/ui-web

name: ui-web
description: Web UI - glassmorphism, Tailwind, dark mode, accessibility
when-to-use: When building or styling web UI components
user-invocable: false
paths: ["**/*.tsx", "**/*.jsx", "**/*.css", "**/*.scss", "tailwind.config.*"]
effort: medium

UI Design Skill (Web)

---

MANDATORY: WCAG 2.1 AA Compliance

**These rules are NON-NEGOTIABLE. Every UI element must pass these checks.**

1. Color Contrast (CRITICAL)

Text Contrast Requirements:
├── Normal text (<18px): 4.5:1 minimum
├── Large text (≥18px bold or ≥24px): 3:1 minimum
├── UI components (buttons, inputs): 3:1 minimum
└── Focus indicators: 3:1 minimum

FORBIDDEN COLOR COMBINATIONS:
✗ gray-400 on white (#9CA3AF on #FFFFFF = 2.6:1) - FAILS
✗ gray-500 on white (#6B7280 on #FFFFFF = 4.6:1) - BARELY PASSES
✗ white on yellow - FAILS
✗ light blue on white - USUALLY FAILS

SAFE COLOR COMBINATIONS:
✓ gray-700 on white (#374151 on #FFFFFF = 9.2:1)
✓ gray-600 on white (#4B5563 on #FFFFFF = 6.4:1)
✓ gray-900 on white (#111827 on #FFFFFF = 16:1)
✓ white on gray-900, blue-600, green-700

2. Visibility Rules (CRITICAL)

ALL BUTTONS MUST HAVE:
✓ Visible background color OR visible border (min 1px)
✓ Text color that contrasts with background
✓ Minimum height: 44px (touch target)
✓ Padding: at least px-4 py-2

NEVER CREATE:
✗ Buttons with transparent background AND no border
✗ Text same color as background
✗ Ghost buttons without visible borders
✗ White text on light backgrounds
✗ Dark text on dark backgrounds

3. Required Element Styles

// EVERY button needs visible boundaries
// PRIMARY: solid background
<button className="bg-gray-900 text-white px-4 py-3 rounded-lg">
  Primary
</button>

// SECONDARY: visible background
<button className="bg-gray-100 text-gray-900 px-4 py-3 rounded-lg">
  Secondary
</button>

// GHOST: MUST have visible border
<button className="border border-gray-300 text-gray-700 px-4 py-3 rounded-lg">
  Ghost
</button>

// NEVER DO THIS:
<button className="text-gray-500">Invisible Button</button> // ✗ NO BOUNDARY
<button className="bg-white text-white">Hidden</button>     // ✗ NO CONTRAST

4. Focus States (REQUIRED)

// EVERY interactive element needs visible focus
className="focus:outline-none focus-visible:ring-2 focus-visible:ring-blue-500 focus-visible:ring-offset-2"

// NEVER remove focus without replacement
className="outline-none" // ✗ FORBIDDEN without ring replacement

5. Dark Mode Contrast

When implementing dark mode:
├── Text must be light (gray-100 to white) on dark backgrounds
├── Borders must be visible (gray-700 or lighter)
├── Never use gray-400 text on gray-900 bg (fails contrast)
└── Test BOTH modes before shipping

SAFE DARK MODE TEXT:
✓ text-white on bg-gray-900
✓ text-gray-100 on bg-gray-800
✓ text-gray-200 on bg-gray-900

UNSAFE (FAILS CONTRAST):
✗ text-gray-500 on bg-gray-900 (2.4:1)
✗ text-gray-400 on bg-gray-800 (3.1:1)

---

Core Philosophy

**Beautiful UI is not decoration - it's communication.** Every visual choice should serve clarity, hierarchy, and user confidence. Default to elegance and restraint.

Design Principles

1. Visual Hierarchy

Primary Action    → Bold, high contrast, prominent
Secondary Action  → Subtle, lower contrast
Tertiary/Links    → Minimal, text-style

2. Spacing System (8px Grid)

// Tailwind spacing scale - USE CONSISTENTLY
const spacing = {
  xs: 'p-1',      // 4px  - tight internal
  sm: 'p-2',      // 8px  - compact
  md: 'p-4',      // 16px - default
  lg: 'p-6',      // 24px - comfortable
  xl: 'p-8',      // 32px - spacious
  '2xl': 'p-12',  // 48px - section gaps
};

// Rule: More whitespace = more premium feel
// Rule: Consistent spacing > perfect spacing

3. Typography Scale

// Limit to 3-4 font sizes per page
const typography = {
  hero: 'text-4xl md:text-5xl font-bold tracking-tight',
  heading: 'text-2xl md:text-3xl font-semibold',
  subheading: 'text-lg md:text-xl font-medium',
  body: 'text-base leading-relaxed',
  caption: 'text-sm text-gray-500',
};

// Rule: Never use more than 2 font families
// Rule: Line height 1.5-1.7 for body text

Glassmorphism (Web)

Base Glass Card

// Modern glass effect - use sparingly for emphasis
const GlassCard = ({ children, className = '' }) => (
  <div className={`
    backdrop-blur-xl
    bg-white/10
    border border-white/20
    rounded-2xl
    shadow-xl
    shadow-black/5
    ${className}
  `}>
    {children}
  </div>
);

Glass Variants

// Light mode glass
const lightGlass = `
  backdrop-blur-xl
  bg-white/70
  border border-white/50
  shadow-lg shadow-gray-200/50
`;

// Dark mode glass
const darkGlass = `
  backdrop-blur-xl
  bg-gray-900/70
  border border-white/10
  shadow-xl shadow-black/20
`;

// Frosted sidebar
const frostedSidebar = `
  backdrop-blur-2xl
  bg-gradient-to-b from-white/80 to-white/60
  border-r border-white/30
`;

// Floating action glass
const floatingGlass = `
  backdrop-blur-md
  bg-white/90
  rounded-full
  shadow-lg shadow-black/10
  border border-white/50
`;

When to Use Glassmorphism

✓ Hero sections with image backgrounds
✓ Floating cards over gradients
✓ Modal overlays
✓ Navigation bars (subtle)
✓ Feature highlights

✗ Every card (overuse kills the effect)
✗ Text-heavy content areas
✗ Forms (reduces contrast)
✗ Data tables

Color System

Semantic Colors

const colors = {
  // Actions
  primary: 'bg-blue-600 hover:bg-blue-700',
  secondary: 'bg-gray-100 hover:bg-gray-200 text-gray-900',
  danger: 'bg-red-600 hover:bg-red-700',
  success: 'bg-green-600 hover:bg-green-700',

  // Surfaces
  background: 'bg-gray-50 dark:bg-gray-950',
  surface: 'bg-white dark:bg-gray-900',
  elevated: 'bg-white dark:bg-gray-800 shadow-lg',

  // Text
  textPrimary: 'text-gray-900 dark:text-white',
  textSecondary: 'text-gray-600 dark:text-gray-400',
  textMuted: 'text-gray-400 dark:text-gray-500',
};