Friend came out as bisexual

Lottie

My friend just came out as bisexual and she told me about a month ago. Well she finally told her parents and her mom apparently doesn't approve and is very mad. I have absolutely no problem with her being bisexual. I want to give her advice but I just don't know what to say to her to make her feel more accepted. To make matters worse we go to a Christian school that doesn't approve of it. I just need some advice on how to help her. Thanks so much for any advice.