Why isn’t this Hello World Splide.js code working?

Maybe I am just too tired, but the most basic Splide example isn’t working and I’ve spent hours on it. Does nayone have any insight? No errors. Nothing seems wrong, it just won’t move off the first image. It will drag a bit to show the second picture, but it won’t navigate to it. Buttons don’t work either.

  document.addEventListener( 'DOMContentLoaded', function() {
                var splide = new Splide( '.splide').mount();
            } );
<html>
    <head>         
        <meta charset="UTF-8">
        <title>Splide test</title>
        <script src="https://cdn.jsdelivr.net/npm/@splidejs/splide@latest/dist/js/splide.min.js"></script>
        <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/@splidejs/splide@latest/dist/css/splide.min.css">        
    </head>
    <body>
        <section id="splide" class="splide" aria-label="Splide Basic HTML Example">
            <div class="splide__track">
                <ul class="splide__list">
                    <li class="splide_slide">         
                        <img alt="one" src="https://zaydite.com/images/uploads/42/181/one.jpg">                    
                    </li>
                    <li class="splide_slide">
                        <img alt="two" src="https://zaydite.com/images/uploads/42/181/two.jpg">                  
                    </li>
                    <li class="splide_slide">
                        <img alt="three" src="https://zaydite.com/images/uploads/42/181/three.jpg">                        
                    </li>
                    <li class="splide_slide">      
                        <img alt="four" src="https://zaydite.com/images/uploads/42/181/four.jpg">
                    </li>
                    <li class="splide_slide">                
                        <img alt="five" src="https://zaydite.com/images/uploads/42/181/five.jpg">
                    </li>
                </ul>
            </div>
        </section>
        <script>
          
        </script>
    </body>