CSS (Cascading Style Sheets) is a programming language used for styling and formatting the appearance of web documents. It works in conjunction with HTML (Hypertext Markup Language) to define how the content of a web page should be presented to users.
Here's a brief overview of CSS:
Separation of Concerns: CSS separates the structure and content of a webpage (handled by HTML) from its visual presentation. This separation allows for easier maintenance and updates.
Selectors: CSS uses selectors to target specific HTML elements. Selectors can be based on element names, classes, IDs, attributes, and more. They define which elements the CSS rules should be applied to.
Properties and Values: CSS properties determine the aspects of an element that you want to style, such as color, font, margin, padding, etc. Each property is assigned a value that specifies how that aspect should appear.
Declaration Blocks: CSS rules consist of a selector followed by a declaration block. The declaration block contains one or more property-value pairs enclosed in curly braces.
Cascading: The "Cascading" in CSS refers to the way styles are applied. If multiple styles are applied to the same element, conflicts are resolved using a set of rules that consider factors like specificity and the order of appearance.
Inheritance: Some CSS properties are inherited from parent elements to their children. This means that a style applied to a parent element might automatically apply to its child elements, unless overridden.
Units: CSS supports various units for specifying measurements, such as pixels (px), em, rem, percentages (%), and more. These units help control the sizing and positioning of elements.
Selectors and Pseudo-Selectors: In addition to basic selectors, CSS allows the use of pseudo-selectors to target specific states or parts of an element, like :hover, :active, :first-child, etc.
Media Queries: Media queries enable responsive design by allowing different styles to be applied based on the characteristics of the user's device, such as screen size, orientation, and resolution.
External, Internal, and Inline Styles: CSS can be included in HTML documents in different ways: as external files (linked using <link>), within the <style> element in the document's <head>, or directly applied to individual elements using the style attribute.