Pedalkraft on "Jetpack contact form not displaying properly"

Hi,

The Jetpack contact form, which I consistently use on sites without issue, is not displaying correctly in Safari (though works fine in Chrome) on a site I'm currently building.

All that's happening is, the boxes for name and email are displaying as tiny squares rather than longer boxes:
Screenshot

I've disabled the JP shortcodes as suggested in a different thread but this hasn't solved it.

Any suggestions? Never had this issue before, am a bit stumped!

Thanks :)

Beth