Index: src/wp-content/themes/twentynineteen/sass/blocks/_blocks.scss
===================================================================
--- src/wp-content/themes/twentynineteen/sass/blocks/_blocks.scss	(revision 44667)
+++ src/wp-content/themes/twentynineteen/sass/blocks/_blocks.scss	(working copy)
@@ -276,6 +276,7 @@
 			border-top: 2px solid $color__border;
 			padding-top: (1 * $size__spacing-unit);
 			margin-bottom: (2 * $size__spacing-unit);
+			word-break: break-word;
 			a {
 				&:after {
 					content: '';
Index: src/wp-content/themes/twentynineteen/style-editor.css
===================================================================
--- src/wp-content/themes/twentynineteen/style-editor.css	(revision 44667)
+++ src/wp-content/themes/twentynineteen/style-editor.css	(working copy)
@@ -1228,6 +1228,7 @@
   border-top: 2px solid #ccc;
   padding-top: 1rem;
   margin-bottom: 2rem;
+  word-break: break-word;
 }
 
 .wp-block-latest-posts.is-grid li a:after {
Index: src/wp-content/themes/twentynineteen/style-editor.scss
===================================================================
--- src/wp-content/themes/twentynineteen/style-editor.scss	(revision 44667)
+++ src/wp-content/themes/twentynineteen/style-editor.scss	(working copy)
@@ -667,6 +667,7 @@
 			border-top: 2px solid $color__border;
 			padding-top: (1 * $size__spacing-unit);
 			margin-bottom: (2 * $size__spacing-unit);
+			word-break: break-word;
 			a {
 				&:after {
 					content: '';
Index: src/wp-content/themes/twentynineteen/style.css
===================================================================
--- src/wp-content/themes/twentynineteen/style.css	(revision 44667)
+++ src/wp-content/themes/twentynineteen/style.css	(working copy)
@@ -5499,6 +5503,7 @@
   border-top: 2px solid #ccc;
   padding-top: 1rem;
   margin-bottom: 2rem;
+  word-break: break-word;
 }
 
 .entry .entry-content .wp-block-latest-posts.is-grid li a:after {