body {font-family:Arial, sans-serif;background:#0d1117;color:#e6edf3;margin:0;text-align:center;}
header {padding:20px;}
.logo {width:80px;margin-bottom:10px;}
.chat-box {background:#161b22;border:1px solid #30363d;border-radius:8px;width:90%;max-width:600px;margin:20px auto;padding:10px;}
#chat-log {text-align:left;height:250px;overflow-y:auto;margin-bottom:10px;background:#0d1117;padding:5px;border:1px solid #30363d;}
.user {color:#58a6ff;} .ai {color:#3fb950;} .error {color:#f85149;}
input {width:70%;padding:8px;border:none;border-radius:4px;}
button {padding:8px 15px;margin-left:5px;background:#238636;border:none;border-radius:4px;color:white;cursor:pointer;}