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Use Query

Use to adapt styling property to MediaQuery.

"".n
    ..useQuery(
        context,
        (v, query) => v..color = Colors.red
    );

n.Box()
    ..useQuery((v, query) => ..bg = Colors.blue);

This will adapt the style to Query you conditional return.

n.Box()
    ..size = [100, 100]
    ..useQuery((v, query) {
        if(query.platformBrightness == Brightness.dark)
            return v..bg = Colors.gray.shade700
        else
            return v..bg = Colors.gray.shade100
    });

Best Practice

If you want to get device theme, then use useThemeSelector instead.
If you're trying to get device screen size, then use useSize instead.
If you want to use predefined screen size, then use useScreen instead.
If you're detecting platform specific UI, then use usePlatform instead.