Ticket #60079: 60079.3.patch

src/wp-content/themes/twentyfifteen/css/blocks.css

@@ -470 +470 @@
         }
 }
 
-/* Seperators */
+/* Separator */
 
 .wp-block-separator {
         border: 0;

src/wp-content/themes/twentyfifteen/css/editor-blocks.css

@@ -806 +806 @@
 /* Separator */
 
 .wp-block-separator {
+        border: 0;
         max-width: 100px;
 }