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Color Modes

Color modes can be used to create a user-configurable dark mode or any number of other color modes.

Defining colors

In the theme.colors object, add a nested modes object that will contain keys for optional color modes.

// example theme colors
{
  colors: {
    text: '#000',
    background: '#fff',
    primary: '#07c',
    modes: {
      dark: {
        text: '#fff',
        background: '#000',
        primary: '#0cf',
      }
    }
  }
}

The colors defined at the root of the colors object will be accessible as default. All colors found in colors.modes will be referenced by their key. The above example will have two modes: default and dark.

Setting the color mode

Use the useColorMode hook in your application to change the color mode. This value will be stored in localStorage and used whenever the page is loaded.

import { useColorMode } from 'theme-ui'
export default (props) => {
  const [colorMode, setColorMode] = useColorMode()
  return (
    <header>
      <button
        onClick={(e) => {
          setColorMode(colorMode === 'default' ? 'dark' : 'default')
        }}>
        Toggle {colorMode === 'default' ? 'Dark' : 'Light'}
      </button>
    </header>
  )
}

Applying colors

The ThemeProvider component will automatically apply color mode styles to the <body> element.

import { ThemeProvider } from 'theme-ui'
import theme from './theme'
export default (props) => (
  <ThemeProvider theme={theme}>{props.children}</ThemeProvider>
)

To disable this behavior, add the useBodyStyles: false flag to your theme.

Gatsby plugin

For use in a Gatsby site, install and use gatsby-plugin-theme-ui to add the ThemeProvider to the root of your application. The plugin will also help prevent the flash of colors that can happen during page load when a user has a non-default color mode set.

npm i gatsby-plugin-theme-ui

This plugin will look for a src/gatsby-plugin-theme-ui/index.js file to import and pass to the ThemeProvider.

// gatsby-config.js
module.exports = {
  plugins: ['gatsby-plugin-theme-ui'],
}

See the Gatsby plugin docs for more info.

Advanced

Theme UI includes a few advanced usage options for color modes.

Turn off custom properties

Theme UI uses CSS custom properties under the hood to help prevent the flash of color on load. If you're targeting browsers that don't support custom properties you can turn off this setting. This will cause the colors to flash on initial page load.

// example theme colors
{
  useCustomProperties: false,
  colors: {
    text: '#000',
    background: '#fff',
    primary: '#07c',
    modes: {
      dark: {
        text: '#fff',
        background: '#000',
        primary: '#0cf',
      }
    }
  }
}

Initialize mode with prefers-color-scheme media query

To initialize a color mode based on the prefers-color-scheme media query, add the useColorSchemeMediaQuery flag to your theme. This will set the initial color mode to dark when @media (prefers-color-scheme: dark) matches, or light when @media (prefers-color-scheme: light) matches. If you do not have a color mode named dark or light, this will have no effect.

{
  useColorSchemeMediaQuery: true,
  colors: {
    text: '#000',
    background: '#fff',
    modes: {
      dark: {
        text: '#fff',
        background: '#000',
      }
    }
  }
}

Disable persisting color mode on localStorage

To disable localStorage add the useLocalStorage: false flag to your theme.

{
  useLocalStorage: false,
  colors: {
    text: '#000',
    background: '#fff',
    modes: {
      dark: {
        text: '#fff',
        background: '#000',
      }
    }
  }
}

Set a custom color mode for printing

By default, when printing a webpage, browsers will use the current color mode enabled. (This means if a user is currently using a dark or colored-background mode, their printed page will share that styling). If you’d like to set a color mode to be used on printing, set that color mode with the configuration option printColorModeName, set to one of your colors.modes names, the initialColorModeName value, or the string 'initial'.

This option sets your color mode in the @media (print) media query, so there’s no additional client-side JavaScript for printing.

{
  initialColorModeName: 'light',
  printColorModeName: 'light',
  colors: {
    text: '#000',
    background: '#fff',
    modes: {
      dark: {
        text: '#fff',
        background: '#000',
      }
    }
  }
}
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