View source for CSS (Cascading Style Sheets)

== Introduction ==
[[Cascading Style Sheets|CSS]] is a stylesheet language used for describing the look and formatting of a document written in [[HTML|HTML]] or [[XML|XML]]. It is a cornerstone technology of the [[World Wide Web|World Wide Web]], alongside HTML and [[JavaScript|JavaScript]]. CSS is designed to enable the separation of presentation and content, including layout, colors, and fonts. This separation can improve content accessibility, provide more flexibility and control in the specification of presentation characteristics, enable multiple web pages to share formatting by specifying the relevant CSS in a separate .css file, and reduce complexity and repetition in the structural content.

== History ==
CSS was first proposed by [[Håkon Wium Lie|Håkon Wium Lie]] on October 10, 1994. At the time, Lie was working with [[Tim Berners-Lee|Tim Berners-Lee]] at [[CERN|CERN]]. Among the many style sheet languages in the mid-1990s, CSS was designed to be a simple, lightweight, and easy-to-use language that could be used to style HTML documents.

== Syntax ==
CSS has a simple syntax and uses a number of English keywords to specify the names of various style properties. A style sheet consists of a list of rules. Each rule or rule-set consists of one or more selectors, and a declaration block. In CSS, selectors declare which part of the markup a style applies to by matching tags and attributes in the markup itself.

[[Image:Detail-71791.jpg|thumb|center|A screenshot of a CSS code snippet showing the syntax.|class=only_on_mobile]]
[[Image:Detail-71792.jpg|thumb|center|A screenshot of a CSS code snippet showing the syntax.|class=only_on_desktop]]

== Selectors ==
Selectors are the part of CSS rule set. CSS selectors select the HTML elements upon which styles are to be applied. While some selectors are simple to understand, others require a more detailed approach.

== Properties ==
Properties are what give the HTML elements in your document their look. They control things like colors, fonts, positioning, spacing, and even complex things like transitions or animations.

== Values ==
Values are assigned to properties to define their behavior, such as color, font, or size. The value can be a keyword, a number, a length, or a percentage.

== CSS Box Model ==
The CSS box model is a box that wraps around HTML elements, and it consists of: margins, borders, padding, and the actual content. The box model allows us to add a border around elements, and to define space between elements.

== CSS Layouts ==
CSS layouts help to arrange elements on the screen and to create a structure for the web page. They include grid, flexbox, and positioning.

== CSS Animations ==
CSS animations make it possible to animate transitions from one CSS style configuration to another. Animations consist of two components, a style describing the CSS animation and a set of keyframes that indicate the start and end states of the animation's style, as well as possible intermediate waypoints.

== CSS Preprocessors ==
CSS preprocessors are scripting languages that extend the default capabilities of CSS. They enable us to use logic in our CSS code, such as variables, nesting, inheritance, mixins, functions, and mathematical operations. Some of the most popular CSS preprocessors are [[Sass|Sass]], [[LESS|LESS]], and [[Stylus|Stylus]].

== CSS Frameworks ==
CSS frameworks are pre-prepared libraries that are meant to allow for easier, more standards-compliant styling of web pages using the CSS language. Some of the most popular CSS frameworks are [[Bootstrap|Bootstrap]], [[Foundation|Foundation]], and [[Bulma|Bulma]].

== See Also ==
* [[HTML]]
* [[JavaScript]]
* [[Web Development]]
* [[Responsive Web Design]]
* [[User Interface Design]]

[[Category:Web Design]]
[[Category:Web Development]]
[[Category:Computer Programming]]