diff --git a/adventskalender/2025/css/main.css b/adventskalender/2025/css/main.css
index 25a13c0..17b8bb0 100644
--- a/adventskalender/2025/css/main.css
+++ b/adventskalender/2025/css/main.css
@@ -42,6 +42,9 @@
     transform 0.25s ease,
     box-shadow 0.25s ease,
     background 0.25s ease;
+
+    transform-style: preserve-3d;
+    perspective: 800px;
 }
 
 /* Hover nur mit leichtem Leuchten und Zoom */
@@ -59,4 +62,35 @@
 
 .door canvas {
   pointer-events: none;
+}
+
+/* Vorderseite – Standardansicht */
+.door::before {
+  content: "";
+  position: absolute;
+  inset: 0;
+  border-radius: inherit;
+  background: inherit;
+  backface-visibility: hidden;
+  z-index: 1;
+}
+
+/* Rückseite – nach dem Öffnen sichtbar */
+.door::after {
+  content: "";
+  position: absolute;
+  inset: 0;
+  border-radius: inherit;
+  background: rgba(255, 255, 255, 0.08); /* leicht transparent wie Loch */
+  box-shadow: inset 0 0 6px rgba(255,255,255,0.15);
+  transform: rotateY(180deg);
+  backface-visibility: hidden;
+}
+
+/* Geöffneter Zustand */
+.door.open {
+  transform: rotateY(180deg);
+  box-shadow:
+    0 0 14px color-mix(in srgb, var(--ci-gold) 45%, transparent),
+    inset 0 0 10px rgba(255,255,255,0.2);
 }
\ No newline at end of file