.row {
  display: -ms-flexbox; /* IE 10 */
  display: flex;
  -ms-flex-wrap: wrap; /* IE 10 */
  flex-wrap: wrap;
  padding: 0 4px;
}

/* Create two equal columns that sits next to each other */
.column {
  -ms-flex: 50%; /* IE 10 */
  flex: 25%;
  padding: 0 4px;
}

.column img {
  margin-top: 8px;
  vertical-align: middle;
  width: 100%;
}

/* Style the buttons */
.btn {
  border: none;
  outline: none;
  padding: 10px 16px;
  background-color: #f1f1f1;
  cursor: pointer;
  font-size: 18px;
}

.btn:hover {
  background-color: #ddd;
}

.btn.active {
  background-color: #666;
  color: white;
}

@media screen and (max-width: 1000px) {
  .column {
    -ms-flex: 50%; /* IE 10 */
    flex: 50%;
    max-width: 50%;
  }
}

@media screen and (max-width: 600px) {
  .column {
    -ms-flex: 100%; /* IE 10 */
    flex: 100%;
    max-width: 100%;
  }
}