diff --git a/adventskalender/2025/css/main.css b/adventskalender/2025/css/main.css
index 9d8490a..a547c05 100644
--- a/adventskalender/2025/css/main.css
+++ b/adventskalender/2025/css/main.css
@@ -5,4 +5,42 @@
   margin: 0 auto;
   border-radius: 12px;
   box-shadow: 0 0 15px rgba(0,0,0,0.3);
+}
+
+/* Overlay über Kalenderbild */
+.kalenderbild {
+  position: relative;
+}
+
+.grid-overlay {
+  position: absolute;
+  inset: 0;
+  z-index: 10;
+  pointer-events: none; /* deaktiviert Klicks vorerst */
+}
+
+/* Türchen-Design */
+.grid-overlay .day {
+  position: absolute;
+  border: 2px solid var(--ci-gold);
+  border-radius: 0.5rem;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  pointer-events: auto;
+  background: transparent;
+  transition: box-shadow 0.3s ease;
+}
+
+.grid-overlay .day span {
+  color: var(--ci-gold);
+  font-family: 'serif'; /* später: z. B. 'Great Vibes' */
+  font-size: 1.8rem;
+  font-weight: bold;
+  text-shadow: 0 0 3px rgba(0, 0, 0, 0.4);
+}
+
+/* Hover-Effekt: leuchtender Glow */
+.grid-overlay .day:hover {
+  box-shadow: 0 0 12px 4px rgba(200, 170, 73, 0.7);
 }
\ No newline at end of file