Fix color cells going over the column name (#160) (#163)

bin/cdb.css

@@ -60,6 +60,7 @@
 }
 .cdb .cdb-sheet tr.separator td {
   position: sticky;
+  z-index: 1;
   top: 19px;
   border-left: none;
   padding-top: 6px;
@@ -127,6 +128,7 @@
 }
 .cdb .cdb-sheet:not(.cdb-sub-sheet) > thead.head > th {
   position: sticky;
+  z-index: 1;
   top: 0;
 }
 .cdb .cdb-sheet tr.head,
@@ -263,6 +265,7 @@
 }
 .cdb .cdb-sheet td.t_color {
   text-align: center;
+  position: relative;
 }
 .cdb .cdb-sheet td.t_color ._hide-modal {
   opacity: 0;

bin/cdb.less

@@ -69,6 +69,7 @@
 			height : 10px;
 			td {
 				position: sticky;
+				z-index: 1;
 				top: 19px;
 				border-left: none;
 				padding-top: 6px;
@@ -140,6 +141,7 @@
 
 		&:not(.cdb-sub-sheet) > thead.head > th {
 			position: sticky;
+			z-index: 1;
 			top: 0;
 		}
 
@@ -293,6 +295,7 @@
 
 		td.t_color {
 			text-align : center;
+			position: relative;
 			._hide-modal {
 				opacity : 0;
 			}