:root {
  color-scheme: light dark;
  --fg: #1a1a1a;
  --bg: #fafafa;
  --panel-bg: #ffffff;
  --border: #ddd;
  --accent: #b8860b;
}

@media (prefers-color-scheme: dark) {
  :root {
    --fg: #eee;
    --bg: #16161a;
    --panel-bg: #202024;
    --border: #3a3a3f;
    --accent: #e0b84a;
  }
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Hiragino Sans", "Yu Gothic", sans-serif;
  color: var(--fg);
  background: var(--bg);
}

header {
  padding: 1.25rem 1rem;
  text-align: center;
}

header h1 {
  font-size: 1.25rem;
  margin: 0;
}

main {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  padding: 0 1rem 2rem;
  max-width: 960px;
  margin: 0 auto;
}

.panel {
  flex: 1 1 320px;
  background: var(--panel-bg);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1.25rem;
}

.panel h2 {
  margin-top: 0;
  font-size: 1.05rem;
}

.field {
  margin-bottom: 0.75rem;
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
}

.field label {
  font-size: 0.85rem;
  opacity: 0.75;
}

select {
  font-size: 1rem;
  padding: 0.4rem 0.5rem;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: var(--panel-bg);
  color: var(--fg);
}

.result {
  margin: 1rem 0 0.5rem;
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 0.4rem 0.75rem;
}

.result dt {
  font-size: 0.85rem;
  opacity: 0.7;
  white-space: nowrap;
}

.result dd {
  margin: 0;
  font-weight: 600;
}

#result-expected {
  color: var(--accent);
  font-size: 1.1rem;
}

.note {
  font-size: 0.75rem;
  opacity: 0.6;
  margin-bottom: 0;
}

@media (max-width: 640px) {
  main {
    flex-direction: column;
  }
}