Mantine PostCSS preset

postcss-preset-mantine provides several CSS functions and mixins to help you write styles. It is not required to use it, but highly recommended. All demos that feature styles assume that you have this preset installed.

postcss-preset-mantine includes the following PostCSS plugins:

• postcss-nested
• postcss-mixins with Mantine specific mixins
• Custom plugin with em/rem functions

Installation

Install postcss-preset-mantine as a dev dependency:

yarn add --dev postcss-preset-mantine

Usage

Note that setting up PostCSS may be different depending on your build tool/framework, check a dedicated framework guide to learn more. Add postcss-preset-mantine to your postcss.config.cjs file (usually it is located in the root of your project):

module.exports = {
  plugins: {
    'postcss-preset-mantine': {},
  },
};

All done! You can now use all the features of the preset.

rem/em functions

rem and em functions can be used to convert pixels to rem/em units. 16px = 1rem and 16px = 1em, em values are supposed to be used in media queries, rem everywhere else. You can learn more about units conversions in this guide.

.demo {
  font-size: rem(16px);

  @media (min-width: em(320px)) {
    font-size: rem(32px);
  }
}

Will be transformed to:

.demo {
  font-size: calc(1rem * var(--mantine-scale));

  @media (min-width: 20em) {
    font-size: calc(2rem * var(--mantine-scale));
  }
}

Auto convert px to rem

autoRem option can be used to automatically convert all pixel values to rem units in .css files:

module.exports = {
  plugins: {
    'postcss-preset-mantine': {
      autoRem: true,
    },
  },
};

This option works similar to rem function. The following code:

.demo {
  font-size: 16px;

  @media (min-width: 320px) {
    font-size: 32px;
  }
}

Will be transformed to:

.demo {
  font-size: calc(1rem * var(--mantine-scale));

  @media (min-width: 320px) {
    font-size: calc(2rem * var(--mantine-scale));
  }
}

Note that autoRem converts only CSS properties, values in @media queries are not converted automatically – you still need to use em function to convert them.

autoRem option does not convert values in the following cases:

• Values in calc(), var(), clamp() and url() functions
• Values in content property
• Values that contain rgb(), rgba(), hsl(), hsla() colors

If you want to convert above values to rem units, use rem function manually.

dark and light mixins

dark and light mixins can be used to create styles that will be applied only in dark or light color scheme.

.demo {
  @mixin light {
    color: red;
  }

  @mixin dark {
    color: blue;
  }
}

Will be transformed to:

[data-mantine-color-scheme='light'] .demo {
  color: red;
}

[data-mantine-color-scheme='dark'] .demo {
  color: blue;
}

Note that usually you do not need to use both light and dark mixins at the same time. It is easier to define styles for light color scheme and then use dark mixin to override them in dark color scheme.

.demo {
  // Value for light color scheme
  color: red;

  @mixin dark {
    // Value for dark color scheme
    color: blue;
  }
}

To define values for light/dark color scheme on the :root/html element, use light-root and dark-root mixins instead:

:root {
  @mixin light-root {
    --color: red;
  }

  @mixin dark-root {
    --color: blue;
  }
}

smaller-than and larger-than mixins

smaller-than and larger-than mixins can be used to create styles that will be applied only when the screen is smaller or larger than specified breakpoint.

.demo {
  @mixin smaller-than 320px {
    color: red;
  }

  @mixin larger-than 320px {
    color: blue;
  }
}

Will be transformed to:

// Breakpoint values are converted to em units
// In smaller-than mixin 0.1px is subtracted from breakpoint value
// to avoid intersection with larger-than mixin
@media (max-width: 19.99375em) {
  .demo {
    color: red;
  }
}

@media (min-width: 20em) {
  .demo {
    color: blue;
  }
}

You can also use smaller-than and larger-than mixins with mantine breakpoints:

.demo {
  @mixin smaller-than $mantine-breakpoint-sm {
    color: red;
  }

  @mixin larger-than $mantine-breakpoint-sm {
    color: blue;
  }
}

light-dark function

light-dark function is an alternative to light and dark mixins. It accepts two arguments: first argument is rule that will be applied in light color scheme, second argument is rule that will be applied in dark color scheme.

.demo {
  color: light-dark(red, blue);
}

Will be transformed to:

.demo {
  color: red;
}

[data-mantine-color-scheme='dark'] .demo {
  color: blue;
}

Note that light-dark function does not work on :root/html element. Use light-root and dark-root mixins instead:

// ❌ Does not work
:root {
  --color: light-dark(red, blue);
}

// ✅ Works
:root {
  @mixin light-root {
    --color: red;
  }

  @mixin dark-root {
    --color: blue;
  }
}

alpha function

alpha function can be used to add alpha channel to color. Note that it uses color-mix which is not supported in some older browsers.

.demo {
  color: alpha(var(--mantine-color-red-4), 0.5);
  border: 1px solid alpha(#ffc, 0.2);
}

Will be transformed to:

.demo {
  color: color-mix(
    in srgb,
    var(--mantine-color-red-4),
    transparent 50%
  );
  border: 1px solid color-mix(in srgb, #ffc, transparent 80%);
}

lighten and darken functions

lighten and darken functions work similar to alpha function, but instead of adding alpha channel they add white or black color to the color with color-mix.

.demo {
  color: lighten(var(--mantine-color-red-4), 0.5);
  border: 1px solid darken(#ffc, 0.2);
}

Will be transformed to:

.demo {
  color: color-mix(in srgb, var(--mantine-color-red-4), white 50%);
  border: 1px solid color-mix(in srgb, #ffc, black 20%);
}

hover mixin

hover mixin can be used to create styles that will be applied on hover.

.demo {
  @mixin hover {
    color: orange;
  }
}

Will be transformed to:

@media (hover: hover) {
  .demo:hover {
    color: orange;
  }
}

@media (hover: none) {
  .demo:active {
    color: orange;
  }
}

rtl/ltr mixins

rtl mixin can be used to create styles that will be applied when dir="rtl" is set on parent element (usually <html />).

.demo {
  margin-left: 1rem;

  @mixin rtl {
    margin-left: 0;
    margin-right: 1rem;
  }
}

Will be transformed to:

.demo {
  margin-left: 1rem;
}

[dir='rtl'] .demo {
  margin-left: 0;
  margin-right: 1rem;
}

ltr mixin works the same way, but for dir="ltr":

.demo {
  margin-left: 1rem;

  @mixin ltr {
    margin-left: 0;
    margin-right: 1rem;
  }
}

Will be transformed to:

.demo {
  margin-left: 1rem;
}

[dir='ltr'] .demo {
  margin-left: 0;
  margin-right: 1rem;
}

not-rtl/not-ltr mixins

not-rtl/not-ltr mixins can be used to create styles that will be applied when the direction is set to the opposite value or not set at all. For example, not-rtl styles will be applied when dir="ltr" or when dir is not set at all.

.demo {
  @mixin not-rtl {
    margin-right: 1rem;
  }
}

Will be transformed to:

:root:not([dir='rtl']) .demo {
  margin-right: 1rem;
}