Index: src/wp-content/themes/twentyseventeen/assets/css/blocks.css
===================================================================
--- src/wp-content/themes/twentyseventeen/assets/css/blocks.css	(revision 48040)
+++ src/wp-content/themes/twentyseventeen/assets/css/blocks.css	(working copy)
@@ -20,13 +20,13 @@
 
 /* Captions */
 
-[class^="wp-block-"]:not(.wp-block-gallery) figcaption {
+[class^="wp-block-"]:not(.wp-block-gallery) > figcaption {
 	font-style: italic;
 	margin-bottom: 1.5em;
 	text-align: left;
 }
 
-.rtl [class^="wp-block-"]:not(.wp-block-gallery) figcaption {
+.rtl [class^="wp-block-"]:not(.wp-block-gallery) > figcaption {
 	text-align: right;
 }
 
Index: src/wp-content/themes/twentyseventeen/assets/css/editor-blocks.css
===================================================================
--- src/wp-content/themes/twentyseventeen/assets/css/editor-blocks.css	(revision 48040)
+++ src/wp-content/themes/twentyseventeen/assets/css/editor-blocks.css	(working copy)
@@ -459,13 +459,13 @@
 
 /* Caption styles*/
 
-[class^="wp-block-"]:not(.wp-block-gallery) figcaption {
+[class^="wp-block-"]:not(.wp-block-gallery) > figcaption {
 	font-style: italic;
 	margin-bottom: 1.5em;
 	text-align: left;
 }
 
-.rtl [class^="wp-block-"]:not(.wp-block-gallery) figcaption {
+.rtl [class^="wp-block-"]:not(.wp-block-gallery) > figcaption {
 	text-align: right;
 }