• Features
• Installation
• How it Works
• Examples
  • Styled Function
  • Style Props
  • CSS Function
  • CSS Prop
  • Media Queries
  • Keyframes
  • Global Styles
  • Theming
  • Variants
  • Pseudo Selectors
  • Child Selectors
• Acknowledgments
• Development

Features

• Generates atomic class names
• 2.2kb minified and gzipped
• Zero dependencies
• Works in Server and Client Components
• Compatible with Suspense and streaming
• Deduplicates styles across environments
• Encourages encapsulation
• Supports css prop with JSX pragma
• Loads styles on demand
• Ship CSS in your NPM packages

Installation

npm install restyle

import { styled } from 'restyle'

export const Box = styled('div', {
  padding: '1rem',
  backgroundColor: 'peachpuff',
})

How it Works

Restyle leverages React's new ability to hoist style elements by generating atomic CSS on-demand to provide a flexible and efficient styling solution for React components.

import { css } from 'restyle'

const [classNames, Styles] = css({
  padding: '1rem',
  backgroundColor: 'peachpuff',
})

// classNames: 'x1y2 x3z4'
// Styles: <style>.x1y2{padding:1rem}.x3z4{background-color:peachpuff}</style>

import { css } from 'restyle'

const [classNames] = css({
  padding: '1rem',
  backgroundColor: 'tomato',
})

// Example output: 'x1y2 xfg3'

import { css } from 'restyle'

const styles = {
  padding: '1rem',
  backgroundColor: 'rebeccapurple',
}

const [classNames, Styles] = css(styles)

// classNames: 'x1y2 x4z1'
// Reuse class names for other elements
const buttonStyles = {
  ...styles,
  border: '1px solid black',
}

const [buttonClassNames, ButtonStyles] = css(buttonStyles)

// buttonClassNames: 'x1y2 x4z1 x5a6'

import { css } from 'restyle'

export default function OnDemandStyles() {
  const [classNames, Styles] = css({
    padding: '1rem',
    backgroundColor: 'papayawhip',
  })

  return (
    <div className={classNames}>
      Hello World
      <Styles />
    </div>
  )
}

/** @jsxImportSource restyle */

export default function MyComponent() {
  return (
    <div
      css={{
        padding: '1rem',
        backgroundColor: 'peachpuff',
      }}
    >
      Hello World
    </div>
  )
}

Examples

• Styled Function
• Style Props
• CSS Function
• CSS Prop
• Media Queries
• Keyframes
• Global Styles
• Theming
• Variants
• Pseudo Selectors
• Child Selectors

Styled Function

The styled utility is a higher-order function that takes an HTML element tag name or a component that accepts a className prop and a initial styles object that returns a styled component that can accept a css prop:

import Link from 'next/link'
import { styled } from 'restyle'

const StyledLink = styled(Link, {
  color: 'rebeccapurple',
  textDecoration: 'none',
})

Style Props

The second argument to the styled utility also accepts a style resolver function that returns an object of styles based on the props passed to the component, referred to as style props. This is useful for creating components that accept dynamic styles based on props.

For example, you can create a Grid component that accepts gridTemplateColumns and gridTemplateRows props:

import { styled } from 'restyle'

interface GridStyleProps {
  gridTemplateColumns: string
  gridTemplateRows: string
}

const Grid = styled('div', (styleProps: GridStyleProps) => ({
  display: 'grid',
  gridTemplateColumns: styleProps.gridTemplateColumns,
  gridTemplateRows: styleProps.gridTemplateRows,
}))

Now you can use these props to style the component:

<Grid gridTemplateColumns="repeat(3, 1fr)">
  <div>1</div>
  <div>2</div>
  <div>3</div>
</Grid>

[!IMPORTANT] A proxy is used to differentiate between style props and those passed directly to the component. Only style props should be accessed from the first parameter of the style resolver function to ensure proper filtering.

To access the props passed to the component, you can use the second parameter of the style resolver function. This is useful for applying styles based on props that are not style props:

import { styled } from 'restyle'

interface ButtonStyleProps {
  backgroundColor: string
  color: string
}

const Button = styled('button', (styleProps: ButtonStyleProps, props) => ({
  backgroundColor: styleProps.backgroundColor,
  color: styleProps.color,
  opacity: props.disabled ? 0.6 : 1,
}))

CSS Function

The css function returns a tuple of class names and the style tags to render. You can use the class names to apply styles to an element and the style tag to inject the styles into the head of the document:

import React from 'react'
import { css } from 'restyle'

export default function BasicUsage() {
  const [classNames, Styles] = css({
    padding: '1rem',
    backgroundColor: 'peachpuff',
  })

  return (
    <>
      <div className={classNames}>Hello World</div>
      <Styles />
    </>
  )
}

CSS Prop

The css function is most useful for components. However, you can use the css prop to style elements directly. The pragma will take care of applying the class names and injecting the style tag.

First, configure the pragma in your tsconfig.json file:

{
  "compilerOptions": {
    "jsxImportSource": "restyle"
  }
}

Now, you can use the css prop to style elements:

export default function CSSProp() {
  return (
    <div
      css={{
        padding: '1rem',
        backgroundColor: 'peachpuff',
      }}
    >
      Hello World
    </div>
  )
}

Alternatively, you can set the pragma at the top of the file:

/** @jsxImportSource restyle */

export default function CSSProp() {
  return (
    <div
      css={{
        padding: '1rem',
        backgroundColor: 'peachpuff',
      }}
    >
      Hello World
    </div>
  )
}

Media Queries

/** @jsxImportSource restyle */

export default function MediaQueries() {
  return (
    <h1
      css={{
        fontSize: '2rem',
        '@media screen and (min-width: 40em)': {
          fontSize: '3.5rem',
        },
      }}
    >
      Resize the window
    </h1>
  )
}

An additional media utility is available to help with creating typed media query keys from objects:

/** @jsxImportSource restyle */
import { media } from 'restyle'

export default function MediaQueries() {
  return (
    <h1
      css={{
        fontSize: '2rem',
        [media({ screen: true, minWidth: '40em' })]: {
          fontSize: '3.5rem',
        },
      }}
    >
      Resize the window
    </h1>
  )
}

Keyframes

Use the keyframes utility to easily create CSS animations:

import { keyframes, styled } from 'restyle'

const FadeInKeyframes = keyframes({
  from: { opacity: 0 },
  to: { opacity: 1 },
})

const FadeIn = styled('div', {
  animation: `${FadeInKeyframes} 1s ease-in-out`,
})

export default function FadeInComponent() {
  return (
    <>
      <FadeInKeyframes />
      <FadeIn>Hello World</FadeIn>
    </>
  )
}

Global Styles

Use the GlobalStyles component to inject global styles into the document. This is useful for setting default styles for the body, headings, etc. This component accepts an object of styles and injects them into the head of the document based on their order in the object as well as when they are rendered in the react tree. Note, styles will not be removed when the component is unmounted. React makes no guarantees about when styles are removed from the document.

import { GlobalStyles } from 'restyle'

export default function Layout({ children }) {
  return (
    <>
      <GlobalStyles>
        {{
          body: {
            margin: 0,
            padding: 0,
            fontFamily: 'sans-serif',
          },
        }}
      </GlobalStyles>
      {children}
    </>
  )
}

Theming

The GlobalStyles component can be used to define CSS variable themes that can be used throughout your application:

import { GlobalStyles, styled } from 'restyle'

const Container = styled('div', {
  backgroundColor: 'var(--background)',
  color: 'var(--foreground)',
  minHeight: '100vh',
  display: 'grid',
  placeItems: 'center',
})

const Button = styled('button', {
  padding: '0.5rem 1rem',
  borderRadius: '0.1rem',
  backgroundColor: 'var(--button-background)',
  color: 'var(--button-foreground)',
  border: 'none',
  cursor: 'pointer',
})

export default function App() {
  return (
    <>
      <GlobalStyles>
        {{
          ':root': {
            '--background': '#ffffff',
            '--foreground': '#000000',
            '--button-background': '#007bff',
            '--button-foreground': '#ffffff',
          },
          '@media (prefers-color-scheme: dark)': {
            ':root': {
              '--background': '#000000',
              '--foreground': '#ffffff',
              '--button-background': '#1a73e8',
              '--button-foreground': '#ffffff',
            },
          },
        }}
      </GlobalStyles>
      <Container>
        <Button>Themed Button</Button>
      </Container>
    </>
  )
}

Variants

Variants can be achieved by using the style props pattern. For example, you can create an Alert component that accepts a variant prop that applies different styles based on the variant:

import { styled, type CSSObject } from 'restyle'

type AlertVariant = 'note' | 'success' | 'warning'

const variantStyles = {
  note: {
    backgroundColor: '#1b487d',
    borderLeftColor: '#82aaff',
  },
  success: {
    backgroundColor: '#2b7b3d',
    borderLeftColor: '#5bc873',
  },
  warning: {
    backgroundColor: '#b36b00',
    borderLeftColor: '#ffb830',
  },
} satisfies Record<AlertVariant, CSSObject>

export const Alert = styled('div', (props: { variant: AlertVariant }) => {
  return {
    padding: '1.5rem 2rem',
    borderRadius: '0.5rem',
    color: 'white',
    ...variantStyles[props.variant],
  }
})

Pseudo Selectors

/** @jsxImportSource restyle */

export default function Hover() {
  return (
    <div
      css={{
        ':hover': {
          opacity: 0.8,
        },
      }}
    >
      Hover me
    </div>
  )
}

Child Selectors

/** @jsxImportSource restyle */

export default function ChildSelectors() {
  return (
    <div
      css={{
        color: 'black',
        '> a': {
          color: 'tomato',
        },
      }}
    >
      Parent
      <a href="#">Link</a>
    </div>
  )
}

Acknowledgments

This project is inspired by and builds upon the ideas and work of several other projects in the CSS-in-JS ecosystem:

• The React team for the style hoisting feature which makes this library possible
• Glamor for introducing the css prop
• Styled-Components for introducing the styled function
• Emotion for types and the modern JSX pragma
• CXS for atomic CSS generation
• Fela for their approach to deterministic atomic class name ordering
• Otion for the regex to parse unitless CSS properties

Thank you to WebReflection for the restyle NPM package name.

Development

In one terminal, run the following command to build the library and watch for changes:

npm install
npm run dev

In another terminal, run the following command to start the development server for the site:

cd site
npm install
npm run dev