---
order: 0
---

import defaultExample from '../../examples/constellation/0-default';
import themeSwitcherExample from '../../examples/constellation/1-theme-switcher';
import routerLinkComponentExample from '../../examples/constellation/2-router-link-component';
import subTreeThemingExample from '../../examples/constellation/3-sub-tree-theming';
import SubTreeThemingOutsideAppProviderExample from '../../examples/constellation/4-sub-tree-theming-outside-app-provider';
import subTreeThemingDynamicExample from '../../examples/constellation/5-sub-tree-theming-dynamic';

## Theming

App provider sets up theming for an app, enabling [design tokens](/foundations/tokens/design-tokens)
to be used.

<Example
	Component={defaultExample.example}
	source={defaultExample.code}
	packageName="@atlaskit/app-provider"
/>

## Color mode and theme switching

The `useColorMode` hook can be used to get the active color mode. When the color mode is set to
`auto`, the active color mode will be determined by the user's system preference.

The `useTheme` hook can be used to get the active themes. The `useSetTheme` hook can be used to
change themes.

<Example
	Component={themeSwitcherExample.example}
	source={themeSwitcherExample.code}
	packageName="@atlaskit/app-provider"
/>

## Sub-tree theming

Use sub-tree theming to apply a different color mode or theme to a specific section of your UI,
independently of the rest of the page. This is useful for content that needs a distinct visual
treatment.

Nest `ThemeProvider` inside `AppProvider` to scope a theme to part of the page.

<Example
	Component={subTreeThemingExample.example}
	source={subTreeThemingExample.code}
	packageName="@atlaskit/app-provider"
/>

### Portalled content

Components that render into a portal render outside the `ThemeProvider`'s DOM subtree. By default,
portalled content inherits the root theme rather than the sub-tree theme.

To support sub-tree theming for portalled content, use the [Portal](/components/portal/examples)
component, which passes the color mode to the content it renders.

### Sub-tree theming outside AppProvider

If `AppProvider` has not yet been adopted in your application, `ThemeProvider` can still be used
standalone to apply scoped theming. In this case, every `ThemeProvider` including the outermost one
behaves as a sub-tree theme. It wraps its children in a scoped `div` and does not set page-level
theme attributes on `html` or `body`.

<Example Component={SubTreeThemingOutsideAppProviderExample} packageName="@atlaskit/app-provider" />

### Dynamic color mode inversion

A common pattern is to create a panel that always displays the opposite color mode to its
surroundings. For example, a dark sidebar in a light-mode app, or a highlighted callout that always
contrasts with its parent.

To do this reliably, read the parent color mode with `useColorMode()`, then call `useSetColorMode()`
inside the sub-tree `ThemeProvider` to update it reactively.

Avoid relying on `defaultColorMode` alone for this pattern. The prop is only applied on initial
mount and does not react to subsequent changes in the parent's color mode.

<Example
	Component={subTreeThemingDynamicExample.example}
	source={subTreeThemingDynamicExample.code}
	packageName="@atlaskit/app-provider"
/>

## Router links

The `routerLinkComponent` prop provides support for configuring router links within Design System
components.

Support for this is limited as Design System components are being updated, starting with:

- [LinkButton](/components/button/link-button/examples).
- [LinkIconButton](/components/button/icon-button/examples#link-icon-button).
- [Link](/components/link/examples).
- [Anchor primitive](/components/primitives/anchor/examples).

This example shows how links can be configured to utilize the router link component supplied by
[React Resource Router](https://github.com/atlassian-labs/react-resource-router), however any
routing library can be used.

<Example
	Component={routerLinkComponentExample.example}
	source={routerLinkComponentExample.code}
	appearance="source-only"
	packageName="@atlaskit/app-provider"
	isCodeSandboxDisabled
/>