My nav code in Bootstrap doesn't works oke CSS : The code at the and of this message I use in WebStorm. Have you any idea what i doing wrong? Maybe some CDN errors or incorrect in the code?

    <!DOCTYPE html>
    <html lang="en">
    <head>
        <meta charset="UTF-8">
        <meta name="viewport" content="width=device-width, initial-scale=1">
        <title>DateLab</title>
        <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta/css/bootstrap.min.css">
        <script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta/js/bootstrap.min.js"></script>
        <script src="https://code.jquery.com/jquery-3.2.1.slim.min.js"></script>
        <script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.11.0/umd/popper.min.js"></script>
    </head>
    <body>
        <nav class="navbar navbar-inverse">
            <div class="container-fluid">
    
                <div class="navbar-header">
                    <a class="navbar-brand" href="#">DateLab</a>
                </div>
                <div>
                    <ul class="navbar navbar-nav">
                        <li class="active"><a href="#">Home</a></li>
                        <li><a href="#">Hoe werkt het</a></li>
                        <li><a href="#">Wie zijn wij</a></li>
                        <li><a href="#">FAQ</a></li>
                        <li><a href="#">Contact</a></li>
                    </ul>
                </div>
            </div>
        </nav>
    </body>
    </html>


Output:
[output of the code][1]


  [1]: https://i.stack.imgur.com/S7ZYl.png
