[paulodeon]

We recently launched dark mode for our email building app Milliner https://www.milliner.app/.

It allows you to build dark mode optimized email, and when you preview the email in dark mode, the whole app changes to dark mode.

Because of this we use a manual toggle instead of prefers-color-scheme.

We picked the colors carefully and changed things like shadows borders etc to make the interface look great in dark mode. Although a solution like OPs could be a quick and dirty way to get a basic dark mode implemented, you'll never get your site or app looking quite as good as getting a designer to look at it.