Move plug-in down the page so it doesn't site behind the site's header

I use a third party booking system called Ovatu which I wanted to add to my Book Now page. Entered a custom code into the Advanced section of my Book Now page and it shows on my page but sits underneath my Header which means I can't access my third party booking bot. I did also try adding it directly onto the page but had no success there.

To do this, I entered this code into the Advanced CSS:

 

</body><div id="bookapp-reservation-widget"></div>

<script type="text/javascript">

!function(e,t,n){var u=n.queue||[];e.BookAppWidgetReady=n=function(e){n.queue.push(e)},n.queue=u;var o="script",a=t.createElement(o),i=t.getElementsByTagName(o)[0];a.src="https://cdn.book.app/embed/v1.js",a.type="text/javascript",a.async=!0,a.addEventListener("load",function(){for(;n.queue.length;)n.queue.shift()()},!1),i.parentNode.insertBefore(a,i)}(window,document,window.BookAppWidgetReady||function(){});

BookAppWidgetReady(function () {

BookApp.widget('#bookapp-reservation-widget', 'goldfinchbeauty');

});

</script>

 

and I would like to know how to move it down the page so it doesn't sit behind my Site Header.