<div id="menu_div">
    <p style="text-align: center;">
        <button id="menu" style="width: 100%;height: 50px; text-align: center;"class="btn btn-primary" type="button" data-toggle="collapse" data-target="#collapseExample" aria-expanded="false" aria-controls="collapseExample">
        </button>
    </p>
</div>
<div>
    <button class="btn btn-secondary rounded-circle" id='top' onclick="window.location.hash='#page_top';window.location.hash = '';"></button>
</div>
