Use the sliders to change the colors or darkness of the fur or the eyes. It is best to keep your darkness range in the middle so you can see more color variety. If you want a white cat, make a very pale gray instead, otherwise your cat will disappear. To make brown, find the orange color and make it a little darker.
Thanks to SnowdropSugar and Zinnea, SnowdropSugar for teaching me more about variables, and Zinnea for the inspiration from how to make a game like cats of all clans.