Scrollbar Style 
This package detects the preferred scroller style for Atom on OS X using the
+preferredScrollerStyle method on NSScroller. For
compatibility, this library always returns "legacy" on Windows and Linux.
const scrollbarStyle = require('scrollbar-style')
const style = scrollbarStyle.getPreferredScrollbarStyle()
console.log(style) // ==> 'legacy' or 'overlay'
scrollbarStyle.onDidChangePreferredScrollbarStyle((newStyle) => {
console.log('style changed', newStyle)
})