:root{--bg:#f7fafc;--card:#ffffff;--muted:#666}
body{font-family:system-ui,-apple-system,Segoe UI,Roboto,Helvetica,Arial; background:var(--bg); margin:0}
.container{max-width:720px;margin:24px auto;padding:16px}
header h1{margin:0;font-size:1.4rem}
.panel{background:var(--card);padding:12px;border-radius:8px;box-shadow:0 1px 3px rgba(0,0,0,.06)}
.hidden{display:none}
#messages{height:60vh;overflow:auto;padding:8px}
.message{padding:8px;margin:6px 0;border-radius:8px;background:#e6f7ff}
.message.me{background:#dff6e0;text-align:right}
form{display:flex;gap:8px;margin-top:8px}
input{flex:1;padding:8px;border-radius:6px;border:1px solid #ddd}
button{padding:8px 12px;border-radius:6px;border:0;background:#0366d6;color:#fff}
footer{margin-top:8px;color:var(--muted);font-size:0.9rem}