Claude Theme: Tailwind Config & Code Asset Overview

⬅️ Previous: Chapter 6: Desktop Architecture & Collaboration Topology · 📚 Back to the 1.x overview · Next: Chapter 8: Front-end UI & Motion Guidelines for AI Agents ➡️

This chapter is the engineering reference for the Claude design system as reproduced in Open Claude UI: a ready-to-use Tailwind config and base CSS, the inventory of all production files in code-examples/, the asset policy with system font and audio substitutes, the Claude Desktop runtime architecture, and how to bridge the tokens into another host. It is a translation of the Chinese handbook chapter; every value is copied from it unchanged, and code blocks are reproduced as-is.

Chapter 7: Engineering Config & Code Asset Overview

Technical domain: Engineering Setup & Asset Inventory Source of the analysis: extracted with REA (Reverse Engineer Anything) v6.5.0 from the macOS production build /Applications/Claude.app (@ant/desktop v2.37337.1, build timestamp 2026-10-13T22:16:06Z), covering all 30 standalone production code files, the Tailwind extension config and the system font/audio asset rules.

7.1 Ready-to-use Tailwind config and base CSS

To reproduce the Claude look directly in an existing front-end project, add the following extensions to tailwind.config.js and your global CSS:

7.1.1 tailwind.config.js configuration

/** @type {import('tailwindcss').Config} */
module.exports = {
  darkMode: 'class',
  content: [
    './src/**/*.{js,ts,jsx,tsx,mdx}',
    './code-examples/**/*.{js,ts,jsx,tsx}',
    './components/**/*.{js,ts,jsx,tsx,mdx}',
    './app/**/*.{js,ts,jsx,tsx,mdx}',
  ],
  theme: {
    extend: {
      colors: {
        clay: {
          DEFAULT: '#d97757',
          hover: '#cc5a36',
          light: '#fbf3ef',
          dark: '#e08264',
        },
        surface: {
          0: 'var(--cds-surface-0)',
          1: 'var(--cds-surface-1)',
          2: 'var(--cds-surface-2)',
          3: 'var(--cds-surface-3)',
          popover: 'var(--cds-surface-popover)',
        },
      },
      fontFamily: {
        sans: [
          'AnthropicSans',
          'Inter',
          'system-ui',
          '-apple-system',
          'BlinkMacSystemFont',
          'Segoe UI',
          'PingFang SC',
          'sans-serif',
        ],
        serif: [
          'AnthropicSerif',
          'Newsreader',
          'ui-serif',
          'Georgia',
          'Times New Roman',
          'serif',
        ],
        mono: [
          'JetBrains Mono',
          'ui-monospace',
          'SF Mono',
          'Menlo',
          'monospace',
        ],
      },
      borderRadius: {
        'xs': 'var(--radius-xs, 2px)',
        'sm': 'var(--radius-sm, 4px)',
        'md': 'var(--radius-md, 6px)',
        'lg': 'var(--radius-lg, 8px)',
        'panel': 'var(--cds-panel-radius, 10px)',
        'xl': 'var(--radius-xl, 12px)',
        '2xl': 'var(--radius-2xl, 16px)',
        'bubble': 'var(--cds-message-bubble-radius, 18px)',
        'composer': 'var(--cds-radius-composer, 20px)',
        'pill': 'var(--df-radius-pill, 999px)',
        'card': 'var(--radius-card, calc(var(--radius-lg, 8px) + calc(4px * var(--cds-rem-scale, 1))))',
      },
      boxShadow: {
        'sm': 'var(--cds-shadow-sm)',
        'md': 'var(--cds-shadow-md)',
        'lg': 'var(--cds-shadow-lg)',
        'popover': 'var(--cds-shadow-popover)',
        'composer': 'var(--cds-shadow-composer)',
        'composer-hover': 'var(--cds-shadow-composer-hover)',
        'composer-focus': 'var(--cds-shadow-composer-focus)',
        'focus-glow': 'var(--cds-focus-shadow)',
        'drop-glow': 'var(--cds-shadow-drop-glow)',
        'panel': 'var(--cds-panel-shadow)',
        'panel-hover': 'var(--cds-panel-shadow-hover)',
      },
      animation: {
        'quiet-dot': 'timeline-quiet-dot 1.9s cubic-bezier(0.4, 0, 0.2, 1) infinite',
        'message-fade-up': 'message-fade-up 0.45s cubic-bezier(0.34, 1.3, 0.64, 1)',
        'saved-decay': 'saved-check-decay 0.35s cubic-bezier(0.165, 0.84, 0.44, 1) 2.2s forwards',
        'clay-breathe': 'dframe-clay-breathe 2.4s infinite ease-in-out',
        'dot-pulse': 'dframe-dot-pulse 1.2s infinite ease-in-out',
        'shimmer-sweep': 'cds-skeleton-sweep 1.8s infinite cubic-bezier(0.4, 0, 0.2, 1)',
        'thumbnail-grow': 'file-thumbnail-grow-in 250ms cubic-bezier(0.165, 0.84, 0.44, 1)',
      },
    },
  },
  plugins: [],
};

7.1.2 Global base CSS (globals.css / cds-base.css)

/* ==========================================================================
   Claude Design System (CDS) Production Core Styles (REA v6.5.0 取证规范)
   ========================================================================== */

:root {
  --cds-rem-scale: calc(16 / 17);
  --cds-surface-0: var(--cds-gray-20, #f9f9f7); /* 侧边栏/底色画布 */
  --cds-surface-1: var(--cds-gray-10, #fcfcfb); /* 聊天主工作台 */
  --cds-surface-2: var(--cds-gray-0, #ffffff);  /* 消息卡片表面 */
  --cds-surface-3: var(--cds-gray-0, #ffffff);  /* 悬浮 Popover 与输入框底盘 */
  --cds-clay: #d97757;
  --cds-clay-emphasized: #cc5a36;
  --cds-border: hsla(0, 0%, 8%, 0.10);
  --cds-border-strong: hsla(0, 0%, 8%, 0.20);
  --cds-segmented-control-track: rgba(0, 0, 0, 0.06);
  --cds-segmented-control-thumb: #ffffff;
}

[data-mode="dark"], .dark {
  --cds-surface-0: var(--cds-gray-900, #0b0b0b); /* 暗色侧边栏 */
  --cds-surface-1: var(--cds-gray-850, #151515); /* 暗色主聊天背景 */
  --cds-surface-2: var(--cds-gray-830, #1a1a19); /* 暗色卡片表面 */
  --cds-surface-3: var(--cds-gray-800, #20201f); /* 暗色高层浮盘 */
  --cds-surface-popover: var(--cds-gray-750, #2c2c2a);
  --cds-border: hsla(0, 0%, 100%, 0.09);
  --cds-border-strong: hsla(0, 0%, 100%, 0.18);
  --cds-segmented-control-track: rgba(255, 255, 255, 0.08);
  --cds-segmented-control-thumb: #2c2c2a;
}

/* 1. 暗色模式光学字重减薄补偿（抵消视网膜光渗发散） */
[data-mode="dark"] .font-medium,
.dark .font-medium {
  font-variation-settings: "wght" 465;
}
[data-mode="dark"] .font-semibold,
.dark .font-semibold {
  font-variation-settings: "wght" 560;
}
[data-mode="dark"] .font-bold,
.dark .font-bold {
  font-variation-settings: "wght" 660;
}

/* 2. 行内图标光学基线校准实用类 */
.align-[-0.125em] { vertical-align: -0.125em; }
.align-[-0.075em] { vertical-align: -0.075em; }
.align-[-1px]     { vertical-align: -1px; }

/* 3. 文本换行与防爆容器约束 */
.text-balance-native { text-wrap: balance; }
.text-pretty-native  { text-wrap: pretty; }
.overflow-wrap-anywhere {
  overflow-wrap: anywhere;
  word-break: normal;
}

/* 4. 等宽数字约束 */
.tabular-nums {
  font-variant-numeric: tabular-nums;
  font-feature-settings: "tnum" 1;
}

/* 5. 矢量图标系统（Phosphor & Anthropicons） */
[data-cds="Icon"] {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  line-height: 1;
  font-feature-settings: "liga" 0;
  vertical-align: -0.125em;
}
[data-cds="Icon"] > [data-cds-icon-layer="secondary"] {
  color: color-mix(in srgb, currentColor 45%, transparent);
}

7.2 Production source file inventory

Technical domain: All 30 standalone production code files

So engineering teams can reuse them independently, every component and piece of motion logic distilled from REA's in-depth analysis is split into standalone production code files in the code-examples/ directory, together with an optically tuned system font fallback stack and sound effects synthesized in code with the Web Audio API.

7.2.1 Basic UI component and motion files (11 modules)

7.2.2 Architecture and engineering physics files (19 modules)

7.3 Asset rules and system font / audio substitutes

Open-source copyright and asset policy (DMCA & Assets Policy):
This open-source repository does not distribute any proprietary binary assets (commercial .ttf fonts, recorded .mp3 audio or commercial app icons). It provides native system-level substitutes and pure-code physics implementations instead:

1. System Font Stacks

No proprietary fonts need to be installed; high-quality, optically tuned system font stacks are used:

• Sans-serif body: font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif
• Serif headings: font-family: "New York", Georgia, Cambria, "Times New Roman", Times, serif
• Monospace code: font-family: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Monaco, Consolas, "Liberation Mono", monospace

2. Synthetic Web Audio SFX

code-examples/ClaudeAudioPlayer.ts includes native Web Audio API oscillators (OscillatorNode) that synthesize gentle notification sounds with zero latency, without downloading any external MP3:

• enter_voice_mode: rising 440Hz → 880Hz two-note
• exit_voice_mode: gently falling 880Hz → 440Hz
• tool_approval_needed: short woody 520Hz two-note resonance
• disconnected: smooth falling decay at 320Hz You can also call player.setSfxPath(name, url) to plug in your own royalty-free sounds.

7.4 Modern runtime architecture: Rolldown, the WASM modules and the Clarkdown compiler

Analysis source and ground truth:
Based on REA v6.5.0's static analysis and symbol inspection of the core runtime in the @ant/desktop v2.37337.1 package:

• Bundler runtime: rolldown-runtime-C3OYiQ02.js
• WASM binaries: cf4728005-C0phcBAH.wasm (8.25MB), c35955a62-DsUXHNAG.wasm (1.35MB), c571a2685-sT_OTiSe.wasm (204KB)
• Clarkdown driver layer: c2abd4ebb-suZcxVhm.js
• Docx parsing driver: cd2c9366b-CcYZgarF.js
• Syntax parsing driver: tree-sitter-BR-18drl.js

Claude Desktop 2.0 moved away from a single monolithic Webpack bundle to a modern client architecture with Rolldown (the Rust-based Vite/Rollup bundler core) as the runtime hub, three high-performance WebAssembly modules for heavy computation, and the proprietary Clarkdown document engine as the shared medium.

7.4.1 Rolldown native Rust bundler runtime (rolldown-runtime-C3OYiQ02.js)

Anthropic ships a Rolldown bundler runtime written in Rust in the production build. With more than 4,000 micro-modules and separate Chunks on desktop, a traditional mixed CommonJS / ESM setup would make cold start very slow and cause module hash collisions. The Rolldown runtime provides:

1. Millisecond module resolution and lookup: a lightweight inline module registry gives O(1) on-demand dynamic Chunk loading, cutting cold-start time by more than 65% compared with the old version:

   Copy Text

   // REA 分析还原：Rolldown 动态模块导入运行时核心抽象
   interface RolldownRuntimeRegistry {
     modules: Record<string, () => Promise<unknown>>;
     resolveChunk: (chunkId: string) => string;
     preloadChunks: (chunkIds: string[]) => void;
   }

2. Zero-overhead Inlining: references between Rolldown Chunks are plain native ESM namespace imports, removing Webpack's heavy __webpack_require__ closures and large lookup tables, so the static overhead of each micro-module is close to zero.

7.4.2 The three core client WASM modules

To combine strict client-side privacy with high performance for heavy computation, Claude Desktop ships three highly optimized WebAssembly binaries:

7.4.3 The Clarkdown format and local/remote document hosts (createLocalDocumentHost, createRemoteDocumentHost, .clark / .cd)

In Artifacts and Cowork spaces, Anthropic defines and ships a proprietary structured document format called Clarkdown, with a compiler covering its full lifecycle.

1. Proprietary file extensions

• .clark: Clarkdown source markup, keeping semantic block-level metadata and thinking markers.
• .cd: a Claude Document binary/serialized structured file, used for fast persistence between device and cloud and instant restore.

2. Core WASM exports

The core Rust-WASM methods exported by c35955a62-DsUXHNAG.wasm are defined as follows:

/**
 * REA 分析还原：Clarkdown WASM 核心编译器接口定义 (来自 c2abd4ebb-suZcxVhm.js)
 */
export interface ClarkdownWasmCompiler {
  /** 初始化 Clarkdown 独立富文本编辑器实例 */
  ClarkdownEditor: new (options?: ClarkdownEditorOptions) => ClarkdownEditorInstance;
  /** 通用双向编译器单例 */
  Compiler: ClarkdownCompilerStatic;
  /** 将外部 HTML 内容清洗并无损转换为 Clarkdown AST */
  import_html(htmlContent: string): ClarkdownAST;
  /** 将 Clarkdown 标记源码解析为结构化 JSON AST */
  parse_to_json(source: string): string; // JSON 字符串
  /** 将 AST 或源码即时渲染为安全的 HTML 结构 */
  to_html(source: string): string;
  /** 提取无标记纯文本（用于 Token 估算与剪贴板复制） */
  to_plain_text(source: string): string;
}

3. Dual Document Host Topology

To support offline editing and real-time multi-device collaboration, the architecture abstracts a single document host contract:

• createLocalDocumentHost(initialContent: string): a local sandbox host for a standalone conversation. All typing and syntax-tree updates run directly in local WASM memory in microseconds, with no network requests and a built-in debounce buffer.
• createRemoteDocumentHost(documentId: string, syncTransport: WebSocket): the authoritative host for Cowork collaboration and cloud sync. It has an incremental patch arbitration mechanism similar to CRDT (conflict-free replicated data types) and OT, and distributes immutable snapshot streams to each Replica render window, preventing data races.

7.5 Host Aliasing & Integration Guide

Technical domain: Host Token Bridging & Portability Architecture

For non-React hosts, custom desktop harnesses (such as an Electron desktop shell or a DSH container), or enterprise front ends that already have their own design system, the CDS architecture can be consumed quickly by bridging CSS variable namespaces and decoupling at runtime.

7.5.1 The Three Portability Tiers

So developers on different stacks can tell which assets they can reuse, all 30 production modules are labeled with their runtime portability:

1. 🎨 Pure CSS:
   • Dependencies: only a modern browser's native CSS engine; zero JavaScript, zero React.
   • Modules: code-examples/cds-theme.css (183 global tokens and the 15-stop spring), code-examples/tailwind.config.js, the pure-CSS scroll fade classes .cds-scroll-fade / .scroll-fade, the status shimmer and breathing bars .dframe-clay-breathe / .cds-skeleton-sweep, and the container-query classes.
2. ⚡ Pure Logic / Headless:
   • Dependencies: plain TypeScript/JavaScript, with no React UI DOM bindings.
   • Modules: code-examples/ClaudeMotionPresets.ts (numerical solution of the second-order damped oscillator), code-examples/ClaudeAudioPlayer.ts (Web Audio oscillator synthesis with no external assets), code-examples/useClaudeScrollPinning.ts (viewport scroll pinning and the 150ms anti-hijack algorithm), code-examples/useRateLimitBackoff.ts (truncated exponential backoff state machine), code-examples/createClaudeMainWindow.ts (the decoupled two-layer factory for the Electron main process).
3. ⚛️ React Component:
   • Dependencies: the React 18+ runtime and component state.
   • Modules: MediaLightboxViewer.tsx, ArtifactsSplitPaneResizer.tsx, DraggableSessionList.tsx, McpToolDecisionCard.tsx, ChatComposer.tsx, StreamingDiffViewer.tsx and others.

7.5.2 Host Aliasing Pattern

Integrators don't need to modify the CDS source. They only need to add an alias mapping in the host's entry stylesheet that binds the host's own prefix (such as --app-* or --dsw-*) to the CDS variables:

/* 宿主主样式表 (Host Application Stylesheet) */
:root {
  /* 品牌色与强调色桥接 */
  --app-brand-primary: var(--brand);                   /* 官方品牌色 #c6613f */
  --app-brand-accent: var(--cds-clay);                 /* 陶土呼吸色 #d97757 */
  
  /* 表面深度阶梯桥接 (0 ~ 3 表面) */
  --app-canvas-base: var(--cds-surface-0);             /* 底层画布 #f9f9f7 / #0b0b0b */
  --app-panel-surface: var(--cds-surface-1);           /* 侧边栏/分栏 #fcfcfb / #151515 */
  --app-card-surface: var(--cds-surface-2);            /* 气泡/卡片 #ffffff / #1a1a19 */
  --app-composer-surface: var(--cds-surface-3);        /* 输入框浮层 #ffffff / #20201f */
  --app-popover-surface: var(--cds-surface-popover);   /* 悬浮菜单 #ffffff / #262624 */

  /* 发丝线边框与弥散阴影 */
  --app-border-subtle: var(--cds-border);              /* 发丝细线 */
  --app-border-focus: var(--cds-border-accent);        /* 聚焦陶土边框 */
  --app-shadow-composer: var(--cds-shadow-composer);   /* 复合弥散阴影 */

  /* 几何同心圆角 */
  --app-radius-base: var(--cds-radius);                /* 8px 基础圆角 */
  --app-radius-card: var(--radius-card);               /* 12px 同心卡片圆角 */
  --app-radius-composer: var(--cds-radius-composer);   /* 20px 终端圆角 */
  --app-radius-pill: var(--cds-radius-pill);           /* 9999px 胶囊圆角 */
}

7.5.3 Zero-JS Scroll-Fade Engine in practice

In modern Electron 44+ / Chromium 115+ containers, scroll feathering needs no React Hooks, listeners or ResizeObserver; native CSS drives it directly:

<!-- 非 React 宿主直接使用纯 CSS 属性驱动 -->
<div data-cds-scroll-fade="vertical" style="height: 400px; overflow-y: auto;">
  <!-- 长列表内容 -->
</div>

Underneath, the pure-CSS implementation registers a CSS @property, giving smooth interpolation with zero JS at runtime:

@property --cds-scroll-fade-top { syntax: '<length>'; inherits: false; initial-value: 0px; }
@property --cds-scroll-fade-bottom { syntax: '<length>'; inherits: false; initial-value: 0px; }

@keyframes cds-scroll-fade-top-in {
  from { --cds-scroll-fade-top: 0px; }
  to { --cds-scroll-fade-top: 28px; }
}
@keyframes cds-scroll-fade-bottom-out {
  from { --cds-scroll-fade-bottom: 28px; }
  to { --cds-scroll-fade-bottom: 0px; }
}

[data-cds-scroll-fade="vertical"] {
  animation: cds-scroll-fade-top-in linear both, cds-scroll-fade-bottom-out linear both;
  animation-timeline: scroll(self block), scroll(self block);
  animation-range: 0 48px, calc(100% - 48px) 100%;
  mask-image: linear-gradient(to bottom, ...); /* 官方 7 档非线性 Alpha 采样 */
}

Measured performance gains:

• CPU usage: down from ~3.2% with JS event listeners to 0.0% (driven entirely by the browser's compositor thread and the GPU);
• Main-thread blocking: 0ms; even while the main thread is parsing a large file for a long list, the scroll edges still fade in and out smoothly at 120 FPS.

⬅️ Chapter 6: Desktop Architecture & Collaboration Topology · 📚 1.x overview · Chapter 8: Front-end UI & Motion Guidelines for AI Agents ➡️

Open Claude UI is an unofficial community analysis, MIT licensed. Claude is a trademark of Anthropic; this project is not affiliated with Anthropic.