What is CSS (Cascading Style Sheets)?
Turkish: CSS
CSS defines the visual presentation of HTML, including colors, typography, spacing, layout, and responsive behavior in browsers.
What is CSS?
CSS (Cascading Style Sheets) is the styling language that controls how HTML content is presented. Heading size, button color, grid layout, mobile breakpoints, animations, and dark mode behavior are all defined with CSS.
How Does the Cascade Work?
More than one CSS rule can apply to the same element. The winning rule is determined by source order, specificity, inheritance, and priorities such as !important. This is the “cascade”: styles combine from multiple rules to form the final rendered appearance.
Core Parts
- Selector: Chooses which elements are targeted.
- Property: Names the feature being changed, such as
colorordisplay. - Value: Provides the value, such as
red,grid, or1rem. - Media query: Applies styles based on screen or device conditions.
- Layout: Uses tools such as Flexbox, Grid, and positioning.
Modern CSS
Modern CSS is no longer just colors and spacing. Grid, flexbox, custom properties, container queries, cascade layers, and :has() make component-based interfaces possible with less JavaScript. Tools such as Tailwind CSS change the authoring style, but the browser still receives CSS.
Business Use
CSS quality directly affects brand consistency, accessibility, mobile usability, and maintenance cost. Messy selectors and uncontrolled overrides can make even small design changes risky in large web projects.
Related Terms
CSS animation changes visual properties such as color, position, opacity, or scale over time directly in the browser.
BootstrapBootstrap is an open-source CSS framework with grid, components, and utilities for building responsive web interfaces quickly.
Container QueryA container query lets CSS change a component's styles based on its container size instead of the browser viewport width.
CSS Custom Properties (Variables)CSS custom properties store reusable design values such as colors and spacing, making themes and component styling easier to manage.
Dark ModeDark mode is a dark-background interface theme that must balance contrast, accessibility, brand colors, and user preference.
CSS FlexboxFlexbox is a CSS layout model for aligning items on one axis, distributing space, and adapting to changing content sizes.
CSS Grid LayoutCSS Grid is a CSS layout system for building flexible, responsive two-dimensional web layouts across rows and columns.
HTML (HyperText Markup Language)HTML is the markup language that defines the structure of headings, paragraphs, links, forms, media, and other web content.
Responsive DesignResponsive design adapts one web interface to different screen widths, input methods, and device capabilities without separate mobile pages.
Tailwind CSSTailwind CSS turns design choices into small utility classes, letting teams style interfaces consistently inside HTML.