     Array.from(document.querySelectorAll('#sidebar a')).forEach(function(link) {
                        link.setAttribute('tabIndex', sidebar === 'visible' ? 0 : -1);
                    });
                </script>

                <div id="content" class="content">
                    <main>
                        <div class="content-wrap">
                            <h1 id="chapter-1"><a class="header" href="#chapter-1">Chapter 1</a></h1>
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