<!DOCTYPE html>
<html lang="en-GB">
    <head>
        <title>One-Nexus</title>

        <meta charset="utf-8">
        <meta http-equiv="X-UA-Compatible">
        <meta name="viewport" content="width=device-width, initial-scale=1">

        <link href="/assets/themes/one-nexus/app.css" rel="stylesheet">
    </head>

    <body>
        <header class="header-fixed">
            <div class="header_logo-dark">...</div>
        </header>

        ...

    </body>

    <script src="/assets/themes/one-nexus/app.js"></script>
</html>