Visual Hierarchy Fluid Typography Scale Use for fluid type that scales between breakpoints without jumps. Key rules: - Body text: 16px minimum (1rem) — never smaller for continuous reading - Line height: 1.4–1.6 for body text; 1.1–1.3 for headings - Optimal line length: 45–90 characters desktop, 30–50 characters mobile - Letter spacing: 0 to +0.02em for body; −0.02em to −0.04em for large headings --- Spacing System (4px base grid) All spacing values should be multiples of 4px for visual consistency. --- User Scanning Patterns Research from Nielsen Norman Group eye-tracking studies (2006–2024)…