Built-In Modules

Dart Sass: since 1.23.0
LibSass: ✗
Ruby Sass: ✗

Only Dart Sass currently supports loading built-in modules with @use. Users of other implementations must call functions using their global names instead.

Sass provides many built-in modules which contain useful functions (and the occasional mixin). These modules can be loaded with the @use rule like any user-defined stylesheet, and their functions can be called like any other module member. All built-in module URLs begin with sass: to indicate that they’re part of Sass itself.

⚠️ Heads up!

Before the Sass module system was introduced, all Sass functions were globally available at all times. Many functions still have global aliases (these are listed in their documentation). The Sass team discourages their use and will eventually deprecate them, but for now they remain available for compatibility with older Sass versions and with LibSass (which doesn’t support the module system yet).

A few functions are only available globally even in the new module system, either because they have special evaluation behavior (if()) or because they add extra behavior on top of built-in CSS functions (rgb() and hsl()). These will not be deprecated and can be used freely.

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  Sass

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    SCSS Syntax@use "sass:color";

.button {
  $primary-color: #6b717f;
  color: $primary-color;
  border: 1px solid color.scale($primary-color, $lightness: 20%);
}

      
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    Sass Syntax@use "sass:color"

.button
  $primary-color: #6b717f
  color: $primary-color
  border: 1px solid color.scale($primary-color, $lightness: 20%)

CSS Output.button {
  color: #6b717f;
  border: 1px solid rgb(135.1641025641, 140.8256410256, 154.0358974359);
}

Sass provides the following built-in modules:

The sass:math module provides functions that operate on numbers.
The sass:string module makes it easy to combine, search, or split apart strings.
The sass:color module generates new colors based on existing ones, making it easy to build color themes.
The sass:list module lets you access and modify values in lists.
The sass:map module makes it possible to look up the value associated with a key in a map, and much more.
The sass:selector module provides access to Sass’s powerful selector engine.
The sass:meta module exposes the details of Sass’s inner workings.

Global FunctionsGlobal Functions permalink

💡 Fun fact:

You can pass special functions like calc() or var() in place of any argument to a global color constructor. You can even use var() in place of multiple arguments, since it might be replaced by multiple values! When a color function is called this way, it returns an unquoted string using the same signature it was called with.

SCSS

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  SCSS Syntax@debug rgb(0 51 102 / var(--opacity)); // rgb(0 51 102 / var(--opacity))
@debug color(display-p3 var(--peach)); // color(display-p3 var(--peach))

    
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  Sass Syntax@debug rgb(0 51 102 / var(--opacity))  // rgb(0 51 102 / var(--opacity))
@debug color(display-p3 var(--peach))  // color(display-p3 var(--peach))

color($space $channel1 $channel2 $channel3)
color($space $channel1 $channel2 $channel3 / $alpha) //=> color

Dart Sass: since 1.78.0
LibSass: ✗
Ruby Sass: ✗

Returns a color in the given color space with the given channel values.

This supports the color spaces srgb, srgb-linear, display-p3, a98-rgb, prophoto-rgb, rec2020, xyz, and xyz-d50, as well as xyz-d65 which is an alias for xyz. For all spaces, the channels are numbers between 0 and 1 (inclusive) or percentages between 0% and 100% (inclusive).

If any color channel is outside the range 0 to 1, this represents a color outside the standard gamut for its color space.

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    SCSS Syntax@debug color(srgb 0.1 0.6 1); // color(srgb 0.1 0.6 1)
@debug color(xyz 30% 0% 90% / 50%); // color(xyz 0.3 0 0.9 / 50%)

      
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    Sass Syntax@debug color(srgb 0.1 0.6 1)  // color(srgb 0.1 0.6 1)
@debug color(xyz 30% 0% 90% / 50%)  // color(xyz 0.3 0 0.9 / 50%)

hsl($hue $saturation $lightness)
hsl($hue $saturation $lightness / $alpha)
hsl($hue, $saturation, $lightness, $alpha: 1)
hsla($hue $saturation $lightness)
hsla($hue $saturation $lightness / $alpha)
hsla($hue, $saturation, $lightness, $alpha: 1) //=> color

Dart Sass: since 1.15.0
LibSass: ✗
Ruby Sass: ✗

LibSass and Ruby Sass only support the following signatures:

hsl($hue, $saturation, $lightness)
hsla($hue, $saturation, $lightness, $alpha)

Note that for these implementations, the $alpha argument is required if the function name hsla() is used, and forbidden if the function name hsl() is used.

Dart Sass: ✓
LibSass: ✗
Ruby Sass: since 3.7.0

LibSass and older versions of Ruby Sass don’t support alpha values specified as percentages.

Returns a color with the given hue, saturation, and lightness and the given alpha channel.

The hue is a number between 0deg and 360deg (inclusive) and may be unitless. The saturation and lightness are typically numbers between 0% and 100% (inclusive) and may not be unitless. The alpha channel can be specified as either a unitless number between 0 and 1 (inclusive), or a percentage between 0% and 100% (inclusive).

A hue outside 0deg and 360deg is equivalent to $hue % 360deg. A saturation less than 0% is clamped to 0%. A saturation above 100% or a lightness outside 0% and 100% are both allowed, and represent colors outside the standard RGB gamut.

⚠️ Heads up!

Sass’s special parsing rules for slash-separated values make it difficult to pass variables for $lightness or $alpha when using the hsl($hue $saturation $lightness / $alpha) signature. Consider using hsl($hue, $saturation, $lightness, $alpha) instead.

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    SCSS Syntax@debug hsl(210deg 100% 20%); // #036
@debug hsl(210deg 100% 20% / 50%); // rgba(0, 51, 102, 0.5)
@debug hsla(34, 35%, 92%, 0.2); // rgba(241.74, 235.552, 227.46, 0.2)

      
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    Sass Syntax@debug hsl(210deg 100% 20%) // #036
@debug hsl(210deg 100% 20% / 50%)  // rgba(0, 51, 102, 0.5)
@debug hsla(34, 35%, 92%, 0.2)  // rgba(241.74, 235.552, 227.46, 0.2)

hwb($hue $whiteness $blackness)
hwb($hue $whiteness $blackness / $alpha)
color.hwb($hue $whiteness $blackness)
color.hwb($hue $whiteness $blackness / $alpha)
color.hwb($hue, $whiteness, $blackness, $alpha: 1) //=> color

Dart Sass: since 1.78.0
LibSass: ✗
Ruby Sass: ✗

Returns a color with the given hue, whiteness, and blackness and the given alpha channel.

The hue is a number between 0deg and 360deg (inclusive) and may be unitless. The whiteness and blackness are numbers typically between 0% and 100% (inclusive) and may not be unitless. The alpha channel can be specified as either a unitless number between 0 and 1 (inclusive), or a percentage between 0% and 100% (inclusive).

A hue outside 0deg and 360deg is equivalent to $hue % 360deg. If $whiteness + $blackness > 100%, the two values are scaled so that they add up to 100%. If $whiteness, $blackness, or both are less than 0%, this represents a color outside the standard RGB gamut.

⚠️ Heads up!

The color.hwb() variants are deprecated. New Sass code should use the global hwb() function instead.

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    SCSS Syntax@debug hwb(210deg 0% 60%); // #036
@debug hwb(210 0% 60% / 0.5); // rgba(0, 51, 102, 0.5)

      
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    Sass Syntax@debug hwb(210deg 0% 60%)  // #036
@debug hwb(210 0% 60% / 0.5)  // rgba(0, 51, 102, 0.5)

if($condition, $if-true, $if-false)

Returns $if-true if $condition is truthy, and $if-false otherwise.

This function is special in that it doesn’t even evaluate the argument that isn’t returned, so it’s safe to call even if the unused argument would throw an error.

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    SCSS Syntax@debug if(true, 10px, 15px); // 10px
@debug if(false, 10px, 15px); // 15px
@debug if(variable-defined($var), $var, null); // null

      
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    Sass Syntax@debug if(true, 10px, 15px)  // 10px
@debug if(false, 10px, 15px)  // 15px
@debug if(variable-defined($var), $var, null)  // null

lab($lightness $a $b)
lab($lightness $a $b / $alpha) //=> color

Dart Sass: since 1.78.0
LibSass: ✗
Ruby Sass: ✗

Returns a color with the given [lightness, a, b], and alpha channels.

The lightness is a number between 0% and 100% (inclusive) and may be unitless. The a and b channels can be specified as either unitless numbers between -125 and 125 (inclusive), or percentages between -100% and 100% (inclusive). The alpha channel can be specified as either a unitless number between 0 and 1 (inclusive), or a percentage between 0% and 100% (inclusive).

A lightness outside the range 0% and 100% is clamped to be within that range. If the a or b channels are outside the range -125 to 125, this represents a color outside the standard CIELAB gamut.

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    SCSS Syntax@debug lab(50% -20 30); // lab(50% -20 30)
@debug lab(80% 0% 20% / 0.5); // lab(80% 0 25 / 0.5);

      
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    Sass Syntax@debug lab(50% -20 30)  // lab(50% -20 30)
@debug lab(80% 0% 20% / 0.5)  // lab(80% 0 25 / 0.5);

lch($lightness $chroma $hue)
lch($lightness $chroma $hue / $alpha) //=> color

Dart Sass: since 1.78.0
LibSass: ✗
Ruby Sass: ✗

Returns a color with the given [lightness, chroma, and hue], and the given alpha channel.

The lightness is a number between 0% and 100% (inclusive) and may be unitless. The chroma channel can be specified as either a unitless number between 0 and 150 (inclusive), or a percentage between 0% and 100% (inclusive). The hue is a number between 0deg and 360deg (inclusive) and may be unitless. The alpha channel can be specified as either a unitless number between 0 and 1 (inclusive), or a percentage between 0% and 100% (inclusive).

A lightness outside the range 0% and 100% is clamped to be within that range. A chroma below 0 is clamped to 0, and a chroma above 150 represents a color outside the standard CIELAB gamut. A hue outside 0deg and 360deg is equivalent to $hue % 360deg.

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    SCSS Syntax@debug lch(50% 10 270deg); // lch(50% 10 270deg)
@debug lch(80% 50% 0.2turn / 0.5); // lch(80% 75 72deg / 0.5);

      
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    Sass Syntax@debug lch(50% 10 270deg)  // lch(50% 10 270deg)
@debug lch(80% 50% 0.2turn / 0.5)  // lch(80% 75 72deg / 0.5);

oklab($lightness $a $b)
oklab($lightness $a $b / $alpha) //=> color

Dart Sass: since 1.78.0
LibSass: ✗
Ruby Sass: ✗

Returns a color with the given perceptually-uniform lightness, a, b, and alpha channels.

The lightness is a number between 0% and 100% (inclusive) and may be unitless. The a and b channels can be specified as either unitless numbers between -0.4 and 0.4 (inclusive), or percentages between -100% and 100% (inclusive). The alpha channel can be specified as either a unitless number between 0 and 1 (inclusive), or a percentage between 0% and 100% (inclusive).

A lightness outside the range 0% and 100% is clamped to be within that range. If the a or b channels are outside the range -0.4 to 0.4, this represents a color outside the standard Oklab gamut.

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    SCSS Syntax@debug oklab(50% -0.1 0.15); // oklab(50% -0.1 0.15)
@debug oklab(80% 0% 20% / 0.5); // oklab(80% 0 0.08 / 0.5)

      
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    Sass Syntax@debug oklab(50% -0.1 0.15)  // oklab(50% -0.1 0.15)
@debug oklab(80% 0% 20% / 0.5)  // oklab(80% 0 0.08 / 0.5)

oklch($lightness $chroma $hue)
oklch($lightness $chroma $hue / $alpha) //=> color

Dart Sass: since 1.78.0
LibSass: ✗
Ruby Sass: ✗

Returns a color with the given [perceptually-uniform lightness, chroma, and hue], and the given alpha channel.

The lightness is a number between 0% and 100% (inclusive) and may be unitless. The chroma channel can be specified as either a unitless number between 0 and 0.4 (inclusive), or a percentage between 0% and 100% (inclusive). The hue is a number between 0deg and 360deg (inclusive) and may be unitless. The alpha channel can be specified as either a unitless number between 0 and 1 (inclusive), or a percentage between 0% and 100% (inclusive).

A lightness outside the range 0% and 100% is clamped to be within that range. A chroma below 0 is clamped to 0, and a chroma above 0.4 represents a color outside the standard Oklab gamut. A hue outside 0deg and 360deg is equivalent to $hue % 360deg.

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      Playground
    SCSS Syntax@debug oklch(50% 0.3 270deg); // oklch(50% 0.3 270deg)
@debug oklch(80% 50% 0.2turn / 0.5); // oklch(80% 0.2 72deg / 0.5);

      
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    Sass Syntax@debug oklch(50% 0.3 270deg)  // oklch(50% 0.3 270deg)
@debug oklch(80% 50% 0.2turn / 0.5)  // oklch(80% 0.2 72deg / 0.5);

rgb($red $green $blue)
rgb($red $green $blue / $alpha)
rgb($red, $green, $blue, $alpha: 1)
rgb($color, $alpha)
rgba($red $green $blue)
rgba($red $green $blue / $alpha)
rgba($red, $green, $blue, $alpha: 1)
rgba($color, $alpha) //=> color

Dart Sass: since 1.15.0
LibSass: ✗
Ruby Sass: ✗

LibSass and Ruby Sass only support the following signatures:

rgb($red, $green, $blue)
rgba($red, $green, $blue, $alpha)
rgba($color, $alpha)

Note that for these implementations, the $alpha argument is required if the function name rgba() is used, and forbidden if the function name rgb() is used.

Dart Sass: ✓
LibSass: ✗
Ruby Sass: since 3.7.0

LibSass and older versions of Ruby Sass don’t support alpha values specified as percentages.

If $red, $green, $blue, and optionally $alpha are passed, returns a color with the given red, green, blue, and alpha channels.

Each channel can be specified as either a unitless number between 0 and 255 (inclusive), or a percentage between 0% and 100% (inclusive). The alpha channel can be specified as either a unitless number between 0 and 1 (inclusive), or a percentage between 0% and 100% (inclusive).

If any color channel is outside the range 0 to 255, this represents a color outside the standard RGB gamut.

⚠️ Heads up!

Sass’s special parsing rules for slash-separated values make it difficult to pass variables for $blue or $alpha when using the rgb($red $green $blue / $alpha) signature. Consider using rgb($red, $green, $blue, $alpha) instead.

  SCSS

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      Playground
    SCSS Syntax@debug rgb(0 51 102); // #036
@debug rgb(95%, 92.5%, 89.5%); // #f2ece4
@debug rgb(0 51 102 / 50%); // rgba(0, 51, 102, 0.5)
@debug rgba(95%, 92.5%, 89.5%, 0.2); // rgba(242, 236, 228, 0.2)

      
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    Sass Syntax@debug rgb(0 51 102)  // #036
@debug rgb(95%, 92.5%, 89.5%)  // #f2ece4
@debug rgb(0 51 102 / 50%)  // rgba(0, 51, 102, 0.5)
@debug rgba(95%, 92.5%, 89.5%, 0.2)  // rgba(242, 236, 228, 0.2)

If $color and $alpha are passed, this returns $color with the given $alpha channel instead of its original alpha channel.

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    SCSS Syntax@debug rgb(#f2ece4, 50%); // rgba(242, 236, 228, 0.5);
@debug rgba(rgba(0, 51, 102, 0.5), 1); // #003366

      
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    Sass Syntax@debug rgb(#f2ece4, 50%)  // rgba(242, 236, 228, 0.5)
@debug rgba(rgba(0, 51, 102, 0.5), 1)  // #003366