Spot the bug - #120: Dashboard Widget Panel

Why is my subgrid layout failing to inherit column tracks?

.dashboard {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 16px;
  padding: 24px;
}

.widget-card {
  grid-column: span 2;
  display: grid;
  grid-template-columns: subgrid;
  background: #1e1e2f;
  border-radius: 12px;
  padding: 12px;
}

.widget-header {
  grid-column: 1 / -1;
  font-weight: 700;
}

.widget-metric {
  grid-column: span 1;
  background: #2a2a3e;
  padding: 8px;
}

Reply with what is broken and how you would fix it.