diff --git a/isometric-park-fna/UI/ContractWindow.cs b/isometric-park-fna/UI/ContractWindow.cs
--- a/isometric-park-fna/UI/ContractWindow.cs
+++ b/isometric-park-fna/UI/ContractWindow.cs
@@ -21,6 +21,8 @@
         private static ImageMap map;
         private static IntPtr _imGuiTexture;
 
+        private static bool show = false;
+
         public static void LoadContent(ImGuiRenderer _imGuiRenderer, ImageMap map)
         {
 
@@ -86,6 +88,16 @@
                 if (delta_trees != null)
                 {
                     ImGui.Text("Sustainability: ");
+                    ImGui.SameLine();
+                    ImGui.TextDisabled("(?)");
+                    if (ImGui.IsItemHovered())
+                    {
+                        var rect = ImGui.GetItemRectMax();
+                        ImGui.SetNextWindowPos(rect + new Num.Vector2(15, 0));
+                        ImGui.BeginTooltip();
+                        ImGui.Text("Are logged trees replaced?");
+                        ImGui.EndTooltip();
+                    }
 
 
                     ImGui.SameLine();
diff --git a/isometric-park-fna/UI/StyleSet.cs b/isometric-park-fna/UI/StyleSet.cs
--- a/isometric-park-fna/UI/StyleSet.cs
+++ b/isometric-park-fna/UI/StyleSet.cs
@@ -11,6 +11,7 @@
         public static Num.Vector4 grey = new Num.Vector4(0.75f, 0.75f, 0.75f, 1f);
         public static Num.Vector4 darkgrey = new Num.Vector4(0.45f, 0.45f, 0.45f, 1f);
         public static Num.Vector4 black = new Num.Vector4(0f, 0f, 0f, 1f);
+        public static Num.Vector4 white = new Num.Vector4(1f, 1f, 1f, 1f);
         public static Num.Vector4 title_bar = new Num.Vector4(0.65f, 0.65f, 0.65f, 1f);
         public static Dictionary<ImGuiStyleVar, float> defaultWindowVars = new Dictionary<ImGuiStyleVar, float>{
             { ImGuiStyleVar.FrameRounding, 0.0f },
@@ -36,6 +37,8 @@
                 {ImGuiCol.Border, black},
                 {ImGuiCol.BorderShadow, black},
 
+                {ImGuiCol.PopupBg, white},
+
                 {ImGuiCol.Button, grey},
                 {ImGuiCol.Text, black}
         };