body{font-family:system-ui,Arial;background:#f6f8fb;margin:0;padding:20px}.chat-wrapper{max-width:640px;margin:0 auto;background:#fff;padding:18px;border-radius:8px;box-shadow:0 6px 18px rgba(0,0,0,.08)}.messages{height:320px;overflow:auto;border:1px solid #eee;padding:10px;margin-bottom:10px;background:#fafafa}