.scene-hierarchy {
  display: flex;
  flex-direction: column;
  height: 100%;
  background-color: var(--color-bg-base);
  color: var(--color-text-primary);
}

.hierarchy-header {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  height: var(--layout-panel-header);
  padding: 0 var(--spacing-md);
  border-bottom: 1px solid var(--color-border-default);
  background-color: var(--color-bg-elevated);
  flex-shrink: 0;
}

.hierarchy-header-icon {
  color: var(--color-text-secondary);
  flex-shrink: 0;
}

.hierarchy-header h3 {
  margin: 0;
  font-size: var(--font-size-sm);
  font-weight: var(--font-weight-semibold);
  color: var(--color-text-primary);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.hierarchy-content {
  flex: 1;
  overflow-y: auto;
  padding: var(--spacing-xs) 0;
}

.empty-state {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: var(--spacing-4xl) var(--spacing-lg);
  text-align: center;
  color: var(--color-text-secondary);
  height: 100%;
}

.empty-icon {
  color: var(--color-text-tertiary);
  margin-bottom: var(--spacing-md);
  opacity: 0.5;
}

.empty-title {
  font-size: var(--font-size-base);
  font-weight: var(--font-weight-medium);
  color: var(--color-text-secondary);
  margin-bottom: var(--spacing-xs);
}

.empty-hint {
  font-size: var(--font-size-sm);
  color: var(--color-text-tertiary);
}

.entity-list {
  list-style: none;
  margin: 0;
  padding: 0;
}

.entity-item {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  padding: var(--spacing-sm) var(--spacing-md);
  cursor: pointer;
  user-select: none;
  transition: all var(--transition-fast);
  position: relative;
}

.entity-item::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 2px;
  background-color: transparent;
  transition: background-color var(--transition-fast);
}

.entity-item:hover {
  background-color: var(--color-bg-hover);
}

.entity-item.selected {
  background-color: var(--color-selected);
}

.entity-item.selected::before {
  background-color: var(--color-primary);
}

.entity-item.selected:hover {
  background-color: var(--color-selected-hover);
}

.entity-icon {
  color: var(--color-text-secondary);
  flex-shrink: 0;
  transition: color var(--transition-fast);
}

.entity-item:hover .entity-icon,
.entity-item.selected .entity-icon {
  color: var(--color-primary);
}

.entity-name {
  font-size: var(--font-size-base);
  color: var(--color-text-primary);
  flex: 1;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.entity-item.selected .entity-name {
  font-weight: var(--font-weight-medium);
}