:root{
  --bg:#0f1720;
  --card:#0b1220;
  --accent:#60a5fa;
  --muted:#94a3b8;
  --ok:#10b981;
  --warn:#f59e0b;
  --danger:#ef4444;
  color-scheme: dark;
}
*{box-sizing:border-box}
body{
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, "PingFang SC", "Noto Sans SC", "Microsoft Yahei", sans-serif;
  background: linear-gradient(180deg,var(--bg), #071127);
  color:#e6eef8;
  margin:0;
  min-height:100vh;
  display:flex;
  align-items:center;
  justify-content:center;
  padding:24px;
}
.container{
  width:100%;
  max-width:720px;
  background:rgba(255,255,255,0.02);
  padding:20px;
  border-radius:10px;
  box-shadow: 0 6px 30px rgba(2,6,23,0.7);
}
h1{margin:0 0 12px 0;color:var(--accent)}
label{display:block;margin:8px 0}
input[type=number]{padding:6px 8px;border-radius:6px;border:1px solid rgba(255,255,255,0.06);background:transparent;color:inherit;width:160px}
button{padding:8px 12px;border-radius:8px;border:none;background:var(--accent);color:#04293a;cursor:pointer}
button.hidden{display:none}
#messages{margin-top:12px;padding:10px;border-radius:8px;background:rgba(255,255,255,0.02);min-height:48px}
.hint{color:var(--muted);font-size:13px;margin-top:8px}
.hidden{display:none}