body {
  font-family: sans-serif;
  background-color: #111;
  color: #eee;
  margin: 0;
  padding: 1em;
  text-align: center;
}
h1 {
  margin-bottom: 1em;
}
.galeria {
  column-count: 4;
  column-gap: 8px;
  padding: 0 12px;
}
.galeria img {
  width: 100%;
  margin-bottom: 8px;
  border-radius: 6px;
  break-inside: avoid;
  background: #222;
  transition: transform 0.2s ease;
  cursor: pointer;
}
.galeria img:hover {
  transform: scale(1.02);
}
@media (max-width: 1000px) {.galeria { column-count: 3; }}
@media (max-width: 700px) {.galeria { column-count: 2; }}
@media (max-width: 500px) {.galeria { column-count: 1; }}

.lightbox {
  position: fixed;
  top: 0; left: 0;
  width: 100%; height: 100%;
  background: rgba(0,0,0,0.9);
  display: flex;
  justify-content: center;
  align-items: center;
  z-index: 1000;
  flex-direction: column;
}
.lightbox.hidden { display: none; }
.lightbox img {
  max-width: 90%;
  max-height: 80%;
  border-radius: 10px;
}
.flechas {
  color: white;
  font-size: 3em;
  margin-top: 1em;
  cursor: pointer;
}
.cerrar {
  position: absolute;
  top: 20px;
  right: 30px;
  font-size: 3em;
  color: white;
  cursor: pointer;
}