# Scroll Area (Lumen Halo): prompt.md (v1.0.0)

- id: `lumen-scroll-area` · version 1.0.0 · component · free
- category: Layout
- build: Base UI (this item also ships a Radix build)
- install (this build): `npx shadcn@latest add https://beautiful-ui.dev/r/lumen-scroll-area.json`
- npm dependencies: @base-ui/react@^1
- registry dependencies: utils, https://beautiful-ui.dev/r/lumen-foundation.json
- docs: https://beautiful-ui.dev/components/lumen-scroll-area
- The install command carries everything this item needs (files, CSS, tokens, npm and registry dependencies). Prefer it to copying source by hand.

A thin rail that brightens while you scroll or hover it and keeps out of the way otherwise. shadcn's Scroll Area, cut from Lumen glass.

## Build it
- Stack: React 19 (`ref` is a plain prop), TypeScript, Tailwind CSS v4 utilities, a shadcn-initialised project with the `@/*` alias.
- Packages: `@base-ui/react@^1` (Base UI build); `radix-ui@^1` (Radix build).
- Files: `components/ui/lumen/scroll-area.tsx`.
- Registry dependencies, installed with it automatically: shadcn `utils` (cn), `lumen-foundation`.
- Builds: separate Base UI and Radix files. Install the one that matches the project (see Install): a free item's bare URL installs the Base UI build of it and its dependencies.
- Exports to keep: `ScrollArea`, `ScrollBar`, and every exported type.
- CSS: the install merges this item's rules (the registry `css` field) into your global stylesheet, in `@layer components`, and adds the lumen foundation (tokens, keyframes, motion levels) once. Nothing to import by hand.
- Re-running `add` (or `--overwrite`) re-applies those rules: put overrides in your own CSS, never in the installed rules.
- Tokens: retheme with the `--lumen-*` custom properties (`--lumen-accent`, `--lumen-accent-text`, `--lumen-bad`, `--lumen-bad-text`, `--lumen-focus`, `--lumen-good`, `--lumen-good-text`, `--lumen-hairline`, `--lumen-ink`, `--lumen-muted-ink`, `--lumen-series-1`, `--lumen-series-2`, `--lumen-series-3`, `--lumen-series-4`, `--lumen-series-5`, `--lumen-series-6`, `--lumen-warn`, `--lumen-warn-text`); this item's CSS also reads `--lumen-radius-k`. Never add Tailwind colour classes inside the component.

```tsx
import { ScrollArea } from "@/components/ui/lumen/scroll-area";
```

## Parts

| Part | data-slot | What it is for |
|---|---|---|
| `ScrollArea` | `scroll-area` | Root and viewport. |
| `ScrollBar` | `scroll-area-scrollbar` | The rail. |

Style a part with `[data-slot="<slot>"]` selectors or its `className`; keep the attributes when editing.

## Sound
- Keep every `data-slot` and `data-sound` attribute: the sound layer reads them.
- Installing this item adds no audio. Nothing plays until the app mounts `GlassSoundProvider` once (install: `npx shadcn@latest add https://beautiful-ui.dev/r/glass-sound.json`, import from `@/components/beautiful-ui/glass-sound`); `GlassSoundToggle` is its mute control. Without a provider the audio engine never loads.

## Match the original
- Read `components/ui/lumen/scroll-area.tsx` as the reference implementation before changing or recreating anything, and match it: sizes, colours per theme, motion timings, copy and behaviour.
- If you deviate (a prop you can't honour, a style you changed, a dependency you swapped), say so in your reply, part by part.
- Keep the accessibility contract, the keyboard map and the motion levels listed below.

## Use it when
- scroll area, custom scrollbar, scroll container, shadcn scroll area, Lumen
- Scrolling panels inside a page: a sidebar list, a log, a menu

### Not when
- The page itself: let it scroll natively

## Mistakes
- Give it a height

## Usage

```tsx
import { ScrollArea } from "@/components/ui/lumen/scroll-area";

<ScrollArea className="h-72">…</ScrollArea>
```

## Props

| Prop | Type | Default | What it does |
|---|---|---|---|
| `ScrollBar orientation` | `"vertical" \| "horizontal"` | `"vertical"` | Add a horizontal bar when needed. |

Full docs: https://beautiful-ui.dev/components/lumen-scroll-area

## Customising
- Colours: set the `--lumen-*` tokens on `:root`, or on a container with the `lumen-scope` class to retheme one area. Add the `lumen-inherit` class to follow your shadcn palette instead (`--chart-N`, `--destructive`).
- Dark mode follows the `.dark` class on an ancestor (the shadcn and next-themes convention).
- Update later by re-running the install with `--overwrite` (review the diff if you edited it). Changelog: https://beautiful-ui.dev/r/changelog.json

## Keyboard

| Keys | Action |
|---|---|
| ↑ ↓ / Page keys | Scroll |

## Motion inventory

| Interaction | What moves |
|---|---|
| Scroll | The rail brightens |

## Accessibility contract (preserve when editing)
- The viewport is focusable and scrolls with the keyboard

## Install

Base UI project (a base-* style in components.json):

```bash
npx shadcn@latest add https://beautiful-ui.dev/r/lumen-scroll-area.json
```

Radix project (a radix-*, new-york or default style):

```bash
npx shadcn@latest add https://beautiful-ui.dev/r/radix-nova/lumen-scroll-area.json
```

Or add the `@beautiful-ui` registry to components.json and run `npx shadcn@latest add @beautiful-ui/lumen-scroll-area`: the CLI picks the build from your style.

## Credits
- Built on shadcn/ui (https://ui.shadcn.com)

## Source (Base UI build)

### components/ui/lumen/scroll-area.tsx

```tsx
"use client";

/**
 * Scroll Area (Lumen Halo) v1.0.0 · Beautiful UI
 * Docs: https://beautiful-ui.dev/components/lumen-scroll-area · Agent prompt: https://beautiful-ui.dev/md/lumen-scroll-area.md
 * Licensed to the purchaser under the Beautiful UI license: https://beautiful-ui.dev/license
 */

import * as React from "react";
import { ScrollArea as ScrollAreaPrimitive } from "@base-ui/react/scroll-area";
import { cn } from "@/lib/utils";

/*
 * Lumen Scroll Area (Base UI build). shadcn's Scroll Area in Lumen Halo: a thin rail that brightens
 * while you scroll or hover it, and stays out of the way otherwise. Same exports and data-slots as
 * shadcn.
 */

function ScrollArea({ className, children, ...props }: ScrollAreaPrimitive.Root.Props) {
  return (
    <ScrollAreaPrimitive.Root data-slot="scroll-area" className={cn(`lumen-scroll-area`, className)} {...props}>
      <ScrollAreaPrimitive.Viewport data-slot="scroll-area-viewport" className={`lumen-scroll-area-viewport`}>
        {/* Content observes its own size, so the rail follows a list that grows without resizing the viewport. */}
        <ScrollAreaPrimitive.Content data-slot="scroll-area-content">{children}</ScrollAreaPrimitive.Content>
      </ScrollAreaPrimitive.Viewport>
      <ScrollBar />
      <ScrollAreaPrimitive.Corner />
    </ScrollAreaPrimitive.Root>
  );
}

function ScrollBar({ className, orientation = "vertical", ...props }: ScrollAreaPrimitive.Scrollbar.Props) {
  return (
    <ScrollAreaPrimitive.Scrollbar data-slot="scroll-area-scrollbar" data-orientation={orientation} orientation={orientation} className={cn(`lumen-scroll-bar`, className)} {...props}>
      <ScrollAreaPrimitive.Thumb data-slot="scroll-area-thumb" className={`lumen-scroll-thumb`} />
    </ScrollAreaPrimitive.Scrollbar>
  );
}

export { ScrollArea, ScrollBar };
```

### CSS (the registry `css` / `cssVars`, merged into the global stylesheet by the shadcn CLI)

```css
@layer components {
  .lumen-scroll-area {
    position: relative;
    overflow: hidden;
  }
  .lumen-scroll-area-viewport {
    width: 100%;
    height: 100%;
    border-radius: inherit;
    outline: none;
  }
  .lumen-scroll-area-viewport:focus-visible {
    box-shadow: 0 0 0 2px var(--gc-gap), 0 0 0 4px var(--gc-p-focus), 0 0 #0000;
  }
  .lumen-scroll-bar {
    display: flex;
    padding: 2px;
    touch-action: none;
    user-select: none;
    opacity: .6;
    transition: opacity min(0.2s, var(--gcp-cm)) ease;
  }
  .lumen-scroll-bar[data-orientation="vertical"] {
    width: 9px;
    height: 100%;
  }
  .lumen-scroll-bar[data-orientation="horizontal"] {
    flex-direction: column;
    height: 9px;
  }
  .lumen-scroll-area:hover .lumen-scroll-bar,.lumen-scroll-bar:is([data-scrolling],[data-hovering],[data-state="visible"]) {
    opacity: 1;
  }
  .lumen-scroll-thumb {
    position: relative;
    flex: 1;
    border-radius: calc(99px * var(--lumen-radius-k, 1));
    background: color-mix(in srgb,var(--gc-ink) 22%,transparent);
    transition: background min(0.2s, var(--gcp-cm)) ease;
  }
  .lumen-scroll-bar:hover .lumen-scroll-thumb {
    background: color-mix(in srgb,var(--gc-ink) 38%,transparent);
  }
}
```

The lumen foundation (the tokens listed above, keyframes and motion levels) installs once with the first component; its CSS is public at https://beautiful-ui.dev/r/lumen-foundation.json.