Fixed z-index definitions to avoid hiding of tree menus

Change-Id: I71044f36ac9c195341dd38735cd8a4c45ee09a36
diff --git a/dev/scss/sidebar/sidebar.scss b/dev/scss/sidebar/sidebar.scss
index 8e6491b..7ef4fde 100644
--- a/dev/scss/sidebar/sidebar.scss
+++ b/dev/scss/sidebar/sidebar.scss
@@ -10,7 +10,7 @@
   display: block;
   background-color: $dark-green;
   position: fixed;
-  z-index: 4000; // Needs to be behind alerts
+  z-index: 100; // Needs to be behind alerts
   color: $nearly-white;
   width: $logo-left-distance;
   top: 0;