fix: refine sidebar folder rows

src/components/folder-tree/folderTreeLayout.ts

@@ -0,0 +1,17 @@
+export const FOLDER_ROW_CONTENT_INSET = 12
+export const FOLDER_ROW_ICON_SIZE = 17
+export const FOLDER_ROW_ICON_GAP = 8
+export const FOLDER_ROW_NESTING_INDENT = FOLDER_ROW_ICON_SIZE + FOLDER_ROW_ICON_GAP
+
+const FOLDER_CONNECTOR_WIDTH = 1
+
+export function getFolderDepthIndent(depth: number) {
+  return depth * FOLDER_ROW_NESTING_INDENT
+}
+
+export function getFolderConnectorLeft(depth: number) {
+  return FOLDER_ROW_CONTENT_INSET
+    + getFolderDepthIndent(depth)
+    + FOLDER_ROW_ICON_SIZE / 2
+    - FOLDER_CONNECTOR_WIDTH / 2
+}