CSS Definition

CSS in terms of software development stands for cascading stylesheet language that is highly used for representing visual elements of a document written in HTML or XML. CSS enables developers to create visually appealing web pages by controlling layout, colors, fonts, and overall presentation. In a nutshell, CSS determines the visual appearance and layout of web page elements.

Browsers interpret CSS alongside HTML to transform plain markup into styled, user-friendly web pages. Within CSS you can implement text styling, image/video display styling, and visual effects. Being a complex language, it’s divided into modules for easy perception and work. This language was developed in 1996, and since then has been used as a tool that turns websites into pleasant pages.

How CSS works: understanding selectors and declarators

CSS funtions as a language of selectors and declarations. Selectors are used to identify which HTML elements need to style; and declarations are instructions given to style all the selected elements. A basic CSS rule is an appropriate selector that is followed by a set of curly braces containing property/value pairs. For example, h1 { color: blue; font-size: 24px; } makes all the elements defined from within tag to appear in blue with 24px size text.

Due to CSS having a cascading order of how styles apply, multiple style rules could technically apply to the same element. It is based on specificity and inheritance where more specific selectors override general ones, and child elements inherit certain properties from their parents. Understanding the cascade and specificity is key to writing maintainable and predictable CSS.

CSS is interpreted by browsers by parsing stylesheets, calculating which style rules are aimed at which document elements based on specificity, and rendering the final visual output. Most modern browsers have their own developer tools, which allow one to inspect the styles being applied, test out modifications in real-time, and efficiently debug style issues.