Duotone Identity Design System

Anthropic-inspired duotone design language for Identity Platform. Strict cream/charcoal palette with intentional typography and animated SVG illustrations.

Quick Reference

Element	Value
Primary Light	`#FAF9F5` (cream)
Primary Dark	`#141413` (charcoal)
Display Font	Instrument Serif
Body Font	Inter
SVG viewBox	`500 x 500`
Chapter Number	`clamp(6rem, 15vw, 12rem)` italic

Color Palette

Core Duotone Colors

css

:root {
  --cream: #FAF9F5;    /* Light backgrounds, dark text */
  --charcoal: #141413; /* Dark backgrounds, light text */
}

Usage Pattern

Section	Background	Text
Light (Hero, Ch1, Ch3)	`var(--cream)`	`var(--charcoal)`
Dark (Ch2, Ch4, Finale)	`var(--charcoal)`	`var(--cream)`

Rule: Never use other colors for primary UI. Accent colors only for interactive elements (wallet button, links).

Section Alternating

tsx

// Chapter 1, 3: Light
<section className="bg-[var(--cream)] text-[var(--charcoal)]">

// Chapter 2, 4: Dark
<section className="bg-[var(--charcoal)] text-[var(--cream)]">

Typography

Font Families

css

/* Display / Headings */
font-family: 'Instrument Serif', Georgia, serif;

/* Body / UI */
font-family: 'Inter', -apple-system, sans-serif;

Display Headings (H1, H2)

css

.landing-h1 {
  font-size: clamp(3rem, 12vw, 8rem);
  line-height: 1;
  letter-spacing: -0.02em;
}

.landing-h2 {
  font-size: clamp(2rem, 6vw, 4.5rem);
  line-height: 1.15;
  letter-spacing: -0.02em;
}

Chapter Labels

tsx

<p className="text-xs md:text-sm font-semibold uppercase tracking-[0.2em] opacity-50 flex items-center gap-4">
  <span className="w-10 h-px bg-current opacity-50"></span>
  {label}
</p>

Pattern: 40px horizontal dash + uppercase text + 0.2em letter-spacing

Chapter Numbers

tsx

<span className="font-serif italic opacity-[0.08]"
      style={{ fontSize: 'clamp(6rem, 15vw, 12rem)', lineHeight: 1 }}>
  {String(number).padStart(2, '0')}
</span>

Positioning: absolute top-4 left-4 md:top-8 md:left-8

Layout Patterns

Chapter Section Structure

tsx

<section className={`chapter ${isLight ? 'light' : 'dark'} min-h-screen flex items-center justify-center relative p-6 md:p-12 ${isLight ? 'bg-[var(--cream)] text-[var(--charcoal)]' : 'bg-[var(--charcoal)] text-[var(--cream)]'}`}>
  {/* Chapter Number - large, positioned */}
  <span className="chapter-number absolute top-4 left-4 md:top-8 md:left-8 font-serif italic opacity-[0.08]"
        style={{ fontSize: 'clamp(6rem, 15vw, 12rem)', lineHeight: 1 }}>
    {String(number).padStart(2, '0')}
  </span>

  <div className="chapter-inner grid grid-cols-1 md:grid-cols-2 gap-8 md:gap-12 max-w-6xl w-full relative z-10">
    {/* Content */}
    <div className="chapter-content">
      <p className="chapter-label text-xs md:text-sm font-semibold uppercase tracking-[0.2em] opacity-50 mb-4 flex items-center gap-4">
        <span className="w-10 h-px bg-current opacity-50"></span>
        {label}
      </p>
      <h2 className={`landing-h2 ${isLight ? 'text-[var(--charcoal)]' : 'text-[var(--cream)]'}`}>
        {title}
      </h2>
    </div>
    {/* Illustration */}
  </div>
</section>

Key Rules:

Even chapters (2, 4): reverse layout (illustration left, content right)
Odd chapters (1, 3): standard layout (content left, illustration right)
Always explicitly set h2 color based on isLight (global CSS overrides)

SVG Illustrations

Standard viewBox

Always use viewBox="0 0 500 500" for consistency.

All coordinates must stay within 0-500 range to prevent clipping.

Path Classes

Class	Purpose	Animation
`.fill-path`	Shapes, filled elements	Opacity 0→0.9, scale 0.8→1
`.draw-path`	Lines, strokes	strokeDashoffset animation
`.label-path`	Text labels	Opacity 0→0.7

CSS Initial States

css

.fill-path {
  opacity: 0;
  transform-origin: center;
  vector-effect: non-scaling-stroke;
}

.draw-path {
  opacity: 0;
  fill: none;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.label-path {
  opacity: 0;
  font-size: 14px;
  font-weight: 500;
  text-anchor: middle;
  pointer-events: none;
}

Common SVG Patterns

Person/Figure (Chapter 1):

tsx

<circle className="fill-path" cx="250" cy="140" r="35" fill="#141413" opacity="0"/>
<path className="fill-path" d="M 215 180 Q 200 220 210 280..." fill="#141413" opacity="0"/>

Process Flow (Chapter 2):

tsx

{/* Horizontal left-to-right flow */}
<rect className="fill-path" x="60" y="200" width="80" height="60" fill="#FAF9F5" opacity="0"/>
<path className="draw-path" d="M 140 230 L 180 230" stroke="#FAF9F5" strokeWidth="2" opacity="0"/>

Growth Trajectory (Chapter 3):

tsx

<path className="draw-path" d="M 50 420 Q 120 400 160 350..." stroke="#141413" strokeWidth="3" opacity="0"/>
<circle className="fill-path" cx="160" cy="350" r="10" fill="#141413" opacity="0"/>

Central Hub (Chapter 4):

tsx

<circle className="fill-path" cx="250" cy="250" r="45" fill="#FAF9F5" opacity="0"/>
<circle className="draw-path" cx="250" cy="250" r="65" fill="none" stroke="#FAF9F5" strokeWidth="2" opacity="0"/>

GSAP Animations

Animation Pattern for Chapters

typescript

import { gsap } from 'gsap';
import ScrollTrigger from 'gsap/ScrollTrigger';

gsap.registerPlugin(ScrollTrigger);

export const useChapterAnimations = () => {
  useEffect(() => {
    const chapters = document.querySelectorAll('.chapter');
    if (chapters.length === 0) return;

    const ctx = gsap.context(() => {
      chapters.forEach((chapter) => {
        const fillPaths = chapter.querySelectorAll('.fill-path');
        const drawPaths = chapter.querySelectorAll('.draw-path');

        // Fill paths: opacity + scale
        if (fillPaths.length > 0) {
          gsap.to(fillPaths, {
            opacity: 0.9,
            scale: 1,
            duration: 0.8,
            stagger: 0.1,
            ease: 'back.out(1.5)',
            scrollTrigger: {
              trigger: chapter,
              start: 'top 80%',
              toggleActions: 'play none none reverse',
            },
          });
        }

        // Draw paths: stroke animation
        if (drawPaths.length > 0) {
          drawPaths.forEach(path => {
            const length = (path as SVGPathElement).getTotalLength() || 1000;
            (path as SVGPathElement).style.strokeDasharray = String(length);
            (path as SVGPathElement).style.strokeDashoffset = String(length);
          });

          gsap.to(drawPaths, {
            strokeDashoffset: 0,
            opacity: 0.6,
            duration: 1.5,
            stagger: 0.1,
            ease: 'power2.inOut',
            scrollTrigger: {
              trigger: chapter,
              start: 'top 75%',
              toggleActions: 'play none none reverse',
            },
          });
        }
      });
    });

    return () => ctx.revert();
  }, []);
};

Key GSAP Rules

Always use gsap.context() for cleanup
toggleActions: 'play none none reverse' for reversible scroll animations
Never use inline style={{ transform: 'scale' }} - let GSAP handle all transforms
Initialize strokeDasharray in the effect, not inline styles
stagger: 0.1 for sequential element animations

Resources

references/

palette.md - Full color definitions with usage examples
typography.md - Font loading, sizing, and heading styles
svg-patterns.md - Common SVG illustration templates
gsap-recipes.md - Copy-paste animation patterns

scripts/

validate_colors.sh - Check if colors match duotone palette
generate_chapter.sh - Scaffold new chapter section

Usage Examples

Creating a new chapter:

1. Use scripts/generate_chapter.sh 5
2. Add SVG to illustration container (500x500 viewBox)
3. Use fill-path/draw-path/label-path classes
4. Set isLight based on position (odd=light, even=dark)

Validating colors:

Use scripts/validate_colors.sh before committing to ensure only cream/charcoal are used

Anti-Patterns

❌ Don't	✅ Do
Use other colors for UI	Only cream/charcoal
Inline `style={{ scale }}`	Let GSAP animate
Different viewBox sizes	Always 500x500
Coordinates outside 0-500	Keep within bounds
Generic class names	Use fill-path/draw-path/label-path

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duotone-identity

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SKILL.md