In the tutorial on that page there is only three columns:
For which Pro version are they valid?
OK. Here is the code. I pasted it in the upper comment, though.
This page is dedicated to the latest version of Bootstrap. It should work with every version of Bootstrap since alpha-6
And what about two columns: col-md-8 and col-md-4
I'm really sorry for the late answer! Beg my pardon!
I tried to make two cards with equal heights - following the same principle, but without success. And that's my question - two cards with equal heights?
You could try this code from this link. I saved it onto Google Drive because it is really quite useful :)
Put JS in footer. In this example the class is js-equal-height. Paste this into all your elements that you want the same height.