That’s really interesting. I looked up the site. I lecture my tour groups for kids on colors and values (ie. shades).
Quick lesson on white and black: in human eyes, they are not their own colors at all, but rather the black is when you see the entire spectrum absorbed by what you’re looking at. The light goes in and stays in, so it’s as if you put all the colors in a pan and smooshed them together. It turns black.
White is the reflection of all light, all the colors in the spectrum bounce off what you’re looking at and go back to your eye, so they all reflect together and when merged – it’s white. So if a bunny has no apparatus in its eye for picking up the red from a spectrum, either they will never see black or white, or more likely, they do, and it’s just the colors they do see merged as above.
The range of light varies for animals, as well as birds. I recently learned that birds have a wider range of color spectrum than humans, so those birds we think look alike (so how do their mates find each other?) actually have this very subtle distinction among them that our eyes cannot pick up, and to them the difference is clear as day.
So the purple will look deep blue. They probably need to recognize sky, grass, fields, and shadows of predators.
Lavender means highest spiritual plane, is at the human head in the chakras, and is spirituality. So if you want to be calm around tension at work, wear a light purple shirt! Purple is equated with royalty, or a stronger devine link, thus kings wear purple robes. A bit more ego than spirit.
Light blue would probably be soothing to bunnies, and green even better, unless it makes them hungry! I expect brown is popular to them for recreating a burrow. Maybe the darker willow huts are more appealing for that reason.
Blue is throat chakra, for communication. Green is the heart chakra, for love and compassion. Etc.