Just to point out a couple of items that do not display the same on desktop as they do on mobile.
Nav Menu hamburger icon (unstyled): Color black on desktop, blue on actual mobile.
Form widget fields (unstyled): Do not have border radius by default when placed on a page and look fine when inspecting in responsive mode (Chrome on Mac). However, when viewed on actual mobile the form fields have a border radius.
Not sure if it’s considered a bug, but it’s unexpected behaviour.