Fix selector for frontend css

packages/block-library/src/common.scss

@@ -107,6 +107,6 @@
 // The following sets baseline border styles with zero specificity such that
 // when a user begins to alter block borders via the block support UI they
 // see immediate visual changes.
-html :where(.wp-block) {
+html :where([class^="wp-block"]) {
 	border: 0 solid currentColor;
 }