diff --git a/lib/web/doctree/meta/model_site.v b/lib/web/doctree/meta/model_site.v
index a6d01d92..d95584ac 100644
--- a/lib/web/doctree/meta/model_site.v
+++ b/lib/web/doctree/meta/model_site.v
@@ -4,7 +4,7 @@ module meta
 pub struct Site {
 pub mut:
 	doctree_path   string     // path to the export of the doctree site
-	config         SiteConfig // Full site configuration	
+	config         SiteConfig // Full site configuration
 	pages          []Page
 	links          []Link
 	categories     []Category
@@ -51,8 +51,11 @@ pub fn (mut s Site) sidebar() SideBar {
 	uncategorized_pages.sort(a.src < b.src)
 
 	// ============================================================
-	// PASS 1: Add categories with their pages
+	// Build nested category structure from path
 	// ============================================================
+	mut category_tree := map[string]&NavCat{}
+
+	// PASS 1: Create all categories and their nested hierarchy
 	for i, category in s.categories {
 		category_id := i + 1 // categories are 1-indexed
 
@@ -61,40 +64,82 @@ pub fn (mut s Site) sidebar() SideBar {
 			continue
 		}
 
-		mut category_items := []NavItem{}
+		// Split path into parts (e.g., "Getting Started/Advanced/Deep" -> ["Getting Started", "Advanced", "Deep"])
+		path_parts := if category.path.contains('/') {
+			category.path.split('/')
+		} else {
+			[category.path]
+		}
 
-		// Add pages in this category
-		for page in category_pages[category_id] {
-			if !page.hide {
-				// Convert page src format "collection:name" to path "collection/name"
-				path := page.src.replace(':', '/')
+		// Navigate/create the nested structure
+		mut current_path := ''
 
-				nav_doc := NavDoc{
-					path:  path
-					label: if page.label.len > 0 { page.label } else { page.title }
+		for part_idx, part in path_parts {
+			if current_path.len > 0 {
+				current_path += '/'
+			}
+			current_path += part
+
+			// Check if this node already exists
+			if current_path !in category_tree {
+				// Create new category node
+				mut new_cat := &NavCat{
+					label:       part
+					collapsible: category.collapsible
+					collapsed:   category.collapsed
+					items:       []NavItem{}
+				}
+				category_tree[current_path] = new_cat
+
+				// If this is not the root of the path, add it to its parent
+				if part_idx > 0 {
+					parent_path := path_parts[0..part_idx].join('/')
+					if parent_path in category_tree {
+						mut parent_cat := category_tree[parent_path]
+						parent_cat.items << new_cat
+					}
 				}
-				category_items << nav_doc
 			}
 		}
 
-		// Only add category if it has visible items
-		if category_items.len > 0 {
-			nav_cat := NavCat{
-				label:       if category.path.len > 0 {
-					category.path
-				} else {
-					'Section ${category_id}'
+		// Add pages to the leaf category
+		if current_path in category_tree {
+			mut leaf_cat := category_tree[current_path]
+			for page in category_pages[category_id] {
+				if !page.hide {
+					// Convert page src format "collection:name" to path "collection/name"
+					path := page.src.replace(':', '/')
+
+					nav_doc := NavDoc{
+						path:  path
+						label: if page.label.len > 0 { page.label } else { page.title }
+					}
+					leaf_cat.items << nav_doc
 				}
-				collapsible: category.collapsible
-				collapsed:   category.collapsed
-				items:       category_items
 			}
-			result.my_sidebar << nav_cat
 		}
 	}
 
 	// ============================================================
-	// PASS 2: Add uncategorized pages at root level
+	// PASS 2: Add root-level categories to sidebar
+	// ============================================================
+	for i, category in s.categories {
+		// Only add the root of each category tree to the sidebar.
+		// If a category path contains '/', it means it's a nested category,
+		// and its root (first part of the path) would have already been processed in PASS 1
+		// and added to the category_tree.
+		// We should only add the top-level categories, or categories without '/',
+		// to the main sidebar.
+		if !category.path.contains('/') && category.path.len > 0 {
+			root_path := category.path
+			if root_path in category_tree {
+				result.my_sidebar << category_tree[root_path]
+			}
+		}
+	}
+
+	// ============================================================
+	// PASS 3: Add uncategorized pages at root level
 	// ============================================================
 	for page in uncategorized_pages {
 		if !page.hide {
@@ -110,7 +155,7 @@ pub fn (mut s Site) sidebar() SideBar {
 	}
 
 	// ============================================================
-	// PASS 3: Add standalone links (if needed)
+	// PASS 4: Add standalone links (if needed)
 	// ============================================================
 	for link in s.links {
 		nav_link := NavLink{