Typography

Principles for effective typography across print and screen.

Type Anatomy

• Baseline: Invisible line letters sit on
• X-height: Height of lowercase 'x', crucial for readability
• Cap height: Capital letter height
• Ascender/Descender: Parts above/below x-height
• Kerning: Adjusting space between specific pairs (AV, To)
• Tracking: Uniform letter-spacing across words
• Leading: Space between baselines (line-height)

Font Classification

Serif

Sans-Serif

Print Typography

Measure (line length): 45-75 characters optimal
Leading: 1.4-1.6× for body, 1.1-1.3× for headlines
Ligatures: Use fi, fl, ff in body text
Small caps: For acronyms (NASA, WHO)
Oldstyle figures: Blend with lowercase

Screen Typography

Minimum sizes:

• Body: 16px (1rem)
• Captions: 12-14px

Line height: 1.5-1.7 for body (more than print)
Contrast: 4.5:1 minimum (WCAG)
Dark mode: Avoid pure white on black

Web Fonts

Formats

• WOFF2: Best choice, excellent compression
• WOFF: Legacy support
• Avoid: TTF (no compression), EOT, SVG

Loading

@font-face {
  font-family: 'MyFont';
  src: url('font.woff2') format('woff2');
  font-display: swap; /* Prevents FOIT */
}

Preload critical fonts

<link rel="preload" href="font.woff2" as="font" type="font/woff2" crossorigin>

Responsive Typography

Units

• rem: Root-relative (use for font sizes)
• em: Parent-relative (use for component spacing)
• px: Absolute (borders, precise elements)
• vw/vh: Viewport-relative (fluid headlines)

Modular Scale

Fluid Type with clamp()

html {
  font-size: clamp(1rem, 0.5rem + 1vw, 1.5rem);
}

Hierarchy

Levels: h1 → h2 → h3 → body → caption
Size contrast: 1.5× minimum between levels
Techniques: Size, weight, color, spacing

Accessibility

WCAG Requirements:

• Normal text: 4.5:1 contrast
• Large text (18px+ bold): 3:1
• Support 200% zoom
• Allow text spacing overrides

Best fonts for accessibility:

• Sans-serif for screens
• Adequate x-height
• Avoid decorative for body

Common Mistakes

❌ Too many fonts (limit to 2-3)
❌ Insufficient contrast
❌ Line lengths >75 or <45 chars
❌ Ignoring dark mode
❌ Using display fonts for body
❌ Justified text on web (creates rivers)

Quick Reference

Web body: 16px, 1.5-1.7 line-height, 60-75 chars
Print body: 10-12pt, 1.4-1.6× leading
Headlines: 1.5-3× body, use modular scale
Pairing: Serif + sans-serif, match x-heights

Tools

• Google Fonts: Free web fonts
• Type Scale: typescalemaker.com
• Fluid Type Calculator: fluidtype.com
• Fontpair: Font pairing ideas
• Color Contrast Checker: WebAIM

Variable Fonts

Single file with multiple weights/widths:

h1 {
  font-variation-settings: 'wght' 700, 'wdth' 80;
}

Common axes: wght (weight), wdth (width), slnt (slant), opsz (optical size)

Resources

• Tufte's typography works
• NN/g typography guidelines
• MDN CSS Fonts Module
• Typewolf (typewolf.com)