Index: src/wp-content/themes/twentyseventeen/assets/css/blocks.css
===================================================================
--- src/wp-content/themes/twentyseventeen/assets/css/blocks.css	(revision 51624)
+++ src/wp-content/themes/twentyseventeen/assets/css/blocks.css	(working copy)
@@ -53,13 +53,20 @@
 }
 
 .wp-block-image figure.alignleft {
+	margin-top: 0;
 	margin-right: 1.5em;
 }
 
 .wp-block-image figure.alignright {
+	margin-top: 0;
 	margin-left: 1.5em;
 }
 
+.entry-content > .wp-block-image:first-child figure.alignleft,
+.entry-content > .wp-block-image:first-child figure.alignright {
+	margin-top: 1.5em;
+}
+
 /* Gallery */
 
 .wp-block-gallery {