Button: display + contain values lead to extra space in containing element

[daneah]

Expected behavior

• A button's rendered content touches all four walls of its real estate
• Elements around the button also behave such that those four walls are the button's edges

Actual behavior

The button itself does touch all four of its walls:

But a containing div placed around it can be observed to have extra space below:

This appears to be due to some combination of the contain: layout and display: inline-flex used for buttons.

This is observable in Storybook as well.