diff --git a/src/wp-content/themes/twentysixteen/css/editor-blocks.css b/src/wp-content/themes/twentysixteen/css/editor-blocks.css
index 0eef6016c3..e57211a935 100644
--- a/src/wp-content/themes/twentysixteen/css/editor-blocks.css
+++ b/src/wp-content/themes/twentysixteen/css/editor-blocks.css
@@ -634,6 +634,13 @@ Description: Used to style blocks in the editor.
 	margin-bottom: 16px;
 }
 
+/* Post Author Block  */
+
+.editor-styles-wrapper .avatar,
+.wp-block-post-author__avatar img {
+  border-radius: 50%;
+}
+
 /*--------------------------------------------------------------
 7.0 Blocks - Colors
 --------------------------------------------------------------*/