diff --git a/theme/style.less b/theme/style.less
index 35e06f78..dbfa2557 100644
--- a/theme/style.less
+++ b/theme/style.less
@@ -46,7 +46,8 @@
 *******************************/
 
 div.blocklyTreeRow {
-    border-bottom: 1px solid #ecf0f1 !important;
+    box-shadow: 0 1px 0 #ecf0f1 inset;
+
     margin-bottom: 0px !important;
 
     -webkit-transition-property: background-color; /* Safari */