Collecting here a list of design tweaks from WordPress/gutenberg#20718

• Can we add ~12px of padding at the top of the page content? I believe we are applying additional padding on top of the post/page title in the editor, so this would align with that (example: https://cloudup.com/cbMvzmdHb6a)
• The App Bar seems a bit too tall compared to the native one (~9 or 10px too tall). Can we shorten it up slightly to align more with the native one? I believe 56px tall should work across platforms (example: https://cloudup.com/c-hVuBGgeVv)
• [iOS] Dark Mode: border-bottom on the navigation bar is a bit too strong. We can probably dim it down a bit?
• [iOS] Dark Mode: I wonder if we should apply a dark gray bg on the Navigation Bar to match the native one.
• Can we apply a 300ms fadeOut to the inline picker buttons when they disappear?

it's not anything critical, but it may be a nice little improvement if it doesn't require a bunch of work