Index: wp-content/themes/twentyfifteen/css/editor-blocks.css
===================================================================
--- wp-content/themes/twentyfifteen/css/editor-blocks.css	(revision 56614)
+++ wp-content/themes/twentyfifteen/css/editor-blocks.css	(working copy)
@@ -1011,3 +1011,7 @@
 :root .editor-styles-wrapper .has-light-blue-background-color {
 	background-color: #e9f2f9;
 }
+
+.wp-block-table.is-style-stripes tbody tr:nth-child(even){
+	background-color: #ffffff;
+}
Index: wp-content/themes/twentyfifteen/style.css
===================================================================
--- wp-content/themes/twentyfifteen/style.css	(revision 56614)
+++ wp-content/themes/twentyfifteen/style.css	(working copy)
@@ -6152,3 +6152,9 @@
 		padding: 0;
 	}
 }
+.wp-block-table table{
+	margin-bottom: 0;
+}
+.wp-block-table.is-style-stripes table{
+	border: none;
+}
\ No newline at end of file