If you want to keep columns on A4 print (which is around 540px) this is a good idea
@media print {
.make-grid(print-A4);
}
.make-print-A4-column(@columns) {
@media print {
float: left;
width: percentage((@columns / @grid-columns));
}
}
You can use it like this:
<div class="col-sm-4 col-print-A4-4">