Regular applications on Mac, Windows, and some Linux distributions can change their colors and appearance when you turn on the system dark mode, but websites and web apps don’t have access to all the same options. They can’t specify a different title bar color for dark mode (except just black), or a different background color for the splash screen when you first open the web app. If the app has a bright splash screen, it can be more blinding in dark mode.
Thankfully, the development team for Chrome is now working on enhanced dark mode support for web apps. The current proposal will allow web apps to choose any color they want for the title bar and splash screen backgrounds, in both light and dark mode, with more settings possibly coming later. The web apps still have to specify the colors, so it won’t immediately fix the blinding problem when it arrives, but it’s a quick fix for anyone hosting a web app.
The feature can be enabled in some versions of Chrome with the feature flag #enable-experimental-web-platform-features, but since it also requires the web apps to define the colors, it won’t make much of a difference right now. Google also says the option won’t be supported on Android phones or tablets. Chrome on iPhone and iPad doesn’t support installing web apps in the first place, due to Apple’s limitations on third-party web browsers.