Added theme, reworked UI

lib/pages/stats/widgets/global_counter.dart

@@ -0,0 +1,39 @@
+import 'package:flutter/material.dart';
+import 'package:intl/intl.dart';
+
+class GlobalCounter extends StatelessWidget {
+  final double value;
+
+  const GlobalCounter({super.key, required this.value});
+
+  @override
+  Widget build(BuildContext context) {
+    return Container(
+      padding: const EdgeInsets.all(10),
+      margin: const EdgeInsets.all(20),
+      decoration: BoxDecoration(
+        borderRadius: BorderRadius.circular(15),
+        color: Theme.of(context).colorScheme.primaryContainer,
+        boxShadow: [
+          BoxShadow(
+            color: Theme.of(context).colorScheme.shadow,
+            blurRadius: 10,
+            offset: const Offset(2, 2),
+            spreadRadius: 0.1,
+            blurStyle: BlurStyle.normal,
+          )
+        ]
+      ),
+      alignment: Alignment.centerRight,
+      child: Text(
+        NumberFormat('000.00 €', 'fr_FR').format(value),
+        style: TextStyle(
+          fontFamily: 'NovaMono',
+          fontSize: 60,
+          fontWeight: FontWeight.w500,
+          color: value > 0 ? Theme.of(context).colorScheme.primary : Theme.of(context).colorScheme.error
+        ),
+      ),
+    );
+  }
+}