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stylefmt is a tool that automatically formats stylesheets.

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Modern CSS Formatter

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stylefmt is a tool that automatically formats CSS according to stylelint rules.

stylefmt'd code is:

  • easier to write : never worry about minor formatting concerns while hacking away.
  • easier to read : when all code looks the same you need not mentally convert others' formatting style into something you can understand.
  • easier to maintain : mechanical changes to the source don't cause unrelated changes to the file's formatting; diffs show only the real changes.
  • uncontroversial : never have a debate about spacing or brace position ever again!

NOTICE: Consider other tools before adopting stylefmt

If you are using stylefmt with stylelint configuration to format according to its rules, you can now use stylelint's --fix option (from v7.11.0) to autofix.

Another on the other hand, prettier supports to format not only JavaScript but also CSS, SCSS and Less code.


  • Supports the latest CSS syntax: Including custom properties, range context for media features,
    and nesting.
  • Understands CSS-like syntaxes: stylefmt is powered by PostCSS, so it understands any syntax that PostCSS can parse, including SCSS.
  • Works well with stylelint: stylelint is a mighty, modern CSS linter. stylefmt can understand the formatting rules specified in your stylelint configuration file (


Future CSS syntax (cssnext)

Input (input.css):

/* custom properties */
:root{--fontSize: 1rem;
  --mainColor       :#12345678;
--highlightColor:hwb(190, 35%, 20%);

/* custom media queries */ @custom-media


/* some var() & calc() */ body{color:var(--mainColor); font-size:var(--fontSize); line-height: calc(var(--fontSize) * 1.5); padding: calc((var(--fontSize) / 2) + 1px)}

/* custom media query usage */ @media (--viewport-medium) { body {font-size: calc(var(--fontSize) * 1.2); } }

/* custom selectors */ @custom-selector :--heading h1,h2,h3, h4,h5,h6; :--heading { margin-top:0 }

/* colors stuff */ a{ color:var(--highlightColor); transition:color 1s; } a:hover{color :gray(255,50%) } a:active{color : rebeccapurple } a:any-link { color:color(var(--highlightColor) blackness(+20%)) }

/* font stuff */ h2 {font-variant-caps:small-caps; }table{font-variant-numeric: lining-nums; }

/* filters */ .blur{filter:blur(4px)}.sepia{ filter: sepia(.8);}


/* custom properties */
:root {
  --fontSize: 1rem;
  --mainColor: #12345678;
  --highlightColor: hwb(190, 35%, 20%);

/* custom media queries */ @custom-media --viewport-medium (width <= 50rem);

/* some var() & calc() */ body { color: var(--mainColor); font-size: var(--fontSize); line-height: calc(var(--fontSize) * 1.5); padding: calc((var(--fontSize) / 2) + 1px); }

/* custom media query usage */ @media (--viewport-medium) { body { font-size: calc(var(--fontSize) * 1.2); } }

/* custom selectors */ @custom-selector :--heading h1, h2, h3, h4, h5, h6;

:--heading { margin-top: 0; }

/* colors stuff */ a { color: var(--highlightColor); transition: color 1s; }

a:hover { color: gray(255, 50%); }

a:active { color: rebeccapurple; }

a:any-link { color: color(var(--highlightColor) blackness(+20%)); }

/* font stuff */ h2 { font-variant-caps: small-caps; }

table { font-variant-numeric: lining-nums; }

/* filters */ .blur { filter: blur(4px); }

.sepia { filter: sepia(.8); }

SCSS syntax

Input (input.scss):

// mixin for clearfix

    @mixin      clearfix    ()      { &amp;:before,

&:after { content:" "; display : table; }

&:after {clear: both;} }.class { padding:10px;@include clearfix();} .base { color: red; }

// placeholder %base {

padding: 12px }

.foo{ @extend .base;}

.bar { @extend %base;



// mixin for clearfix
@mixin clearfix () {
  &:after {
    content: " ";
    display: table;

&:after { clear: both; } }

.class { padding: 10px; @include clearfix(); }

.base { color: red; }

// placeholder %base { padding: 12px; }

.foo { @extend .base; }

.bar { @extend %base; }


$ npm install stylefmt


in Command Line

CLI Help:

$ stylefmt --help
Usage: stylefmt [options] input-name [output-name]


-b, --config-basedir Path to the directory that relative paths defining "extends" -c, --config Path to a specific configuration file (JSON, YAML, or CommonJS) -d, --diff Output diff against original file -r, --recursive Format list of space seperated files(globs) in place -v, --version Output the version number -h, --help Output usage information -i, --ignore-path Path to a file containing patterns that describe files to ignore. --stdin-filename A filename to assign stdin input.

stylefmt can also read a file from stdin if there are no input-file as argument in CLI.

$ cat input.css | stylefmt --stdin-filename input.css

in Node.js

var fs = require('fs');
var postcss = require('postcss');
var scss = require('postcss-scss'); // when you use scss syntax
var stylefmt = require('stylefmt');

var css = fs.readFileSync('input.css', 'utf-8');

postcss([ stylefmt ]).process(css, { from: 'input.css', syntax: scss }) .then(function (result) { result.css; // formatted code });

in Task Runners

We can use stylefmt in Grunt, gulp, and Fly.

stylelint rules that stylefmt can handle

stylefmt :heart: stylelint

stylefmt supports the following stylelint rules:

and we can also format from the other stylelint's configration files or packages (e.g. stylelint-config-standard, stylelint-config-suitcss and so on) using


Default formatting rules (without stylelint config file)


  • 2 spaces indentation
  • require 1 space between a simple selector and combinator
  • require 1 space between selectors and
  • require new line after
  • disallow any spaces between property and
  • require 1 space between
    and values
  • require new line after declarations
  • require
    in last declaration
  • require 1 space between values and
  • disallow any spaces between
  • leave 1 blank line between rules
  • leave 1 blank line between rules in atrules
  • disallow any blank lines between

for nested selector syntax

  • leave 1 line between declarations and nested rules


  • require 1 space between
    and mixin name
  • require 1 space between mixin name and
  • require 1 space between
    and base rules
  • require 1 space between
    and mixin name
  • disallow any spaces between
  • require 1 space between
    and name of variable

Option projects

Editor plugins

for Task Runners


The MIT License (MIT)

Copyright (c) 2015 Masaaki Morishita

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