To specify one kind of color on the web page, it is necessary to Use RGB mode to determine, the method is to specify R/G/B, that is, red/green/blue three kinds of primary color intensity, usually stipulated that the minimum intensity of each one kind of color is 0, The maximum value is 255, and is usually expressed as a hexadecimal number value, then 255 corresponds to the hexadecimal is FF, and the three number values in sequence, starting with #.

Example, color value "#FF0000" is red color, because the red color value reaches the highest value FF (i.e. 255 in decimal), and the remaining two colors have a strength of 0. In Example, "#FFFF00" represents yellow, because when red color and green are both at their maximum and blue is 0, yellow is produced.