Can CSS color values be abbreviated?

In the HTML page, each color is a blend of RGB three colors (“red, green, and blue” three primary colors) in different proportions. In web pages, the default color representation is hexadecimal representation, such as #00000, the first two digits are the red component, the middle two digits are the green component, and the last two digits are the blue component. . Hexadecimal representation can also be abbreviated, such as #F90, the complete representation of the color is #FF9900.