Nothing to see on phone or tablet

There is a site made in Wappler that show well on PC, but show a white screen with a few strange signs when viewes on phone or tablet.
ijsselmeercharterevent.nl

Can anyone tell me what is wrong and how I can fix this?

There’s that element:

<div class="y-loading" id="y-loading">
        <img src="assets/images/loading.gif" alt="">
    </div>

which does not get hidden on mobile. Maybe you are using a third party plugin for it, that should hide it - so check it.

Thanks for the quick response (as usual)