Equal Column heights in single row

I’m using three, 1/3rd column in a single row. They are displayed fine and I am styling them with a class added to the column shortcode.

The issue is the column sizes conform to the text in each column, which means if I have different amount of text in each column I will have different sized “boxes”. You can see the effect here:

https://www.practicalnetworking.net/classes/tls

How can I have all three of the boxes/columns have the same height as the largest one?

I know I can statically set a height: 100px attribute. But this means I have to manually set it every page. I need a way that is “auto-magic”. Thanks.