Fold all top-level navigation items in doc

Change-Id: Ia6651c8be6eb0803699b38506eb5a30fa9e3c7fa
diff --git a/dev/scss/sidebar/sidebar.scss b/dev/scss/sidebar/sidebar.scss
index 496f701..01979b4 100644
--- a/dev/scss/sidebar/sidebar.scss
+++ b/dev/scss/sidebar/sidebar.scss
@@ -80,10 +80,10 @@
       }
 
       &.folded {
-        &.active ul {
+        &.active > ul {
           display: block;
         }
-        ul {
+        > ul {
           display: none;
           &.active {
             display: block !important;