.demonstrations { float: left; clear: both; width: 100%; margin-bottom: 18px; }
.demonstrations a {
  float: left;
  width: 250px;
  height: 300px;
  margin: 0 10px 10px 0;
  cursor: pointer;
}
.demonstrations a img { float: left; }
.demonstrations .rightmost { margin-right: 0; }