Match the start and main game frames

The white border on the start was wider, which was jarring.

project/ui/start_scene.tscn

@@ -1,14 +1,19 @@
-[gd_scene load_steps=10 format=3 uid="uid://d2m2pbepn6rip"]
+[gd_scene load_steps=11 format=3 uid="uid://d2m2pbepn6rip"]
 
 [ext_resource type="Theme" uid="uid://bqnq26iud8rn3" path="res://common/theme.tres" id="1_gluso"]
 [ext_resource type="Script" path="res://ui/start_scene.gd" id="2_27iv5"]
-[ext_resource type="StyleBox" path="res://ui/blue_style_box.tres" id="3_yrlow"]
-[ext_resource type="StyleBox" path="res://ui/white_rounded_style_box.tres" id="4_esrti"]
+[ext_resource type="StyleBox" uid="uid://0lv825v0nskc" path="res://ui/blue_style_box.tres" id="3_yrlow"]
+[ext_resource type="StyleBox" uid="uid://dlbigrenfpyvm" path="res://ui/white_rounded_style_box.tres" id="4_esrti"]
 [ext_resource type="PackedScene" uid="uid://dkyrbpxgqqngv" path="res://ui/settings_button.tscn" id="5_2onti"]
 [ext_resource type="PackedScene" uid="uid://dcuhgkvouhkiq" path="res://ui/cast_carousel.tscn" id="5_rvet4"]
 [ext_resource type="PackedScene" uid="uid://b8q1tdpaxtldy" path="res://ui/audible_button.tscn" id="5_sj70n"]
 [ext_resource type="FontFile" uid="uid://c57ulb1d8v5ug" path="res://common/Rounds Black.otf" id="7_v2dbv"]
 
+[sub_resource type="StyleBoxFlat" id="StyleBoxFlat_r2s8j"]
+bg_color = Color(0.133333, 0.305882, 0.65098, 1)
+corner_radius_bottom_right = 30
+corner_radius_bottom_left = 30
+
 [sub_resource type="LabelSettings" id="LabelSettings_nx01s"]
 font = ExtResource("7_v2dbv")
 font_size = 56
@@ -56,14 +61,10 @@ layout_mode = 2
 [node name="MarginContainer" type="MarginContainer" parent="BlueBackground/MarginContainer/WhiteBackground/VBoxContainer"]
 layout_mode = 2
 size_flags_vertical = 3
-theme_override_constants/margin_left = 10
-theme_override_constants/margin_top = 10
-theme_override_constants/margin_right = 10
-theme_override_constants/margin_bottom = 10
 
 [node name="MainPanel" type="PanelContainer" parent="BlueBackground/MarginContainer/WhiteBackground/VBoxContainer/MarginContainer"]
 layout_mode = 2
-theme_override_styles/panel = ExtResource("3_yrlow")
+theme_override_styles/panel = SubResource("StyleBoxFlat_r2s8j")
 
 [node name="VBoxContainer" type="VBoxContainer" parent="BlueBackground/MarginContainer/WhiteBackground/VBoxContainer/MarginContainer/MainPanel"]
 layout_mode = 2
@@ -77,7 +78,7 @@ stretch = true
 [node name="SubViewport" type="SubViewport" parent="BlueBackground/MarginContainer/WhiteBackground/VBoxContainer/MarginContainer/MainPanel/VBoxContainer/SubViewportContainer"]
 transparent_bg = true
 handle_input_locally = false
-size = Vector2i(660, 720)
+size = Vector2i(680, 720)
 render_target_update_mode = 4
 
 [node name="ParallaxBackground" parent="BlueBackground/MarginContainer/WhiteBackground/VBoxContainer/MarginContainer/MainPanel/VBoxContainer/SubViewportContainer/SubViewport" instance=ExtResource("5_rvet4")]