White background shows in Safari on iPhone when pulling page down (Wix Studio)

Hi. I have a Wix Studio site with a solid black footer and page sections.
Everything looks fine during normal scrolling.
But when slightly pulling the page down in Safari on iPhone,
a white background appears under the footer.

On other websites this background appears transparent
and blends with the site design.

Question:
Is it possible to change the page background color
for the pull-to-refresh behavior in iOS Safari,
so that it matches the site design?
Or is this an iOS system limitation?

Thanks.

  1. Apply Custom CSS Styling

  2. About CSS Styling

Using this method, you can change the white to any colour of your choice: