Concepts

Merging Styles

Panda CSS provides a few ways to efficiently merge styles together without conflicts.

Merging css objects

You can merge multiple style objects together using the css function.

import { css } from 'styled-system/css'
 
const style1 = {
  bg: 'red',
  color: 'white'
}
 
const style2 = {
  bg: 'blue'
}
 
const className = css(style1, style2) // => 'bg_blue text_white'

In some cases though, the style object might not be colocated in the same file as the component. In this case, you can use the css.raw function to preserve the original style object.

💡

All .raw(...) signatures are identity functions that return the same value as the input, but > serve as a hint to the compiler that the value is a style object.

// style.js
import { css } from 'styled-system/css'
 
export const style1 = css.raw({
  bg: 'red',
  color: 'white'
})
 
// component.js
import { css } from 'styled-system/css'
import { style1 } from './style.js'
 
const style2 = css.raw({
  bg: 'blue'
})
 
const className = css(style1, style2) // => 'bg_blue text_white'

Merging cva + css styles

The same technique can be used to merge an atomic cva recipe and a style object.

import { css, cx, cva } from 'styled-system/css'
 
const overrideStyles = css.raw({
  bg: 'red',
  color: 'white'
})
 
const buttonStyles = cva({
  base: {
    bg: 'blue',
    border: '1px solid black'
  },
  variants: {
    size: {
      small: { fontSize: '12px' }
    }
  }
})
 
const className = css(
  // returns the resolved style object
  buttonStyles.raw({ size: 'small' }),
  // add the override styles
  overrideStyles
)
 
// => 'bg_red border_1px_solid_black color_white font-size_12px'

Merging sva + css styles

The same technique can be used to merge an atomic sva recipe and a style object.

import { css, sva } from 'styled-system/css'
 
const overrideStyles = css.raw({
  bg: 'red',
  color: 'white'
})
 
const buttonStyles = sva({
  slots: ['root']
  base: {
    root: {
      bg: 'blue',
      border: '1px solid black'
    }
  },
  variants: {
    size: {
      root: {
        small: { fontSize: '12px' }
      }
    }
  }
})
 
// returns the resolved style object for all slots
const { root } = buttonStyles.raw({ size: 'small' })
 
const className = css(
  root,
  // add the override styles
  overrideStyles
)
 
// => 'bg_red border_1px_solid_black color_white font-size_12px'

Merging config recipe and style object

Due to the fact that the generated styles of a config recipe is saved in the @layer recipe cascade layer, they can overriden with any atomic styles. Use the cx function to achieve that.

💡

The utilties layer has more precedence than the recipe layer.

import { css, cx } from 'styled-system/css'
import { button } from 'styled-system/recipes'
 
const className = cx(
  // returns the resolved class name: `button button--size-small`
  button({ size: 'small' }),
  // add the override styles
  css({ bg: 'red' }) // => 'bg_red'
)
 
// => 'button button--size-small bg_red'

Merging within JSX component

Using these techniques, you can apply them to a component to merge styles together.

💡

Tip: Panda extracts the css prop from the JSX component

const cardStyles = css.raw({
  bg: 'red',
  color: 'white'
})
 
function Card({ title, description, css: cssProp }) {
  return (
    // merge the `cardStyles` with the `cssProp` passed in
    <div className={css(cardStyles, cssProp)}>
      <h1>{title}</h1>
      <p>{description}</p>
    </div>
  )
}
 
// usage
function Demo() {
  return (
    <Card
      title="Hello World"
      description="This is a card component"
      css={{ bg: 'blue' }}
    />
  )
}

If you use any other prop name other than css, then you must use the css.raw(...) function to ensure Panda extracts the style object.

const cardStyles = css.raw({
  bg: 'red',
  color: 'white'
})
 
function Card({ title, description, style }) {
  return (
    // merge the `cardStyles` with the `style` passed in
    <div className={css(cardStyles, style)}>
      <h1>{title}</h1>
      <p>{description}</p>
    </div>
  )
}
 
// usage
function Demo() {
  return (
    <Card
      title="Hello World"
      description="This is a card component"
      // use `css.raw(...)` to ensure Panda extracts the style object
      style={css.raw({ bg: 'blue' })}
    />
  )
}
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