* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
/* Three image containers (use 25% for four, and 50% for two, etc) */
.column {
  margin: 20px;
  float: left;
  width: 30%;
  padding: 5px;
}
.column img{
  width: 25%;
}
/* Clear floats after image containers */
.row::after {
  content: "";
  clear: both;
  display: table;
}
.dropdown{
  position: relative;
  display: inline-block;
}
.dropdown button {
      padding: 10px 20px;
      cursor: pointer;
    }
.dropdown-link {
      display: none;
      position: absolute;
      background: #f1f1f1;
      min-width: 160px;
      box-shadow: 0px 8px 16px rgba(0,0,0,0.2);
      z-index: 1;
    }
.dropdown-link a {
      display: block;
      padding: 10px;
      text-decoration: none;
    }

    .dropdown-link a:hover {
      background: #ddd;
    }

    .dropdown:hover .dropdown-link {
      display: block;
    }
@media screen and(max-width:720px){
  .column{
    width: 100%;
  }
}