Blue Hour palette
Mineral Reef
From #004688 ink through #006dcc, #2f89eb, #529aed to #7bb7ff light, Mineral Reef is a tetradic progression that holds together at any size. Use it for book covers that read at thumbnail size. The darkest and lightest stops clear AA as a text pair.
skybluehourfive-stophigh-contrast
#004688
#006dcc
#2f89eb
#529aed
#7bb7ff
The generator opens with #004688 as the primary and the next two stops as secondary and accent — adjust, check contrast, and export tokens or CSS from there.