.gallery {
  display: flex;
  flex-wrap: wrap;
}
.gallery img {
  margin: 2.5px;
  width: calc(90vw / 2 - 5px);
  display: block;
}
@media only screen and (min-width: 600px) {
  main {
    font-size: 20px;
  }
}
@media only screen and (min-width: 1000px) {
  main {
    font-size: 24px;
  }
  .gallery img {
    width: calc(90vw / 4 - 10px);
  }
}
@media only screen and (min-width: 2000px) {
  main {
    font-size: 32px;
  }
}