.population-grid {
  display: grid;
  grid-template-columns: repeat(25, minmax(0, 1fr));
  grid-auto-rows: 18px;
  gap: 2px;
  justify-items: center;
  align-items: center;
  border: 1px solid #e5e7eb;
  padding: 6px;
  background-color: #f9fafb;
  position: relative;
}

.person {
  width: 18px;
  height: 18px;
  border-radius: 9999px;
  border: 1px solid #e5e7eb;
  box-sizing: border-box;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 8px;
  color: #111827;
  transition: opacity 0.15s ease, box-shadow 0.15s ease, border-color 0.15s ease;
}

.person.sampled {
  border-color: #111827;
  box-shadow: 0 0 0 2px rgba(37, 99, 235, 0.6);
  opacity: 1;
}

.person.not-sampled {
  opacity: 0.25;
}

.person-icon {
  width: 16px;
  height: 16px;
  display: block;
}

.cluster-overlay {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  pointer-events: none;
}

.cluster-line {
  position: absolute;
  background-color: #d1d5db;
  opacity: 0.6;
}

.cluster-line.vertical {
  width: 2px;
  top: 0;
  bottom: 0;
}

.cluster-line.horizontal {
  height: 2px;
  left: 0;
  right: 0;
}

.convenience-overlay {
  position: absolute;
  border: 2px solid #9ca3af;
  background-color: rgba(156, 163, 175, 0.15);
  pointer-events: none;
}

.chart-placeholder {
  width: 100%;
  min-height: 340px;
}