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

* {
  box-sizing: border-box;
}

.responsive {
  padding: 0 10px 20px 10px;
  float: left;
  width: 24.9999%;
}

.responsive2 {
  padding: 0 10px 20px 10px;
  float: left;
  width: 40%;
}

.responsive3 {
  padding: 0 10px 20px 10px;
  float: left;
  width: 33%;
}

.clearfix:after {
  content: "";
  display: table;
  clear: both;
}