Custom widget/script not showing completely

[NaomiMardaci]

Hi,

I have a script on our site to embed/add a Treatwell code to a page. 

<script src="https://widget.treatwell.be/common/venue-menu/javascript/widget-button.js?v1"></script> <script>
(function()

{ var link = document.createElement("link"); link.type = "text/css"; link.href = "https://widget.treatwell.be/common/venue-menu/css/widget-button.css"; link.rel = "stylesheet"; link.media = "screen"; document.getElementsByTagName("head")[0].appendChild(link); }
());
</script>
<div data-widget-url="https://widget.treatwell.be/salon/327883/menu/" id="wahanda-online-booking-widget-iframe"></div>

but