Content disappearing and buttons changing colour

Hi there,

I’m having issues with a site I’m working on for a friend. All seems fine when I publish and check on my devices, but when she opens it in Safari on her iPhone 13 Pro, the Voiceovers button on the homepage changes to blue and all the content on the Writing page disappears - apart from the button which moves to the top corner and, again, turns blue.

Would be very grateful for some advice if anyone can help me troubleshoot?

Thanks so much

Here is my site Read-Only:
(how to share your site Read-Only link)

Can you publish it & share that link as well?