}A media query applies its rules only when the screen is 600 pixels wide or less. Inside the query, the sidebar class is hidden with display none, and the body text is set to 16 pixels. This is the usual way to make one page layout work on a phone.
.row {
display: flex;
gap: 16px;
justify-content: space-between;
align-items: center;
}The flex value of display places the children of the row in one line. The gap property adds 16 pixels of space between them. The justify-content and align-items properties set the horizontal and vertical position of the children inside the row.
:root {
--brand-color: #0b5ed7;
}
h1 {
color: var(--brand-color);
}A custom property starts with two hyphens and stores a value that other rules can read. The root selector matches the top of the document, so the variable is available everywhere. The var function reads the value, so one change to the variable updates every heading that uses it.
References
These sources are outside Websnoogie and were checked on 2026-10-12.
Cascading Style Sheets
Wikipedia
The encyclopedia article on CSS. It covers selector and rule syntax. It traces the history from the 1994 proposal to the 2014 level 3 work. It also covers the browser problems of the late 1990s. Each claim cites a source.
CSS: Cascading Style Sheets
MDN Web Docs (Mozilla)
The MDN reference for CSS. It lists each property, selector and function. Each entry has examples and browser support tables. Each page links to the W3C or WHATWG specification behind the feature.
Cascading Style Sheets home page
World Wide Web Consortium (W3C)
The W3C home page for CSS. It links to the CSS Working Group and the current work page. It lists the modules and their status. It also links to the test suites that check browser support.
CSS Snapshot 2026
World Wide Web Consortium (W3C)
The W3C Group Note dated 22 June 2026. It gathers the CSS specifications that are stable in 2026. It lists the editors and the status of each module. It links to the snapshot series.
Cascading Style Sheets Level 2 Revision 1 (CSS 2.1)
World Wide Web Consortium (W3C)
The W3C specification for CSS 2.1. It is the revision that consolidated CSS level 2. It defines the box model, positioning, the cascade and media types. Many CSS modules refer back to it.
RFC 2318: The text/css Media Type
RFC Editor (IETF)
The IETF document from March 1998. It registers the text/css media type. Servers send this type with style sheet files. Browsers then treat the file as CSS.
Keep the style rules steady on every page
Ignore the style rules and pages break on phones. Cascading Style Sheets (CSS) control the colors, fonts, spacing and layout of every page on a site. One missing rule can hide a menu. One rule that conflicts with another can push text off the screen. Visitors leave before they read your offer, and you never see them go. Clean style rules keep each page looking like the rest of your site.
We review the style sheets on every site we build or move. We check that each rule loads once and only where it is needed. We test the layout at phone width and at desktop width, and we confirm that the text is easy to read. If your site is moving to us, we carry its style rules across with the pages. A normal-size WordPress site transfers free. Larger sites cost $199 one time to move.
A new site from us takes 3 to 5 days to deliver once we have your words and photos. The price is $300 for a site with up to five pages plus a contact page. Ask us about the style rules on your current site by phone at 402-813-4034, which we answer from 7 am to 10 pm every day, and we will tell you what we find.
