Fix behaviour of folded subdirectories in navigation

Change-Id: I1d0de6f46291141a237aeea926a50a8abeccf284
diff --git a/dev/scss/sidebar/sidebar.scss b/dev/scss/sidebar/sidebar.scss
index f67d4f3..496f701 100644
--- a/dev/scss/sidebar/sidebar.scss
+++ b/dev/scss/sidebar/sidebar.scss
@@ -85,6 +85,9 @@
         }
         ul {
           display: none;
+          &.active {
+            display: block !important;
+          }
         }
       }