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Start coding free →Cascading Style Sheets (CSS) is the language that controls the visual presentation of HTML documents. It handles layout, colors, fonts, and spacing through rules defined in stylesheets. CSS separates presentation from document structure, letting you update the look of an entire site by editing one file. On RunCode, you get a workspace with VS Code, a terminal, and Node.js tools preloaded, ready in under a minute.
Open a CSS workspace →CSS rules apply styles to elements using selectors. Selectors target elements by tag name, class, ID, attribute, or position in the document. When multiple rules match the same element, specificity and cascade order determine which one wins. External stylesheets keep styles in separate `.css` files linked to HTML documents, so a single change propagates across every page that links to it. Modern CSS includes Flexbox for one-dimensional layouts and Grid for two-dimensional ones, which handle most responsive design needs without a framework. Preprocessors like Sass and Less add variables, nesting, and mixins on top of standard CSS and compile down to plain stylesheets.