## 1.32.9

### Dart API

* Allow the null safety release of args and watcher.

## 1.32.8

* Update chokidar version for Node API tests.

### JavaScript API

* Allow a custom function to access the `render()` options object within its
  local context, as `this.options`.

## 1.32.7

* Allow the null safety release of stream_transform.

* Allow `@forward...with` to take arguments that have a `!default` flag without
  a trailing comma.

* Improve the performance of unitless and single-unit numbers.

## 1.32.6

### Node JS API

* Fix Electron support when `nodeIntegration` is disabled.

### Dart API

* All range checks for `SassColor` constructors now throw `RangeError`s with
  `start` and `end` set.

## 1.32.5

* **Potentially breaking bug fix:** When using `@for` with numbers that have
  units, the iteration variable now matches the unit of the initial number. This
  matches the behavior of Ruby Sass and LibSass.

### Node JS API

* Fix a few infrequent errors when calling `render()` with `fiber` multiple
  times simultaneously.

* Avoid possible mangled error messages when custom functions or importers throw
  unexpected exceptions.

* Fix Electron support when `nodeIntegration` is disabled.

## 1.32.4

* No user-visible changes.

## 1.32.3

* Optimize `==` for numbers that have different units.

## 1.32.2

* Print the actual number that was received in unit deprecation warnings for
  color functions.

## 1.32.1

* Don't emit permissions errors on Windows and OS X when trying to determine the
  real case of path names.

## 1.32.0

* Deprecate passing non-`%` numbers as lightness and saturation to `hsl()`,
  `hsla()`, `color.adjust()`, and `color.change()`. This matches the CSS
  specification, which also requires `%` for all lightness and saturation
  parameters. See [the Sass website][color-units] for more details.

* Deprecate passing numbers with units other than `deg` as the hue to `hsl()`,
  `hsla()`, `adjust-hue()`, `color.adjust()`, and `color.change()`. Unitless
  numbers *are* still allowed here, since they're allowed by CSS. See [the Sass
  website][color-units] for more details.

* Improve error messages about incompatible units.

* Properly mark some warnings emitted by `sass:color` functions as deprecation
  warnings.

### Dart API

* Rename `SassNumber.valueInUnits()` to `SassNumber.coerceValue()`. The old name
  remains, but is now deprecated.

* Rename `SassNumber.coerceValueToUnit()`, a shorthand for
  `SassNumber.coerceValue()` that takes a single numerator unit.

* Add `SassNumber.coerceToMatch()` and `SassNumber.coerceValueToMatch()`, which
  work like `SassNumber.coerce()` and `SassNumber.coerceValue()` but take a
  `SassNumber` whose units should be matched rather than taking the units
  explicitly. These generate better error messages than `SassNumber.coerce()`
  and `SassNumber.coerceValue()`.

* Add `SassNumber.convertToMatch()` and `SassNumber.convertValueToMatch()`,
  which work like `SassNumber.coerceToMatch()` and
  `SassNumber.coerceValueToMatch()` except they throw exceptions when converting
  unitless values to or from units.

* Add `SassNumber.compatibleWithUnit()`, which returns whether the number can be
  coerced to a single numerator unit.

## 1.31.0

* Add support for parsing `clamp()` as a special math function, the same way
  `calc()` is parsed.

* Properly load files in case-sensitive Windows directories with upper-case
  names.

## 1.30.0

* Fix a bug where `@at-root (without: all)` wouldn't properly remove a
  `@keyframes` context when parsing selectors.

### Node JS API

* The generated `main()` function in `sass.js` now returns a `Promise` that
  completes when the executable is finished running.

### Dart API

* Fix a bug that prevented importers from returning null when loading from a
  URL that they had already canonicalized.

## 1.29.0

* Support a broader syntax for `@supports` conditions, based on the latest
  [Editor's Draft of CSS Conditional Rules 3]. Almost all syntax will be allowed
  (with interpolation) in the conditions' parentheses, as well as function
  syntax such as `@supports selector(...)`.

[Editor's Draft of CSS Conditional Rules 3]: https://drafts.csswg.org/css-conditional-3/#at-supports

## 1.28.0

* Add a [`color.hwb()`] function to `sass:color` that can express colors in [HWB] format.

[`color.hwb()`]: https://sass-lang.com/documentation/modules/color#hwb
[HWB]: https://en.wikipedia.org/wiki/HWB_color_model

* Add [`color.whiteness()`] and [`color.blackness()`] functions to `sass:color`
  to get a color's [HWB] whiteness and blackness components.

[`color.whiteness()`]: https://sass-lang.com/documentation/modules/color#whiteness
[`color.blackness()`]: https://sass-lang.com/documentation/modules/color#blackness

* Add `$whiteness` and `$blackness` parameters to [`color.adjust()`],
  [`color.change()`], and [`color.scale()`] to modify a color's [HWB] whiteness
  and blackness components.

[`color.adjust()`]: https://sass-lang.com/documentation/modules/color#adjust
[`color.change()`]: https://sass-lang.com/documentation/modules/color#change
[`color.scale()`]: https://sass-lang.com/documentation/modules/color#scale

### Dart API

* Add [HWB] support to the `SassColor` class, including a `SassColor.hwb()`
  constructor, `whiteness` and `blackness` getters, and a `changeHwb()` method.

[HWB]: https://en.wikipedia.org/wiki/HWB_color_model

## 1.27.2

* No user-visible changes.

## 1.27.1

* **Potentially breaking bug fix:** `meta.load-css()` now correctly uses the
  name `$url` for its first argument, rather than `$module`.

* Don't crash when using `Infinity` or `NaN` as a key in a map.

* Emit a proper parse error for a `=` with no right-hand side in a function.

* Avoid going exponential on certain recursive `@extend` edge cases.

## 1.27.0

* Adds an overload to `map.merge()` that supports merging a nested map.

  `map.merge($map1, $keys..., $map2)`: The `$keys` form a path to the nested map
  in `$map1`, into which `$map2` gets merged.

  See [the Sass documentation][map-merge] for more details.

  [map-merge]: https://sass-lang.com/documentation/modules/map#merge

* Adds an overloaded `map.set()` function.

  `map.set($map, $key, $value)`: Adds to or updates `$map` with the specified
  `$key` and `$value`.

  `map.set($map, $keys..., $value)`: Adds to or updates a map that is nested
  within `$map`. The `$keys` form a path to the nested map in `$map`, into
  which `$value` is inserted.

  See [the Sass documentation][map-set] for more details.

  [map-set]: https://sass-lang.com/documentation/modules/map#set

* Add support for nested maps to `map.get()`.
  For example, `map.get((a: (b: (c: d))), a, b, c)` would return `d`.
  See [the documentation][map-get] for more details.

  [map-get]: https://sass-lang.com/documentation/modules/map#get

* Add support for nested maps in `map.has-key`.
  For example, `map.has-key((a: (b: (c: d))), a, b, c)` would return true.
  See [the documentation][map-has-key] for more details.

  [map-has-key]: https://sass-lang.com/documentation/modules/map#has-key

* Add a `map.deep-merge()` function. This works like `map.merge()`, except that
  nested map values are *also* recursively merged. For example:

  ```
  map.deep-merge(
    (color: (primary: red, secondary: blue),
    (color: (secondary: teal)
  ) // => (color: (primary: red, secondary: teal))
  ```

  See [the Sass documentation][map-deep-merge] for more details.

  [map-deep-merge]: https://sass-lang.com/documentation/modules/map#deep-merge

* Add a `map.deep-remove()` function. This allows you to remove keys from
  nested maps by passing multiple keys. For example:

  ```
  map.deep-remove(
    (color: (primary: red, secondary: blue)),
    color, primary
  ) // => (color: (secondary: blue))
  ```

  See [the Sass documentation][map-deep-remove] for more details.

  [map-deep-remove]: https://sass-lang.com/documentation/modules/map#deep-remove

* Fix a bug where custom property values in plain CSS were being parsed as
  normal property values.

### Dart API

* Add a `Value.tryMap()` function which returns the `Value` as a `SassMap` if
  it's a valid map, or `null` otherwise. This allows function authors to safely
  retrieve maps even if they're internally stored as empty lists, without having
  to catch exceptions from `Value.assertMap()`.

## 1.26.12

* Fix a bug where nesting properties beneath a Sass-syntax custom property
  (written as `#{--foo}: ...`) would crash.

## 1.26.11

* **Potentially breaking bug fix:** `selector.nest()` now throws an error
  if the first arguments contains the parent selector `&`.

* Fixes a parsing bug with inline comments in selectors.

* Improve some error messages for edge-case parse failures.

* Throw a proper error when the same built-in module is `@use`d twice.

* Don't crash when writing `Infinity` in JS mode.

* Produce a better error message for positional arguments following named
  arguments.

## 1.26.10

* Fixes a bug where two adjacent combinators could cause an error.

## 1.26.9

* Use an updated version of `node_preamble` when compiling to JS.

## 1.26.8

* Fixes an error when emitting source maps to stdout.

## 1.26.7

* No user-visible changes.

## 1.26.6

* Fix a bug where escape sequences were improperly recognized in `@else` rules.

### JavaScript API

* Add `sass.NULL`, `sass.TRUE`, and `sass.FALSE` constants to match Node Sass's
  API.

* If a custom Node importer returns both `file` and `contents`, don't attempt to
  read the `file`. Instead, use the `contents` provided by the importer, with
  `file` as the canonical url.

## 1.26.5

* No user-visible changes.

## 1.26.4

* Be more memory-efficient when handling `@forward`s through `@import`s.

## 1.26.3

* Fix a bug where `--watch` mode could go into an infinite loop compiling CSS
  files to themselves.

## 1.26.2

* More aggressively eliminate redundant selectors in the `selector.extend()` and
  `selector.replace()` functions.

## 1.26.1

### Command Line Interface

* Fix a longstanding bug where `--watch` mode could enter into a state where
  recompilation would not occur after a syntax error was introduced into a
  dependency and then fixed.

## 1.26.0

* **Potentially breaking bug fix:** `@use` rules whose URLs' basenames begin
  with `_` now correctly exclude that `_` from the rules' namespaces.

* Fix a bug where imported forwarded members weren't visible in mixins and
  functions that were defined before the `@import`.

* Don't throw errors if the exact same member is loaded or forwarded from
  multiple modules at the same time.

## 1.25.2

* Fix a bug where, under extremely rare circumstances, a valid variable could
  become unassigned.

## 1.25.0

* Add functions to the built-in "sass:math" module.

  * `clamp($min, $number, $max)`. Clamps `$number` in between `$min` and `$max`.

  * `hypot($numbers...)`. Given *n* numbers, outputs the length of the
    *n*-dimensional vector that has components equal to each of the inputs.

  * Exponential. All inputs must be unitless.
    * `log($number)` or `log($number, $base)`. If no base is provided, performs
       a natural log.
    * `pow($base, $exponent)`
    * `sqrt($number)`

  * Trigonometric. The input must be an angle. If no unit is given, the input is
    assumed to be in `rad`.
    * `cos($number)`
    * `sin($number)`
    * `tan($number)`

  * Inverse trigonometric. The output is in `deg`.
    * `acos($number)`. Input must be unitless.
    * `asin($number)`. Input must be unitless.
    * `atan($number)`. Input must be unitless.
    * `atan2($y, $x)`. `$y` and `$x` must have compatible units or be unitless.

* Add the variables `$pi` and `$e` to the built-in "sass:math" module.

### JavaScript API

* `constructor.value` fields on value objects now match their Node Sass
  equivalents.

## 1.24.5

* Highlight contextually-relevant sections of the stylesheet in error messages,
  rather than only highlighting the section where the error was detected.

## 1.24.4

### JavaScript API

* Fix a bug where source map generation would crash with an absolute source map
  path and a custom importer that returns string file contents.

## 1.24.3

### Command Line Interface

* Fix a bug where `sass --version` would crash for certain executable
  distributions.

## 1.24.2

### JavaScript API

* Fix a bug introduced in the previous release that prevented custom importers
  in Node.js from loading import-only files.

## 1.24.1

* Fix a bug where the wrong file could be loaded when the same URL is used by
  both a `@use` rule and an `@import` rule.

## 1.24.0

* Add an optional `with` clause to the `@forward` rule. This works like the
  `@use` rule's `with` clause, except that `@forward ... with` can declare
  variables as `!default` to allow downstream modules to reconfigure their
  values.

* Support configuring modules through `@import` rules.

## 1.23.8

* **Potentially breaking bug fix:** Members loaded through a nested `@import`
  are no longer ever accessible outside that nested context.

* Don't throw an error when importing two modules that both forward members with
  the same name. The latter name now takes precedence over the former, as per
  the specification.

### Dart API

* `SassFormatException` now implements `SourceSpanFormatException` (and thus
  `FormatException`).

## 1.23.7

* No user-visible changes

## 1.23.6

* No user-visible changes.

## 1.23.5

* Support inline comments in the indented syntax.

* When an overloaded function receives the wrong number of arguments, guess
  which overload the user actually meant to invoke, and display the invalid
  argument error for that overload.

* When `@error` is used in a function or mixin, print the call site rather than
  the location of the `@error` itself to better match the behavior of calling a
  built-in function that throws an error.

## 1.23.4

### Command-Line Interface

* Fix a bug where `--watch` wouldn't watch files referred to by `@forward`
  rules.

## 1.23.3

* Fix a bug where selectors were being trimmed over-eagerly when `@extend`
  crossed module boundaries.

## 1.23.2

### Command-Line Interface

* Fix a bug when compiling all Sass files in a directory where a CSS file could
  be compiled to its own location, creating an infinite loop in `--watch` mode.

* Properly compile CSS entrypoints in directories outside of `--watch` mode.

## 1.23.1

* Fix a bug preventing built-in modules from being loaded within a configured
  module.

* Fix a bug preventing an unconfigured module from being loaded from within two
  different configured modules.

* Fix a bug when `meta.load-css()` was used to load some files that included
  media queries.

* Allow `saturate()` in plain CSS files, since it can be used as a plain CSS
  filter function.

* Improve the error messages for trying to access functions like `lighten()`
  from the `sass:color` module.

## 1.23.0

* **Launch the new Sass module system!** This adds:

  * The [`@use` rule][], which loads Sass files as *modules* and makes their
    members available only in the current file, with automatic namespacing.

    [`@use` rule]: https://sass-lang.com/documentation/at-rules/use

  * The [`@forward` rule][], which makes members of another Sass file available
    to stylesheets that `@use` the current file.

    [`@forward` rule]: https://sass-lang.com/documentation/at-rules/forward

  * Built-in modules named `sass:color`, `sass:list`, `sass:map`, `sass:math`,
    `sass:meta`, `sass:selector`, and `sass:string` that provide access to all
    the built-in Sass functions you know and love, with automatic module
    namespaces.

  * The [`meta.load-css()` mixin][], which includes the CSS contents of a module
    loaded from a (potentially dynamic) URL.

    [`meta.load-css()` mixin]: https://sass-lang.com/documentation/modules/meta#load-css

  * The [`meta.module-variables()` function][], which provides access to the
    variables defined in a given module.

    [`meta.module-variables()` function]: https://sass-lang.com/documentation/modules/meta#module-variables

  * The [`meta.module-functions()` function][], which provides access to the
    functions defined in a given module.

    [`meta.module-functions()` function]: https://sass-lang.com/documentation/modules/meta#module-functions

  Check out [the Sass blog][migrator blog] for more information on the new
  module system. You can also use the new [Sass migrator][] to automatically
  migrate your stylesheets to the new module system!

  [migrator blog]: https://sass-lang.com/blog/the-module-system-is-launched
  [Sass migrator]: https://sass-lang.com/documentation/cli/migrator

## 1.22.12

* **Potentially breaking bug fix:** character sequences consisting of two or
  more hyphens followed by a number (such as `--123`), or two or more hyphens on
  their own (such as `--`), are now parsed as identifiers [in accordance with
  the CSS spec][ident-token-diagram].

  [ident-token-diagram]: https://drafts.csswg.org/css-syntax-3/#ident-token-diagram

  The sequence `--` was previously parsed as multiple applications of the `-`
  operator. Since this is unlikely to be used intentionally in practice, we
  consider this bug fix safe.

### Command-Line Interface

* Fix a bug where changes in `.css` files would be ignored in `--watch` mode.

### JavaScript API

* Allow underscore-separated custom functions to be defined.

* Improve the performance of Node.js compilation involving many `@import`s.

## 1.22.11

* Don't try to load unquoted plain-CSS indented-syntax imports.

* Fix a couple edge cases in `@extend` logic and related selector functions:

  * Recognize `:matches()` and similar pseudo-selectors as superselectors of
    matching complex selectors.

  * Recognize `::slotted()` as a superselector of other `::slotted()` selectors.

  * Regonize `:current()` with a vendor prefix as a superselector.

## 1.22.10

* Fix a bug in which `get-function()` would fail to find a dash-separated
  function when passed a function name with underscores.

## 1.22.9

* Include argument names when reporting range errors and selector parse errors.

* Avoid double `Error:` headers when reporting selector parse errors.

* Clarify the error message when the wrong number of positional arguments are
  passed along with a named argument.

### JavaScript API

* Re-add support for Node Carbon (8.x).

## 1.22.8

### JavaScript API

* Don't crash when running in a directory whose name contains URL-sensitive
  characters.

* Drop support for Node Carbon (8.x), which doesn't support `url.pathToFileURL`.

## 1.22.7

* Restrict the supported versions of the Dart SDK to `^2.4.0`.

## 1.22.6

* **Potentially breaking bug fix:** The `keywords()` function now converts
  underscore-separated argument names to hyphen-separated names. This matches
  LibSass's behavior, but not Ruby Sass's.

* Further improve performance for logic-heavy stylesheets.

* Improve a few error messages.

## 1.22.5

### JavaScript API

* Improve performance for logic-heavy stylesheets.

## 1.22.4

* Fix a bug where at-rules imported from within a style rule would appear within
  that style rule rather than at the root of the document.

## 1.22.3

* **Potentially breaking bug fix:** The argument name for the `saturate()`
  function is now `$amount`, to match the name in LibSass and originally in Ruby
  Sass.

* **Potentially breaking bug fix:** The `invert()` function now properly returns
  `#808080` when passed `$weight: 50%`. This matches the behavior in LibSass and
  originally in Ruby Sass, as well as being consistent with other nearby values
  of `$weight`.

* **Potentially breaking bug fix:** The `invert()` function now throws an error
  if it's used [as a plain CSS function][plain-CSS invert] *and* the Sass-only
  `$weight` parameter is passed. This never did anything useful, so it's
  considered a bug fix rather than a full breaking change.

  [plain-CSS invert]: https://developer.mozilla.org/en-US/docs/Web/CSS/filter-function/invert

* **Potentially breaking bug fix**: The `str-insert()` function now properly
  inserts at the end of the string if the `$index` is `-1`. This matches the
  behavior in LibSass and originally in Ruby Sass.

* **Potentially breaking bug fix**: An empty map returned by `map-remove()` is
  now treated as identical to the literal value `()`, rather than being treated
  as though it had a comma separator. This matches the original behavior in Ruby
  Sass.

* The `adjust-color()` function no longer throws an error when a large `$alpha`
  value is combined with HSL adjustments.

* The `alpha()` function now produces clearer error messages when the wrong
  number of arguments are passed.

* Fix a bug where the `str-slice()` function could produce invalid output when
  passed a string that contains characters that aren't represented as a single
  byte in UTF-16.

* Improve the error message for an unknown separator name passed to the `join()`
  or `append()` functions.

* The `zip()` function no longer deadlocks if passed no arguments.

* The `map-remove()` function can now take a `$key` named argument. This matches
  the signature in LibSass and originally in Ruby Sass.

## 1.22.2

### JavaScript API

* Avoid re-assigning the `require()` function to make the code statically
  analyzable by Webpack.

## 1.22.1

### JavaScript API

* Expand the dependency on `chokidar` to allow 3.x.

## 1.22.0

* Produce better stack traces when importing a file that contains a syntax
  error.

* Make deprecation warnings for `!global` variable declarations that create new
  variables clearer, especially in the case where the `!global` flag is
  unnecessary because the variables are at the top level of the stylesheet.

### Dart API

* Add a `Value.realNull` getter, which returns Dart's `null` if the value is
  Sass's null.

## 1.21.0

### Dart API

* Add a `sass` executable when installing the package through `pub`.

* Add a top-level `warn()` function for custom functions and importers to print
  warning messages.

## 1.20.3

* No user-visible changes.

## 1.20.2

* Fix a bug where numbers could be written using exponential notation in
  Node.js.

* Fix a crash that would appear when writing some very large integers to CSS.

### Command-Line Interface

* Improve performance for stand-alone packages on Linux and Mac OS.

### JavaScript API

* Pass imports to custom importers before resolving them using `includePaths` or
  the `SASS_PATH` environment variable. This matches Node Sass's behavior, so
  it's considered a bug fix.

## 1.20.1

* No user-visible changes.

## 1.20.0

* Support attribute selector modifiers, such as the `i` in `[title="test" i]`.

### Command-Line Interface

* When compilation fails, Sass will now write the error message to the CSS
  output as a comment and as the `content` property of a `body::before` rule so
  it will show up in the browser (unless compiling to standard output). This can
  be disabled with the `--no-error-css` flag, or forced even when compiling to
  standard output with the `--error-css` flag.

### Dart API

* Added `SassException.toCssString()`, which returns the contents of a CSS
  stylesheet describing the error, as above.

## 1.19.0

* Allow `!` in `url()`s without quotes.

### Dart API

* `FilesystemImporter` now doesn't change its effective directory if the working
  directory changes, even if it's passed a relative argument.

## 1.18.0

* Avoid recursively listing directories when finding the canonical name of a
  file on case-insensitive filesystems.

* Fix importing files relative to `package:`-imported files.

* Don't claim that "package:" URLs aren't supported when they actually are.

### Command-Line Interface

* Add a `--no-charset` flag. If this flag is set, Sass will never emit a
  `@charset` declaration or a byte-order mark, even if the CSS file contains
  non-ASCII characters.

### Dart API

* Add a `charset` option to `compile()`, `compileString()`, `compileAsync()` and
  `compileStringAsync()`. If this option is set to `false`, Sass will never emit
  a `@charset` declaration or a byte-order mark, even if the CSS file contains
  non-ASCII characters.

* Explicitly require that importers' `canonicalize()` methods be able to take
  paths relative to their outputs as valid inputs. This isn't considered a
  breaking change because the importer infrastructure already required this in
  practice.

## 1.17.4

* Consistently parse U+000C FORM FEED, U+000D CARRIAGE RETURN, and sequences of
  U+000D CARRIAGE RETURN followed by U+000A LINE FEED as individual newlines.

### JavaScript API

* Add a `sass.types.Error` constructor as an alias for `Error`. This makes our
  custom function API compatible with Node Sass's.

## 1.17.3

* Fix an edge case where slash-separated numbers were written to the stylesheet
  with a slash even when they're used as part of another arithmetic operation,
  such as being concatenated with a string.

* Don't put style rules inside empty `@keyframes` selectors.

## 1.17.2

* Deprecate `!global` variable assignments to variables that aren't yet defined.
  This deprecation message can be avoided by assigning variables to `null` at
  the top level before globally assigning values to them.

### Dart API

* Explicitly mark classes that were never intended to be subclassed or
  implemented as "sealed".

## 1.17.1

* Properly quote attribute selector values that start with identifiers but end
  with a non-identifier character.

## 1.17.0

* Improve error output, particularly for errors that cover multiple lines.

* Improve source locations for some parse errors. Rather than pointing to the
  next token that wasn't what was expected, they point *after* the previous
  token. This should generally provide more context for the syntax error.

* Produce a better error message for style rules that are missing the closing
  `}`.

* Produce a better error message for style rules and property declarations
  within `@function` rules.

### Command-Line Interface

* Passing a directory on the command line now compiles all Sass source files in
  the directory to CSS files in the same directory, as though `dir:dir` were
  passed instead of just `dir`.

* The new error output uses non-ASCII Unicode characters by default. Add a
  `--no-unicode` flag to disable this.

## 1.16.1

* Fix a performance bug where stylesheet evaluation could take a very long time
  when many binary operators were used in sequence.

## 1.16.0

* `rgb()` and `hsl()` now treat unquoted strings beginning with `env()`,
  `min()`, and `max()` as special number strings like `calc()`.

## 1.15.3

* Properly merge `all and` media queries. These queries were previously being
  merged as though `all` referred to a specific media type, rather than all
  media types.

* Never remove units from 0 values in compressed mode. This wasn't safe in
  general, since some properties (such as `line-height`) interpret `0` as a
  `<number>` rather than a `<length>` which can break CSS transforms. It's
  better to do this optimization in a dedicated compressor that's aware of CSS
  property semantics.

* Match Ruby Sass's behavior in some edge-cases involving numbers with many
  significant digits.

* Emit escaped tab characters in identifiers as `\9` rather than a backslash
  followed by a literal tab.

### Command-Line Interface

* The source map generated for a stylesheet read from standard input now uses a
  `data:` URL to include that stylesheet's contents in the source map.

### Node JS API

* `this.includePaths` for a running importer is now a `;`-separated string on
  Windows, rather than `:`-separated. This matches Node Sass's behavior.

### Dart API

* The URL used in a source map to refer to a stylesheet loaded from an importer
  is now `ImportResult.sourceMapUrl` as documented.

## 1.15.2

### Node JS API

* When `setValue()` is called on a Sass string object, make it unquoted even if
  it was quoted originally, to match the behavior of Node Sass.

## 1.15.1

* Always add quotes to attribute selector values that begin with `--`, since IE
  11 doesn't consider them to be identifiers.

## 1.15.0

* Add support for passing arguments to `@content` blocks. See [the
  proposal][content-args] for details.

* Add support for the new `rgb()` and `hsl()` syntax introduced in CSS Colors
  Level 4, such as `rgb(0% 100% 0% / 0.5)`. See [the proposal][color-4-rgb-hsl]
  for more details.

* Add support for interpolation in at-rule names. See [the
  proposal][at-rule-interpolation] for details.

* Add paths from the `SASS_PATH` environment variable to the load paths in the
  command-line interface, Dart API, and JS API. These load paths are checked
  just after the load paths explicitly passed by the user.

* Allow saturation and lightness values outside of the `0%` to `100%` range in
  the `hsl()` and `hsla()` functions. They're now clamped to be within that
  range rather than producing an error if they're outside it.

* Properly compile selectors that end in escaped whitespace.

[content-args]: https://github.com/sass/language/blob/master/accepted/content-args.md
[color-4-rgb-hsl]: https://github.com/sass/language/blob/master/accepted/color-4-rgb-hsl.md
[at-rule-interpolation]: https://github.com/sass/language/blob/master/accepted/at-rule-interpolation.md

### JavaScript API

* Always include the error location in error messages.

## 1.14.4

* Properly escape U+0009 CHARACTER TABULATION in unquoted strings.

## 1.14.3

* Treat `:before`, `:after`, `:first-line`, and `:first-letter` as
  pseudo-elements for the purposes of `@extend`.

* When running in compressed mode, remove spaces around combinators in complex
  selectors, so a selector like `a > b` is output as `a>b`.

* Properly indicate the source span for errors involving binary operation
  expressions whose operands are parenthesized.

## 1.14.2

* Fix a bug where loading the same stylesheet from two different import paths
  could cause its imports to fail to resolve.

* Properly escape U+001F INFORMATION SEPARATOR ONE in unquoted strings.

### Command-Line Interface

* Don't crash when using `@debug` in a stylesheet passed on standard input.

### Dart API

* `AsyncImporter.canonicalize()` and `Importer.canonicalize()` must now return
  absolute URLs. Relative URLs are still supported, but are deprecated and will
  be removed in a future release.

## 1.14.1

* Canonicalize escaped digits at the beginning of identifiers as hex escapes.

* Properly parse property declarations that are both *in* content blocks and
  written *after* content blocks.

### Command-Line Interface

* Print more readable paths in `--watch` mode.

## 1.14.0

### BREAKING CHANGE

In accordance with our [compatibility policy][], breaking changes made for CSS
compatibility reasons are released as minor version revision after a three-month
deprecation period.

[compatibility policy]: README.md#compatibility-policy

* Tokens such as `#abcd` that are now interpreted as hex colors with alpha
  channels, rather than unquoted ID strings.

## 1.13.4

### Node JS

* Tweak JS compilation options to substantially improve performance.

## 1.13.3

* Properly generate source maps for stylesheets that emit `@charset`
  declarations.

### Command-Line Interface

* Don't error out when passing `--embed-source-maps` along with
  `--embed-sources` for stylesheets that contain non-ASCII characters.

## 1.13.2

* Properly parse `:nth-child()` and `:nth-last-child()` selectors with
  whitespace around the argument.

* Don't emit extra whitespace in the arguments for `:nth-child()` and
  `:nth-last-child()` selectors.

* Fix support for CSS hacks in plain CSS mode.

## 1.13.1

* Allow an IE-style single equals operator in plain CSS imports.

## 1.13.0

* Allow `@extend` to be used with multiple comma-separated simple selectors.
  This is already supported by other implementations, but fell through the
  cracks for Dart Sass until now.

* Don't crash when a media rule contains another media rule followed by a style
  rule.

## 1.12.0

### Dart API

* Add a `SassException` type that provides information about Sass compilation
  failures.

### Node JS API

* Remove the source map comment from the compiled JS. We don't ship with the
  source map, so this pointed to nothing.

## 1.11.0

* Add support for importing plain CSS files. They can only be imported *without*
  an extension—for example, `@import "style"` will import `style.css`. Plain CSS
  files imported this way only support standard CSS features, not Sass
  extensions.

  See [the proposal][css-import] for details.

* Add support for CSS's `min()` and `max()` [math functions][]. A `min()` and
  `max()` call will continue to be parsed as a Sass function if it involves any
  Sass-specific features like variables or function calls, but if it's valid
  plain CSS (optionally with interpolation) it will be emitted as plain CSS instead.

  See [the proposal][css-min-max] for details.

* Add support for range-format media features like `(10px < width < 100px)`. See
  [the proposal][media-ranges] for details.

* Normalize escape codes in identifiers so that, for example, `éclair` and
  `\E9clair` are parsed to the same value. See
  [the proposal][identifier-escapes] for details.

* Don't choke on a [byte-order mark][] at the beginning of a document when
  running in JavaScript.

[math functions]: https://drafts.csswg.org/css-values/#math-function
[css-import]: https://github.com/sass/language/blob/master/accepted/css-imports.md
[css-min-max]: https://github.com/sass/language/blob/master/accepted/min-max.md
[media-ranges]: https://github.com/sass/language/blob/master/accepted/media-ranges.md
[identifier-escapes]: https://github.com/sass/language/blob/master/accepted/identifier-escapes.md
[byte-order mark]: https://en.wikipedia.org/wiki/Byte_order_mark

### Command-Line Interface

* The `--watch` command now continues to recompile a file after a syntax error
  has been detected.

### Dart API

* Added a `Syntax` enum to indicate syntaxes for Sass source files.

* The `compile()` and `compileAsync()` functions now parse files with the `.css`
  extension as plain CSS.

* Added a `syntax` parameter to `compileString()` and `compileStringAsync()`.

* Deprecated the `indented` parameter to `compileString()` and `compileStringAsync()`.

* Added a `syntax` parameter to `new ImporterResult()` and a
  `ImporterResult.syntax` getter to set the syntax of the source file.

* Deprecated the `indented` parameter to `new ImporterResult()` and the
  `ImporterResult.indented` getter in favor of `syntax`.

## 1.10.4

### Command-Line Interface

* Fix a Homebrew installation failure.

## 1.10.3

### Command-Line Interface

* Run the Chocolatey script with the correct arguments so it doesn't crash.

## 1.10.2

* No user-visible changes.

## 1.10.1

### Node JS API

* Don't crash when passing both `includePaths` and `importer`.

## 1.10.0

* When two `@media` rules' queries can't be merged, leave nested rules in place
  for browsers that support them.

* Fix a typo in an error message.

## 1.9.2

### Node JS API

* Produce more readable filesystem errors, such as when a file doesn't exist.

## 1.9.1

### Command-Line Interface

* Don't emit ANSI codes to Windows terminals that don't support them.

* Fix a bug where `--watch` crashed on Mac OS.

## 1.9.0

### Node API

* Add support for `new sass.types.Color(argb)` for creating colors from ARGB hex
  numbers. This was overlooked when initially adding support for Node Sass's
  JavaScript API.

## 1.8.0

### Command-Line Interface

* Add a `--poll` flag to make `--watch` mode repeatedly check the filesystem for
  updates rather than relying on native filesystem notifications.

* Add a `--stop-on-error` flag to stop compiling additional files once an error
  is encountered.

## 1.7.3

* No user-visible changes.

## 1.7.2

* Add a deprecation warning for `@-moz-document`, except for cases where only an
  empty `url-prefix()` is used. Support is [being removed from Firefox][] and
  will eventually be removed from Sass as well.

[being removed from Firefox]: https://www.fxsitecompat.com/en-CA/docs/2018/moz-document-support-has-been-dropped-except-for-empty-url-prefix/

* Fix a bug where `@-moz-document` functions with string arguments weren't being
  parsed.

### Command-Line Interface

* Don't crash when a syntax error is added to a watched file.

## 1.7.1

* Fix crashes in released binaries.

## 1.7.0

* Emit deprecation warnings for tokens such as `#abcd` that are ambiguous
  between ID strings and hex colors with alpha channels. These will be
  interpreted as colors in a release on or after 19 September 2018.

* Parse unambiguous hex colors with alpha channels as colors.

* Fix a bug where relative imports from files on the load path could look in the
  incorrect location.

## 1.6.2

### Command-Line Interface

* Fix a bug where the source map comment in the generated CSS could refer to the
  source map file using an incorrect URL.

## 1.6.1

* No user-visible changes.

## 1.6.0

* Produce better errors when expected tokens are missing before a closing brace.

* Avoid crashing when compiling a non-partial stylesheet that exists on the
  filesystem next to a partial with the same name.

### Command-Line Interface

* Add support for the `--watch`, which watches for changes in Sass files on the
  filesystem and ensures that the compiled CSS is up-to-date.

* When using `--update`, surface errors when an import doesn't exist even if the
  file containing the import hasn't been modified.

* When compilation fails, delete the output file rather than leaving an outdated
  version.

## 1.5.1

* Fix a bug where an absolute Windows path would be considered an `input:output`
  pair.

* Forbid custom properties that have no values, like `--foo:;`, since they're
  forbidden by the CSS spec.

## 1.5.0

* Fix a bug where an importer would be passed an incorrectly-resolved URL when
  handling a relative import.

* Throw an error when an import is ambiguous due to a partial and a non-partial
  with the same name, or multiple files with different extensions. This matches
  the standard Sass behavior.

### Command-Line Interface

* Add an `--interactive` flag that supports interactively running Sass
  expressions (thanks to [Jen Thakar][]!).

[Jen Thakar]: https://github.com/jathak

## 1.4.0

* Improve the error message for invalid semicolons in the indented syntax.

* Properly disallow semicolons after declarations in the indented syntax.

### Command-Line Interface

* Add support for compiling multiple files at once by writing
  `sass input.scss:output.css`. Note that unlike Ruby Sass, this *always*
  compiles files by default regardless of when they were modified.

  This syntax also supports compiling entire directories at once. For example,
  `sass templates/stylesheets:public/css` compiles all non-partial Sass files
  in `templates/stylesheets` to CSS files in `public/css`.

* Add an `--update` flag that tells Sass to compile only stylesheets that have
  been (transitively) modified since the CSS file was generated.

### Dart API

* Add `Importer.modificationTime()` and `AsyncImporter.modificationTime()` which
  report the last time a stylesheet was modified.

### Node API

* Generate source maps when the `sourceMaps` option is set to a string and the
  `outFile` option is not set.

## 1.3.2

* Add support for `@elseif` as an alias of `@else if`. This is not an
  intentional feature, so using it will cause a deprecation warning. It will be
  removed at some point in the future.

## 1.3.1

### Node API

* Fix loading imports relative to stylesheets that were themselves imported
  though relative include paths.

## 1.3.0

### Command-Line Interface

* Generate source map files by default when writing to disk. This can be
  disabled by passing `--no-source-map`.

* Add a `--source-map-urls` option to control whether the source file URLs in
  the generated source map are relative or absolute.

* Add an `--embed-sources` option to embed the contents of all source files in
  the generated source map.

* Add an `--embed-source-map` option to embed the generated source map as a
  `data:` URL in the generated CSS.

### Dart API

* Add a `sourceMap` parameter to `compile()`, `compileString()`,
  `compileAsync()`, and `compileStringAsync()`. This takes a callback that's
  called with a [`SingleMapping`][] that contains the source map information for
  the compiled CSS file.

[`SingleMapping`]: https://www.dartdocs.org/documentation/source_maps/latest/source_maps.parser/SingleMapping-class.html

### Node API

* Added support for the `sourceMap`, `omitSourceMapUrl`, `outFile`,
  `sourceMapContents`, `sourceMapEmbed`, and `sourceMapRoot` options to
  `render()` and `renderSync()`.

* Fix a bug where passing a relative path to `render()` or `renderSync()` would
  cause relative imports to break.

* Fix a crash when printing warnings in stylesheets compiled using `render()` or
  `renderSync()`.

* Fix a bug where format errors were reported badly on Windows.

## 1.2.1

* Always emit units in compressed mode for `0` dimensions other than lengths and
  angles.

## 1.2.0

* The command-line executable will now create the directory for the resulting
  CSS if that directory doesn't exist.

* Properly parse `#{$var} -#{$var}` as two separate values in a list rather than
  one value being subtracted from another.

* Improve the error message for extending compound selectors.

## 1.1.1

* Add a commit that was accidentally left out of 1.1.0.

## 1.1.0

* The command-line executable can now be used to write an output file to disk
  using `sass input.scss output.css`.

* Use a POSIX-shell-compatible means of finding the location of the `sass` shell
  script.

## 1.0.0

**Initial stable release.**

### Changes Since 1.0.0-rc.1

* Allow `!` in custom property values ([#260][]).

[#260]: https://github.com/sass/dart-sass/issues/260

#### Dart API

* Remove the deprecated `render()` function.

#### Node API

* Errors are now subtypes of the `Error` type.

* Allow both the `data` and `file` options to be passed to `render()` and
  `renderSync()` at once. The `data` option will be used as the contents of the
  stylesheet, and the `file` option will be used as the path for error reporting
  and relative imports. This matches Node Sass's behavior.

## 1.0.0-rc.1

* Add support for importing an `_index.scss` or `_index.sass` file when
  importing a directory.

* Add a `--load-path` command-line option (alias `-I`) for passing additional
  paths to search for Sass files to import.

* Add a `--quiet` command-line option (alias `-q`) for silencing warnings.

* Add an `--indented` command-line option for using the indented syntax with a
  stylesheet from standard input.

* Don't merge the media queries `not type` and `(feature)`. We had previously
  been generating `not type and (feature)`, but that's not actually the
  intersection of the two queries.

* Don't crash on `$x % 0`.

* The standalone executable distributed on GitHub is now named `sass` rather
  than `dart-sass`. The `dart-sass` executable will remain, with a deprecation
  message, until 1.0.0 is released.

### Dart API

* Add a `Logger` class that allows users to control how messages are printed by
  stylesheets.

* Add a `logger` parameter to `compile()`, `compileAsync()`, `compileString()`,
  and `compileStringAsync()`.

### Node JS API

* Import URLs passed to importers are no longer normalized. For example, if a
  stylesheet contains `@import "./foo.scss"`, importers will now receive
  `"./foo.scss"` rather than `"foo.scss"`.

## 1.0.0-beta.5.3

* Support hard tabs in the indented syntax.

* Improve the formatting of comments that don't start on the same line as the
  opening `/*`.

* Preserve whitespace after `and` in media queries in compressed mode.

### Indented Syntax

* Properly parse multi-line selectors.

* Don't deadlock on `/*` comments.

* Don't add an extra `*/` to comments that already have it.

* Preserve empty lines in `/*` comments.

## 1.0.0-beta.5.2

* Fix a bug where some colors would crash `compressed` mode.

## 1.0.0-beta.5.1

* Add a `compressed` output style.

* Emit a warning when `&&` is used, since it's probably not what the user means.

* `round()` now returns the correct results for negative numbers that should
  round down.

* `var()` may now be passed in place of multiple arguments to `rgb()`, `rgba()`,
  `hsl()` and `hsla()`.

* Fix some cases where equivalent numbers wouldn't count as the same keys in
  maps.

* Fix a bug where multiplication like `(1/1px) * (1px/1)` wouldn't properly
  cancel out units.

* Fix a bug where dividing by a compatible unit would produce an invalid
  result.

* Remove a non-`sh`-compatible idiom from the standalone shell script.

### Dart API

* Add a `functions` parameter to `compile()`, `compleString()`,
  `compileAsync()`, and `compileStringAsync()`. This allows users to define
  custom functions in Dart that can be invoked from Sass stylesheets.

* Expose the `Callable` and `AsyncCallable` types, which represent functions
  that can be invoked from Sass.

* Expose the `Value` type and its subclasses, as well as the top-level
  `sassTrue`, `sassFalse`, and `sassNull` values, which represent Sass values
  that may be passed into or returned from custom functions.

* Expose the `OutputStyle` enum, and add a `style` parameter to `compile()`,
  `compleString()`, `compileAsync()`, and `compileStringAsync()` that allows
  users to control the output style.

### Node JS API

* Support the `functions` option.

* Support the `"compressed"` value for the `outputStyle` option.

## 1.0.0-beta.4

* Support unquoted imports in the indented syntax.

* Fix a crash when `:not(...)` extends a selector that appears in
  `:not(:not(...))`.

### Node JS API

* Add support for asynchronous importers to `render()` and `renderSync()`.

### Dart API

* Add `compileAsync()` and `compileStringAsync()` methods. These run
  asynchronously, which allows them to take asynchronous importers (see below).

* Add an `AsyncImporter` class. This allows imports to be resolved
  asynchronously in case no synchronous APIs are available. `AsyncImporter`s are
  only compatible with `compileAysnc()` and `compileStringAsync()`.

## 1.0.0-beta.3

* Properly parse numbers with exponents.

* Don't crash when evaluating CSS variables whose names are entirely
  interpolated (for example, `#{--foo}: ...`).

### Node JS API

* Add support for the `importer` option to `render()` and `renderSync()`.
  Only synchronous importers are currently supported.

### Dart API

* Added an `Importer` class. This can be extended by users to provide support
  for custom resolution for `@import` rules.

* Added built-in `FilesystemImporter` and `PackageImporter` implementations that
  support resolving `file:` and `package:` URLs, respectively.

* Added an `importers` argument to the `compile()` and `compileString()`
  functions that provides `Importer`s to use when resolving `@import` rules.

* Added a `loadPaths` argument to the `compile()` and `compileString()`
  functions that provides paths to search for stylesheets when resolving
  `@import` rules. This is a shorthand for passing `FilesystemImporter`s to the
  `importers` argument.

## 1.0.0-beta.2

* Add support for the `::slotted()` pseudo-element.

* Generated transparent colors will now be emitted as `rgba(0, 0, 0, 0)` rather
  than `transparent`. This works around a bug wherein IE incorrectly handles the
  latter format.

### Command-Line Interface

* Improve the logic for whether to use terminal colors by default.

### Node JS API

* Add support for `data`, `includePaths`, `indentedSyntax`, `lineFeed`,
  `indentWidth`, and `indentType` options to `render()` and `renderSync()`.

* The result object returned by `render()` and `renderSync()` now includes the
  `stats` object which provides metadata about the compilation process.

* The error object thrown by `render()` and `renderSync()` now includes `line`,
  `column`, `file`, `status`, and `formatted` fields. The `message` field and
  `toString()` also provide more information.

### Dart API

* Add a `renderString()` method for rendering Sass source that's not in a file
  on disk.

## 1.0.0-beta.1

* Drop support for the reference combinator. This has been removed from the
  spec, and will be deprecated and eventually removed in other implementations.

* Trust type annotations when compiling to JavaScript, which makes it
  substantially faster.

* Compile to minified JavaScript, which decreases the code size substantially
  and makes startup a little faster.

* Fix a crash when inspecting a string expression that ended in "\a".

* Fix a bug where declarations and `@extend` were allowed outside of a style
  rule in certain circumstances.

* Fix `not` in parentheses in `@supports` conditions.

* Allow `url` as an identifier name.

* Properly parse `/***/` in selectors.

* Properly parse unary operators immediately after commas.

* Match Ruby Sass's rounding behavior for all functions.

* Allow `\` at the beginning of a selector in the indented syntax.

* Fix a number of `@extend` bugs:

  * `selector-extend()` and `selector-replace()` now allow compound selector
    extendees.

  * Remove the universal selector `*` when unifying with other selectors.

  * Properly unify the result of multiple simple selectors in the same compound
    selector being extended.

  * Properly handle extensions being extended.

  * Properly follow the [first law of `@extend`][laws].

  * Fix selector specificity tracking to follow the
    [second law of `@extend`][laws].

  * Allow extensions that match selectors but fail to unify.

  * Partially-extended selectors are no longer used as parent selectors.

  * Fix an edge case where both the extender and the extended selector
    have invalid combinator sequences.

  * Don't crash with a "Bad state: no element" error in certain edge cases.

[laws]: https://github.com/sass/sass/issues/324#issuecomment-4607184

## 1.0.0-alpha.9

* Elements without a namespace (such as `div`) are no longer unified with
  elements with the empty namespace (such as `|div`). This unification didn't
  match the results returned by `is-superselector()`, and was not guaranteed to
  be valid.

* Support `&` within `@at-root`.

* Properly error when a compound selector is followed immediately by `&`.

* Properly handle variable scoping in `@at-root` and nested properties.

* Properly handle placeholder selectors in selector pseudos.

* Properly short-circuit the `or` and `and` operators.

* Support `--$variable`.

* Don't consider unitless numbers equal to numbers with units.

* Warn about using named colors in interpolation.

* Don't emit loud comments in functions.

* Detect import loops.

* Fix `@import` with a `supports()` clause.

* Forbid functions named "and", "or", and "not".

* Fix `type-of()` with a function.

* Emit a nicer error for invalid tokens in a selector.

* Fix `invert()` with a `$weight` parameter.

* Fix a unit-parsing edge-cases.

* Always parse imports with queries as plain CSS imports.

* Support `&` followed by a non-identifier.

* Properly handle split media queries.

* Properly handle a placeholder selector that isn't at the beginning of a
  compound selector.

* Fix more `str-slice()` bugs.

* Fix the `%` operator.

* Allow whitespace between `=` and the mixin name in the indented syntax.

* Fix some slash division edge cases.

* Fix `not` when used like a function.

* Fix attribute selectors with single-character values.

* Fix some bugs with the `call()` function.

* Properly handle a backslash followed by a CRLF sequence in a quoted string.

* Fix numbers divided by colors.

* Support slash-separated numbers in arguments to plain CSS functions.

* Error out if a function is passed an unknown named parameter.

* Improve the speed of loading large files on Node.

* Don't consider browser-prefixed selector pseudos to be superselectors of
  differently- or non-prefixed selector pseudos with the same base name.

* Fix an `@extend` edge case involving multiple combinators in a row.

* Fix a bug where a `@content` block could get incorrectly passed to a mixin.

* Properly isolate the lexical environments of different calls to the same mixin
  and function.

## 1.0.0-alpha.8

* Add the `content-exists()` function.

* Support interpolation in loud comments.

* Fix a bug where even valid semicolons and exclamation marks in custom property
  values were disallowed.

* Disallow invalid function names.

* Disallow extending across media queries.

* Properly parse whitespace after `...` in argument declaration lists.

* Support terse mixin syntax in the indented syntax.

* Fix `@at-root` query parsing.

* Support special functions in `@-moz-document`.

* Support `...` after a digit.

* Fix some bugs when treating a map as a list of pairs.

## 1.0.0-alpha.7

* Fix `function-exists()`, `variable-exists()`, and `mixin-exists()` to use the
  lexical scope rather than always using the global scope.

* `str-index()` now correctly inserts at negative indices.

* Properly parse `url()`s that contain comment-like text.

* Fix a few more small `@extend` bugs.

* Fix a bug where interpolation in a quoted string was being dropped in some
  circumstances.

* Properly handle `@for` rules where each bound has a different unit.

* Forbid mixins and functions from being defined in control directives.

* Fix a superselector-computation edge case involving `:not()`.

* Gracefully handle input files that are invalid UTF-8.

* Print a Sass stack trace when a file fails to load.

## 1.0.0-alpha.6

* Allow `var()` to be passed to `rgb()`, `rgba()`, `hsl()`, and `hsla()`.

* Fix conversions between numbers with `dpi`, `dpcm`, and `dppx` units.
  Previously these conversions were inverted.

* Don't crash when calling `str-slice()` with an `$end-at` index lower than the
  `$start-at` index.

* `str-slice()` now correctly returns `""` when `$end-at` is negative and points
  before the beginning of the string.

* Interpolation in quoted strings now properly preserves newlines.

* Don't crash when passing only `$hue` or no keyword arguments to
  `adjust-color()`, `scale-color()`, or `change-color()`.

* Preserve escapes in identifiers. This used to only work for identifiers in
  SassScript.

* Fix a few small `@extend` bugs.

## 1.0.0-alpha.5

* Fix bounds-checking for `opacify()`, `fade-in()`, `transparentize()`, and
  `fade-out()`.

* Fix a bug with `@extend` superselector calculations.

* Fix some cases where `#{...}--` would fail to parse in selectors.

* Allow a single number to be passed to `saturate()` for use in filter contexts.

* Fix a bug where `**/` would fail to close a loud comment.

* Fix a bug where mixin and function calls could set variables incorrectly.

* Move plain CSS `@import`s to the top of the document.

## 1.0.0-alpha.4

* Add support for bracketed lists.

* Add support for Unicode ranges.

* Add support for the Microsoft-style `=` operator.

* Print the filename for `@debug` rules.

* Fix a bug where `1 + - 2` and similar constructs would crash the parser.

* Fix a bug where `@extend` produced the wrong result when used with
  selector combinators.

* Fix a bug where placeholder selectors were not allowed to be unified.

* Fix the `mixin-exists()` function.

* Fix `:nth-child()` and `:nth-last-child()` parsing when they contain `of
  selector`.

## 1.0.0-alpha.3

* Fix a bug where color equality didn't take the alpha channel into account.

* Fix a bug with converting some RGB colors to HSL.

* Fix a parent selector resolution bug.

* Properly declare the arguments for `opacify()` and related functions.

* Add a missing dependency on the `stack_trace` package.

* Fix broken Windows archives.

* Emit colors using their original representation if possible.

* Emit colors without an original representation as names if possible.

## 1.0.0-alpha.2

* Fix a bug where variables, functions, and mixins were broken in imported
  files.

## 1.0.0-alpha.1

* Initial alpha release.