body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  max-width: 760px;
  margin: 2rem auto;
  padding: 0 1rem;
  color: #222;
}

h1 {
  font-size: 1.4rem;
}

textarea {
  width: 100%;
  height: 220px;
  box-sizing: border-box;
  padding: 0.5rem;
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
  font-size: 0.95rem;
}

.controls {
  display: flex;
  gap: 0.5rem;
  align-items: center;
  margin: 0.5rem 0;
}

select,
button {
  padding: 0.35rem 0.7rem;
  font-size: 0.95rem;
}

button:disabled {
  opacity: 0.5;
}

#output {
  min-height: 3rem;
  padding: 0.75rem;
  border: 1px solid #ddd;
  border-radius: 4px;
  background: #f6f6f6;
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
  white-space: pre-wrap;
}

#output.error {
  color: #b00020;
}

.hint {
  color: #666;
  font-size: 0.85rem;
}

.runtime-state {
  display: inline-block;
  margin: 0 0 0.75rem;
  padding: 0.25rem 0.5rem;
  border: 1px solid #ddd;
  border-radius: 4px;
  background: #f6f6f6;
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
  font-size: 0.85rem;
}