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Getting Started

Styled-system is a collection of utility functions that add style props to your React components, which allows for controlling styles based on global theme constants.

To use styled-system, you'll most likely want to use a CSS-in-JS library. These examples use styled-components, but styled-system works with other libraries like emotion and glamorous as well.

npm i styled-system styled-components

Create a Component

Create a new component that uses style functions from styled-system. To start with, add the color function to the component's styles argument.

import styled from 'styled-components'
import { color } from 'styled-system'

const Box = styled.div`
  ${color}
`

export default Box

Now, this component will have two style props available: color to set foreground color, and bg to set background color.

<Box color='#fff' bg='tomato'>
  Tomato
</Box>

So far, this component can be styled with any valid CSS color. To create a more consistent UI, create a theme module with a colors object.

// theme.js
export default {
  colors: {
    black: '#000e1a',
    white: '#fff',
    blue: '#007ce0',
    navy: '#004175'
  }
}

Theming

Most CSS-in-JS libraries use a ThemeProvider to handle theming in React. Import the styled-components ThemeProvider in the root of your application and pass the theme to the theme prop.

import React from 'react'
import { ThemeProvider } from 'styled-components'
import theme from './theme'

const App = props => (
  <ThemeProvider theme={theme}>
    {/* application elements */}
  </ThemeProvider>
)

export default App

With the ThemeProvider, the Box component now has access to the colors defined in the theme object.

<Box color='black' bg='blue'>
  Blue Box
</Box>

Styled-system will attempt to find a value based on keys in the theme and fallback to the raw value if it's not defined in the theme.

// uses the CSS color keyword `tomato` since it's not defined in the theme
<Box bg='tomato' />

To make the Box component a little more useful, add a few more styled-system functions to handle layout styles.

import styled from 'styled-components'
import { color, space, width } from 'styled-system'

const Box = styled.div`
  ${space}
  ${width}
  ${color}
`

// prop types can also be added from the style functions
Box.propTypes = {
  ...space.propTypes,
  ...width.propTypes,
  ...color.propTypes
}

Box.displayName = 'Box'

export default Box

Margin & Padding

The space function adds margin and padding props. The margin and padding props use a shorthand syntax, similar to Basscss, Tachyons, and Bootstrap.

Margin Props

  • m margin
  • mt margin-top
  • mr margin-right
  • mb margin-bottom
  • ml margin-left
  • mx margin-left and margin-right
  • my margin-top and margin-bottom

Padding Props

  • p padding
  • pt padding-top
  • pr padding-right
  • pb padding-bottom
  • pl padding-left
  • px padding-left and padding-right
  • py padding-top and padding-bottom

Space Theming

To set a consistent white-space scale, add a space array to your theme. Use numbers to set pixel values, or use strings for other CSS units such as rem.

// theme.js
export default {
  space: [
    0, 4, 8, 16, 32, 64, 128, 256, 512
  ]
}

All spacing props accept numbers, strings, or arrays as values, where:

  • Numbers between 0 and the last index of the space array are values from the space array defined in theme
  • Numbers greater than the length of the space array are converted to pixels
  • String values can be used for any valid CSS value (e.g. 'auto' or '2em'
  • Margin props accept negative values to set negative margin
  • Arrays can be used for responsive styles

Width

The width function adds a single width prop for setting responsive width styles.

The width prop accepts number, string, or array values, where:

  • Numbers between 0 and 1 are converted to percentage based widths (e.g. 1/2 becomes '50%')
  • Numbers greater than 1 are converted to pixels
  • Strings can be used for other CSS values (e.g. '50vw' or '30em')
  • Arrays can be used for responsive styles

Responsive Styles

All styled-system functions accept arrays as values to set styles responsively using a mobile-first approach.

<Box
  width={[
    1,    // 100% below the smallest breakpoint
    1/2,  // 50% from the next breakpoint and up
    1/4   // 25% from the next breakpoint and up
  ]}
/>
// responsive margin
<Text m={[ 0, 1, 2 ]} />

// responsive padding
<Text p={[ 2, 3, 4 ]} />

// responsive font-size
<Text fontSize={[ 3, 4, 5 ]} />