Breakpoint(start:  0 , end: 400, name: MOBILE)

ResponsiveBreakpoint(

breakpoints: const [

Breakpoint(start: 0, end: 400, name: MOBILE),

Breakpoint (start: 401, end: 1400, name: PHONE),

],

child: child!,

),

Condition.equals(name: PHONE, value: 200, landscapeValue: 400)

Condition.betweeen(start: 400, end: 800, value: 300)

width: ResponsiveValue<double>(context, conditionalValues: 

[

Condition.equals(name:MOBILE, value: 400), 

Condition.equals(name:PHONE, value: 200)

]).value

ResponsiveScaledBox(

width: 100,

child: child

)

MaxWidthBox(

maxWidth: 1300,

child: child);

return MaterialApp(

 builder: (context, child) => ResponsiveBreakpoints(

   breakpoints: const [

     // Ширина от 0 до 400 для планшета с низким разрешением

     Breakpoint(start: 0, end: 400, name: MOBILE),

     // Ширина от 401 до 1400 для телефона

     Breakpoint(start: 401, end: 1400, name: TABLET),

   ],

   child: child!,

 ),

    …

);

return ResponsiveScaledBox(

 width: 1200,

 child: Scaffold(

   …

);

return ResponsiveScaledBox(

 width: ResponsiveValue<double>(context, conditionalValues: [

    // Для планшета

   Condition.equals(name: MOBILE, value: 400),

    // Для телефона

   Condition.equals(name: TABLET, value: 1200),

 ]).value,

 child: Scaffold(

…

);