Both red and yellow belong to warm color system, which is in a symmetrical position in Munsell color ring, second only to extremely warm orange. Using these two colors completely will give people a strong sense of impetuousness, so we should handle the color matching well. If you add another color, blue is the first choice. Blue and yellow are complementary colors in the color phase ring, that is, diagonal 180 degrees in the color phase ring. This color scheme will look very lively and fashionable. On this basis, it can be decorated with green to make the layout more layered and vivid.