Brightness contrast
"Yellow + white" forms a strong contrast, and the yellow with high saturation and the white with high brightness add a bright and dazzling feeling.
The color difference between "blue + white" is large, forming a strong contrast, clean, refreshing, and calm.
"Red + white" forms a contrast in brightness, and white balances the passionate and unrestrained feeling brought by the strong Chinese red.
The white area is large and the black area is small, which is not enough to form a strong contrast. The clean and simple black lines decorate the large area of white, making the white more attractive and elegant.