Basic budget sliders

lib/pages/transactions/widgets/transactions_header.dart

@@ -57,8 +57,12 @@ class TransactionsHeader extends StatelessWidget {
     return Container(
       padding: const EdgeInsets.symmetric(vertical: 9, horizontal: 10),
       margin: const EdgeInsets.symmetric(vertical: 2, horizontal: 10),
-      decoration: const BoxDecoration(
-        border: Border(bottom: BorderSide(color: Colors.black))
+      decoration: BoxDecoration(
+        border: Border(
+          bottom: BorderSide(
+            color: Theme.of(context).colorScheme.onPrimaryContainer
+          )
+        )
       ),
       child: Row(
         mainAxisAlignment: MainAxisAlignment.spaceBetween,