Fix Meldungen mobile toggle by using explicit display none

patterns/vsf-list-detailseite.html

@@ -336,7 +336,7 @@
         const nextExpanded = !isExpanded;
 
         cards.forEach((card) => {
-          card.hidden = !nextExpanded;
+          card.style.display = nextExpanded ? '' : 'none';
         });
 
         button.setAttribute('aria-expanded', String(nextExpanded));