Equal columns height

Hi!

I would like to have equal columns sizes (height). It looks a little bit strange when we have columns with borders and they’re not equal in height.

I tried two things:
a) Additional class that wrapped the columns with height: 100%;
b) This solution: https://www.w3schools.com/howto/tryit.asp?filename=tryhow_css_equal_height

Unfortunately nothing works with Twenty Twenty One layout.

Thanks for any help!