postcssnested

PostCSS Nested, commonly referred to as postcss-nested, is a PostCSS plugin that enables nesting of CSS selectors inside a parent rule. It allows developers to write nested rules in a style similar to Sass, then expands them into standard CSS that browsers can parse. The plugin handles nested selectors and nested at-rules such as media queries, preserving the logical structure while emitting flat, valid CSS. The ampersand can be used to reference the parent selector, enabling concise composition of selectors.

To use it, install the package, then include it in the PostCSS processing pipeline. For example, a nested style like a parent rule containing a nested child rule and a nested media block is transformed into equivalent flat selectors in the output. A simple demonstration: writing a rule like .button { color: red; .icon { margin-right: 8px; } } compiles to .button { color: red; } and .button .icon { margin-right: 8px; }. Nested blocks inside media queries and other at-rules are also expanded accordingly.

Limitations include a focus on nesting only; the plugin does not provide variables or mixins. It is designed to complement the PostCSS workflow and can be used alongside other plugins such as autoprefixer or cssnano to enhance compatibility and optimization. It is an alternative to using a preprocessor like Sass for those who prefer a PostCSS-based approach to writing more readable CSS with hierarchical structure. See also PostCSS and CSS nesting concepts.