.gcd-board {
  margin: 1rem auto 1.25rem;
  max-width: 28rem;
  text-align: left;
}

.gcd-orig {
  font-size: 1.05rem;
  opacity: 0.85;
  min-height: 1.4em;
  text-align: center;
}

.gcd-pair {
  margin-top: 0.5rem;
  font-size: clamp(2rem, 5vw, 2.8rem);
  font-weight: 700;
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.04em;
  text-align: center;
}

.gcd-prompt {
  margin-top: 1rem;
  font-size: 1.1rem;
  text-align: center;
}

.gcd-viz {
  margin: 1.1rem 0 0;
}

.gcd-bar-row {
  display: grid;
  grid-template-columns: 3.25rem 1fr;
  gap: 0.55rem;
  align-items: center;
  margin: 0.5rem 0;
}

.gcd-bar-label {
  font-variant-numeric: tabular-nums;
  font-weight: 600;
  text-align: right;
  font-size: 0.95rem;
}

.gcd-bar-track {
  height: 1.5rem;
  background: #e8eef3;
  border: 1px solid #c5d4e0;
  border-radius: 0.3rem;
  overflow: hidden;
}

.gcd-bar-fill {
  height: 100%;
  border-radius: 0.2rem;
  min-width: 0.4rem;
  transition: width 0.35s ease;
}

.gcd-bar-fill--a {
  background: #2a6f97;
}

.gcd-bar-fill--b {
  background: #c47a2c;
}

.gcd-bar-fill--gcd {
  background: #2d6a4f;
}

.gcd-history {
  display: block;
  margin: 1.15rem 0 0;
  padding: 0;
  list-style: none;
}

.gcd-history[hidden] {
  display: none !important;
}

.gcd-history-item {
  display: block;
  margin: 0.7rem 0;
  padding: 0.65rem 0.75rem;
  background: #f4f7fa;
  border: 1px solid #d7e2ea;
  border-radius: 0.4rem;
}

.gcd-history-label {
  font-variant-numeric: tabular-nums;
  font-weight: 600;
  font-size: 1.02rem;
  margin-bottom: 0.4rem;
}

.gcd-fit-track {
  display: flex;
  width: 100%;
  height: 1.45rem;
  border: 1px solid #c5d4e0;
  border-radius: 0.3rem;
  overflow: hidden;
  background: #e8eef3;
}

.gcd-fit-unit {
  height: 100%;
  background: #2a6f97;
  border-right: 1px solid #fff;
  box-sizing: border-box;
  min-width: 2px;
}

.gcd-fit-unit:last-child {
  border-right: none;
}

.gcd-fit-unit--more {
  display: flex;
  align-items: center;
  justify-content: center;
  background: #5b8fad;
  color: #fff;
  font-size: 0.75rem;
  font-weight: 700;
  min-width: 2.2rem;
  border-right: 1px solid #fff;
}

.gcd-fit-rem {
  height: 100%;
  background: #c47a2c;
  min-width: 2px;
}

.gcd-fit-caption {
  margin-top: 0.3rem;
  font-size: 0.85rem;
  opacity: 0.8;
}

.gcd-history-done {
  font-weight: 700;
  font-size: 1.1rem;
  text-align: center;
  padding: 0.35rem 0;
}