diff --git a/src/wp-includes/js/tinymce/skins/wordpress/wp-content.css b/src/wp-includes/js/tinymce/skins/wordpress/wp-content.css
index 2895fd9bdd..6f52773378 100644
--- a/src/wp-includes/js/tinymce/skins/wordpress/wp-content.css
+++ b/src/wp-includes/js/tinymce/skins/wordpress/wp-content.css
@@ -211,6 +211,11 @@ audio {
 	visibility: hidden;
 }
 
+/* Fix for proprietary Mozilla display attribute, see #38757 */
+[_moz_abspos] {
+	outline: none;
+}
+
 a[data-wplink-url-error],
 a[data-wplink-url-error]:hover,
 a[data-wplink-url-error]:focus {