visual-design-foundations

SKILL.md

Visual Design Foundations

Build cohesive, accessible visual systems using typography, color, spacing, and iconography fundamentals.

When to Use This Skill

Establishing design tokens for a new project

Creating or refining a spacing and sizing system

Selecting and pairing typefaces

Building accessible color palettes

Designing icon systems and visual assets

Improving visual hierarchy and readability

Auditing designs for visual consistency

Implementing dark mode or theming

Core Systems

1. Typography Scale
Modular Scale (ratio-based sizing):

:root {
  --font-size-xs: 0.75rem; /* 12px */
  --font-size-sm: 0.875rem; /* 14px */
  --font-size-base: 1rem; /* 16px */
  --font-size-lg: 1.125rem; /* 18px */
  --font-size-xl: 1.25rem; /* 20px */
  --font-size-2xl: 1.5rem; /* 24px */
  --font-size-3xl: 1.875rem; /* 30px */
  --font-size-4xl: 2.25rem; /* 36px */
  --font-size-5xl: 3rem; /* 48px */
}

Line Height Guidelines:

Text Type
Line Height

Headings
1.1 - 1.3

Body text
1.5 - 1.7

UI labels
1.2 - 1.4

2. Spacing System

8-point grid (industry standard):

:root {
  --space-1: 0.25rem; /* 4px */
  --space-2: 0.5rem; /* 8px */
  --space-3: 0.75rem; /* 12px */
  --space-4: 1rem; /* 16px */
  --space-5: 1.25rem; /* 20px */
  --space-6: 1.5rem; /* 24px */
  --space-8: 2rem; /* 32px */
  --space-10: 2.5rem; /* 40px */
  --space-12: 3rem; /* 48px */
  --space-16: 4rem; /* 64px */
}

3. Color System

Semantic color tokens:

:root {
  /* Brand */
  --color-primary: #2563eb;
  --color-primary-hover: #1d4ed8;
  --color-primary-active: #1e40af;

  /* Semantic */
  --color-success: #16a34a;
  --color-warning: #ca8a04;
  --color-error: #dc2626;
  --color-info: #0891b2;

  /* Neutral */
  --color-gray-50: #f9fafb;
  --color-gray-100: #f3f4f6;
  --color-gray-200: #e5e7eb;
  --color-gray-300: #d1d5db;
  --color-gray-400: #9ca3af;
  --color-gray-500: #6b7280;
  --color-gray-600: #4b5563;
  --color-gray-700: #374151;
  --color-gray-800: #1f2937;
  --color-gray-900: #111827;
}

Quick Start: Design Tokens in Tailwind

// tailwind.config.js
module.exports = {
  theme: {
    extend: {
      fontFamily: {
        sans: ["Inter", "system-ui", "sans-serif"],
        mono: ["JetBrains Mono", "monospace"],
      },
      fontSize: {
        xs: ["0.75rem", { lineHeight: "1rem" }],
        sm: ["0.875rem", { lineHeight: "1.25rem" }],
        base: ["1rem", { lineHeight: "1.5rem" }],
        lg: ["1.125rem", { lineHeight: "1.75rem" }],
        xl: ["1.25rem", { lineHeight: "1.75rem" }],
        "2xl": ["1.5rem", { lineHeight: "2rem" }],
      },
      colors: {
        brand: {
          50: "#eff6ff",
          500: "#3b82f6",
          600: "#2563eb",
          700: "#1d4ed8",
        },
      },
      spacing: {
        // Extends default with custom values
        18: "4.5rem",
        88: "22rem",
      },
    },
  },
};

Typography Best Practices

Font Pairing

Safe combinations:

Heading: Inter / Body: Inter (single family)

Heading: Playfair Display / Body: Source Sans Pro (contrast)

Heading: Space Grotesk / Body: IBM Plex Sans (geometric)

Responsive Typography

/* Fluid typography using clamp() */
h1 {
  font-size: clamp(2rem, 5vw + 1rem, 3.5rem);
  line-height: 1.1;
}

p {
  font-size: clamp(1rem, 2vw + 0.5rem, 1.125rem);
  line-height: 1.6;
  max-width: 65ch; /* Optimal reading width */
}

Font Loading

/* Prevent layout shift */
@font-face {
  font-family: "Inter";
  src: url("/fonts/Inter.woff2") format("woff2");
  font-display: swap;
  font-weight: 400 700;
}

Color Theory

Contrast Requirements (WCAG)

Element
Minimum Ratio

Body text
4.5:1 (AA)

Large text (18px+)
3:1 (AA)

UI components
3:1 (AA)

Enhanced
7:1 (AAA)

Dark Mode Strategy

:root {
  --bg-primary: #ffffff;
  --bg-secondary: #f9fafb;
  --text-primary: #111827;
  --text-secondary: #6b7280;
  --border: #e5e7eb;
}

[data-theme="dark"] {
  --bg-primary: #111827;
  --bg-secondary: #1f2937;
  --text-primary: #f9fafb;
  --text-secondary: #9ca3af;
  --border: #374151;
}

Color Accessibility

// Check contrast programmatically
function getContrastRatio(foreground: string, background: string): number {
  const getLuminance = (hex: string) => {
    const rgb = hexToRgb(hex);
    const [r, g, b] = rgb.map((c) => {
      c = c / 255;
      return c <= 0.03928 ? c / 12.92 : Math.pow((c + 0.055) / 1.055, 2.4);
    });
    return 0.2126 * r + 0.7152 * g + 0.0722 * b;
  };

  const l1 = getLuminance(foreground);
  const l2 = getLuminance(background);
  const lighter = Math.max(l1, l2);
  const darker = Math.min(l1, l2);

  return (lighter + 0.05) / (darker + 0.05);
}

Spacing Guidelines

Component Spacing

Card padding:      16-24px (--space-4 to --space-6)
Section gap:       32-64px (--space-8 to --space-16)
Form field gap:    16-24px (--space-4 to --space-6)
Button padding:    8-16px vertical, 16-24px horizontal
Icon-text gap:     8px (--space-2)

Visual Rhythm

/* Consistent vertical rhythm */
.prose > * + * {
  margin-top: var(--space-4);
}

.prose > h2 + * {
  margin-top: var(--space-2);
}

.prose > * + h2 {
  margin-top: var(--space-8);
}

Iconography

Icon Sizing System

:root {
  --icon-xs: 12px;
  --icon-sm: 16px;
  --icon-md: 20px;
  --icon-lg: 24px;
  --icon-xl: 32px;
}

Icon Component

interface IconProps {
  name: string;
  size?: "xs" | "sm" | "md" | "lg" | "xl";
  className?: string;
}

const sizeMap = {
  xs: 12,
  sm: 16,
  md: 20,
  lg: 24,
  xl: 32,
};

export function Icon({ name, size = "md", className }: IconProps) {
  return (
    <svg
      width={sizeMap[size]}
      height={sizeMap[size]}
      className={cn("inline-block flex-shrink-0", className)}
      aria-hidden="true"
    >
      <use href={`/icons.svg#${name}`} />
    </svg>
  );
}

Best Practices

Establish Constraints: Limit choices to maintain consistency

Document Decisions: Create a living style guide

Test Accessibility: Verify contrast, sizing, touch targets

Use Semantic Tokens: Name by purpose, not appearance

Design Mobile-First: Start with constraints, add complexity

Maintain Vertical Rhythm: Consistent spacing creates harmony

Limit Font Weights: 2-3 weights per family is sufficient

Common Issues

Inconsistent Spacing: Not using a defined scale

Poor Contrast: Failing WCAG requirements

Font Overload: Too many families or weights

Magic Numbers: Arbitrary values instead of tokens

Missing States: Forgetting hover, focus, disabled

No Dark Mode Plan: Retrofitting is harder than planning