Note that scaleFactor is not used in MyButtonStyle. It can be eliminated. Looking at my actual application, the exampleView looks like the following: .buttonStyle(GameButtonStyle(labelWidth: 140 * scaleFactor, labelHeight: 20 * scaleFactor, minWidth: 70 * scaleFactor, verticalPadding: 3 * scaleFactor)) I determine the scaleFactor depending upon the size of the window on OSX or the size of the screen on IOS.

I believe NB means "Note well" That is, pay attention or important notice here. It is Latin for "nota bene"