---
title: CSS Variables
description: Learn how to customize CSS variables in Chakra UI
---

:::info

Please read the [overview](/docs/theming/customization/overview) first to learn
how to properly customize the styling engine, and get type safety.

:::

## Variable Root

Here's an example of how to customize the selector that token CSS variables are
applied to.

```tsx title="theme.ts"
import { createSystem, defaultConfig, defineConfig } from "@chakra-ui/react"

const customConfig = defineConfig({
  cssVarsRoot: ":where(html)",
})

export const system = createSystem(defaultConfig, customConfig)
```

The emitted CSS variables will now be applied to the `html` element.

```css
:where(html) {
  --chakra-colors-gray-100: #e6f2ff;
  --chakra-colors-gray-200: #bfdeff;
  --chakra-colors-gray-300: #99caff;
}
```

## Variable Prefix

Here's an example of how to customize the prefix of the emitted CSS variables.

```tsx title="theme.ts"
import { createSystem, defaultConfig, defineConfig } from "@chakra-ui/react"

const customConfig = defineConfig({
  cssVarsPrefix: "sui",
})

export const system = createSystem(defaultConfig, customConfig)
```

The emitted CSS variables will now use the `sui` prefix.

```css
:where(html) {
  --sui-colors-gray-100: #e6f2ff;
  --sui-colors-gray-200: #bfdeff;
  --sui-colors-gray-300: #99caff;
}
```