diff --git a/themes/original/css/navigation.css.php b/themes/original/css/navigation.css.php
index e27ba21dd0..634e6ebdac 100644
--- a/themes/original/css/navigation.css.php
+++ b/themes/original/css/navigation.css.php
@@ -26,6 +26,7 @@ if (! defined('PMA_MINIMUM_COMMON') && ! defined('TESTSUITE')) {
     <?php echo $left; ?>: 0;
     height: 100%;
     border-<?php echo $right; ?>: 1px solid gray;
+    z-index: 800;
 }
 
 #pma_navigation_content {
diff --git a/themes/pmahomme/css/navigation.css.php b/themes/pmahomme/css/navigation.css.php
index a7f34e1540..7382c4d853 100644
--- a/themes/pmahomme/css/navigation.css.php
+++ b/themes/pmahomme/css/navigation.css.php
@@ -25,6 +25,7 @@ if (! defined('PMA_MINIMUM_COMMON') && ! defined('TESTSUITE')) {
     height: 100%;
     background: url(./themes/pmahomme/img/left_nav_bg.png) repeat-y right 0% <?php echo $GLOBALS['cfg']['NaviBackground']; ?>;
     color: <?php echo $GLOBALS['cfg']['NaviColor']; ?>;
+    z-index: 800;
 }
 
 #pma_navigation_content {