Radix UI

Radix UI

Radix provides two complementary libraries for React:

• Radix Themes: Pre-styled, ready-to-use component library with built-in theming
• Radix Primitives: Unstyled, accessible component primitives for custom design systems

Choosing Between Themes and Primitives

Use Radix Themes when:

• Building applications quickly with minimal styling effort
• Wanting a consistent, polished design out of the box
• Theming via configuration props is sufficient

Use Radix Primitives when:

• Building a custom design system with complete styling control
• Integrating with existing styling solutions (Tailwind, styled-components, CSS modules)
• Needing only specific components without a full theme system

Quick Start

Radix Themes Setup

npm install @radix-ui/themes

import "@radix-ui/themes/styles.css";
import { Theme } from "@radix-ui/themes";

export default function App() {
    return (
        <Theme accentColor="indigo" grayColor="slate" radius="medium">
            <MyApp />
        </Theme>
    );
}

Radix Primitives Setup

Install individual components:

npm install @radix-ui/react-dialog @radix-ui/react-dropdown-menu

Or install the full package:

npm install radix-ui

Radix Themes

Theme Configuration

The Theme component accepts these props:

Component Variants

Most Themes components support these variant props:

<Button variant="solid" size="2" color="indigo" highContrast />

Common variants: classic, solid, soft, surface, outline, ghost

Sizes: "1", "2", "3", "4" (component-specific)

Layout Components

import { Flex, Box, Grid, Container, Section } from "@radix-ui/themes";

<Flex direction="column" gap="3" align="center" justify="between">
  <Box p="4" style={{ background: "var(--gray-3)" }}>
    Content
  </Box>
</Flex>

<Grid columns="3" gap="4" width="auto">
  <Box>1</Box>
  <Box>2</Box>
  <Box>3</Box>
</Grid>

Typography

import { Text, Heading, Code, Em, Strong } from "@radix-ui/themes";

<Heading size="6" weight="bold">Title</Heading>
<Text size="2" color="gray">Body text</Text>
<Code variant="soft">const x = 1</Code>

For complete Themes component reference, see references/themes-components.md.

Radix Primitives

Core Concepts

Compound Components: Primitives use a compound component pattern with multiple parts:

import * as Dialog from "@radix-ui/react-dialog";

<Dialog.Root>
    <Dialog.Trigger>Open</Dialog.Trigger>
    <Dialog.Portal>
        <Dialog.Overlay className="overlay" />
        <Dialog.Content className="content">
            <Dialog.Title>Title</Dialog.Title>
            <Dialog.Description>Description</Dialog.Description>
            <Dialog.Close>Close</Dialog.Close>
        </Dialog.Content>
    </Dialog.Portal>
</Dialog.Root>;

Uncontrolled by Default: Components work without state management:

// Uncontrolled - manages its own state
<Dialog.Root>...</Dialog.Root>

// Controlled - you manage the state
<Dialog.Root open={isOpen}

The asChild Prop

Use asChild to compose Radix behaviour onto custom components:

import * as Tooltip from "@radix-ui/react-tooltip";
import { MyButton } from "./MyButton";

<Tooltip.Trigger asChild>
    <MyButton>Hover me</MyButton>
</Tooltip.Trigger>;

Requirements for custom components with asChild:

1. Spread all props onto the underlying DOM element
2. Forward refs using React.forwardRef

const MyButton = React.forwardRef<HTMLButtonElement, ButtonProps>(
    ({ children, ...props }, ref) => (
        <button ref={ref} {...props}>
            {children}
        </button>
    ),
);

Styling Primitives

With CSS classes:

<Dialog.Overlay className="dialog-overlay" />
<Dialog.Content className="dialog-content" />

With data attributes for state:

.accordion-item[data-state="open"] {
    background: var(--accent-3);
}

.accordion-item[data-state="closed"] {
    background: transparent;
}

With Tailwind CSS:

<Dialog.Overlay className="fixed inset-0 bg-black/50" />
<Dialog.Content className="fixed top-1/2 left-1/2 -translate-x-1/2 -translate-y-1/2 bg-white p-6 rounded-lg" />

For complete Primitives patterns, see references/primitives-patterns.md.

Accessibility

Radix Primitives implement WAI-ARIA patterns automatically:

• Focus management and trapping (modals)
• Keyboard navigation (arrow keys, Tab, Escape)
• Screen reader announcements
• Proper ARIA attributes

Ensure custom implementations maintain accessibility:

// Dialog requires Title for screen readers
<Dialog.Content aria-describedby={undefined}>
    <Dialog.Title>Required for a11y</Dialog.Title>
    {/* If no description, set aria-describedby={undefined} on Content */}
</Dialog.Content>