As mentioned, it is easier at times to think of colors in the HSV model versus the RGB model. For example, orange is a hue between red (hue=0) and yellow (hue=60). We mix a shade of orange in this example by starting with hue = 25. Next we darken the color by reducing its value to 0.85. Last, we use full saturation.

Another reason for using the HSV model is the ease in varying the saturation of the colors being applied to our nested squares.