I need to convert an integer color code into an HTML color code.

For example, if a user is prompted to select a color with getcolor(), and they choose red, the integer value returned is 255. In order to display the color red in HTML text, I need to either use 'font color="#FF0000"' or 'font color="red"'. How do I derive that "#FF0000" value from 255, or from any other valid color integer?

Thanks