Try to imagine this : 3 selectlists (one called "red", another one called "green" and a third one "blue"). Each of them have 6 options (0%,20%,40%,60%,80%,100% -> corresponding with values of 00,33,66,99,cc,ff). Below that is a line of text. Now when you change one of the selectors, the 3 values currently selected will be mixed (put together in "#rrggbb" style) and the line of text below will immediatly get changed into that color, without reloading the page.

Is this possible in javascript+css , and if so : how ?