diff --git a/themes/style1/defaults.less b/themes/style1/defaults.less
index 31f19e8..45fec06 100644
--- a/themes/style1/defaults.less
+++ b/themes/style1/defaults.less
@@ -96,6 +96,7 @@ i.e. top margin or bottom margin for each grid
 .dc-fixed-header{}
 .dc-fixed{}
 .dc-header{
+	z-index:9;
 	.row{
 		.block{
 			background:none;
diff --git a/themes/style2/defaults.less b/themes/style2/defaults.less
index 31f19e8..45fec06 100644
--- a/themes/style2/defaults.less
+++ b/themes/style2/defaults.less
@@ -96,6 +96,7 @@ i.e. top margin or bottom margin for each grid
 .dc-fixed-header{}
 .dc-fixed{}
 .dc-header{
+	z-index:9;
 	.row{
 		.block{
 			background:none;
diff --git a/themes/style3/defaults.less b/themes/style3/defaults.less
index 31f19e8..45fec06 100644
--- a/themes/style3/defaults.less
+++ b/themes/style3/defaults.less
@@ -96,6 +96,7 @@ i.e. top margin or bottom margin for each grid
 .dc-fixed-header{}
 .dc-fixed{}
 .dc-header{
+	z-index:9;
 	.row{
 		.block{
 			background:none;