Firefox 60.2.0esr on Windows 10 Pro version 1803 on Parallels version 14.0.0 (45124), macOS 10.13.6 (17G65), MacBook Pro (13-inch, Late 2011) does not show e.g. zoom plus and minus controls. The control area appears all white e.g. in the following example but zooming by pressing the place where the plus and minus should appear works. https://github.com/openlayers/openlayers/issues/8606
https://openlayers.org/en/latest/examples/static-image.html
https://openlayers.org/en/latest/examples/static-image.html