<div class="main-container">
        <header class="header header-6">
            ...
        </header>
        <nav class="subnav">
            ...
        </nav>
        <div class="content-container">
            <div class="content-area">
                ...
            </div>
            <nav class="sidenav">
                ...
            </nav>
        </div>
    </div>