If you want to detect it from JS, you can use this code:
```js
if (window.matchMedia && window.matchMedia('(prefers-color-scheme: dark)').matches) {
// dark mode
}
```
To watch for changes:
```js
window.matchMedia('(prefers-color-scheme: dark)').addEventListener('change', e => {
const newColorScheme = e.matches ? "dark" : "light";
});
```
https://stackoverflow.com/a/57795518/9731176
If implemented, allow the user to force browser theme preference over https://github.com/singlelink-co/Singlelink/issues/231#issue-1144804185.