Thanks @alcampopiano, that helped. In principle I got it working, but when I copied over the two buttons from the App you referenced (just a copy & paste in the IDE), the icons got smaller and when running the App in Chrome, the two buttons where replaced with “…”. In Firefox all worked well. Any idea why that could be?
And btw, is there a trick to place these two buttons directly above each other? When I copy them over, they are exactly stacked. But when I start moving them around I never get them back to their original position (on top of each other).
Any hint is kindly appreciated!