Best of JS • Tokenami

CSS-in-JS Reinvented for Scalable, Typesafe Design Systems

A modern approach to just-in-time atomic CSS using CSS variables—no bundler required.

Warning

This is a pre-alpha version of tokenami so there will be bugs, breaking changes, and missing features. Please check the existing issues for planned features/known bugs before creating new ones.

Demo

If you prefer to get stuck straight in, give the vite starter a try and remember to choose the workspace version of TypeScript.

Why another CSS library?

CSS-in-JS solutions that rely on style injection were no longer recommended by the React team, and instead they suggested:

Our preferred solution is to use <link rel="stylesheet"> for statically extracted styles and plain inline styles for dynamic values. E.g. <div style={{...}}>

In other words—write CSS like we used to. But what about the benefits that CSS-in-JS gave us?

There are CSS-in-JS solutions that extract static rules from your template files into external .css files, however, these approaches often require bundler integration and come with build-time limitations.

The learning curve can be intimidating but developers invest regardless so they can have type errors and intellisense for their design system tokens as well as style deduping, critical path CSS, scoping, and composition.

Tailwind CSS adopts a different strategy to achieve these goals:

We can style inline to prototype quickly
Editor extensions for intellisense based on your theme
Statically generated styles with a simple CLI script, no bundler integration
Atomic CSS so styles have a cap on how large they can grow

On the flip side:

Removing values from your theme won't flag redundant references
We must memorise Tailwind's custom class names which spawns things like the Tailwind Cheatsheet
Specificity issues when composing unless we use third-party packages like tailwind-merge
Styling inline can be unpleasant to maintain, resulting in third-party packages like cva
Classes must exist as complete unbroken strings
Debugging in dev tools is tricky because styles are spread across atomic classes

Introducing Tokenami

Tokenami aims to improve some of these areas by using CSS variables instead of CSS properties in the style attribute, and bringing all necessary tools under one roof. It features:

Simple naming convention—use the CSS properties you already know, prefixed with double-dash
Smaller stylesheet made possible by atomic CSS variables
Config file for defining your theme
Feature-rich intellisense when authoring styles
A tiny css utility with variants, and responsive variants support
Seamless composition across component boundaries using the css utility
Runtime style support e.g. style={css({ '--color': props.color })}
Aliasable properties e.g. style={css({ '--p': 4 })} for padding
Custom selector support enabling descendant selectors
Improved debugging experience in dev tools (coming soon)
Statically generated styles
No bundler integration

Getting started

Tokenami offers a CLI tool for generating static styles, a ~2kb CSS utility for authoring your styles, and a TypeScript plugin to enhance the developer experience.

Installation

Install using your package manager of choice. For example:

npm install -D @tokenami/dev @tokenami/ts-plugin && npm install @tokenami/css

And then initialise your tokenami project:

npx tokenami init

Configure TypeScript

Add Tokenami to include and plugins in your tsconfig.json or jsconfig.json.

{
  "include": [".tokenami/tokenami.env.d.ts", "src"],
  "compilerOptions": {
    "plugins": [{ "name": "@tokenami/ts-plugin" }]
  }
}

Ensure your editor is configured to use the project's TypeScript version. Instructions can be found in your editor's documentation, such as VSCode's guide. VSCode users should also enable editor.quickSuggestions for strings.

Start the CLI watch script

Run the CLI tool to scan your template files for tokenami properties and build your CSS. This would usually exist as a script in your package.json.

npx tokenami --output ./public/styles.css --watch

Make sure to adjust the output path to your desired location for styles. It will use ./public/tokenami.css by default if omitted.

Use Tokenami

Reference your output CSS file in the <head> of your document, and start styling inline with Tokenami properties:

import { css } from '@tokenami/css';

function Page() {
  return <h1 style={css({ '--margin-top': 0, '--margin-bottom': 5 })}>Hello, World!</h1>;
}

Core concepts

Theming

Tokenami relies on your theme to provide design system constraints. There isn't a predefined theme so you must add your own to the .tokenami/tokenami.config.

Note

If you'd prefer to use a pre-built theme, you can use the offical design system and skip this section.

module.exports = createConfig({
  // ...
  responsive: {
    medium: '@media (min-width: 700px)',
    large: '@media (min-width: 1024px)',
  },
  theme: {
    color: {
      'slate-100': '#f1f5f9',
      'slate-700': '#334155',
      'sky-500': '#0ea5e9',
    },
    radii: {
      rounded: '10px',
      circle: '9999px',
      none: 'none',
    },
  },
});

The keys in your responsive and theme objects can be anything you wish. These keys will be used to name your tokens (more on this later).

Multiple themes

Use the modes key to define multiple themes if desired.

You can choose any names for your modes. Tokens that are shared across themes should be placed alongisde your modes in the root object:

module.exports = createConfig({
  theme: {
    modes: {
      light: {
        color: {
          primary: '#f1f5f9',
          secondary: '#334155',
        },
      },
      dark: {
        color: {
          primary: '#0ea5e9',
          secondary: '#f1f5f9',
        },
      },
    },
    root: {
      radii: {
        rounded: '10px',
        circle: '9999px',
        none: 'none',
      },
    },
  },
});

By default this will apply the CSS variables to .theme-${mode} classes. Add the classes to an element on your page to apply the relevant theme.

Custom theme selector

To customise the theme selector, update the themeSelector config.

module.exports = createConfig({
  themeSelector: (mode) => (mode === 'root' ? ':root' : `.theme-${mode}`),
});

Styling

With your theme set up, there are only a few rules to remember:

A Tokenami property is any CSS property prefixed with double dash, e.g. --font-size (why?). Use --- (triple dash) to add custom CSS variables to an element.
A Tokenami token is any theme key followed by a value identifier, and separated by an underscore. For example, a color object in theme with a red-100 entry maps to var(--color_red-100).
Properties can include selectors like media queries, pseudo-classes, and pseudo-elements separated with an underscore. For instance, --hover_background-color, --md_hover_background-color.

Grid values

Tokenami uses a grid value for spacing. Properties like padding and margin are multiples of this when passed a numeric value. For example, with a grid set to 4px, using --padding: 2 adds 8px of padding to your element.

By default, Tokenami sets the grid to 0.25rem but you can override it:

module.exports = createConfig({
  // ...
  grid: '10px',
});

Arbitrary selectors

Use arbitrary selectors to prototype quickly:

<div
  style={css({
    '--{&:hover}_color': 'var(--color_primary)',
    '--{&:has(:focus)}_border-color': 'var(--color_highlight)',
    '--{&[data-state=open]}_border-color': 'var(--color_primary)',
    '--{&_p}_color': 'var(--color_primary)',
  })}
/>

They can be used to style the current element, and its descendants only.

Arbitrary values

You can avoid TypeScript errors for one-off inline values by using a triple dash fallback. For instance, --padding: var(---, 20px) prevents errors and sets padding to 20px.

Tokenami intentionally adds friction to the developer experience here. This is to encourage sticking to your theme guidelines and to help you quickly spot values in your code that don't.

Responsive styles

Define responsive rules in the responsive object in your config. This can include @container queries:

module.exports = createConfig({
  // ...
  responsive: {
    medium: '@media (min-width: 1024px)',
    'medium-self': '@container (min-width: 400px)',
  },
});

Use by following the property spec:

<div style={css({ '--medium_padding': 4 })} />

Responsive rules can also be combined with selectors:

<div style={css({ '--medium_hover_padding': 4 })} />

For documentation on responsive variants, refer to the CSS compose section.

Global styles

Tokenami supports global styles in your tokenami.config. It can be useful for including them as part of a design system.

module.exports = createConfig({
  // ...
  globalStyles: {
    '*, *::before, *::after': {
      boxSizing: 'border-box',
    },
    body: {
      fontFamily: 'system-ui, sans-serif',
      lineHeight: 1.5,
      margin: 0,
      padding: 0,
    },
  },
});

Animation

Add keyframes to your config and reference them in your theme:

module.exports = createConfig({
  // ...
  keyframes: {
    wiggle: {
      '0%, 100%': { transform: 'rotate(-3deg)' },
      '50%': { transform: 'rotate(3deg)' },
    },
  },
  theme: {
    anim: {
      wiggle: 'wiggle 1s ease-in-out infinite',
    },
  },
});

Use by following the token spec:

<div style={css({ '--animation': 'var(--anim_wiggle)' })} />

CSS utility

Tokenami provides a CSS utility to author your styles and correctly merge them across component boundaries.

Usage

The css utility accepts your base styles as the first parameter, and then any number of overrides as additional parameters.

function Button({ size, style, ...props }) {
  return <button {...props} style={css({ '--padding': 4 }, props.style)} />;
}

In the above example we're passing props.style as an override to ensure composed styles will merge correctly across component boundaries.

Overrides

Overrides can be applied conditionally and last override wins. They are applied as additional parameters to the css utility.

function Button({ style, ...props }) {
  const disabled = props.disabled && { '--opacity': 0.5 };
  return <button {...props} style={css({ '--p': 4 }, disabled, style)} />;
}

CSS compose

Use the css.compose API to author variants.

Variants

const button = css.compose({
  '--padding': 4,

  variants: {
    size: {
      small: { '--padding': 2 },
      large: { '--padding': 6 },
    },
  },
});

function Button({ size, style, ...props }) {
  return <button {...props} style={button({ size }, style)} />;
}

The function returned by css.compose accepts your chosen variants as the first parameter, and then any number of overrides as additional parameters.

Responsive variants

Responsive variants allow you to prefix the variant name with a responsive key from your configuration. For example, the following button will apply the large size variant at the medium breakpoint:

function Button() {
  return <button style={button({ medium_size: 'large' })} />;
}

To enable it, rename the variants property to responsiveVariants. This will generate the atomic CSS for the responsive variants regardless of whether they're used, so it is purposefully opt-in to allow greater control.

const button = css.compose({
  '--padding': 4,

-  variants: {
+  responsiveVariants: {
    size: {
      small: { '--padding': 2 },
      large: { '--padding': 6 },
    },
  },
});

TypeScript

Variants

Use the Variants type to extend your component prop types:

import { type Variants } from '@tokenami/css';

type ButtonElementProps = React.ComponentPropsWithoutRef<'button'>;
interface ButtonProps extends ButtonElementProps, Variants<typeof button> {}

TokenamiStyle

The TokenamiStyle type allows you to extend the style prop of your component with Tokenami-specific properties.

import { type TokenamiStyle, css } from '@tokenami/css';

interface ButtonProps extends TokenamiStyle<React.ComponentProps<'button'>> {}

function Button(props: ButtonProps) {
  return <button {...props} style={css({}, props.style)} />;
}

You can then use the component as usual, overriding styles as needed. Since the component is already typed and integrates the css utility internally, you no longer need to use the utility to apply styles:

<Button style={{ '--padding': 4 }} />

Continuous Integration

To improve performance during development, Tokenami widens its types and uses the TypeScript plugin for completions. Using tsc in the command line defaults to these widened types so it will not highlight errors for your properties or tokens. To get accurate types for CI, do the following:

Create a file named tsconfig.ci.json or jsconfig.ci.json. It should extend your original config and include the CI-specific Tokenami types
```
{
  "extends": "./tsconfig.json",
  "include": [".tokenami/tokenami.env.ci.d.ts", "src"]
}
```
Use tsc with your new configuration
```
tsc --noEmit --project tsconfig.ci.json
```

Design systems

Integrating a design system built with Tokenami is straightforward. Include its tokenami.config.js file and corresponding stylesheet (where applicable) in your project:

import designSystemConfig from '@acme/design-system';
import { createConfig } from '@tokenami/css';

export default createConfig({
  ...designSystemConfig,
  include: ['./app/**/*.{ts,tsx}', 'node_modules/@acme/design-system/tokenami.css'],
});

Tokenami will automatically generate styles and merge them correctly across component boundaries.

Note: It is only necessary to include the design system stylesheet if the design system provides components that you'd like to use in your project.

Official design system

Tokenami has an official design system package you can use as a starting point for your project.

It features:

Global reset based on Preflight from Tailwind
Radix UI colours enabling dark mode by default
Fluid spacing and font sizes for responsive design
Right-to-left support out of the box (padding-left becomes padding-inline-start etc.)
Custom aliases for common properties, such as --p for padding and --px for padding-left and padding-right

Follow the package docs to get started.

Advanced

Selectors

Tokenami provides some common default selectors in your project for you, but you can define your own or override the defaults.

Use the ampersand (&) to specify where the current element's selector should be injected:

const { createConfig } = require('@tokenami/css');

module.exports = createConfig({
  // ...
  selectors: {
    //...
    'parent-hover': '.parent:hover > &',
  },
});

Use by following the property spec:

<div className="parent">
  <img src="..." alt="" />
  <button style={css({ '--parent-hover_font-weight': 'bold' })} />
</div>

Selectors can also be combined with responsive rules:

<button style={css({ '--medium_parent-hover_font-weight': 'bold' })} />

Nested selectors

Use an array value for custom selectors to generate nested rules:

module.exports = createConfig({
  // ...
  selectors: {
    // ...
    hover: ['@media (hover: hover) and (pointer: fine)', '&:hover'],
  },
});

This example will apply hover styles for users with a precise pointing device, such as a mouse, when --hover_{property} is used.

Aliases

Aliases allow you to create shorthand names for properties. When using custom aliases, the css utility must be configured to ensure aliased properties are merged correctly across component boundaries.

Configure utility

Create a file in your project to configure the utility. You can name this file however you like, e.g. css.ts:

// css.ts
import { createCss } from '@tokenami/css';
import config from '../.tokenami/tokenami.config';

export const css = createCss(config);

Use the css utility exported from the file you created and it will handle aliases correctly.

Create aliases

The configuration expects the name of your new alias followed by an array of properties it maps to.

module.exports = createConfig({
  // ...
  aliases: {
    p: ['padding'],
    px: ['padding-left', 'padding-right'],
    py: ['padding-top', 'padding-bottom'],
    pt: ['padding-top'],
    pr: ['padding-right'],
    pb: ['padding-bottom'],
    pl: ['padding-left'],
    size: ['width', 'height'],
  },
});

With the above config, px is shorthand for padding-left and padding-right. This allows the css utility to apply padding on the left and right when --px is used.

Map properties to theme

Tokenami provides sensible defaults to restrict which values can be passed to properties based on your theme. For instance, --border-color will only accept tokens from your color object in theme, --padding allows multiples of your grid, and --height expects tokens from a size key or multiples of your grid.

You can customise the default configuration generated in your project by updating the properties object:

const { createConfig } = require('@tokenami/css');

module.exports = createConfig({
  theme: {
    container: {
      half: '50%',
    },
    pet: {
      cat: '"🐱"',
      dog: '"🐶"',
    },
  },
  properties: {
    // ...
    width: ['grid', 'container'],
    height: ['grid', 'container'],
    content: ['pet'],
  },
});

With this configuration, passing var(--container_half) to a content property would error because container does not exist in its property config, but var(--pet_dog) would be allowed:

<div
  style={css({
    '--width': 75 /*  300px with a 4px grid */,
    '--height': 'var(--container_half)',
    '--after_content': 'var(--pet_cat)',
  })}
/>

Map custom properties to theme

Tokenami allows custom properties in the properties config. This helps to create a configurable design system. For example, you can create --gradient-from and --gradient-to properties that accept color tokens to make reusable gradients:

module.exports = createConfig({
  // ...
  properties: {
    // ...
    'gradient-from': ['color'],
    'gradient-to': ['color'],
  },
});

And use the properties in your theme:

module.exports = createConfig({
  theme: {
    color: {
      primary: '#f1f5f9',
      secondary: '#334155',
    },
    surface: {
      'radial-gradient':
        'radial-gradient(circle at top, var(--gradient-from), var(--gradient-to) 80%)',
    },
  },
  // ...
});

Now you can set different gradient stops when applying the gradient, and intellisense will suggest colours from your theme.

<div
  style={css({
    '--gradient-from': 'var(--color_primary)',
    '--gradient-to': 'var(--color_secondary)',
    '--background': 'var(--surface_radial-gradient)',
  })}
/>

Browserslist

You can use browserslist to add autoprefixing to your CSS properties in the generated CSS file. However, Tokenami currently doesn't support vendor-prefixed values, which is being tracked in this issue.

Note

Tokenami does not support browsers below the listed supported browser versions.

Support

Before raising a bug, please double-check that it isn't already in my todo list. Some common pitfalls are listed below. If you need additional support or encounter any issues, please don't hesitate to join the Tokenami discord server.

Why the double-dash prefix?

To minimise runtime style calculations, Tokenami directly applies your styles to the style attribute. Since the style attribute doesn't support media queries or pseudo-selectors, Tokenami uses CSS variables to enable them, and simplifies the learning curve by making all properties CSS variables.

Note

Don't worry about the extra characters! Simply type bord (without quotes), and Tokenami's Intellisense will automatically complete it for you, including hyphens and quotes.

Additionaly, CSS properties applied to the style attribute have highest specificity making them hard to override. By using CSS variables instead, you can easily override Tokeanami's styles by adding a stylesheet after Tokenami's to your document.

VSCode intellisense configuration

By default, VSCode will not trigger intellisense for strings which can hinder the developer experience if you've chosen an incomplete suggestion from the suggestion list. To fix this, add the following to your .vscode/settings.json:

"editor.quickSuggestions": {
  "strings": true
}

BEFORE	AFTER

Supported frameworks

Tokenami is in early stages of development and currently only supports applications built using React (NextJS, Remix, etc.), Vue, or SolidJS.

Supported browsers

Tokenami relies on cascade layers so only supports browsers with @layer support.

Edge	Firefox	Chrome	Safari	iOS Safari	Opera
99+	97+	99+	15.4+	15.4+	86+

Contributors

Paweł Błaszczyk (@pawelblaszczyk_)

Credits

A big thanks to:

Tailwind CSS for inspiring most of the features in Tokenami
Stitches for variants and responsive variants inspiration
CSS Hooks for custom selectors inspiration
Lightning CSS for generating the Tokenami stylesheet

Please do take the time to check these projects out if you feel Tokenami isn't quite right for you.

Tokenami

CSS-in-JS Reinvented for Scalable, Typesafe Design Systems

Demo

Contents

Why another CSS library?

Introducing Tokenami

Getting started

Installation

Configure TypeScript

Start the CLI watch script

Use Tokenami

Core concepts

Theming

Multiple themes

Custom theme selector

Styling

Grid values

Arbitrary selectors

Arbitrary values

Responsive styles

Global styles

Animation

CSS utility

Usage

Overrides

CSS compose

Variants

Responsive variants

TypeScript

Variants

TokenamiStyle

Continuous Integration

Design systems

Official design system

Advanced

Selectors

Nested selectors

Aliases

Configure utility

Create aliases

Map properties to theme

Map custom properties to theme

Browserslist

Support

Why the double-dash prefix?

VSCode intellisense configuration

Supported frameworks

Supported browsers

Contributors

Credits