// styles.css.ts

import { createTheme, style } from '@vanilla-extract/css';

export const [themeClass, themeVars] = createTheme({
  color: {
    brand: 'blue'
  },
  font: {
    body: 'arial'
  }
});

export const exampleStyle = style({
  backgroundColor: themeVars.color.brand,
  fontFamily: themeVars.font.body,
  color: 'white',
  padding: 10
});

💡 These .css.ts files will be evaluated at build time. None of the code in these files will be included in your final bundle. Think of it as using TypeScript as your preprocessor instead of Sass, Less, etc.

Then consume them in your markup.

// app.ts

import { themeClass, exampleStyle } from './styles.css.ts';

document.write(`
  <section class="${themeClass}">
    <h1 class="${exampleStyle}">Hello world!</h1>
  </section>
`);

Setup

There are currently a few integrations to choose from.

webpack

Install the dependencies.

$ yarn add --dev @vanilla-extract/css @vanilla-extract/babel-plugin @vanilla-extract/webpack-plugin

Add the Babel plugin.

{
  "plugins": ["@vanilla-extract/babel-plugin"]
}

Add the webpack plugin.

const { VanillaExtractPlugin } = require('@vanilla-extract/webpack-plugin');

module.exports = {
  plugins: [new VanillaExtractPlugin()],
};

You'll need to ensure you're handling CSS files in your webpack config.

For example:

const { VanillaExtractPlugin } = require('@vanilla-extract/webpack-plugin');
const MiniCssExtractPlugin = require('mini-css-extract-plugin');

module.exports = {
  plugins: [
    new VanillaExtractPlugin(),
    new MiniCssExtractPlugin()
  ],
  module: {
    rules: [
      {
        test: /\.css$/i,
        use: [
          MiniCssExtractPlugin.loader,
          'css-loader',
        ],
      },
    ],
  },
};

esbuild

Install the dependencies.

$ yarn add --dev @vanilla-extract/css @vanilla-extract/esbuild-plugin

Add the esbuild plugin to your build script.

const { vanillaExtractPlugin } = require('@vanilla-extract/esbuild-plugin');

require('esbuild').build({
  entryPoints: ['app.ts'],
  bundle: true,
  plugins: [vanillaExtractPlugin()],
  outfile: 'out.js',
}).catch(() => process.exit(1))

Please note: There are currently no automatic readable class names during development. However, you can still manually provide a debug ID as the last argument to functions that generate scoped styles, e.g. export const className = style({ ... }, 'className');

Gatsby

To add to your Gatsby site, use the gatsby-plugin-vanilla-extract plugin.

API

🍬 If you're a treat user, check out our migration guide.

style

Creates styles attached to a locally scoped class name.

import { style } from '@vanilla-extract/css';

export const className = style({
  display: 'flex'
});

CSS Variables, simple pseudos, selectors and media/feature queries are all supported.

import { style } from '@vanilla-extract/css';

export const className = style({
  display: 'flex',
  vars: {
    '--global-variable': 'purple'
  },
  ':hover': {
    color: 'red'
  },
  selectors: {
    '&:nth-child(2n)': {
      background: '#fafafa'
    }
  },
  '@media': {
    'screen and (min-width: 768px)': {
      padding: 10
    }
  },
  '@supports': {
    '(display: grid)': {
      display: 'grid'
    }
  }
});

Selectors can also contain references to other scoped class names.

import { style } from '@vanilla-extract/css';

export const parentClass = style({});

export const childClass = style({
  selectors: {
    [`${parentClass}:focus &`]: {
      background: '#fafafa'
    }
  },
});

💡 To improve maintainability, each style block can only target a single element. To enforce this, all selectors must target the & character which is a reference to the current element. For example, '&:hover:not(:active)' is considered valid, while '& > a' and [`& ${childClass}`] are not.

If you want to target another scoped class then it should be defined within the style block of that class instead. For example, [`& ${childClass}`] is invalid since it targets ${childClass}, so it should instead be defined in the style block for childClass.

If you want to globally target child nodes within the current element (e.g. '& > a'), you should use globalStyle instead.

globalStyle

Creates styles attached to a global selector.

import { globalStyle } from '@vanilla-extract/css';

globalStyle('html, body', {
  margin: 0
});

Global selectors can also contain references to other scoped class names.

import { globalStyle } from '@vanilla-extract/css';

export const parentClass = style({});

globalStyle(`${parentClass} > a`, {
  color: 'pink'
});

mapToStyles

Creates an object that maps style names to hashed class names.

💡 This is useful for mapping to component props, e.g. <div className={styles.padding[props.padding]}>

import { mapToStyles } from '@vanilla-extract/css';

export const padding = mapToStyles({
  small: { padding: 4 },
  medium: { padding: 8 },
  large: { padding: 16 }
});

You can also transform the values by providing a map function as the second argument.

import { mapToStyles } from '@vanilla-extract/css';

const spaceScale = {
  small: 4,
  medium: 8,
  large: 16
};

export const padding = mapToStyles(spaceScale, (space) => ({
  padding: space
}));

createTheme

Creates a locally scoped theme class and a collection of scoped CSS Variables.

import { createTheme, style } from '@vanilla-extract/css';

export const [themeClass, themeVars] = createTheme({
  color: {
    brand: 'blue'
  },
  font: {
    body: 'arial'
  }
});

You can create theme variants by passing a collection of theme variables as the first argument to createTheme.

import { createTheme, style } from '@vanilla-extract/css';

export const [themeA, themeVars] = createTheme({
  color: {
    brand: 'blue'
  },
  font: {
    body: 'arial'
  }
});

export const themeB = createTheme(themeVars, {
  color: {
    brand: 'pink'
  },
  font: {
    body: 'comic sans ms'
  }
});

💡 All theme variants must provide a value for every variable or it’s a type error.

createGlobalTheme

Creates a theme attached to a global selector, but with locally scoped variable names.

import { createGlobalTheme } from '@vanilla-extract/css';

export const themeVars = createGlobalTheme(':root', {
  color: {
    brand: 'blue'
  },
  font: {
    body: 'arial'
  }
});

💡 All theme variants must provide a value for every variable or it’s a type error.

createThemeVars

Creates a collection of CSS Variables without coupling them to a specific theme variant.

💡 This is useful if you want to split your themes into different bundles. In this case, your themes would be defined in separate files, but we'll keep this example simple.

import {
  createThemeVars,
  createTheme
} from '@vanilla-extract/css';

export const themeVars = createThemeVars({
  color: {
    brand: null
  },
  font: {
    body: null
  }
});

export const themeA = createTheme(themeVars, {
  color: {
    brand: 'blue'
  },
  font: {
    body: 'arial'
  }
});

export const themeB = createTheme(themeVars, {
  color: {
    brand: 'pink'
  },
  font: {
    body: 'comic sans ms'
  }
});

assignVars

Assigns a collection of CSS Variables anywhere within a style block.

💡 This is useful for creating responsive themes since it can be used within @media blocks.

import { style, createThemeVars, assignVars } from '@vanilla-extract/css';

export const themeVars = createThemeVars({
  space: {
    small: null,
    medium: null,
    large: null
  }
});

export const responsiveSpaceTheme = style({
  vars: assignVars(themeVars.space, {
    small: '4px',
    medium: '8px',
    large: '16px'
  }),
  '@media': {
    'screen and (min-width: 1024px)': {
      vars: assignVars(themeVars.space, {
        small: '8px',
        medium: '16px',
        large: '32px'
      })
    }
  }
});

💡 All variables passed into this function must be assigned or it’s a type error.

createVar

Creates a single CSS Variable.

import { createVar, style } from '@vanilla-extract/css';

export const colorVar = createVar();

export const exampleStyle = style({
  color: colorVar
});

Scoped variables can be set via the vars property on style objects.

import { createVar, style } from '@vanilla-extract/css';
import { colorVar } from './vars.css.ts';

export const parentStyle = style({
  vars: {
    [colorVar]: 'blue'
  }
});

fallbackVar

Provides fallback values when consuming variables.

import { createVar, fallbackVar, style } from '@vanilla-extract/css';

export const colorVar = createVar();

export const exampleStyle = style({
  color: fallbackVar(colorVar, 'blue');
});

Multiple fallbacks are also supported.

import { createVar, fallbackVar, style } from '@vanilla-extract/css';

export const primaryColorVar = createVar();
export const secondaryColorVar = createVar();

export const exampleStyle = style({
  color: fallbackVar(primaryColorVar, secondaryColorVar, 'blue');
});

fontFace

Creates a custom font attached to a locally scoped font name.

import { fontFace, style } from '@vanilla-extract/css';

const myFont = fontFace({
  src: 'local("Comic Sans MS")'
});

export const text = style({
  fontFamily: myFont
});

globalFontFace

Creates a globally scoped custom font.

import {
  globalFontFace,
  style
} from '@vanilla-extract/css';

globalFontFace('MyGlobalFont', {
  src: 'local("Comic Sans MS")'
});

export const text = style({
  fontFamily: 'MyGlobalFont'
});

keyframes

Creates a locally scoped set of keyframes.

import { keyframes, style } from '@vanilla-extract/css';

const rotate = keyframes({
  '0%': { rotate: '0deg' },
  '100%': { rotate: '360deg' },
});

export const animated = style({
  animation: `3s infinite ${rotate}`;
});

globalKeyframes

Creates a globally scoped set of keyframes.

import { globalKeyframes, style } from '@vanilla-extract/css';

globalKeyframes('rotate', {
  '0%': { rotate: '0deg' },
  '100%': { rotate: '360deg' },
});

export const animated = style({
  animation: `3s infinite rotate`;
});

Dynamic API

We also provide a lightweight standalone package to support dynamic runtime theming.

$ yarn add --dev @vanilla-extract/dynamic

createInlineTheme

Generates a custom theme at runtime as an inline style object.

import { createInlineTheme } from '@vanilla-extract/dynamic';
import { themeVars, exampleStyle } from './styles.css.ts';

const customTheme = createInlineTheme(themeVars, {
  small: '4px',
  medium: '8px',
  large: '16px'
});

document.write(`
  <section style="${customTheme}">
    <h1 class="${exampleStyle}">Hello world!</h1>
  </section>
`);

setElementTheme

Sets a collection of CSS Variables on an element.

import { setElementTheme } from '@vanilla-extract/dynamic';
import { themeVars } from './styles.css.ts';

const element = document.getElementById('myElement');
setElementTheme(element, themeVars, {
  small: '4px',
  medium: '8px',
  large: '16px'
});

💡 All variables passed into this function must be assigned or it’s a type error.

setElementVar

Sets a single var on an element.

import { setElementVar } from '@vanilla-extract/dynamic';
import { themeVars } from './styles.css.ts';

const element = document.getElementById('myElement');
setElementVar(element, themeVars.color.brand, 'darksalmon');

Utility functions

We also provide a standalone package of optional utility functions to make it easier to work with CSS in TypeScript.

💡 This package can be used with any CSS-in-JS library.

$ yarn add --dev @vanilla-extract/css-utils

calc

Streamlines the creation of CSS calc expressions.

import { calc } from '@vanilla-extract/css-utils';

const styles = {
  height: calc.multiply('var(--grid-unit)', 2)
};

The following functions are available.

calc.add
calc.subtract
calc.multiply
calc.divide
calc.negate

The calc export is also a function, providing a chainable API for complex calc expressions.

import { calc } from '@vanilla-extract/css-utils';

const styles = {
  marginTop: calc('var(--space-large)')
    .divide(2)
    .negate()
    .toString()
};

Thanks

Nathan Nam Tran for creating css-in-js-loader, which served as the initial starting point for treat, the precursor to this library.
Stitches for getting us excited about CSS-Variables-in-JS.
SEEK for giving us the space to do interesting work.

License

MIT.

FAQs

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Package last updated on 12 Apr 2021

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Install

@vanilla-extract/dynamic

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