Just a hint/question. Refering to
https://kriesi.at/support/topic/icon-box-fixed-size/
isn´t it better to use
.iconbox_content {
min-height: 300px;
}
?,
cause it works responsive, so longer text in boxes is not getting cut of.
its a very old question, but your solution works as well.
It seems like the text does not cut off with a fix size, but the box does not expand and can cause other layout problems