.col_600 img {
  max-height: 400px;
}

@media screen and (max-width: 1024px)
{
  .col_400 img {
    max-height: 300px;
  }

}

@media screen and (max-width: 665px)
{
  .col_400 img {
    max-height: 200px;
  }
}