CSS, which stands for Cascading Style Sheets, is a style sheet language used to describe the presentation and formatting of HTML (HyperText Markup Language) documents. CSS defines how HTML elements should be displayed on a web page, including their layout, colors, fonts, spacing, and other visual properties.
Key features of CSS include:
- Style Rules: CSS uses a set of rules to define the styling of HTML elements. Each rule consists of a selector and one or more declarations enclosed within curly braces
{ }. The selector identifies the HTML element(s) to which the style applies, and the declarations specify the style properties and their values.Example of a CSS rule:h1 {
color: blue;
font-size: 24px;
}
- Selectors: CSS selectors target specific HTML elements based on their element type, class, ID, attributes, or relationships with other elements. Selectors allow developers to apply styles selectively to different parts of a web page.Example of CSS selectors:
- Element type selector:
h1,p,div - Class selector:
.header,.btn - ID selector:
#main-content - Attribute selector:
[type="submit"] - Descendant selector:
div p
- Element type selector:
- Cascading: CSS follows a cascading mechanism where styles can be inherited from parent elements and overridden by more specific styles or styles defined later in the document. This allows for consistent styling across an entire website while enabling customization for individual elements.
- External, Internal, and Inline Styles: CSS styles can be applied to HTML documents in three ways:
- External Stylesheets: Linked external CSS files using the
<link>element in the HTML<head>section. - Internal Stylesheets: CSS rules can be defined within a
<style>element in the HTML document’s<head>section. - Inline Styles: Style attributes can be applied directly to individual HTML elements using the
styleattribute.
- External Stylesheets: Linked external CSS files using the
- Responsive Design: CSS supports responsive design techniques, allowing developers to create websites that adapt and respond to different screen sizes and devices. Media queries, flexbox, and grid layout systems are some of the features used to create responsive layouts.
CSS is a critical component of web development, enabling developers to separate content from presentation and create visually appealing, consistent, and responsive web pages across different devices and browsers. It works in tandem with HTML and JavaScript to build engaging and interactive web experiences.