diff --git a/src/wp-content/themes/twentyfifteen/css/editor-style.css b/src/wp-content/themes/twentyfifteen/css/editor-style.css
index 2995cd1bd9..b2660b1ea8 100644
--- a/src/wp-content/themes/twentyfifteen/css/editor-style.css
+++ b/src/wp-content/themes/twentyfifteen/css/editor-style.css
@@ -28,7 +28,7 @@ body {
 	font-weight: 400;
 	font-size: 17px;
 	line-height: 1.6471;
-	margin: 20px 40px;
+	margin: auto 20px;
 	max-width: 660px;
 	vertical-align: baseline;
 }
diff --git a/src/wp-content/themes/twentysixteen/css/editor-style.css b/src/wp-content/themes/twentysixteen/css/editor-style.css
index 69584798d9..e1b3445e86 100644
--- a/src/wp-content/themes/twentysixteen/css/editor-style.css
+++ b/src/wp-content/themes/twentysixteen/css/editor-style.css
@@ -28,7 +28,7 @@ body {
 	font-size: 16px;
 	font-weight: 400;
 	line-height: 1.75;
-	margin: 20px 40px;
+	margin: auto 20px;
 	max-width: 600px;
 	vertical-align: baseline;
 }