Remember nav scroll depth

frontend.html

@@ -201,6 +201,17 @@
                 });
             }
         })();
+
+        // Preserve sidebar scroll depth between page loads
+        (function() {
+            var sidebar = document.getElementById('sidebar');
+            if (!sidebar) return;
+            var saved = sessionStorage.getItem('sidebar-scroll');
+            if (saved !== null) sidebar.scrollTop = parseInt(saved, 10);
+            sidebar.addEventListener('scroll', function() {
+                sessionStorage.setItem('sidebar-scroll', sidebar.scrollTop);
+            });
+        })();
     </script>
 </body>
 </html>