Block dropzones

css/drop-zone.css

@@ -8,9 +8,14 @@
   padding: .5em 0;
   font-weight: 800;
   color: white;
+  z-index: 15;
 }
 .drop-zone-hover {
   color: black;
   outline: 2px dashed #fedb60;
   background-color: #ffd;
 }
+
+.js-layout-builder-region {
+  min-height: 40px;
+}