Index: src/wp-content/themes/twentyfifteen/css/blocks.css
===================================================================
--- src/wp-content/themes/twentyfifteen/css/blocks.css	(revision 58067)
+++ src/wp-content/themes/twentyfifteen/css/blocks.css	(working copy)
@@ -373,11 +373,17 @@
 /* Table */
 
 .wp-block-table th,
-.wp-block-table td {
+.wp-block-table td,
+.wp-block-table.is-style-stripes th,
+.wp-block-table.is-style-stripes td {
 	border-color: #eaeaea;
 	border-width: 0 1px 1px 0;
 }
 
+figure.wp-block-table.is-style-stripes {
+	border-width: 0;
+}
+
 /*--------------------------------------------------------------
 4.0 Blocks - Layout Elements
 --------------------------------------------------------------*/
Index: src/wp-content/themes/twentyfifteen/css/editor-blocks.css
===================================================================
--- src/wp-content/themes/twentyfifteen/css/editor-blocks.css	(revision 58067)
+++ src/wp-content/themes/twentyfifteen/css/editor-blocks.css	(working copy)
@@ -731,6 +731,17 @@
 	text-align: right;
 }
 
+.wp-block-table th,
+.wp-block-table td,
+.wp-block-table.is-style-stripes th,
+.wp-block-table.is-style-stripes td {
+	border-color: #eaeaea;
+}
+
+figure.wp-block-table.is-style-stripes {
+	border-width: 0;
+}
+
 /* Verse */
 
 .editor-styles-wrapper .wp-block-verse {