body {
  background-image: url('../images/1900.jpg');
  background-size: cover;
  background-position: center;
  background-attachment: fixed;
  color: #fff;
}

/* Boxen */
.box {
  position: relative;
  overflow: visible;
  height: 350px;
  cursor: zoom-in;
}

.box img {
  max-width: 100%;
  height: 100%;
  object-fit: contain;
  transition: transform 0.4s ease, filter 0.4s ease;
  display: block;
}

.box:hover img {
  transform: scale(1.8);
  filter: brightness(0.8);
}

.visible_heading {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  color: #fff;
  font-size: 1.5rem;
  font-weight: bold;
  opacity: 0;
  transition: opacity 0.3s ease;
  text-shadow: 0 0 10px rgba(0,0,0,0.5);
}

.box:hover .visible_heading {
  opacity: 1;
}

/* Abstand */
.g-4 {
  gap: 1.5rem;
}

/* Lightbox */
#lightbox {
  display: none;
  position: fixed;
  z-index: 1050;
  top: 0; left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0,0,0,0.9);
  justify-content: center;
  align-items: center;
}

#lightbox img {
  max-width: 90%;
  max-height: 90%;
  box-shadow: 0 0 25px #fff;
  animation: zoomIn 0.3s ease;
}

@keyframes zoomIn {
  from { transform: scale(0.5); opacity: 0; }
  to   { transform: scale(1); opacity: 1; }
}

/* Responsive */
@media (max-width: 768px) {
  .box { height: 300px; }
  .visible_heading { font-size: 1.3rem; }
}

@media (max-width: 480px) {
  .box { height: 250px; }
  .visible_heading { font-size: 1.1rem; padding: 0 10px; text-align: center; }
}