async function sendMessage() {
  const input = document.getElementById('user-input');
  const message = input.value;
  if (!message.trim()) return;

  const chatBox = document.getElementById('chat-box');
  chatBox.innerHTML += `<div class='user'>You: ${message}</div>`;
  input.value = '';

  const response = await fetch('/chat', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ message })
  });

  const data = await response.json();
  chatBox.innerHTML += `<div class='bot'>Bot: ${data.response}</div>`;
  chatBox.scrollTop = chatBox.scrollHeight;
}