Bug: Button alignment on modal in Safari

In Safari: when switching a package's holding status to off, a modal pops up asking to confirm. The buttons in the modal footer are misaligned.

Cannot reproduce on Chrome.

Example: https://folio.frontside.io/eholdings/packages/127-1387569?searchType=packages&q=science

Likely diagnosis: the selector from https://github.com/folio-org/stripes-components/blob/master/lib/Button/Button.css#L241 is applying in Safari, but not in Chrome.