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Sass Changelog

  • Table of contents {:toc}

2.4.0 (Unreleased)


SassScript color values are much more powerful than they were before. Support was added for alpha channels, and most of Chris Eppstein's compass-colors plugin was merged in, providing color-theoretic functions for modifying colors.

One of the most interesting of these functions is {Sass::Script::Functions#mix mix}, which mixes two colors together. This provides a much better way of combining colors and creating themes than standard color arithmetic.

Alpha Channels

Sass now supports colors with alpha channels, constructed via the {Sass::Script::Functions#rgba rgba} and {Sass::Script::Functions#hsla hsla} functions. Alpha channels are unaffected by color arithmetic. However, the {Sass::Script::Functions#opacify opacify} and {Sass::Script::Functions#transparentize transparentize} functions allow colors to be made more and less opaque, respectively.

Sass now also supports functions that return the values of the {Sass::Script::Functions#red red}, {Sass::Script::Functions#blue blue}, {Sass::Script::Functions#green green}, and {Sass::Script::Functions#alpha alpha} components of colors.

HSL Colors

Sass has many new functions for using the HSL values of colors. For an overview of HSL colors, check out the CSS3 Spec. All these functions work just as well on RGB colors as on colors constructed with the {Sass::Script::Functions#hsl hsl} function.

  • The {Sass::Script::Functions#lighten lighten} and {Sass::Script::Functions#darken darken} functions adjust the lightness of a color.

  • The {Sass::Script::Functions#saturate saturate} and {Sass::Script::Functions#desaturate desaturate} functions adjust the saturation of a color.

  • The {Sass::Script::Functions#adjust_hue adjust-hue} function adjusts the hue of a color.

  • The {Sass::Script::Functions#hue hue}, {Sass::Script::Functions#saturation saturation}, and {Sass::Script::Functions#lightness lightness} functions return the corresponding HSL values of the color.

  • The {Sass::Script::Functions#grayscale grayscale} function converts a color to grayscale.

  • The {Sass::Script::Functions#complement complement} function returns the complement of a color.


Watching for Updates

The sass command-line utility has a new flag: --watch. sass --watch monitors files or directories for updated Sass files and compiles those files to CSS automatically. This will allow people not using Ruby or Compass to use Sass without having to manually recompile all the time.

Here's the syntax for watching a directory full of Sass files:

sass --watch app/stylesheets:public/stylesheets

This will watch every Sass file in app/stylesheets. Whenever one of them changes, the corresponding CSS file in public/stylesheets will be regenerated. Any files that import that file will be regenerated, too.

The syntax for watching individual files is the same:

sass --watch style.sass:out.css

You can also omit the output filename if you just want it to compile to name.css. For example:

sass --watch style.sass

This will update style.css whenever style.sass changes.

You can list more than one file and/or directory, and all of them will be watched:

sass --watch foo/style:public/foo bar/style:public/bar
sass --watch screen.sass print.sass awful-hacks.sass:ie.css
sass --watch app/stylesheets:public/stylesheets public/stylesheets/test.sass

File and directory watching is accessible from Ruby, using the {Sass::Plugin#watch} function.

Bulk Updating

Another new flag for the sass command-line utility is --update. It checks a group of Sass files to see if their CSS needs to be updated, and updates if so.

The syntax for --update is just like watch:

sass --update app/stylesheets:public/stylesheets
sass --update style.sass:out.css
sass --watch screen.sass print.sass awful-hacks.sass:ie.css

In fact, --update work exactly the same as --watch, except that it doesn't continue watching the files after the first check.

Variable Names

SassScript variable names may now contain hyphens. For example:

!prettiest-color = #542FA9

Single-Quoted Strings

SassScript now supports single-quoted strings. They behave identically to double-quoted strings, except that single quotes need to be backslash-escaped and double quotes do not.

Error Backtraces

Numerous bugs were fixed with the backtraces given for Sass errors, especially when importing files and using mixins. All imports and mixins will now show up in the Ruby backtrace, with the proper filename and line number.

In addition, when the sass executable encounters an error, it now prints the filename where the error occurs, as well as a backtrace of Sass imports and mixins.


Properties of the form

margin: auto
  top: 10px
  bottom: 20px

That is, properties with a value and also nested properties, are now rendered as such in nested output mode:

margin: auto;
  margin-top: 10px;
  margin-bottom: 20px;

That is, with the nested properties indented in the source.

Ruby 1.9 Support

  • Sass and css2sass now produce more descriptive errors when given a template with invalid byte sequences for that template's encoding, including the line number and the offending character.

  • Sass and css2sass now accept Unicode documents with a byte-order-mark.

Rack Support

The Sass Rails plugin now works using Rack middleware by default in versions of Rails that support it (2.3 and onwards).

Sass::Plugin Callbacks

{Sass::Plugin} now has a large collection of callbacks that allow users to run code when various actions are performed. For example:

Sass::Plugin.on_updating_stylesheet do |template, css|
  puts "#{template} has been compiled to #{css}!"

For a full list of callbacks and usage notes, see the {Sass::Plugin} documentation.

:compressed Style

When the :compressed style is used, colors will be output as the minimal possible representation. This means whichever is smallest of the HTML4 color name and the hex representation (shortened to the three-letter version if possible).

css2sass Error Handling

Several bug fixes and minor improvements have been made, including:

  • Fixing line-number reporting for errors on the last line of templates that didn't have trailing newlines.

  • Only displaying the text for the current line when reporting CSS parsing errors.

  • Displaying the expected strings as strings rather than regular expressions whenever possible.

Minor Changes

  • If a CSS or Sass function is used that has the name of a color, it will now be parsed as a function rather than as a color. For example, fuchsia(12) now renders as fuchsia(12) rather than fuchsia 12, and tealbang(12) now renders as tealbang(12) rather than teal bang(12).


Tagged on GitHub.

  • If the cache file for a given Sass file is corrupt because it doesn't have enough content, produce a warning and read the Sass file rather than letting the exception bubble up. This is consistent with other sorts of sassc corruption handling.

  • Calls to defined? shouldn't interfere with Rails' autoloading in very old versions (1.2.x).


Tagged on GitHub.

There were no changes made to Sass between versions 2.2.18 and 2.2.19.


Tagged on GitHub.

  • Use Rails.env rather than RAILS_ENV when running under Rails 3.0. Thanks to Duncan Grazier.

  • Support :line_numbers as an alias for { :line_comments}, since that's what the docs have said forever. Similarly, support --line-numbers as a command-line option.

  • Add a --unix-newlines flag to all executables for outputting Unix-style newlines on Windows.

  • Add a { :unix_newlines option} for {Sass::Plugin} for outputting Unix-style newlines on Windows.

  • Fix the --cache-location flag, which was previously throwing errors. Thanks to tav.

  • Allow comments at the beginning of the document to have arbitrary indentation, just like comments elsewhere. Similarly, comment parsing is a little nicer than before.


Tagged on GitHub.

  • When the { :full_exception option} is false, raise the error in Ruby code rather than swallowing it and printing something uninformative.

  • Fixed error-reporting when something goes wrong when loading Sass using the sass executable. This used to raise a NameError because Sass::SyntaxError wasn't defined. Now it'll raise the correct exception instead.

  • Report the filename in warnings about selectors without properties.

  • nil values for Sass options are now ignored, rather than raising errors.

  • Fix a bug that appears when Plugin template locations have multiple trailing slashes. Thanks to Jared Grippe.

Must Read!

  • When @import is given a filename without an extension, the behavior of rendering a CSS @import if no Sass file is found is deprecated. In future versions, @import foo will either import the template or raise an error.


Tagged on GitHub.

  • Fixed a bug where modules containing user-defined Sass functions weren't made available when simply included in {Sass::Script::Functions} ({Sass::Script::Functions Functions} needed to be re-included in {Sass::Script::Functions::EvaluationContext Functions::EvaluationContext}). Now the module simply needs to be included in {Sass::Script::Functions}.


Tagged on GitHub.

  • Added {Sass::Script::Color#with} for a way of setting color channels that's easier than manually constructing a new color and is forwards-compatible with alpha-channel colors (to be introduced in Sass 2.4).

  • Added a missing require in Sass that caused crashes when it was being run standalone.


Tagged on GitHub.

  • All Sass functions now raise explicit errors if their inputs are of the incorrect type.

  • Allow the SassScript rgb() function to take percentages in addition to numerical values.

  • Fixed a bug where SassScript strings with # followed by #{} interpolation didn't evaluate the interpolation.

SassScript Ruby API

These changes only affect people defining their own Sass functions using {Sass::Script::Functions}.

  • {Sass::Script::Color#value} attribute is deprecated. Use {Sass::Script::Color#rgb} instead. The returned array is now frozen as well.

  • Add an assert_type function that's available to {Sass::Script::Functions}. This is useful for typechecking the inputs to functions.

Rack Support

Sass 2.2.14 includes Rack middleware for running Sass, meaning that all Rack-enabled frameworks can now use Sass. To activate this, just add

require 'sass/plugin/rack'
use Sass::Plugin::Rack

to your See the {Sass::Plugin::Rack} documentation for more details.


Tagged on GitHub.

There were no changes made to Sass between versions 2.2.12 and 2.2.13.


Tagged on GitHub.

  • Fix a stupid bug introduced in 2.2.11 that broke the Sass Rails plugin.


Tagged on GitHub.

  • Added a note to errors on properties that could be pseudo-classes (e.g. :focus) indicating that they should be backslash-escaped.

  • Automatically interpret properties that could be pseudo-classes as such if { :property_syntax} is set to :new.

  • Fixed css2sass's generation of pseudo-classes so that they're backslash-escaped.

  • Don't crash if the Haml plugin skeleton is installed and rake gems:install is run.

  • Don't use RAILS_ROOT directly. This no longer exists in Rails 3.0. Instead abstract this out as Haml::Util.rails_root. This changes makes Haml fully compatible with edge Rails as of this writing.

  • Make use of a Rails callback rather than a monkeypatch to check for stylesheet updates in Rails 3.0+.


Tagged on GitHub.

  • Add support for attribute selectors with spaces around the =. For example:

    a[href =]
      color: blue


Tagged on GitHub.

There were no changes made to Sass between versions 2.2.8 and 2.2.9.


Tagged on GitHub.

There were no changes made to Sass between versions 2.2.7 and 2.2.8.


Tagged on GitHub.

There were no changes made to Sass between versions 2.2.6 and 2.2.7.


Tagged on GitHub.

  • Don't crash when the __FILE__ constant of a Ruby file is a relative path, as apparently happens sometimes in TextMate (thanks to Karl Varga).

  • Add "Sass" to the --version string for the executables.


Tagged on GitHub.

There were no changes made to Sass between versions 2.2.4 and 2.2.5.


Tagged on GitHub.

  • Don't add require 'rubygems' to the top of init.rb when installed via sass --rails. This isn't necessary, and actually gets clobbered as soon as haml/template is loaded.

  • Document the previously-undocumented { :line option}, which allows the number of the first line of a Sass file to be set for error reporting.


Tagged on GitHub.

Sass 2.2.3 prints line numbers for warnings about selectors with no properties.


Tagged on GitHub.

Sass 2.2.2 is a minor bug-fix release. Notable changes include better parsing of mixin definitions and inclusions and better support for Ruby 1.9.


Tagged on GitHub.

Sass 2.2.1 is a minor bug-fix release.

Must Read!

  • It used to be acceptable to use - immediately following variable names, without any whitespace in between (for example, !foo-!bar). This is now deprecated, so that in the future variables with hyphens can be supported. Surround - with spaces.


Tagged on GitHub.

The 2.2 release marks a significant step in the evolution of the Sass language. The focus has been to increase the power of Sass to keep your stylesheets maintainable by allowing new forms of abstraction to be created within your stylesheets and the stylesheets provided by others that you can download and import into your own. The fundamental units of abstraction in Sass are variables and mixins. Please read below for a list of changes:

Must Read!

  • Sass Comments (//) used to only comment out a single line. This was deprecated in 2.0.10 and starting in 2.2, Sass comments will comment out any lines indented under them. Upgrade to 2.0.10 in order to see deprecation warnings where this change affects you.

  • Implicit Strings within SassScript are now deprecated and will be removed in 2.4. For example: border= !width solid #00F should now be written as border: #{!width} solid #00F or as border= !width "solid" #00F. After upgrading to 2.2, you will see deprecation warnings if you have sass files that use implicit strings.

Sass Syntax Changes

Flexible Indentation

The indentation of Sass documents is now flexible. The first indent that is detected will determine the indentation style for that document. Tabs and spaces may never be mixed, but within a document, you may choose to use tabs or a flexible number of spaces.

Multiline Sass Comments

Sass Comments (//) will now comment out whatever is indented beneath them. Previously they were single line when used at the top level of a document. Upgrading to the latest stable version will give you deprecation warnings if you have silent comments with indentation underneath them.

Mixin Arguments

Sass Mixins now accept any number of arguments. To define a mixin with arguments, specify the arguments as a comma-delimited list of variables like so:

=my-mixin(!arg1, !arg2, !arg3)

As before, the definition of the mixin is indented below the mixin declaration. The variables declared in the argument list may be used and will be bound to the values passed to the mixin when it is invoked. Trailing arguments may have default values as part of the declaration:

=my-mixin(!arg1, !arg2 = 1px, !arg3 = blue)

In the example above, the mixin may be invoked by passing 1, 2 or 3 arguments to it. A similar syntax is used to invoke a mixin that accepts arguments:
  +my-mixin(1em, 3px)

When a mixin has no required arguments, the parenthesis are optional.

The default values for mixin arguments are evaluated in the global context at the time when the mixin is invoked, they may also reference the previous arguments in the declaration. For example:

!default_width = 30px
=my-fancy-mixin(!width = !default_width, !height = !width)
  width= !width
  height= !height



  +my-fancy-mixin(25px, 75px)

!default_width = 10px

compiles to:

.default-box {
  width: 30px;
  height: 30px; }

.square-box {
  width: 50px;
  height: 50px; }

.rectangle-box {
  width: 25px;
  height: 75px; }

.small-default-box {
  width: 10px;
  height: 10px; }

Sass, Interactive

The sass command line option -i now allows you to quickly and interactively experiment with SassScript expressions. The value of the expression you enter will be printed out after each line. Example:

$ sass -i
>> 5px
>> 5px + 10px
>> !five_pixels = 5px
>> !five_pixels + 10px


The features of SassScript have been greatly enhanced with new control directives, new fundamental data types, and variable scoping.

New Data Types

SassScript now has four fundamental data types:

  1. Number
  2. String
  3. Boolean (New in 2.2)
  4. Colors

More Flexible Numbers

Like JavaScript, SassScript numbers can now change between floating point and integers. No explicit casting or decimal syntax is required. When a number is emitted into a CSS file it will be rounded to the nearest thousandth, however the internal representation maintains much higher precision.

Improved Handling of Units

While Sass has long supported numbers with units, it now has a much deeper understanding of them. The following are examples of legal numbers in SassScript:

0, 1000, 6%, -2px, 5pc, 20em, or 2foo.

Numbers of the same unit may always be added and subtracted. Numbers that have units that Sass understands and finds comparable, can be combined, taking the unit of the first number. Numbers that have non-comparable units may not be added nor subtracted -- any attempt to do so will cause an error. However, a unitless number takes on the unit of the other number during a mathematical operation. For example:

>> 3mm + 4cm
>> 4cm + 3mm
>> 3cm + 2in
>> 5foo + 6foo
>> 4% + 5px
SyntaxError: Incompatible units: 'px' and '%'.
>> 5 + 10px

Sass allows compound units to be stored in any intermediate form, but will raise an error if you try to emit a compound unit into your css file.

>> !em_ratio = 1em / 16px
>> !em_ratio * 32px
>> !em_ratio * 40px


A color value can be declared using a color name, hexadecimal, shorthand hexadecimal, the rgb function, or the hsl function. When outputting a color into css, the color name is used, if any, otherwise it is emitted as hexadecimal value. Examples:

> #fff
>> white
>> hsl(180, 100, 100)
>> rgb(255, 255, 255)
>> #AAA

Math on color objects is performed piecewise on the rgb components. However, these operations rarely have meaning in the design domain (mostly they make sense for gray-scale colors).

>> #aaa + #123
>> #333 * 2


Boolean objects can be created by comparison operators or via the true and false keywords. Booleans can be combined using the and, or, and not keywords.

>> true
>> true and false
>> 5 < 10
>> not (5 < 10)
>> not (5 < 10) or not (10 < 5)
>> 30mm == 3cm
>> 1px == 1em


Unicode escapes are now allowed within SassScript strings.

Control Directives

New directives provide branching and looping within a sass stylesheet based on SassScript expressions. See the Sass Reference for complete details.


The @for directive loops over a set of numbers in sequence, defining the current number into the variable specified for each loop. The through keyword means that the last iteration will include the number, the to keyword means that it will stop just before that number.

@for !x from 1px through 5px
    border-width= !x

compiles to:

.border-1px {
  border-width: 1px; }

.border-2px {
  border-width: 2px; }

.border-3px {
  border-width: 3px; }

.border-4px {
  border-width: 4px; }

.border-5px {
  border-width: 5px; }

@if / @else if / @else

The branching directives @if, @else if, and @else let you select between several branches of sass to be emitted, based on the result of a SassScript expression. Example:

!type = "monster"
  @if !type == "ocean"
    color: blue
  @else if !type == "matador"
    color: red
  @else if !type == "monster"
    color: green
    color: black

is compiled to:

p {
  color: green; }


The @while directive lets you iterate until a condition is met. Example:

!i = 6
@while !i > 0
    width = 2em * !i
  !i = !i - 2

is compiled to:

.item-6 {
  width: 12em; }

.item-4 {
  width: 8em; }

.item-2 {
  width: 4em; }

Variable Scoping

The term "constant" has been renamed to "variable." Variables can be declared at any scope (a.k.a. nesting level) and they will only be visible to the code until the next outdent. However, if a variable is already defined in a higher level scope, setting it will overwrite the value stored previously.

In this code, the !local_var variable is scoped and hidden from other higher level scopes or sibling scopes:

    !local_var = 1px
    width= !local_var
    // this will raise an undefined variable error.
    width= !local_var
  // as will this
  width= !local_var

In this example, since the !global_var variable is first declared at a higher scope, it is shared among all lower scopes:

!global_var = 1px
    !global_var = 2px
    width= !global_var
    width= !global_var
  width= !global_var

compiles to:

.foo {
  width: 2px; }
  .foo .bar {
    width: 2px; }
  .foo .baz {
    width: 2px; }


Interpolation has been added. This allows SassScript to be used to create dynamic properties and selectors. It also cleans up some uses of dynamic values when dealing with compound properties. Using interpolation, the result of a SassScript expression can be placed anywhere:

!x = 1
!d = 3
!property = "border"
  #{!property}: #{!x + !d}px solid
  #{!property}-color: blue

is compiled to:

div.border {
  border: 4px solid;
  border-color: blue; }

Sass Functions

SassScript defines some useful functions that are called using the normal CSS function syntax:

  color = hsl(0, 100%, 50%)

is compiled to:

#main {
  color: #ff0000; }

The following functions are provided: hsl, percentage, round, ceil, floor, and abs. You can define additional functions in ruby.

See {Sass::Script::Functions} for more information.

New Options


To aid in debugging, You may set the :line_comments option to true. This will cause the sass engine to insert a comment before each selector saying where that selector was defined in your sass code.


The {Sass::Plugin} :template_location option now accepts a hash of sass paths to corresponding css paths. Please be aware that it is possible to import sass files between these separate locations -- they are not isolated from each other.

Miscellaneous Features

@debug Directive

The @debug directive accepts a SassScript expression and emits the value of that expression to the terminal (stderr).


@debug 1px + 2px

During compilation the following will be printed:

Line 1 DEBUG: 3px

Ruby 1.9 Support

Sass now fully supports Ruby 1.9.1.

Sass Cache

By default, Sass caches compiled templates and partials. This dramatically speeds up re-compilation of large collections of Sass files, and works best if the Sass templates are split up into separate files that are all @imported into one large file.

Without a framework, Sass puts the cached templates in the .sass-cache directory. In Rails and Merb, they go in tmp/sass-cache. The directory can be customized with the :cache_location option. If you don't want Sass to use caching at all, set the :cache option to false.