Improved layout, fixed transaction popup

lib/pages/transactions/transactions_page.dart

@@ -8,18 +8,19 @@ class TransactionsPage extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    return const Flex(
-      direction: Axis.horizontal,
-      children: [
-        Expanded(
-          child: Column(
+    return Center(
+      child: ConstrainedBox(
+        constraints: const BoxConstraints(
+          maxWidth: 1000 
+        ),
+        child: const Column(
           children: [
             TransactionsActions(),
             TransactionsHeader(),
             TransactionsList(),
           ],
-        ))
-      ],
+        ),
+      )
     );
   }
 }