Question: what is the difference between dark blue and navy blue?
Answer: Regular blue is 0,0,1 so navy and dark blue are pure blue (no red or green light) with intensity reduced to about 50% (making it darker). So navy blue is slightly darker than dark blue. In Photoshop I made a square of navy blue (0,0,129/256) in a background of dark blue (0,0,140/256).