feat: don't print background slot

Author: peterpeterparker

src/components/deck/deckdeckgo-deck/deckdeckgo-deck.scss

@@ -33,4 +33,8 @@ div.deckgo-pager {
     display: initial;
     position: initial;
   }
+
+  ::slotted([slot="background"]) {
+    display: none;
+  }
 }