Storybook Addon CSS Variables Theme

Storybook CSS Variables Theme can be used to switch out CSS files in Storybook.

Installation

npm install @etchteam/storybook-addon-css-variables-theme --save-dev

Configuration

Step 1: Add the addon

Create a file called main.js in your .storybook folder.

Add the following code to it:

module.exports = {
  addons: ['@etchteam/storybook-addon-css-variables-theme'],
};

Step 2: Include your CSS files

Create a file called preview.js in your .storybook folder.

In this file you will need to import your style files using a loader. Here's an example of how to do this:

import light from '!!style-loader?injectType=lazyStyleTag!css-loader!../src/styles/light.css'
import dark from '!!style-loader?injectType=lazyStyleTag!css-loader!../src/styles/dark.css'

This code calls style-loader with ?injectType=lazyStyleTag so that it doesn't run the CSS immediately.

You can swap out css-loader for your preferred SCSS/Less/etc loaders.

Any loaders used here will need to be installed in your project: npm i -D style-loader css-loader

Step 3: Add the Decorator

In the same preview.js file import the decorator from the CSS Variables Theme addon

import cssVariablesTheme from '@etchteam/storybook-addon-css-variables-theme'

export const decorators = [
  cssVariablesTheme,
];

Then pass the CSS files to the addon via the exported parameters.

export const parameters = {
  cssVariables: {
    files: {
      'Light Theme': light,
      'Dark Theme': dark,
    }
  }
}

If a default theme should be selected from first load add 'defaultTheme' to the options.

export const parameters = {
  cssVariables: {
    files: {
      'Light Theme': light,
      'Dark Theme': dark,
    },
    defaultTheme: 'Light Theme'
  }
}

How to

Set a specific theme for a story

Pass the theme key as the theme parameter on the story to default to a specific theme:

export default {
  title: 'Example/Header',
  component: Header,
  parameters: {
    cssVariables: {
      theme: 'dark'
    }
  }
};

Get the currently enabled theme within stories

You can access the currently set theme from the context object provided by storybook as the second parameter.

const Template: ComponentStory<typeof Button> = (args, context) => (
  <Button {...args}>{context.globals.cssVariables ?? 'No theme'}</Button>
);

Alternatively watch the custom storybookcssvariables:theme:change event on the document.

document.addEventListener(
  'storybookcssvariables:theme:change',
  (event: CustomEvent) => {
    console.info(`The theme changed to ${event?.detail?.theme}`);
  },
);

Set a Theme by Query String

Themes are stored in storybook globals.

Pass the theme to the url as a query by adding &globals=cssVariables:mytheme to the url. If multi word theme query is &globals=cssVariables:my+theme

Use in MDX docs

This addon applies styles through a decorator.

So, within MDX files, styles will only apply to a <Story> or <Canvas>.

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