{
  box-sizing: border-box;
}

div.gallery {
  display: flex;
  flex-wrap: wrap;
  justify-content: flex-start;
}

div.gallery-item {
  margin: 5px;
  border: 1px solid #ccc;
  width: calc(25% - 20px);
}

div.gallery-item:hover {
  border: 1px solid #777;
}

div.gallery-item img {
  width: 100%;
  height: auto;
}

div.gallery-item div.desc {
  padding: 15px;
  text-align: center;
}

@media only screen and (max-width: 768px) {
  div.gallery-item {
    width: calc(50% - 20px);
  }
}

@media only screen and (max-width: 480px) {
  div.gallery-item {
    width: calc(100% - 20px);
  }
}