Compatibility:

Dart Sass

since 1.23.0

LibSass

✗

Ruby Sass

✗

▶

The simplest @use rule is written @use "<url>", which loads the module at the given URL. Any styles loaded this way will be included exactly once in the compiled CSS output, no matter how many times those styles are loaded.

// foundation/_code.scss
code {
  padding: .25em;
  line-height: 0;
}

// foundation/_lists.scss
ul, ol {
  text-align: left;

  & & {
    padding: {
      bottom: 0;
      left: 0;
    }
  }
}

// style.scss
@use 'foundation/code';
@use 'foundation/lists';

// foundation/_code.sass
code
  padding: .25em
  line-height: 0

// foundation/_lists.sass
ul, ol
  text-align: left

  & &
    padding:
      bottom: 0
      left: 0

// style.sass
@use 'foundation/code'
@use 'foundation/lists'

code {
  padding: .25em;
  line-height: 0;
}

ul, ol {
  text-align: left;
}
ul ul, ol ol {
  padding-bottom: 0;
  padding-left: 0;
}

Loading Members

You can access variables, functions, and mixins from another module by writing <namespace>.<variable>, <namespace>.<function>(), or @include <namespace>.<mixin>(). By default, the namespace is just the last component of the module’s URL.

Members (variables, functions, and mixins) loaded with @use are only visible in the stylesheet that loads them. Other stylesheets will need to write their own @use rules if they also want to access them. This helps make it easy to figure out exactly where each member is coming from. If you want to load members from many files at once, you can use the @forward rule to forward them all from one shared file.

// src/_corners.scss
$radius: 3px;

@mixin rounded {
  border-radius: $radius;
}

// style.scss
@use "src/corners";

.button {
  @include corners.rounded;
  padding: 5px + corners.$radius;
}

// src/_corners.sass
$radius: 3px

@mixin rounded
  border-radius: $radius

// style.sass
@use "src/corners"

.button
  @include corners.rounded
  padding: 5px + corners.$radius

.button {
  border-radius: 3px;
  padding: 8px;
}

Choosing a Namespace

By default, a module’s namespace is just the last component of its URL without a file extension. However, sometimes you might want to choose a different namespace—you might want to use a shorter name for a module you refer to a lot, or you might be loading multiple modules with the same filename. You can do this by writing @use "<url>" as <namespace>.

// src/_corners.scss
$radius: 3px;

@mixin rounded {
  border-radius: $radius;
}

// style.scss
@use "src/corners" as c;

.button {
  @include c.rounded;
  padding: 5px + c.$radius;
}

// src/_corners.sass
$radius: 3px

@mixin rounded
  border-radius: $radius

// style.sass
@use "src/corners" as c

.button
  @include c.rounded
  padding: 5px + c.$radius

.button {
  border-radius: 3px;
  padding: 8px;
}

You can even load a module without a namespace by writing @use "<url>" as *. We recommend you only do this for stylesheets written by you, though; otherwise, they may introduce new members that cause name conflicts!

// src/_corners.scss
$radius: 3px;

@mixin rounded {
  border-radius: $radius;
}

// style.scss
@use "src/corners" as *;

.button {
  @include rounded;
  padding: 5px + $radius;
}

// src/_corners.sass
$radius: 3px

@mixin rounded
  border-radius: $radius

// style.sass
@use "src/corners" as *

.button
  @include rounded
  padding: 5px + $radius

.button {
  border-radius: 3px;
  padding: 8px;
}

Private Members

As a stylesheet author, you may not want all the members you define to be available outside your stylesheet. Sass makes it easy to define a private member by starting its name with either - or _. These members will work just like normal within the stylesheet that defines them, but they won’t be part of a module’s public API. That means stylesheets that load your module can’t see them!

// src/_corners.scss
$-radius: 3px;

@mixin rounded {
  border-radius: $-radius;
}

// style.scss
@use "src/corners";

.button {
  @include corners.rounded;

  // This is an error! $-radius isn't visible outside of `_corners.scss`.
  padding: 5px + corners.$-radius;
}

// src/_corners.sass
$-radius: 3px

@mixin rounded
  border-radius: $radius

// style.sass
@use "src/corners"

.button
  @include corners.rounded

  // This is an error! $-radius isn't visible outside of `_corners.scss`.
  padding: 5px + corners.$-radius

Configuration

A stylesheet can define variables with the !default flag to make them configurable. To load a module with configuration, write @use <url> with (<variable>: <value>, <variable>: <value>). The configured values will override the variables’ default values.

// _library.scss
$black: #000 !default;
$border-radius: 0.25rem !default;
$box-shadow: 0 0.5rem 1rem rgba($black, 0.15) !default;

code {
  border-radius: $border-radius;
  box-shadow: $box-shadow;
}

// style.scss
@use 'library' with (
  $black: #222,
  $border-radius: 0.1rem
);

// _library.sass
$black: #000 !default
$border-radius: 0.25rem !default
$box-shadow: 0 0.5rem 1rem rgba($black, 0.15) !default

code
  border-radius: $border-radius
  box-shadow: $box-shadow

// style.sass
@use 'library' with ($black: #222, $border-radius: 0.1rem)

code {
  border-radius: 0.1rem;
  box-shadow: 0 0.5rem 1rem rgba(34, 34, 34, 0.15);
}

With Mixins

Configuring modules with @use ... with can be very handy, especially when using libraries that were originally written to work with the @import rule. But it’s not particularly flexible, and we don’t recommend it for more advanced use-cases. If you find yourself wanting to configure many variables at once, pass maps as configuration, or update the configuration after the module is loaded, consider writing a mixin to set your variables instead and another mixin to inject your styles.

// _library.scss
$-black: #000;
$-border-radius: 0.25rem;
$-box-shadow: null;

/// If the user has configured `$-box-shadow`, returns their configured value.
/// Otherwise returns a value derived from `$-black`.
@function -box-shadow() {
  @return $-box-shadow or (0 0.5rem 1rem rgba($-black, 0.15));
}

@mixin configure($black: null, $border-radius: null, $box-shadow: null) {
  @if $black {
    $-black: $black !global;
  }
  @if $border-radius {
    $-border-radius: $border-radius !global;
  }
  @if $box-shadow {
    $-box-shadow: $box-shadow !global;
  }
}

@mixin styles {
  code {
    border-radius: $-border-radius;
    box-shadow: -box-shadow();
  }
}

// style.scss
@use 'library';

@include library.configure(
  $black: #222,
  $border-radius: 0.1rem
);

@include library.styles;

// _library.sass
$-black: #000
$-border-radius: 0.25rem
$-box-shadow: null

/// If the user has configured `$-box-shadow`, returns their configured value.
/// Otherwise returns a value derived from `$-black`.
@function -box-shadow()
  @return $-box-shadow or (0 0.5rem 1rem rgba($-black, 0.15))


@mixin configure($black: null, $border-radius: null, $box-shadow: null)
  @if $black
    $-black: $black !global
  @if $border-radius
    $-border-radius: $border-radius !global
  @if $box-shadow
    $-box-shadow: $box-shadow !global


@mixin styles
  code
    border-radius: $-border-radius
    box-shadow: -box-shadow()

// style.sass
@use 'library'
@include library.configure($black: #222, $border-radius: 0.1rem)
@include library.styles

code {
  border-radius: 0.1rem;
  box-shadow: 0 0.5rem 1rem rgba(34, 34, 34, 0.15);
}

Finding the Module

It wouldn’t be any fun to write out absolute URLs for every stylesheet you load, so Sass’s algorithm for finding a module makes it a little easier. For starters, you don’t have to explicitly write out the extension of the file you want to load; @use "variables" will automatically load variables.scss, variables.sass, or variables.css.

Load Paths

All Sass implementations allow users to provide load paths: paths on the filesystem that Sass will look in when locating modules. For example, if you pass node_modules/susy/sass as a load path, you can use @use "susy" to load node_modules/susy/sass/susy.scss.

Modules will always be loaded relative to the current file first, though. Load paths will only be used if no relative file exists that matches the module’s URL. This ensures that you can’t accidentally mess up your relative imports when you add a new library.

Partials

As a convention, Sass files that are only meant to be loaded as modules, not compiled on their own, begin with _ (as in _code.scss). These are called partials, and they tell Sass tools not to try to compile those files on their own. You can leave off the _ when importing a partial.

Index Files

If you write an _index.scss or _index.sass in a folder, the index file will be loaded automatically when you load the URL for the folder itself.

// foundation/_code.scss
code {
  padding: .25em;
  line-height: 0;
}

// foundation/_lists.scss
ul, ol {
  text-align: left;

  & & {
    padding: {
      bottom: 0;
      left: 0;
    }
  }
}

// foundation/_index.scss
@use 'code';
@use 'lists';

// style.scss
@use 'foundation';

// foundation/_code.sass
code
  padding: .25em
  line-height: 0

// foundation/_lists.sass
ul, ol
  text-align: left

  & &
    padding:
      bottom: 0
      left: 0

// foundation/_index.sass
@use 'code'
@use 'lists'

// style.sass
@use 'foundation'

code {
  padding: .25em;
  line-height: 0;
}

ul, ol {
  text-align: left;
}
ul ul, ol ol {
  padding-bottom: 0;
  padding-left: 0;
}

Loading CSS

In addition to loading .sass and .scss files, Sass can load plain old .css files.

// code.css
code {
  padding: .25em;
  line-height: 0;
}

// style.scss
@use 'code';

// code.css
code {
  padding: .25em;
  line-height: 0;
}

// style.sass
@use 'code'

code {
  padding: .25em;
  line-height: 0;
}

CSS files loaded as modules don’t allow any special Sass features and so can’t expose any Sass variables, functions, or mixins. In order to make sure authors don’t accidentally write Sass in their CSS, all Sass features that aren’t also valid CSS will produce errors. Otherwise, the CSS will be rendered as-is. It can even be extended!