As a non‑Muslim, I’m worried I may have unintentionally offended my Muslim classmate - what should I do?

Assalamu alaikum - I'm posting anonymously because I'm embarrassed about something I think I might have done. I'm a college student and there's a kind Muslim classmate of mine. I'm not Muslim and don't know much about Islamic customs, but I want to be respectful. Today I had to do a public speaking assignment and I messed up pretty badly, which was really humiliating. She quietly slid me a note telling me not to be so hard on myself and offering comfort. I've always thought she was very nice and I also personally thought she dressed well, so in my reply note I thanked her and, since I felt I'd already embarrassed myself, I wrote something like “I might as well say I think you’re pretty and have nice fashion taste.” I added that I didn’t mean it in a “weird way” because I’m not romantically interested in women. I was trying to be friendly, but after searching online I read that men should generally avoid commenting on Muslim women’s appearance. I'm really worried I might have unintentionally embarrassed her or crossed a boundary. Should I send an apology email? How should I phrase it? Or should I assume she understood I didn’t know the rules and let it go? I’d appreciate practical advice from Muslims about what to do and how to avoid repeating this mistake in the future. Thank you.