Hi,
I'm experiencing the same issue. Within iOS Safari (itself) it works as expected, but after installing/adding to homescreen it does not switch light/dark mode automatically (as mentioned you need to close/open the web-app for updated styling). I can confirm it does work on macOS (after installing the web-app to the Dock and in Safari itself).
Snippet from my css:
:root {
color-scheme: light dark;
--theme-background-color: rgb(225, 225, 225);
}
@media (prefers-color-scheme: dark) {
:root {
--theme-background-color: rgb(56, 55, 54);
}
}
Kind regards,
Rob