{"id":27160,"library":"muro-css","title":"Muro CSS (.mss preprocessor)","description":"A TypeScript CSS preprocessor and bundler for .mss files. Current stable version is 26.0.2. Actively maintained with regular releases. Compiles a single entry file or an entire directory of .mss sources into one CSS output. Supports variables, nesting, mixins, imports (including built-in modules like muro:reset), conditionals, loops, theme baking (light/dark), semantic layering, guard locks, and automatic raster asset rewriting to webp. Includes CLI with watch, minify, purge, sourcemap, and asset-dir options. Ships TypeScript types. Differentiators: designed as a TypeScript-first alternative to Sass/PostCSS with built-in utilities and zero-config polyfilling.","status":"active","version":"26.0.2","language":"javascript","source_language":"en","source_url":"https://github.com/isaacmuliro/xerxisfy-elite-style-sheet","tags":["javascript","muro","mss","x2s","css","compiler","preprocessor","bundler","sass","typescript"],"install":[{"cmd":"npm install muro-css","lang":"bash","label":"npm"},{"cmd":"yarn add muro-css","lang":"bash","label":"yarn"},{"cmd":"pnpm add muro-css","lang":"bash","label":"pnpm"}],"dependencies":[],"imports":[{"note":"ESM-only; package.json type is module. Ships types.","wrong":"const muro = require('muro-css')","symbol":"default","correct":"import muro from 'muro-css'"},{"note":"Named export for programmatic use. Available since v26.","wrong":"import compile from 'muro-css/compile'","symbol":"compile","correct":"import { compile } from 'muro-css'"},{"note":"Type-only import; MuroOptions is an interface, not a value.","wrong":"import { MuroOptions } from 'muro-css'","symbol":"MuroOptions","correct":"import type { MuroOptions } from 'muro-css'"}],"quickstart":{"code":"// app.mss\n$primary: #224466;\n\n.button {\n  color: $primary;\n  &:hover {\n    color: darken($primary, 10%);\n  }\n}\n\n// Install: npm i -D muro-css\n// Run: muro app.mss app.css\n\n// Programmatic usage in Node.js >=18\nimport { compile } from 'muro-css';\n\nconst result = compile({\n  input: 'styles.mss',\n  output: 'styles.css',\n  sourcemap: true,\n});\n\nconsole.log('CSS compiled:', result.css);","lang":"typescript","description":"Compiles an .mss file to CSS using CLI and programmatic API with TypeScript types."},"warnings":[{"fix":"Rename .x2s files to .mss and replace x2s:*/@x2s/* imports with muro:* equivalents.","message":"Since v26, legacy .x2s files and imports (x2s:*, @x2s/*) are deprecated and will be removed in the next major version.","severity":"breaking","affected_versions":">=26.0.0"},{"fix":"Upgrade Node.js to version 18 or later.","message":"Node.js >=18 required in v26. Older Node versions will fail.","severity":"breaking","affected_versions":">=26.0.0"},{"fix":"Use muro CLI and muro: built-in imports instead.","message":"The x2s CLI alias and x2s: built-in imports are deprecated in v26 and will be removed next release.","severity":"deprecated","affected_versions":">=26.0.0 <27.0.0"},{"fix":"Use @import 'muro:reset' for built-in, or @import './partial.mss' for files.","message":"When using @import in .mss files, paths beginning with 'muro:' refer to built-in modules. Other relative paths must include the file extension.","severity":"gotcha","affected_versions":">=1.0.0"},{"fix":"Avoid putting space before # for comments; use // or ** for safer comment syntax.","message":"The # character at line start is treated as a comment only if it's the first non-whitespace character. Hex colors and ID selectors like #hero work normally.","severity":"gotcha","affected_versions":">=1.0.0"},{"fix":"Ensure a .webp converter (e.g., cwebp) is available in PATH, or use --no-assets to skip rewriting.","message":"Automatic raster asset rewriting to .webp requires an external converter to be installed on the system. Without it, assets are left as-is.","severity":"gotcha","affected_versions":">=26.0.0"}],"env_vars":null,"last_verified":"2026-04-25T00:00:00.000Z","next_check":"2026-07-24T00:00:00.000Z","problems":[{"fix":"Run 'npm i muro-css' or 'npm i -D muro-css' to install.","cause":"Package not installed in node_modules.","error":"Error: Cannot find module 'muro-css'"},{"fix":"Use import { compile } from 'muro-css'.","cause":"Incorrect import path or using default import when import { compile } is required.","error":"TypeError: compile is not a function"},{"fix":"Ensure # comments start at line beginning; use // for inline comments.","cause":"A # comment is placed after non-whitespace on a line, or hex color/scss syntax is mistakenly treated.","error":"SyntaxError: Unexpected token '#'"}],"ecosystem":"npm","meta_description":null,"install_score":null,"install_tag":null,"quickstart_score":null,"quickstart_tag":null}