Images in card columns do not scale well

Created by: mrkkrp

When using card-columns with images, the images do not seem to scale well. Here I attach a complete reproducing example which you can just open in your browser and see.

bad-cards.txt

(Change extension from txt to html because GitHub wouldn't allow me to put HTML doc here.)

The example is composed as per your v4 docs, as combination of the “starter example” and the example code for the card-columns feature. For image placeholders I used https://placehold.it service.

I checked with Firefox and Chromum, and got the same results:

With every zoom value imaginable images look wrong. (Also note the ugly corner.)

Maybe I don't understand something and the images are not supposed to scale and look well?