How do I get a certain girl to like me?

I am a mulatto person and I like a white girl. However, it's very obvious that she likes another guy. He is also white. The guy that she likes is a blatant racist. I used to be one of her very close friends, but now she acts like she hates me and often doesn't talk to me anymore. I used to sit at the same table as her during lunch, but since she has become colder. I now sit with the minority kids at lunch, and when she used to say hi when ping me in the halls she rarely even looks at me. I am pretty sure that I haven't ever said anything to upset her in any way ever. How can I get her to like me again?