diff --git a/content/nested/sibling.md b/content/nested/sibling.md
new file mode 100644
index 0000000..9933f1a
--- /dev/null
+++ b/content/nested/sibling.md
@@ -0,0 +1 @@
+# Sibling
diff --git a/hooks/nav.py b/hooks/nav.py
new file mode 100644
index 0000000..7d9f723
--- /dev/null
+++ b/hooks/nav.py
@@ -0,0 +1,8 @@
+def is_list_page(page) -> bool:
+    if not page.parent:
+        return False
+
+    return page.parent.children[0] == page
+
+def on_env(env, config, files):
+    env.filters["is_list_page"] = is_list_page
diff --git a/mkdocs.yml b/mkdocs.yml
index 6a3cde4..dda4cf7 100644
--- a/mkdocs.yml
+++ b/mkdocs.yml
@@ -5,3 +5,6 @@ strict: true
 theme:
   name: null
   custom_dir: theme
+
+hooks:
+  - hooks/nav.py
diff --git a/theme/main.html b/theme/main.html
index e6b9185..7ea4026 100644
--- a/theme/main.html
+++ b/theme/main.html
@@ -1,3 +1,10 @@
 {{ page.content }}
 
-{{ nav }}
+Nav: {{ nav }}
+
+Parent: {{ page.parent }}
+Section: {{ page.is_section }}
+
+Is lits page: {{ page|is_list_page }}
+
+Children: {{ page.children }}