Is Zebra a white animal with black stripes or a black animal with white ones?

Huh?
google.com/search?tbm=isch&q=star+trek+frank+gorshin

Black animal with White Stripes

What is the largest size bra?

A Z-bra!

I'd say white, given how it is the more dominant color, partially on their belly.

https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcRZ8zJzeHl1oue1zxR5Q7uhvObUaxexTyGiRw&usqp=CAU

Say hello to the Zonky
google.com/search?tbm=isch&q=zonky

BASED ON THE FUR PATTERNS OF MY CATS...ZEBRAS ARE WHITE WITH BLACK STRIPES.

My grandma had an Italian boyfriend in her later years who loved telling Catholic jokes, and he had one about this very subject:

There was a zebra who had died and gone to heaven. When she came to the Pearly Gates and met St. Peter, he asked her "So, are you a white zebra with black stripes, or a black zebra with white stripes?" The poor zebra was very confused. "I don't know," she told him. "Well, you have to tell me so I can let you in," St. Peter tells her. "Well how am I supposed to find out?" she asked him. He sent her over to an angel named St. Paul. "Ask him, he'll know," St. Peter told her. So she went to St. Paul and asked him, "Am I a white zebra with black stripes, or a black zebra with white stripes?" St. Paul smile and said, "Just tell St. Peter, 'I am who I am,' and that will tell him all he needs to know." So the zebra went back to St. Peter, and he asked her the same question. She replied, "I am who I am." So St. Peter said, "Ah, so you are a white zebra with black stripes. Okay, You can go in now."

The zebra was about to head into heaven, but she briefly turned back one last time and asked St. Peter, "How could you tell I was a white zebra with black stripes and not the other way around?" St. Peter replied, "Oh that's easy. A white zebra with black stripes says, 'I am who I am.' A black zebra with white stripes will answer, 'I is what I is.'"

Depends on your definition of white and black in this context. If you have a white cat with one small black spot, is it a white cat? If so, why?
Most likely you call it white because white is the dominant color. i.e the cat is 'mostly' white. So by this logic, we are going by quantity. If we apply the same rules to the Zebra, we simply determine which is the dominant color. If your Zebra is mostly white, then your Zebra is white with black stripes.
QED