Welcome David!! Now you're entered into the drawing twice! This is a great question.
Pigment from plants, antibiotics, even cold weather can determine urine color.
The only urine color I'm worried about is the white urine. This can be an indication of too much calcium, which can cause bladder stones. I actually have a bunny that is very sensitive to calcium.
There are ways to lower calcium in your bunny's diet.
1st: Try and find a pellet that doesn't have any nuts, seeds, etc in it. This is actually better regardless of calcium problems, but this is a key way to keep the levels low. I know she seems to have been fine on this stuff for this long - she's four years old, but even other serious digestive problems can arise from long term use of this kind of feed. If you want to know more about that, I can cover that it another post.
Also make sure the pellet itself is timothy based (no alfalfa - it's high in calcium) with AT LEAST 18% fiber, and low in fat (around 2%). There are some really great pellets made from companies like Oxbow Hay, American Pet Diner, etc.
Note: If you do decide to go with a healthier pellet, then make sure that any switch you make is done gradually over about a month, otherwise it can cause serious digestive upsets. I would bet your bunny won't like the new pellet. I know mine didn't! It's like going from ice cream and candy to broccoli and brussel sprouts. No fun. But now, mine love their pellets.
2nd: Greens are a healthy necessary part of a bunny's diet. All greens have calcium, but some just have more than others, like Kale, so replace the Kale with endive/chicory and romaine lettuce (or some other dark leafed lettuce). You can try and add Kale back in once a week and see if it returns. (Kale should be given sparingly anyway because of it's high vit A content, which over time can be bad for a bunny)
3rd: Make sure greens are fresh, not wilted, and spritz with water. This really keeps the ratio of water to calcium at a healthier level.
4th: Make sure she has unlimited timothy hay.
Also, here is a really helpful article from the House Rabbit Society about lowering calcium
If the white urine continues even after the diet change, then she should be seen by a vet.
The rest of the color variation is usually due to just diet – different plant pigment. Red urine is usually just a sign of eating something with beta carotene. It can happen if a bunny is on antibiotics, or even if the weather has been unusually cold. Kooky Huh?
But if the red urine lasts for over a month at time even when diet changes are happening, it might be a good idea to also consult with a vet.
Otherwise, is your bunny peeing normally? No straining? Or hanging out in the box longer than normal?
Boy, I bet you never thought their would be so much poop about urine!
Keep us updated! Let us know if this gets the white out.