Index: wp-content/themes/twentyfifteen/css/editor-style.css
===================================================================
--- wp-content/themes/twentyfifteen/css/editor-style.css	(revision 56656)
+++ wp-content/themes/twentyfifteen/css/editor-style.css	(working copy)
@@ -298,7 +298,6 @@
 .mce-item-table td {
 	border-width: 0 1px 1px 0;
 	font-family: "Noto Serif", serif;
-	font-size: 17px;
 	padding: 7px;
 	vertical-align: baseline;
 }