View file Hostbox/Hostbox-by-Brandio/WHMCS/hostbox-colourful/error/page-not-found.tpl

<div class="container">

    <div class="error-container boxed">

        <h1><i class="fa fa-warning"></i> {lang key="errorPage.404.title"}</h1>
        <h3>{lang key="errorPage.404.subtitle"}</h3>
        <p>{lang key="errorPage.404.description"}</p>

        <div class="buttons">
            <a href="{$systemurl}" class="btn btn-default">
                {lang key="errorPage.404.home"}
            </a>
            <a href="{$systemurl}submitticket.php" class="btn btn-default">
                {lang key="errorPage.404.submitTicket"}
            </a>
        </div>

    </div>

</div>