.contenedor {
  margin-top: 100px;
  margin-bottom: 40px;
  display: grid;
  grid-template-columns: repeat(2, 600px);
  grid-template-rows: repeat(3, auto);
  gap: 5px;
  justify-content: center;
  align-items: center;
}
.galeria {
  object-fit: cover;
  height: 350px;
  width: 600px;
  background-color: gray;
}
.galeria:hover {
  filter: grayscale(100%);
}
main a {
  height: 350px;
  width: 600px;
}
@media screen and (max-width: 900px) {
  .contenedor {
    grid-template-columns: repeat(1, 400px);
    grid-template-rows: repeat(5, auto);
    gap: 5px;
  }
  .galeria {
    height: 230px;
    width: 400px;
  }
  main a {
    height: 230px;
    width: 400px;
  }
}

@media (min-width: 900px) and (max-width: 1198px) {
  .contenedor {
    grid-template-columns: repeat(2, 400px);
    grid-template-rows: repeat(3, auto);
    gap: 5px;
  }
  main a {
    height: 230px;
    width: 400px;
  }
  .galeria {
    height: 230px;
    width: 400px;
  }
}