diff -r 48c4eec2b7e6 -r 8c2e4d02f4ef wp/wp-includes/blocks/comments/editor.css
--- a/wp/wp-includes/blocks/comments/editor.css	Fri Sep 05 18:40:08 2025 +0200
+++ b/wp/wp-includes/blocks/comments/editor.css	Fri Sep 05 18:52:52 2025 +0200
@@ -98,10 +98,14 @@
   padding:calc(.667em + 2px);
 }
 
-:where(.wp-block-post-comments input[type=submit]){
+:where(.wp-block-post-comments input[type=submit],.wp-block-comments__legacy-placeholder input[type=submit]){
   border:none;
 }
 
+.wp-block-comments{
+  box-sizing:border-box;
+}
+
 .block-library-comments-toolbar__popover .components-popover__content{
   min-width:230px;
 }