With following example I have got a very bad visual experience with combination of WebView and BorderPane. Please see attached screen shot. It looks like Left and Top slots obscure opposite part of WebView.

Here is a source code of the example:

package browserissue;

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.layout.BorderPane;
import javafx.scene.web.WebEngine;
import javafx.scene.web.WebView;
import javafx.stage.Stage;

public class BrowserIssue extends Application {

    public static void main(String[] args) {
        Application.launch(BrowserIssue.class, args);
    }
    
    @Override
    public void start(Stage primaryStage) {
        primaryStage.setTitle("Hello World");
        BorderPane root = new BorderPane();
        Scene scene = new Scene(root);
        
        root.setTop(new Label("Top"));
        root.setLeft(new Label("This is Left slot..."));
        
        root.setCenter(new WebView(new WebEngine("http://javafx.com")));
        
        primaryStage.setScene(scene);
        primaryStage.setVisible(true);
    }
}