What color should cats' urine be?

Gus is 6 months old, on kitten food, and his pee is sort of dark yellow.

Satey's urine is fairly light yellow. He's on a high-fiber weight loss food.

I was just wondering because Gus' urine was really dark when we changed his litter. He also seems to pee a lot, which doesn't surprise me since every time he passes a water bowl he just has to take a drink from it.

Pee can vary a little. Yellow to brownish means it is concentrated and it's almost colorless if it's dilute. Warning signs would be reddish/brown, yellow/brown, or yellow/green. The color can vary by diet or water intake.