ISTWCMS-5898: adjust previous attempt to something that also works in layout builder

src/patterns/03-layouts/block/_block.scss

@@ -14,7 +14,7 @@
     margin-bottom: 0;
   }
   // On nodes, move block title to top of block, while preserving spacing underneath.
-  .node & > {
+  .uw-main & > {
     h2:first-child,
     .uw-admin-label + h2 {
       margin-top: -0.25em; /* Using ems so it adjusts to font size. */
@@ -25,8 +25,8 @@
     margin-bottom: 0;
   }
   // On nodes, move an initial header in copy text to top of block, while preserving spacing underneath, unless there was a block title..
-  .node & .uw-admin-label + .contextual + .uw-copy-text,
-  .node & .uw-copy-text:first-child {
+  .uw-main & .uw-admin-label + .contextual + .uw-copy-text,
+  .uw-main & .uw-copy-text:first-child {
     .uw-copy-text__wrapper > :where(h2, h3, h4, h5, h6):first-child {
       margin-top: -0.25em; /* Using ems so it adjusts to font size. */
       padding-top: 0;