Theme UI
Build consistent, themeable React UIs based on design system constraints and design tokens
https://theme-ui.com
- Style your application consistently with a global theme object and customizable design tokens
- Style MDX content with themes
- Follows the Theme Specification for interoperability with other libraries
- Style elements directly with the
css
prop and @styled-system/css - Works with or without custom styled components and Styled System
- First-class support for Typography.js themes
- First-class support for dark mode and other color modes
- Use contextual theming for nested stylistic changes
- Primitive page layout components
- Keep styles isolated with Emotion
Getting Started
npm i theme-ui @emotion/core @mdx-js/react
Wrap your application with the ThemeProvider
component and pass in a custom theme
object.
import React from 'react'
import { ThemeProvider } from 'theme-ui'
import theme from './theme'
export default props => (
<ThemeProvider theme={theme}>{props.children}</ThemeProvider>
)
The theme
object should follow the System UI Theme Specification,
which lets you define custom color palettes, typographic scales, fonts, and more.
export default {
fonts: {
body: 'system-ui, sans-serif',
heading: '"Avenir Next", sans-serif',
monospace: 'Menlo, monospace',
},
colors: {
text: '#000',
background: '#fff',
primary: '#33e',
},
}
css
prop
Use the css
prop throughout your application, along with the css
utility to pick up values from the theme.
Using the css
utility means that
color and other values can reference values defined in theme
object.
import React from 'react'
import { css } from 'theme-ui'
export default () => (
<div
css={css({
fontWeight: 'bold',
fontSize: 4, // picks up value from `theme.fontSizes[4]`
color: 'primary', // picks up value from `theme.colors.primary`
})}
>
Hello
</div>
)
Read more about the css
utility in the @styled-system/css docs.
Responsive styles
The css
utility also supports using arrays as values to change properties responsively with a mobile-first approach.
import React from 'react'
import { css } from 'theme-ui'
export default props => (
<div
css={css({
// applies width 100% to all viewport widths,
// width 50% above the first breakpoint,
// and 25% above the next breakpoint
width: ['100%', '50%', '25%'],
})}
/>
)
jsx
pragma
To use values from the theme
object without importing the css
utility, use the custom jsx
pragma, which will automatically convert Theme UI css
prop values.
import { jsx } from 'theme-ui'
export default props => (
<div
css={{
fontSize: 4,
color: 'primary',
bg: 'lightgray',
}}
/>
)
Read more in the custom pragma docs.
MDX Components
Use the components
prop to add components to MDX scope.
This can be used to introduce new behavior to markdown elements in MDX, such as adding linked headings or live-editable code examples.
Internally, the ThemeProvider
is a combination of MDXProvider
and Emotion's ThemeProvider
.
import React from 'react'
import { ThemeProvider } from 'theme-ui'
import mdxComponents from './mdx-components'
import theme from './theme'
export default props => (
<ThemeProvider components={mdxComponents} theme={theme}>
{props.children}
</ThemeProvider>
)
theme.styles
The MDX components can also be styled via the theme.styles
object.
This can be used as a mechanism to pass in fully-baked themes and typographic styles to MDX content.
export default {
colors: {
primary: '#33e',
},
styles: {
h1: {
fontSize: 32,
color: 'primary',
},
},
}
Styled components
These components' styles can also be consumed outside of an MDX doc with the Styled
component.
Note that these are only styled using the same theme.styles
object and not the same components passed to the ThemeProvider
context.
import React from 'react'
import { Styled } from 'theme-ui'
export default props => (
<Styled.div>
<Styled.h1>Hello</Styled.h1>
</Styled.div>
)
To change the underlying component in Styled
, use the as
prop.
<Styled.a as={Link} to="/">
Home
</Styled.a>
Layout Components
Theme UI includes several components for creating page layouts.
Layout
: sets a flex column with 100vh min-heightHeader
: flexbox rowFooter
: flexbox rowMain
: flex auto container for pushing the Footer to the bottom of the viewportContainer
: max-width, centered container
import React from 'react'
import { Layout, Header, Main, Container, Footer } from 'theme-ui'
export default props => (
<Layout>
<Header>Hello</Header>
<Main>
<Container>{props.children}</Container>
</Main>
<Footer>© 2019</Footer>
</Layout>
)
Box & Flex
The Box
& Flex
layout components are similar to the ones found in Rebass, but are built with Emotion and @styled-system/css
.
import React from 'react'
import { Flex, Box } from 'theme-ui'
export default props => (
<Flex flexWrap="wrap">
<Box width={[1, 1 / 2]} />
<Box width={[1, 1 / 2]} />
</Flex>
)
More Documentation
MIT License