Vertically matching dashboard widget heights within a row, with Bootstrap?

I come to you today with an age-old web-design puzzle – I want to make 2 widget divs (div.card) have matching heights for purely aesthetic reasons. …The classic this doesn’t seem like it should be so hard puzzle.

Making things harder on myself, I really never touched Bootstrap until a couple weeks ago, so I am mostly fumbling around and getting by on basic css I’m better familiar with.

I actually had a stroke of brilliance just now so i think I found a solution that works for me, but still I guess I’ll post here to ask: is it to be expected that the h-100 class effectively cancels out the mb-# classes when applied on the same object? By which I mean: the margin still renders in the browser, but it slips beneath the next row/widget:

I tried way too many variations of things to try and force that to work elegantly but did ultimately kludge a solution by including an extra container div that ALSO has the h-100 class (and contains the card div) but also includes bottom-padding to force the spacing I wanted.

Anyway, if anyone has an elegant way of accomplishing this, lemme know, thanks!