diff --git a/src/root/static/css/rotated-th.css b/src/root/static/css/rotated-th.css
index f5e5c113..94079d7f 100644
--- a/src/root/static/css/rotated-th.css
+++ b/src/root/static/css/rotated-th.css
@@ -33,6 +33,7 @@ td.centered {
     transform:skew(-45deg,0deg);
     overflow: hidden;
     border-left: 1px solid #dddddd;
+    z-index: 1;
 }
 
 .table-header-rotated th.rotate-45 span {