Major UI overhaul

lib/widgets/app_breakpoints.dart

@@ -0,0 +1,27 @@
+import 'package:flutter/widgets.dart';
+
+class AppBreakpoints {
+  static const double mobile = 600;
+  static const double tablet = 900;
+  static const double desktop = 1200;
+
+  static bool isMobile(BuildContext context) {
+    return MediaQuery.of(context).size.width < mobile;
+  }
+
+  static bool isTablet(BuildContext context) {
+    final width = MediaQuery.of(context).size.width;
+    return width >= mobile && width < desktop;
+  }
+
+  static bool isDesktop(BuildContext context) {
+    return MediaQuery.of(context).size.width >= desktop;
+  }
+
+  static double horizontalPadding(double width) {
+    if (width >= desktop) return 96;
+    if (width >= tablet) return 64;
+    if (width >= mobile) return 32;
+    return 16;
+  }
+}