2. Dark blue refers to dark blue, which is relatively dark blue. Blue is the coldest color in cool tones, representing profundity, eternity, tranquility and rationality. Black is mysterious and cold, representing lofty, serious and vigorous; Therefore, the blue and black dark blue is more mysterious, profound and dignified, and is often used in weddings, work suits and some more formal occasions in the vast starry sky.

3. Color is composed of three primary colors: red, green and blue. The colors of the three primary colors are added in different proportions to produce various colors, that is, different colors. Color is the visual effect of light through eyes, brain and our life experience. People's perception of color is not only determined by the physical properties of light, but also influenced by the surrounding colors.