Unable to remove left & right borders on NSTableview in an NSScrollView

I have code that creates an NSTableView in a NSScrollView. It works but I end up with borders on the left and right side of the displayed table. The table call in ContextView has a frame but changing it does not remove the borders. I have set column widths in the makeNSView function which lets me control the width of the columns but the borders remain. Assistance would be appreciated. Below is my table code along with what gets displayed.

// in context view:
BetterTableView()
  .frame(width: 350, height: 150, alignment: .center)

// better table view and associated data
struct ClosingValue: Identifiable {
    var id: UUID
    var name: String
    var date: String
    var close: Float
    
    static var closingValues = [
        ClosingValue(id: UUID(), name: "Stock1", date: "Nov 01, 2009", close: 1.10),
        ClosingValue(id: UUID(), name: "Stock1", date: "Nov 02, 2009", close: 2.10),
        ClosingValue(id: UUID(), name: "Stock1", date: "Nov 03, 2009", close: 3.10),
        ClosingValue(id: UUID(), name: "Stock1", date: "Nov 04, 2009", close: 4.10),
        ClosingValue(id: UUID(), name: "Stock1", date: "Nov 05, 2009", close: 5.10),
        ClosingValue(id: UUID(), name: "Stock1", date: "Nov 06, 2009", close: 6.10)
    ]
}

struct BetterTableView: NSViewRepresentable {
    
    func makeCoordinator() -> Coordinator {
        Coordinator()
    }
    
    class Coordinator: NSObject, NSTableViewDelegate, NSTableViewDataSource {
        
        @State var closingValues: [ClosingValue] = ClosingValue.closingValues
        
        func numberOfRows(in tableView: NSTableView) -> Int {
            closingValues.count
        }
        
        func tableView(_ tableView: NSTableView, viewFor tableColumn: NSTableColumn?, row: Int) -> NSView? {
            
            var nsView = NSView()
            
            let paragraphStyle = NSMutableParagraphStyle()
            paragraphStyle.alignment = .center
            
            let attributes1: [NSAttributedString.Key: Any] = [
                .foregroundColor: NSColor.blue,
                .paragraphStyle: paragraphStyle,
                .font: NSFont(name: "Arial", size: 14.0) as Any
            ]
            
            var attributedString = NSAttributedString()
            let tempNSView = NSTextField()
            
            switch tableColumn {
                
            case tableView.tableColumns[0]:
                attributedString = NSAttributedString(string: closingValues[row].name, attributes: attributes1)
                
            case tableView.tableColumns[1]:
                attributedString = NSAttributedString(string: closingValues[row].date, attributes: attributes1)
                
            case tableView.tableColumns[2]:
                let closeAsString = String(format: "$%.2f", closingValues[row].close)
                attributedString = NSAttributedString(string: closeAsString, attributes: attributes1)
                
            default:
                print("problem in table view switch statement")
            }
            
            tempNSView.backgroundColor = NSColor.white
            tempNSView.isBordered = true
            tempNSView.isEditable = false
            tempNSView.attributedStringValue = attributedString
            nsView = tempNSView
            
            return nsView
        }
    } // end of coordinator class
    
    func makeNSView(context: Context) -> NSScrollView {
        
        let tableView = NSTableView()
        
        tableView.delegate = context.coordinator
        tableView.dataSource = context.coordinator
        tableView.addTableColumn(NSTableColumn())
        tableView.addTableColumn(NSTableColumn())
        tableView.addTableColumn(NSTableColumn())
        tableView.intercellSpacing = NSSize(width: 0.0, height: 0.0)
        let paragraphStyle = NSMutableParagraphStyle()
        paragraphStyle.alignment = .center
        
        let attributes: [NSAttributedString.Key: Any] = [
            .foregroundColor: NSColor.black,
            .paragraphStyle: paragraphStyle,
            .font: NSFont.systemFont(ofSize: 16)
        ]
        
        let column0AttributedString = NSAttributedString(string: "Stock", attributes: attributes)
        let column0Header = tableView.tableColumns[0]
        column0Header.headerCell.drawsBackground = true
        column0Header.headerCell.backgroundColor = NSColor.systemMint
        column0Header.headerCell.alignment = .center
        column0Header.headerCell.attributedStringValue = column0AttributedString
        column0Header.sizeToFit()
        column0Header.width = 90.0
        
        let column1AttributedString = NSAttributedString(string: "Date", attributes: attributes)
        let column1Header = tableView.tableColumns[1]
        column1Header.headerCell.drawsBackground = true
        column1Header.headerCell.backgroundColor = NSColor.systemMint
        column1Header.headerCell.alignment = .center
        column1Header.headerCell.attributedStringValue = column1AttributedString
        column1Header.sizeToFit()
        column1Header.width = 130.0
        
        let column2AttributedString = NSAttributedString(string: "Closing", attributes: attributes)
        let column2Header = tableView.tableColumns[2]
        column2Header.headerCell.drawsBackground = true
        column2Header.headerCell.backgroundColor = NSColor.systemMint
        column2Header.headerCell.alignment = .center
        column2Header.headerCell.attributedStringValue = column2AttributedString
        column2Header.sizeToFit()
        column2Header.width = 70.0
        
        let scrollView = NSScrollView()
        scrollView.documentView = tableView
        
        return scrollView
    }
    
    func updateNSView(_ nsView: NSScrollView, context: Context) {
        let tableView = (nsView.documentView as! NSTableView)
        // work on this section
    }
}

Set tableView.style = .plain. Here's the documentation.