to specify a color on a web page, you must use the rgb mode to determine it. the method is to specify r/g/b respectively, that is, the intensity of the three primary colors of red, green, and blue. it is usually stipulated that the minimum intensity of each color is 0, the highest is 255, and are usually represented by hexadecimal values. then 255 corresponds to hexadecimal ff, and the three values ​​​​are juxtaposed in sequence, starting with #.

for example, the color value "#ff0000" is red because the value of red reaches the highest value ff (which is 255 in decimal), and the remaining two colors have an intensity of 0. for example, "#ffff00" represents yellow, because when both red and green are at their maximum values, and blue is 0, yellow is produced.