body {
  font-family: Arial, sans-serif;
  background: url('../pictures/background.png') no-repeat center center fixed;
  background-size: cover;
  text-align: center;
  padding: 20px;
  margin: 0;
}

footer {
  text-align: center;
  margin-top: 20px;
  padding: 10px;
  background-color: #f0f0f0;
  border-top: 1px solid #ccc;
  position: fixed;
  width: 100%;
  bottom: 0;
  left: 0;
  font-size: clamp(0.8rem, 2vw, 1rem);
}

.calendar {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 15px;
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 10px;
}

.door {
  width: 100%;
  aspect-ratio: 4 / 3;
  /* Rechteckig */
  border: 3px solid #999;
  border-radius: 10px;
  display: flex;
  justify-content: center;
  align-items: center;
  font-size: clamp(1rem, 2.5vw, 2rem);
  font-weight: bold;
  color: white;
  cursor: pointer;
  transition: all 0.3s ease;
  position: relative;
  overflow: hidden;
}

.door.open {
  color: #306f91;
}

.door img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  position: absolute;
  top: 0;
  left: 0;
  opacity: 0;
  transition: opacity 0.3s ease;
}

.door img.closed {
  opacity: 0.1;
}

.door.open img {
  opacity: 1;
}

.locked {
  cursor: not-allowed;
}

.locked img {
  opacity: 0;
}

#currentDate {
  margin-bottom: 20px;
  font-size: clamp(1rem, 2.5vw, 1.5rem);
  font-weight: bold;
}

.symbol {
  font-size: 2em;
  line-height: 1;
}

/* Mobile Feintuning */
@media (max-width: 900px) {
  .calendar {
    grid-template-columns: repeat(3, 1fr);
    /* 3 Türen pro Reihe */
  }
}

@media (max-width: 600px) {
  .calendar {
    grid-template-columns: repeat(2, 1fr);
    /* 2 Türen pro Reihe */
    gap: 8px;
  }

  .door {
    aspect