Index: wp-content/themes/twentysixteen/css/blocks.css
===================================================================
--- wp-content/themes/twentysixteen/css/blocks.css	(revision 56614)
+++ wp-content/themes/twentysixteen/css/blocks.css	(working copy)
@@ -213,7 +213,7 @@
 .wp-block-table,
 .wp-block-table th,
 .wp-block-table td {
-	border: 1px solid #d1d1d1;
+	border: 1px solid;
 }
 
 .wp-block-table {
Index: wp-content/themes/twentysixteen/style.css
===================================================================
--- wp-content/themes/twentysixteen/style.css	(revision 56614)
+++ wp-content/themes/twentysixteen/style.css	(working copy)
@@ -524,7 +524,7 @@
 table,
 th,
 td {
-	border: 1px solid #d1d1d1;
+	border: 1px solid;
 }
 
 table {