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name: app-shell-ui description: > Build or restyle frontends using App Shell UI — a clean, restrained macOS-style desktop-tool shell (left nav + content, soft surfaces, raised cards, single brand accent, settings-list language) with first-class light and dark themes. Use when the user asks for app-shell-ui, /app-shell-ui, 桌面工具风 UI, 系统设置感界面, 应用外壳, sidebar shell, Clash/设置风格前端, light/dark desktop client UI, 深色主题, 浅色主题, theme toggle, or wants pages that share one reusable app chrome across chat / settings / console / mail-like layouts. Also use for high-fidelity HTML/React demos from tokens and component recipes.

App Shell UI

You are implementing App Shell UI: a reusable application chrome + visual language. Business content changes; the shell does not.

Positioning (one line)

Not a marketing landing page. Not a dense ops admin.
A system-settings / desktop-utility shell: soft neutral canvas, raised cards, one accent, light borders, stroke icons first — in both light and dark.
Content areas stay calm: do not sprinkle emoji on every card/row.

When this skill applies

• New page / demo / prototype in this style
• Restyle an existing screen to match the family
• Extract tokens / sidebar / settings list / empty composer
• Add or fix light + dark theme pairs / theme toggle
• User says: app shell、桌面工具风、系统设置感、浅色/深色侧栏、开关列表

If the user wants flashy landing, heavy Material elevation, or multi-primary rainbow dashboards — do not force this skill; ask or pick another direction.

Workflow

1. Pick a layout template (required before pixels):
   • 设置型 — narrow left nav + form / toggle list
   • 控制台型 — left nav + card grid / status list
   • 工作台型 — session tree + centered empty state + composer card
   • IM / 三栏型 — icon rail + list + detail
2. Lock dual-theme tokens — use references/tokens.md (light + dark are both required by default).
3. Compose from recipes — use references/components.md (nav item, card, list row, toggle, pill, empty/composer). Recipes are theme-agnostic; only variables change.
4. Implement with CSS variables + data-theme="light"|"dark"; add a theme toggle; Tailwind/shadcn mapping optional.
5. Self-check — run the checklist at the end of this file in both themes before delivery.

Default stack when free to choose:

Layer	Default
Markup	Semantic HTML or React
Style	CSS variables + light utility/Tailwind
Components	shadcn / @coss style (New York + zinc-like neutrals)
Icons	Lucide-style 1.5–2px stroke, one family only
Theme	Light + Dark (toggle + optional OS prefers-color-scheme)

Prefer a single self-contained HTML for demos unless the user wants project integration.

Architecture (always)

L0  Window chrome (optional traffic lights / title bar / top tools + theme toggle)
L1  Sidebar or icon rail
L2  Content canvas (soft gray light / soft charcoal dark)
L3  Surfaces (raised cards, panels, lists)

Sidebar width: 220–260px (text nav) or 48–56px (icon rail).
Content padding: 20–28px. Spacing on 4px grid.

Non-negotiables

1. Two themes: ship light and dark token sets unless the user explicitly wants only one.
2. One brand primary for: primary buttons, toggle ON, progress fill, selected border/bg, links. Dark primary may be a slightly brighter twin (e.g. #007AFF → #0A84FF).
3. Surface ladder (both themes): app bg → sidebar bg → raised surface (weak contrast). Light: soft gray + white cards. Dark: soft charcoal + elevated gray cards — not pure #000 page + pure #fff cards.
4. Text ladder: primary / secondary / tertiary (values differ per theme).
5. Hierarchy via 1px borders first; shadow optional and theme-specific.
6. Radius ladder: 8 / 12 / 16 / 999 (shared across themes).
7. Copy pattern: title + one muted subtitle line.
8. Motion: 150–200ms color/background only; no bounce theater.
9. Theme switch: data-theme on root + visible toggle; persist with localStorage when possible.
10. Icon restraint (content): right-hand content defaults to text + stroke icons + status pills. Emoji/illustration are optional accents only — never the default for every list row or card. Prefer zero emoji in dense lists; at most one decorative mark in a banner or empty state.
11. Equal-height peers: any side-by-side content pair (list + composer, panel + panel, stats siblings that form a pair of cards in one row) must share the same outer bottom edge. Use grid/flex stretch + column flex + flex: 1 on surfaces — never align-items: start that leaves one short card. See references/layouts.md → Equal-height side-by-side columns.

Do / Don't

Do	Don't
Left nav + right content	Full-bleed hero art as the whole app
Soft canvas + raised cards in both themes	Neon cyber dark or pure OLED black by default
Single accent (paired light/dark)	Rainbow nav icons as multiple primaries
Stroke icons (Lucide-style) in nav + content	Mixed filled + stroke icon sets
Text-first cards/lists; pill for status	Emoji on every row / card / section header
Status as small pills / muted text	Loud full-width alert banners for normal states
Theme toggle in chrome	Dark mode via filter: invert()
Border separation via tokens	Hard-coded #fff / #000 chrome colors
Airy spacing	Dense spreadsheet packing
≤1 emoji accent per major region (or none)	Banner + cards + lists all emoji-heavy
Side-by-side cards equal height (stretch)	One tall / one short peer (align-items: start)

Page assembly order

1. Shell (window + sidebar + main)
2. Brand block in sidebar
3. Nav groups + active item
4. Page header (H1 + muted subtitle + actions)
5. Theme toggle in titlebar or settings (required for demos)
6. Optional toolbar (search + segmented filter)
7. Content blocks by priority: banner → stats → primary grid/list → secondary two-column
8. For every two-column peer row: apply equal-height recipe (stretch + flex surfaces)
9. Wire interaction: nav switch, selection, toggles, filters, theme toggle

Implementation notes

• Put light tokens on :root, :root[data-theme="light"] and dark on :root[data-theme="dark"] (see references/tokens.md).
• Components only consume variables — no hard-coded brand/surface hex in component rules.
• Selected nav: soft primary wash + primary text, radius 8px (wash mix differs by theme).
• Cards: --bg-surface + 1px --border + radius 12; selected: primary ring/border. Leading mark = stroke icon in muted plate or no mark — not emoji by default.
• Settings / feed rows: 16–18px stroke icon (optional soft plate) + title + muted desc + right control. Avoid emoji list icons.
• Empty / new session: centered title + large rounded composer; chips + primary CTA. Empty watermark may be one faint stroke icon or a single subdued glyph — not a stack of emoji.
• Banner: text-first; optional one small accent tile max (often none).
• Dashed add zone for “empty collection + create” (plus sign, not emoji).
• Secondary buttons, segment tracks, toggle OFF tracks must use theme tokens (--secondary-btn-bg, --seg-track, --toggle-off) — light gray rgba does not work on dark.

Theme API (canonical)

// data-theme = "light" | "dark"
// localStorage key: "app-shell-theme"
// toggle flips attribute; init reads storage then prefers-color-scheme

Minimal CSS token block

Copy the dual-theme block from references/tokens.md.

Minimal HTML skeleton

<html data-theme="light">
…
<div class="window">
  <header class="titlebar">
    …
    <button type="button" data-theme-toggle aria-label="切换深浅色">…</button>
  </header>
  <div class="shell">
    <aside class="sidebar">…</aside>
    <main class="main">…</main>
  </div>
</div>

Prompt seed (when generating designs)

Light

macOS desktop-utility light UI: 240px soft-gray sidebar (stroke icons + label, selected = light primary wash + 8px radius), main canvas soft gray with white rounded cards; single primary #007AFF for buttons, toggles, progress, selection ring; three text grays; radius 8–16px; almost no shadow, 1px light borders; settings/list rows with small stroke icons (not emoji) + title/desc + right toggle or status pill; content area text-first, minimal or no emoji; empty state = centered title + large rounded composer.

Dark

Same shell in dark mode: soft charcoal canvas #1C1C1E, sidebar #161617, raised cards #2C2C2E, borders white 8% alpha, text #F5F5F7 / #A1A1A6 / #6C6C70, primary #0A84FF, selected nav = primary 22% mix into card surface; no pure black page; no invert filter; include theme toggle.

Swap business nouns only; keep shell + dual-theme rules.

Reference files

• references/tokens.md — light + dark colors, type, radius, spacing, toggle script
• references/components.md — component recipes
• references/layouts.md — four layout templates + page recipes

Read them when implementing; do not invent a competing palette unless the user specifies a brand color (then replace only --primary light/dark pair and derived selected/wash colors).

Delivery checklist

Before finishing, verify once in light and once in dark:

• Both data-theme="light" and data-theme="dark" token sets exist
• Visible theme toggle works and (if web) preference can persist
• Exactly one primary accent in interactive UI (per theme pair OK)
• Canvas is soft gray / soft charcoal (not pure white page / pure black page)
• Cards use raised --bg-surface + light border + 8–16 radius
• No black text stuck on dark surfaces; no white boxes that ignore dark tokens
• Sidebar selected state is soft wash, not loud
• Title + muted subtitle on main pages
• Primary / secondary / ghost buttons all readable in both themes
• Toggle ON = primary, OFF = visible gray track in both themes
• Spacing roughly multiples of 4
• No heavy shadows, rainbow icons, landing hero chrome, or filter: invert
• Content area is not emoji-dense (lists/cards use stroke icons or text only)
• Side-by-side peer panels/cards align on the same bottom edge (no short+tall pair)
• Same shell would still work if business content is swapped

Optional local example

If present on this machine, study structure (not business copy):

~/Desktop/project/UI/fruit-ui/index.html

Teaching longform (human docs, not required for agents):

~/Desktop/桌面工具风UI教学.md