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Help finding a book I read

Help!! I remember reading a book when I was around 13 and only semi-understanding it as it was maybe too mature for me at the time. I can't remember if I finished it, but I would quite like to revisit it and read it again (hopefully with understanding this time). However, I can't remember the title or the author.
I have a rough memory of the plot of the book - if anyone has any faint idea it would help. I read it in school (the teacher I borrowed it from has now left so cannot ask), so it's possibly a book aimed at teenagers - young adults?

I'm fairly certain it's wrote by a female author, and possibly has a red/white book cover (not too sure on that). It's set in South Africa during apartheid and the main character is a teenage (white) female character from a wealthy family. The story follows her as she supports an impoverished teenage (black) male character showcase his art. This is something her mother (or possibly entire family?) does, however it's illegal due to the apartheid laws at the time the book is set. I remember they got into trouble with the police but not too much more. I also remember something about the female character attending a private school, class presidency and getting something thrown at her in the corridor? (not really sure why I remember that last part lol)
I'm fairly sure it was published more recently (e.g not a classic or from early-mid 1900s).
Thank you in advance!