The colors shown here are a dark blue (R0R0B128/navy), a fairly bright red (R254G0B4), and a nice sunny yellow (R255G251B0).
Darker shades of blue denote importance, confidence, power, authority, intelligence, stability, unity, and conservatism. Red is another power color but it grabs attention more than blue. Yellow adds some brightness and joy. Using equal amounts of each color would make it a more childlike (think primary colors) palette but if only small doses of the red and yellow are used with a mostly dark blue color sheme, it's quite suitable for adult projects that you don't want to appear too serious.
You don't have to use these exact shades. Go a touch lighter or darker, or step one spot to the left or the right on the color wheel. These color combinations are just to help you find a suitable color palette using dark blue as the main component.


