# Color modes

> CoreUI now supports color modes, or themes, as of v5.0.0. Explore our default light color mode and the new dark mode, or create your own using our styles as your template.

**Try it yourself!** Download the source code and working demo for using CoreUI for Bootstrap with Stylelint, and the color modes from the [twbs/examples repository](https://github.com/twbs/examples/tree/main/color-modes). You can also [open the example in StackBlitz](https://stackblitz.com/github/twbs/examples/tree/main/color-modes?file=index.html).

## Dark mode

**CoreUI for Bootstrap now supports color modes, starting with dark mode!** With v5.0.0 you can implement your own color mode toggler (see below for an example from CoreUI for Bootstrap's docs) and apply the different color modes as you see fit. We support a light mode (default) and now dark mode. Color modes can be toggled globally on the `<html>` element, or on specific components and elements, thanks to the `data-coreui-theme` attribute.

Alternatively, you can also switch to a media query implementation thanks to our color mode mixin—see [the usage section for details](#building-with-sass). Heads up though—this eliminates your ability to change themes on a per-component basis as shown below.

## Example

For example, to change the color mode of a dropdown menu, add `data-coreui-theme="light"` or `data-coreui-theme="dark"` to the parent `.dropdown`. Now, no matter the global color mode, these dropdowns will display with the specified theme value.

```html
<div class="dropdown" data-coreui-theme="light">
  <button class="btn-solid theme-secondary dropdown-toggle" type="button" id="dropdownMenuButtonLight" data-coreui-toggle="dropdown" aria-expanded="false">
    Default dropdown
  </button>
  <ul class="dropdown-menu" aria-labelledby="dropdownMenuButtonLight">
    <li><a class="dropdown-item active" href="#">Action</a></li>
    <li><a class="dropdown-item" href="#">Action</a></li>
    <li><a class="dropdown-item" href="#">Another action</a></li>
    <li><a class="dropdown-item" href="#">Something else here</a></li>
    <li><hr class="dropdown-divider"></li>
    <li><a class="dropdown-item" href="#">Separated link</a></li>
  </ul>
</div>

<div class="dropdown" data-coreui-theme="dark">
  <button class="btn-solid theme-secondary dropdown-toggle" type="button" id="dropdownMenuButtonDark" data-coreui-toggle="dropdown" aria-expanded="false">
    Dark dropdown
  </button>
  <ul class="dropdown-menu" aria-labelledby="dropdownMenuButtonDark">
    <li><a class="dropdown-item active" href="#">Action</a></li>
    <li><a class="dropdown-item" href="#">Action</a></li>
    <li><a class="dropdown-item" href="#">Another action</a></li>
    <li><a class="dropdown-item" href="#">Something else here</a></li>
    <li><hr class="dropdown-divider"></li>
    <li><a class="dropdown-item" href="#">Separated link</a></li>
  </ul>
</div>
```

## How it works

- As shown above, color mode styles are controlled by the `data-coreui-theme` attribute. This attribute can be applied to the `<html>` element, or to any other element or CoreUI for Bootstrap component. If applied to the `<html>` element, it will apply to everything. If applied to a component or element, it will be scoped to that specific component or element.

- For each color mode you wish to support, you'll need to add new overrides for the shared global CSS variables. We do this already in our `_root.scss` stylesheet for dark mode, with light mode being the default values. In writing color mode specific styles, use the mixin:

  ```scss
  // Color mode variables in _root.scss
  @include color-mode(dark) {
    // CSS variable overrides here...
  }
  ```

- Almost every global color is declared once, as a native [`light-dark()`](https://developer.mozilla.org/en-US/docs/Web/CSS/color_value/light-dark) pair, so there is no second set of dark declarations to keep in sync. The `data-coreui-theme="dark"` selector only has to declare `color-scheme: dark` and every pair — plus the native form widgets — follows. The exceptions are values `light-dark()` cannot hold: the colors baked into embedded SVGs (the select chevron, the switch knob) and filters keep their own dark rule.

  Note that `light-dark()` is the *mechanism*, not the switch. `:root` declares `color-scheme: light` outright rather than `light dark`, so a pair resolves to its light value until something sets `color-scheme: dark` — which, in practice, means the `data-coreui-theme` attribute. The operating system preference does not reach the pairs on its own; see [Building with Sass](#building-with-sass) for the media-query build if that is what you want.

## Usage

### Enable dark mode

Enable the built in dark color mode across your entire project by adding the `data-coreui-theme="dark"` attribute to the `<html>` element. This will apply the dark color mode to all components and elements, other than those with a specific `data-coreui-theme` attribute applied. Building on the [quick start template](https://coreui.io/bootstrap/docs/getting-started/introduction/#quick-start):

```html
<!doctype html>
<html lang="en" data-coreui-theme="dark">
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <title>CoreUI for Bootstrap demo</title>
    <link href="https://cdn.jsdelivr.net/npm/@coreui/coreui@5.9.0/dist/css/coreui.min.css" rel="stylesheet" integrity="sha384-9DZ6o3pJWcTwBR8W196XizUEf2kNMD35tkeyWqOB0yzml+nZrEe/13PMCpAIrT4r" crossorigin="anonymous">
  </head>
  <body>
    <h1>Hello, world!</h1>
    <script src="https://cdn.jsdelivr.net/npm/@coreui/coreui@5.9.0/dist/js/coreui.bundle.min.js" integrity="sha384-FTek6QoTuxz6Bb078pS0kYQ0qH2LZVB5LWwZl8944mluH+TCk0q3OP4PqA+dHJRl" crossorigin="anonymous"></script>
  </body>
</html>
```

CoreUI for Bootstrap does not yet ship with a built-in color mode picker, but you can use the one from our own documentation if you like. [Learn more in the JavaScript section.](#javascript)

### Building with Sass

Our new dark mode option is available to use for all users of CoreUI for Bootstrap, but it's controlled via data attributes instead of media queries and does not automatically toggle your project's color mode. You can disable our dark mode entirely via Sass by changing `$enable-dark-mode` to `false`.

We use a custom Sass mixin, `color-mode()`, to help you control _how_ color modes are applied. By default, we use a `data` attribute approach, allowing you to create more user-friendly experiences where your visitors can choose to have an automatic dark mode or control their preference (like in our own docs here). This is also an easy and scalable way to add different themes and more custom color modes beyond light and dark.

In case you want to use media queries and only make color modes automatic, you can change the mixin's default type via Sass variable. Consider the following snippet and its compiled CSS output.

```scss
$color-mode-type: data;

@include color-mode(dark) {
  .element {
    color: var(--cui-primary-fg-emphasis);
    background-color: var(--cui-primary-bg-subtle);
  }
}
```

Outputs to:

```css
[data-coreui-theme=dark] .element {
  color: var(--cui-primary-fg-emphasis);
  background-color: var(--cui-primary-bg-subtle);
}
```

And when setting to `media-query`:

```scss
$color-mode-type: media-query;

@include color-mode(dark) {
  .element {
    color: var(--cui-primary-fg-emphasis);
    background-color: var(--cui-primary-bg-subtle);
  }
}
```

Outputs to:

```css
@media (prefers-color-scheme: dark) {
  .element {
    color: var(--cui-primary-fg-emphasis);
    background-color: var(--cui-primary-bg-subtle);
  }
}
```

## Custom color modes

While the primary use case for color modes is light and dark mode, custom color modes are also possible. Create your own `data-coreui-theme` selector with a custom value as the name of your color mode, then modify our Sass and CSS variables as needed. Set `color-scheme` on your selector as well, so the `light-dark()` pairs and the native widgets pick the right side.

For example, you can create a "blue theme" with the selector `data-coreui-theme="blue"`. In your custom Sass or CSS file, add the new selector and override any global or component CSS variables as needed. If you're using Sass, you can also use Sass's functions within your CSS variable overrides.

```scss
[data-coreui-theme="blue"] {
  --cui-body-color: var(--cui-white);
  --cui-body-color-rgb: #{to-rgb(#fff)};
  --cui-body-bg: #{$cd-blue-500};
  --cui-body-bg-rgb: #{to-rgb($cd-blue-500)};
  --cui-tertiary-bg: #{$cd-blue-600};

  .dropdown-menu {
    --cui-dropdown-bg: #{color.mix($cd-blue-500, $cd-blue-600, 50%, rgb)};
    --cui-dropdown-link-active-bg: #{$cd-blue-700};
  }

  .btn-secondary {
    --cui-btn-bg: #{$cd-btn-secondary-bg};
    --cui-btn-border-color: #{rgba(#fff, .25)};
    --cui-btn-hover-bg: #{color.scale($cd-btn-secondary-bg, $lightness: -8%)}; // stylelint-disable-line scss/at-function-named-arguments
    --cui-btn-hover-border-color: #{rgba(#fff, .25)};
    --cui-btn-active-bg: #{color.scale($cd-btn-secondary-bg, $lightness: -16%)}; // stylelint-disable-line scss/at-function-named-arguments
    --cui-btn-active-border-color: #{rgba(#fff, .5)};
    --cui-btn-focus-border-color: #{rgba(#fff, .5)};
    --cui-btn-focus-box-shadow: 0 0 0 .25rem rgba(255, 255, 255, .2);
  }
}
```

```html
<div data-coreui-theme="blue">
  ...
</div>
```

## JavaScript

To allow visitors or users to toggle color modes, you'll need to create a toggle element to control the `data-coreui-theme` attribute on the root element, `<html>`. We've built a toggler in our documentation that initially defers to a user's current system color mode, but provides an option to override that and pick a specific color mode.

Here's a look at the JavaScript that powers it. Feel free to inspect our own documentation navbar to see how it's implemented using HTML and CSS from our own components. It is suggested to include the JavaScript at the top of your page to reduce potential screen flickering during reloading of your site. Note that if you decide to use media queries for your color modes, your JavaScript may need to be modified or removed if you prefer an implicit control.

```js
/*!
 * Color mode toggler for CoreUI's docs (https://coreui.io/)
 * Copyright (c) 2026 creativeLabs Łukasz Holeczek
 * Licensed under the Creative Commons Attribution 3.0 Unported License.
 */

(() => {
  'use strict'

  const THEME = 'coreui-docs-theme'

  const getStoredTheme = () => localStorage.getItem(THEME)
  const setStoredTheme = theme => localStorage.setItem(THEME, theme)

  const getPreferredTheme = () => {
    const storedTheme = getStoredTheme()
    if (storedTheme) {
      return storedTheme
    }

    return window.matchMedia('(prefers-color-scheme: dark)').matches ? 'dark' : 'light'
  }

  const setTheme = theme => {
    if (theme === 'auto') {
      document.documentElement.setAttribute('data-coreui-theme', (window.matchMedia('(prefers-color-scheme: dark)').matches ? 'dark' : 'light'))
      document.documentElement.setAttribute('data-bs-theme', (window.matchMedia('(prefers-color-scheme: dark)').matches ? 'dark' : 'light'))
    } else {
      document.documentElement.setAttribute('data-coreui-theme', theme)
      document.documentElement.setAttribute('data-bs-theme', theme)
    }
  }

  setTheme(getPreferredTheme())

  const showActiveTheme = theme => {
    const activeThemeIcon = document.querySelector('.theme-icon-active')
    const btnToActive = document.querySelector(`[data-coreui-theme-value="${theme}"]`)
    const svgOfActiveBtn = btnToActive.querySelector('svg.theme-icon')

    document.querySelectorAll('[data-coreui-theme-value]').forEach(element => {
      element.classList.remove('active')
    })

    btnToActive.classList.add('active')
    activeThemeIcon.innerHTML = svgOfActiveBtn.innerHTML
  }

  window.matchMedia('(prefers-color-scheme: dark)').addEventListener('change', () => {
    const storedTheme = getStoredTheme()
    if (storedTheme !== 'light' && storedTheme !== 'dark') {
      setTheme(getPreferredTheme())
    }
  })

  window.addEventListener('DOMContentLoaded', () => {
    showActiveTheme(getPreferredTheme())

    document.querySelectorAll('[data-coreui-theme-value]')
      .forEach(toggle => {
        toggle.addEventListener('click', () => {
          const theme = toggle.getAttribute('data-coreui-theme-value')
          setStoredTheme(theme)
          setTheme(theme)
          showActiveTheme(theme)
        })
      })
  })
})()
```

## Adding theme colors

A theme color is a hue in `$colors` and one entry in the `$theme-colors` map — a map of slots covering both color modes, described on [the Theme page](https://coreui.io/bootstrap/docs/customize/theme/). Merge both and the library generates everything else: the 025–975 runtime scale of the hue, the `--cui-custom-color-*` slot tokens that read it, and the `.theme-custom-color` class.

> Heads up! Reach our Sass with @use. The *.import.scss files that let @import resolve our modules are gone, so the snippet below will not compile behind an @import.

```scss
@use "@coreui/coreui/scss/coreui" with (
  $colors: (
    "custom-color": #712cf9,
  ),
  $theme-colors: (
    "custom-color": (
      "base":        var(--cui-custom-color-500),
      "fg":          light-dark(var(--cui-custom-color-600), var(--cui-custom-color-400)),
      "fg-emphasis": light-dark(var(--cui-custom-color-800), var(--cui-custom-color-200)),
      "bg":          var(--cui-custom-color-500),
      "bg-subtle":   light-dark(var(--cui-custom-color-100), var(--cui-custom-color-900)),
      "bg-muted":    light-dark(var(--cui-custom-color-200), var(--cui-custom-color-800)),
      "border":      light-dark(var(--cui-custom-color-300), var(--cui-custom-color-600)),
      "focus-ring":  color-mix(in oklch, var(--cui-custom-color-500) calc(var(--cui-focus-ring-opacity) * 100%), transparent),
      "contrast":    var(--cui-white),
    ),
  )
);
```

The slots are `light-dark()` pairs of the runtime scale, so both color modes are covered by the one entry — there is no second, dark set of maps to fill in.

## Customizing

### CSS variables

Global colors are declared once as `light-dark()` pairs, so the color mode selector — which defaults to `data-coreui-theme` but [can be configured](#building-with-sass) to use a `prefers-color-scheme` media query — only declares the scheme:

```scss
--cui-shadow-strength: 2.4;
--cui-backdrop-opacity: 65%;
```

Do the same in your own color modes: declare `color-scheme` and override only the tokens whose value is genuinely mode-specific.

### Sass variables

_Deprecated in 6.0.0._

Sass variables set these defaults at build time and are removed in v7. The CSS variables above reach the same values without recompiling, and can be set on a single element.

Each theme color gets a 100–900 scale of `color-mix()` tokens in `:root`, mixed at runtime from the color's own token. The subtle backgrounds, borders and emphasis text are `light-dark()` pairs of those stops, so overriding `$primary` (or the `--cui-primary-500` token at runtime) retints the whole family in both color modes. These set what the scale mixes towards, and in which color space:

```scss
$color-mix-space: oklch !default;
$tint-color:      var(--cui-white) !default;
$shade-color:     var(--cui-black) !default;
```

The one value that cannot be a `light-dark()` pair is a color baked into an SVG, because a data URI cannot read a custom property. The select chevron is the only one left: it carries `--cui-control-select-bg-img` and `--cui-control-select-bg-img-dark` side by side on the control, and dark mode switches which one the `background-image` reads. Both are translucent black and white, so the chevron tints itself against whatever the field sits on.

### Sass maps

The two maps are the stops of that scale: each entry is one step number and how far it mixes towards the tint or the shade color. Add an entry and every theme color gains that stop; set one to `null` to drop it everywhere at once.

```scss
$color-tints: () !default;

// stylelint-disable-next-line scss/dollar-variable-default
$color-tints: defaults(
  (
    "025": 94%,
    "050": 90%,
    "100": 80%,
    "200": 60%,
    "300": 40%,
    "400": 20%
  ),
  $color-tints
);

$color-shades: () !default;

// stylelint-disable-next-line scss/dollar-variable-default
$color-shades: defaults(
  (
    "600": 16%,
    "700": 32%,
    "800": 48%,
    "900": 64%,
    "950": 70%,
    "975": 76%
  ),
  $color-shades
);
```

### Sass mixins

Styles for dark mode, and any custom color modes you create, can be scoped appropriately to the `data-coreui-theme` attribute selector or media query with the customizable `color-mode()` mixin. See the [Sass usage section](#building-with-sass) for more details.

```scss
@mixin color-mode($mode: light, $root: false) {
  @if $color-mode-type == "media-query" {
    @if $root == true {
      @media (prefers-color-scheme: $mode) {
        :root,
        :host {
          @content;
        }
      }
    } @else {
      @media (prefers-color-scheme: $mode) {
        @content;
      }
    }
  } @else {
    [data#{$data-infix}theme="#{$mode}"] {
      @content;
    }
  }
}
```