:root {
  color-scheme: light dark;
  font-family: system-ui, -apple-system, Segoe UI, Roboto, sans-serif;
}

body {
  margin: 0;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  background: #f2f3f5;
}

.card {
  width: min(420px, 90vw);
  background: #fff;
  border-radius: 12px;
  box-shadow: 0 2px 12px rgba(0, 0, 0, 0.1);
  padding: 2rem;
}

h1 {
  margin-top: 0;
  font-size: 1.4rem;
}

.readout {
  margin: 1.5rem 0;
}

.readout dt {
  font-size: 0.8rem;
  color: #666;
  margin-top: 0.75rem;
}

.readout dd {
  margin: 0;
  font-size: 1.1rem;
  font-weight: 600;
}

.gmt-label {
  font-style: italic;
}

.gmt-value {
  font-size: 0.95rem;
  font-weight: 400;
  color: #444;
}

form {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  margin-top: 1.5rem;
}

label {
  font-size: 0.85rem;
  color: #333;
}

input[type="datetime-local"] {
  font-size: 1rem;
  padding: 0.5rem;
}

button {
  margin-top: 0.5rem;
  padding: 0.6rem;
  font-size: 1rem;
  border: none;
  border-radius: 6px;
  background: #2563eb;
  color: #fff;
  cursor: pointer;
}

button:hover {
  background: #1d4ed8;
}

#status {
  min-height: 1.2em;
  font-size: 0.9rem;
}

#status.error {
  color: #b91c1c;
}

#status.success {
  color: #15803d;
}

@media (prefers-color-scheme: dark) {
  body {
    background: #111317;
  }
  .card {
    background: #1b1e24;
    box-shadow: 0 2px 12px rgba(0, 0, 0, 0.4);
  }
  h1 {
    color: #f2f3f5;
  }
  .readout dd {
    color: #f2f3f5;
  }
  .readout dt {
    color: #9aa0a6;
  }
  .gmt-value {
    color: #c3c7cd;
  }
  label {
    color: #c3c7cd;
  }
}