.kolom {
  display: block;
  max-width: 30%;
  float: left;
  margin-right: 1%;
  /*border: 3px solid red;*/
}
.producttitel {
  text-align: center;
  /*border: 3px solid green;*/
}
.prijs {
  text-align: center;
  /*border: 3px solid yellow;*/
}