Blue Hour palette
Halcyon Heath
Dark anchor, working middle, light release: #003f7a, #2a67ab, #4582c8, #5f92ce, #7aaeec form a tetradic blue hour set with somewhere to stand at every lightness. Made for book covers that read at thumbnail size. The darkest and lightest stops clear AA as a text pair.
skybluehourfive-stophigh-contrast
#003f7a
#2a67ab
#4582c8
#5f92ce
#7aaeec
The generator opens with #003f7a as the primary and the next two stops as secondary and accent — adjust, check contrast, and export tokens or CSS from there.