body {
  font-family: system-ui, sans-serif;
  background: #0f172a;
  color: #e5e7eb;
  display: grid;
  place-items: center;
  height: 100vh;
}
.card {
  background: #111827;
  padding: 24px;
  border-radius: 12px;
  max-width: 600px;
}
.btn {
  background: #22d3ee;
  border: none;
  padding: 12px 16px;
  border-radius: 8px;
  color: #031317;
  font-weight: 600;
  cursor: pointer;
}
.muted { color: #9ca3af; }
pre.mono {
  background: #1e293b;
  color: #d1d5db;
  padding: 8px;
  border-radius: 6px;
  overflow-x: auto;
}
.footer {
  margin-top: 10px;
  font-size: 12px;
  color: #9ca3af;
  text-align: center;
}
.mono, pre.mono {
  overflow-x: auto;
  white-space: pre; /* keep it all one line but scroll horizontally */
}