[allannienhuis]

I'm too lazy/busy to confirm/test this, but providing a new stacking context on the parent by either by adding a position: relative (or whatever) or adding transform: translateZ(0) (or X or Y) avoids the need to specify every parent's height. Someone less lazy than me could confirm :)

[cfj]

I'm just as lazy as you, but I just wanted to point out that you can create a new stacking context explicitly with

isolation: isolate;

[allannienhuis]

oh, great tip - thanks! That's much more explicit. The other approaches have the new stacking context as almost a side effect.