Designers have agreed on one box-shadow to rule them (dialog, dropdown menu, toolbar dropdown) all (ok, toolbar itself is excluded as it would get too prominent): `box-shadow: 0 2px 2px 0 rgba( 0, 0, 0, 0.25 ). This is resembled in M101 and related to T119462.

It solves the following issue and improves identifiability of those elements a bit by setting a slightly higher contrast: