     override func viewDidLoad() {
         super.viewDidLoad()
         
-        //add highlight view
+        //add highlight and overlay views (highlight above)
+        self.view.addSubview(overlayView)
         self.view.addSubview(highlightView)
         
         //observe position

    
    let highlight: Highlight
    let highlightView: HighlightView
    
    required init(highlight: Highlight) {
        self.highlightView = HighlightView()
        self.highlight = highlight
        
        super.init(nibName: nil, bundle: nil)
    }

        
        //update on layout
        syncHighlight()
        
        //update overlay view based on highlight position
        overlayView.layer.borderColor = UIColor.orange.cgColor
        overlayView.layer.borderWidth = 2
        
        switch self.traitCollection.horizontalSizeClass {
        case .compact:
            overlayView.frame = self.view.bounds
        case .regular:
            //check if highlight view is to left or right of screen
            if highlightView.frame.midX > self.view.bounds.midX {
                overlayView.frame = CGRect(x: 0, y: 0, width: highlightView.frame.minX, height: self.view.bounds.height)
            } else {
                overlayView.frame = CGRect(x: highlightView.frame.maxX, y: 0, width: self.view.bounds.width - highlightView.frame.maxX, height: self.view.bounds.height)
            }
        case.unspecified:
            overlayView.frame = .zero
        }
        
    }
}
