pyScss, a Scss compiler for Python
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pyScss, a Scss compiler for Python

Author:German M. Bravo (Kronuz) <>


pyScss compiles Scss (Sass), a superset of CSS that is more powerful, elegant and easier to maintain than plain-vanilla CSS. The library acts as a CSS source code preprocesor which allows you to use variables, nested rules, mixins, and have inheritance of rules, all with a CSS-compatible syntax which the preprocessor then compiles to standard CSS.

Scss, as an extension of CSS, helps keep large stylesheets well-organized. It borrows concepts and functionality from projects such as OOCSS and other similar frameworks like as Sass. It's build on top of the original PHP xCSS codebase structure but it's been completely rewritten, many bugs have been fixed and it has been extensively extended to support almost the full range of Sass' Scss syntax and functionality.

Click here to lend your support to pyScss and make a donation at!


pyScss is fully compatible with SCSS (Sass) 3.2 has:

  • Compass: Compass 0.11 Support
  • Nested rules
  • Keyword arguments
  • Mixins: @mixin, @include
  • Functions: @function, @return
  • Inheritance: @extend
  • Conditions: @if, @else if, @else
  • Loops: @for, @each
  • Variables: $, @variables, @vars
  • Sprites: sprite-map(), sprite(), sprite-position(), sprite-url(), ...
  • Images: image-url(), image-width(), image-height(), ...
  • Embedded (inline) images: inline-image()
  • Colors handling: adjust-color(), scale-color(), opacify()/transparentize(), lighten()/darken(), mix(), ...
  • Math functions: sin(), cos(), tan(), round(), ceil(), floor(), pi(), ...
  • CSS Compression: @option compress:yes;


  • python >= 2.5


pyScss should be installed using pip or setuptools:

pip install pyScss

easy_install pyScss


Usage example:

from scss import Scss
css = Scss()
css.compile("a { color: red + green; }")

Or compile from the command line:

python -mscss < file.scss

Interactive mode:

python -mscss --interactive


-mscss will only work in Python 2.7 and above, for Python 2.5 and 2.6 you need to invoke:

python -mscss.tool


  1. Nested Rules


    @option compress: no;
    .selector {
        a {
            display: block;
            strong {
            color: blue;


    .selector a {
        display: block;
    .selector strong {
        color: #00f;
  2. Variables


    @option compress: no;
    $main-color: #ce4dd6;
    $style: solid;
    $side: bottom;
    #navbar {
        border-#{$side}: {
            color: $main-color;
            style: $style;


    #navbar {
        border-bottom-color: #ce4dd6;
        border-bottom-style: solid;
  3. Mixins


    @option compress: no;
    @mixin rounded($side, $radius: 10px) {
        border-#{$side}-radius: $radius;
        -moz-border-radius-#{$side}: $radius;
        -webkit-border-#{$side}-radius: $radius;
    #navbar li { @include rounded(top); }
    #footer { @include rounded(top, 5px); }
    #sidebar { @include rounded(left, 8px); }


    #navbar li {
        border-top-radius: 10px;
        -moz-border-radius-top: 10px;
        -webkit-border-top-radius: 10px;
    #footer {
        border-top-radius: 5px;
        -moz-border-radius-top: 5px;
        -webkit-border-top-radius: 5px;
    #sidebar {
        border-left-radius: 8px;
        -moz-border-radius-left: 8px;
        -webkit-border-left-radius: 8px;
  4. Extend (using @extend)


    @option compress: no;
    .error {
        border: 1px #f00;
        background-color: #fdd;
    .error.intrusion {
        background-image: url("/image/hacked.png");
    .seriousError {
        @extend .error;
        border-width: 3px;


    .seriousError {
        border: 1px red;
        background-color: #fdd;
    .seriousError.intrusion {
        background-image: url("/image/hacked.png");
    .seriousError {
        border-width: 3px;
  5. Sprites (using sprite-map())


    @option compress: no;
    $icons: sprite-map("sociable/*.png"); // contains sociable/facebook.png among others.
    div {
        background: $icons;
    @each $icon in sprites($icons) {
        div .#{$icon} {
            width: image-width(sprite-file($icons, $icon));
            height: image-height(sprite-file($icons, $icon));
            background-position: sprite-position($icons, $icon);

    ...generates a new sprite file and produces something like:

    div {
        background: url("/static/assets/u8Y7yEQL0UffAVw5rX7yhw.png?_=1298240989") 0px 0px no-repeat;
    div .facebook {
        width: 32px;
        height: 32px;
        background-position: 0px 0px;
    div .twitter {
        width: 32px;
        height: 32px;
        background-position: 0px -32px;
  6. Interactive mode


    $ python --interactive
    >>> @import "compass/css3"
    >>> show()
    ['functions', 'mixins', 'options', 'vars']
    >>> show(mixins)
    >>> show(mixins, transparent)
    @mixin transparent() {
        @include opacity(0);
    >>> 1px + 5px
    >>> _

Sass Sassy CSS

pyScss is a Scss (Sass) implementation for Python. Currently it implements @mixin, @include, @if, @else, @for, and @import... it also implements many of the Sass functions including color functions like hsla(), hsl(), darken(), lighten(), mix(), opacify(), transparentize(), saturate(), desaturate(), etc.) as well as sprite-map(), sprite-file(), image-width(), image-height() and the others.

In the file, by the top, you can configure the LOAD_PATHS to point to your Sass frameworks path (I have sass/frameworks/compass/*.scss and sass/framework/blueprint/*.scss files in my project directory: /usr/local/www/project/, where lives, so it defaults to use the sass/framework/ path, relative to the file) or configure using the command line --load-path option, see python --help.

I have succesfully compiled some Compass using python < myfile.css the following myfile.css:

@option compress: no;

$blueprint-grid-columns : 24;
$blueprint-grid-width   : 30px;
$blueprint-grid-margin  : 10px;
$font-color             : #333;

@import "compass/reset";
@import "compass/utilities";
@import "blueprint";

// Stuff goes here...

Django Example

The following shows some code that can be used with django:

import os
import fnmatch

import scss

from django.conf import settings
from django.utils.datastructures import SortedDict
from django.contrib.staticfiles import finders

def finder(glob):
    Finds all files in the django finders for a given glob,
    returns the file path, if available, and the django storage object.
    storage objects must implement the File storage API:
    for finder in finders.get_finders():
        for path, storage in finder.list([]):
            if fnmatch.fnmatchcase(path, glob):
                yield path, storage

# STATIC_ROOT is where pyScss looks for images and static data.
# STATIC_ROOT can be either a fully qualified path name or a "finder"
# iterable function that receives a filename or glob and returns a tuple
# of the file found and its file storage object for each matching file.
# (
scss.STATIC_ROOT = finder
scss.STATIC_URL = settings.STATIC_URL

# ASSETS_ROOT is where the pyScss outputs the generated files such as spritemaps
# and compile cache:
scss.ASSETS_ROOT = os.path.join(settings.MEDIA_ROOT, 'assets/')
scss.ASSETS_URL = settings.MEDIA_URL + 'assets/'

# These are the paths pyScss will look ".scss" files on. This can be the path to
# the compass framework or blueprint or compass-recepies, etc.
scss.LOAD_PATHS = [

# This creates the Scss object used to compile SCSS code. In this example,
# _scss_vars will hold the context variables:
_scss_vars = {}
_scss = scss.Scss(
        'compress': True,
        'debug_info': True,

# 1. Compile from a string:
compiled_css_from_string = _scss.compile('@import "file2"; a {color: red + green; }')

# 2. Compile from a file:
compiled_css_from_file = _scss.compile(scss_file='file1.scss')

# 3. Compile from a set of files (use SortedDict or collections.OrderedDict to
# maintain the compile order):
_scss._scss_files = SortedDict((
    ('file2.scss', open('file2.scss').read()),
    ('file3.scss', open('file3.scss').read()),
    ('file4.scss', open('file4.scss').read()),
compiled_css_from_files = _scss.compile()

Bug tracker

If you have any suggestions, bug reports or annoyances please report them to the issue tracker at


1.1.4 ???
  • Added --debug-info command line option (for FireSass output).
  • Added compass helper function reject().
  • Added undefined keyword for undefined variables.
1.1.3 Jan 9, 2012
  • Support for the new Sass 3.2.0 features (@content and placeholder selectors)
  • Fixed bug with line numbers throwing an exception.
1.1.2 Jan 3, 2012
  • Regression bug fixed from 1.1.1
1.1.1 Jan 2, 2012
  • Added optional C speedup module for an amazing boost in scanning speed!
  • Added headings, stylesheet-url, font-url, font-files, inline-font-files and sprite-names.
1.1.0 - Dec 22, 2011
  • Added min() and max() for lists.
  • Removed exception raise.
1.0.9 - Dec 22, 2011
  • Optimizations in the scanner.
  • Added background-noise() for compass-recipes support.
  • enumerate() and range() can go backwards. Ex.: range(3, 0) goes from 3 to 0.
  • Added line numbers and files for errors.
  • Added support for Firebug with FireSass.
  • nth(n) is round (returns the nth mod len item of the list).
  • --watch added to the command line.
  • Several bugs fixed.
1.0.8 - May 13, 2011
  • Changed source color ($src-color) default to black.
  • Moved the module filename to and module renamed back to scss.


Development of pyScss happens at github:


MIT License. See LICENSE for details.


Copyright (c) 2012 German M. Bravo (Kronuz) Bits of code in pyScss come from various projects:

(c) 2009 Christopher M. Eppstein
(c) 2006-2009 Hampton Catlin and Nathan Weizenbaum
(c) 2010 Anton Pawlik