WIP: use viewport to allow sizes of scroll to extend further than renderable screen

examples/container.zig

@@ -31,17 +31,19 @@ pub fn main() !void {
             .separator = .{ .enabled = false },
         },
         .layout = .{
-            // .gap = 1,
-            .sizing = .{
-                .width = .{ .percent = 50 },
-                .height = .{ .percent = 50 },
-            },
+            .gap = 1,
             .padding = .all(5),
             .direction = .horizontal,
         },
     });
     try container.append(try App.Container.init(allocator, .{
         .rectangle = .{ .fill = .blue },
+        .layout = .{
+            .sizing = .{
+                .width = .{ .fixed = 70 },
+                .height = .{ .fixed = 18 },
+            },
+        },
     }));
     try container.append(try App.Container.init(allocator, .{
         .border = .{ .color = .light_blue, .corners = .squared },