Index: wp-includes/kses.php
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- wp-includes/kses.php	(date 1559667999000)
+++ wp-includes/kses.php	(date 1559700779000)
@@ -2163,6 +2163,7 @@
 			'justify-content',
 			'align-content',
 			'align-items',
+			'justify-self',
 			'align-self',
 			'flex-basis',
 			'flex-grow',