/* explorer.css - Left Library Tree View & Filter Panels */
.panel-header {
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 12px;
  background-color: var(--bg-surface);
  border-bottom: 1px solid var(--border-color);
  font-weight: 600;
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  color: var(--text-secondary);
}

.panel-header-actions {
  display: flex;
  align-items: center;
  gap: 4px;
}

.panel-content {
  flex: 1;
  overflow-y: auto;
  overflow-x: hidden;
  padding: 6px 0;
}

/* Tree node structure */
.tree-node {
  display: flex;
  flex-direction: column;
}

.tree-item {
  display: flex;
  align-items: center;
  height: 26px;
  padding: 0 8px;
  gap: 6px;
  cursor: pointer;
  border-radius: var(--radius-sm);
  margin: 1px 4px;
  color: var(--text-main);
  transition: background var(--transition-fast);
}

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

.tree-item.active {
  background-color: var(--accent-light);
  color: var(--accent);
  font-weight: 500;
}

.tree-toggle {
  width: 16px;
  height: 16px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-size: 10px;
  color: var(--text-muted);
  cursor: pointer;
}

.tree-toggle.collapsed svg {
  transform: rotate(-90deg);
}

.tree-icon {
  width: 14px;
  height: 14px;
  fill: currentColor;
  opacity: 0.7;
}

.tree-label {
  flex: 1;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  font-size: 12px;
}

.tree-badge {
  font-size: 10px;
  padding: 1px 5px;
  border-radius: var(--radius-full);
  background-color: var(--bg-surface);
  color: var(--text-muted);
  font-family: var(--font-mono);
}

.tree-children {
  padding-left: 14px;
  display: flex;
  flex-direction: column;
}

.tree-children.hidden {
  display: none;
}