Less.js

The dynamic stylesheet language. lesscss.org

Less extends CSS with variables, mixins, functions, nesting, and more — then compiles to standard CSS. Write cleaner stylesheets with less code.

@primary: #4a90d9;

.button {
  color: @primary;
  &:hover {
    color: darken(@primary, 10%);
  }
}

Install

npm install less

Usage

Node.js

import less from 'less';

const output = await less.render('.class { width: (1 + 1) }');
console.log(output.css);

Command Line

npx lessc styles.less styles.css

Browser

<link rel="stylesheet/less" type="text/css" href="styles.less" />
<script src="https://cdn.jsdelivr.net/npm/less"></script>

Why Less?

• Variables — define reusable values once
• Mixins — reuse groups of declarations across rulesets
• Nesting — mirror HTML structure in your stylesheets
• Functions — transform colors, manipulate strings, do math
• Imports — split stylesheets into manageable pieces
• Extend — reduce output size by combining selectors

Documentation

Full documentation, usage guides, and configuration options at lesscss.org.

Contributing

Less.js is open source. Report bugs, submit pull requests, or help improve the documentation.

See CONTRIBUTING.md for development setup.

License

Copyright (c) 2009-2025 Alexis Sellier & The Core Less Team Licensed under the Apache License.