.column {
  float: left;
  padding: 10px;
  height: 300px; /* Should be removed. Only for demonstration */
}

.left, .right {
  width: 23%;
}

.middle {
  width: 42%;
}

/* Clear floats after the columns */
.row:after {
  content: "";
  display: table;
  clear: both;
}