The page named no theme-color, so the status bar iOS draws around the Dynamic Island was its own
black or white, a band across the top of every theme. The page and the admin page now carry one,
set to the page's background whenever the theme or mode changes; Android's toolbar takes it too.
Not seen on a phone yet: the browser test checks the colour matches, not what iOS does with it.
A browser test at 360px covers this and #146's row of buttons. The stub DOM gains
getComputedStyle, which every browser has.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>