The main difference between Dark Blue and Cobalt Blue is hue — Dark Blue is a cool purple, while Cobalt Blue is a cool blue. Dark Blue (#00008B) has an HSL of 240°, 100%, 27%, whereas Cobalt Blue (#0047AB) sits at 215°, 100%, 34%.
Dark Blue (#00008B) is a dark, vivid purple with a cool undertone — it feels rich, serious, substantial and bright, energetic, eye-catching.
Cobalt Blue (#0047AB) is a dark, vivid blue with a cool undertone — it feels rich, serious, substantial and bright, energetic, eye-catching.
Text legibility depends on the contrast ratio between foreground and background. WCAG 2.1 AA requires at least 4.5:1 for normal text and 3:1 for large text; AAA requires 7:1. Use these numbers to choose accessible combinations for your design.
Each color has a dedicated page with shades, tints, CSS name, pairings, and color psychology.