.content {
  max-width: 500px;
  margin: center;
      margin-left: auto;
  margin-right: auto;
  width: 50%;
}
.row {
  display: flex;
  flex-wrap: wrap;
  padding: 0 4px;
      margin-left: auto;
  margin-right: auto;
  width: 97%;
}

/* Create four equal columns that sits next to each other */
.column {
  flex: 25%;
  max-width: 50%;
  padding: 0 4px;
}

.column img {
  margin-top: 8px;
  vertical-align: middle;
  width: 100%;
}
img {
  max-width: 100%;
  height: auto;
}
.center {
  display: block;
  margin-left: auto;
  margin-right: auto;
  width: 50%;
}