A: I think you're really smart and beautiful. B: Thanks. So kind of you to say that. We usually don't say "... kind of you to say that" in this kind of situation. The conversation might go as follows. A: X 씨는 정말 똑똑하고 아름다우세요. B: 아 뭘요, 그렇게 봐 주시면 고맙죠. (뭘요? is like "What's that?", or "Not really", sort of a light denial) (alternatively) 아 그래요? 그렇게 말씀하시니 감사하네요. (그래요? = "Is that right?", or "Really")