Colour Theory — Choosing Colours That Work

Sources: Flux Academy, The Complete Guide for Choosing Colors (Ran Segall et al.); WCAG 2.1; CSS Color 4 (OKLCH).

Use when

• Picking a brand or website palette from a brief (with or without existing brand colours).
• Auditing an existing palette for accessibility, ratio balance, or visual coherence.
• Generating a tonal scale (50–900) from a single brand colour.
• Resolving a contrast failure without abandoning the brand colour.
• Deciding which colour harmony fits a brief (calm / playful / premium / punchy CTA).

Do not use when

• The user wants a design-system audit (load design-system / design-audit).
• The task is purely typography or layout (load practical-ui-design / every-layout).
• The user wants generative palettes from a photograph alone (point them at coolors.co / Canva, then return here for refinement).

Prerequisites