index.html

<!DOCTYPE HTML>
<html>
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <title>Cubik</title>
    <style>
        html,
        head,
        body {
            padding: 0;
            margin: 0;
        }

        body {
            background: #010140;
        }
    </style>
</head>
<body>
    <div id="elm"></div>
    <script src="elm.js"></script>
    <script>
        // Load initial state from localStorage
        var initialState;
        try {
            initialState = JSON.parse(localStorage.getItem('elm-cubik')) || {};
        } catch (e) {
            initialState = {};
        }

        var app = Elm.Main.init({
            node: document.getElementById('elm'),
            flags: Object.assign(
                {
                    width: innerWidth,
                    height: innerHeight,
                    devicePixelRatio: devicePixelRatio
                },
                initialState || {}
            )
        });

        app.ports.save.subscribe(function (state) {
            // Save game state to localStorage
            localStorage.setItem('elm-cubik', state)
        });

        // Prevent scrolling with arrow and space keys
        window.addEventListener('keydown', function (e) {
            if ([32, 37, 38, 39, 40].indexOf(e.keyCode) > -1) {
                e.preventDefault();
            }
        }, false);

        // Capture focus
        window.focus();
    </script>
</body>
</html>