multiple payout page and small fixes

frontend/pweb/lib/pages/with_footer.dart

@@ -16,20 +16,20 @@ class PageWithFooter extends StatelessWidget {
   @override
   Widget build(BuildContext context) => Scaffold(
     appBar: appBar,
-    body: LayoutBuilder(
-        builder: (context, constraints) => SingleChildScrollView(
-          child: ConstrainedBox(
-            constraints: BoxConstraints(minHeight: constraints.maxHeight),
-            child: IntrinsicHeight(
-              child: Column(
-                children: [
-                  Expanded(child: child),
-                  FooterWidget(),
-                ],
+    body: CustomScrollView(
+      slivers: [
+        SliverFillRemaining(
+          hasScrollBody: false,
+          child: Column(
+            children: [
+              Expanded(
+                child: Center(child: child),
               ),
-            ),
+              FooterWidget(),
+            ],
           ),
         ),
-      ),
+      ],
+    ),
   );
-}
+}