When I found the texture of the game entry main menu, I had got an idea to replace it with a new background. After I ran game and tested it, I liked the new background very much.
May conflict with mods that affect the game entry main menu.
Source is ATLAS_GameEntryMainMenu_00, in DeltaBuild0.package.
Now in Gray UI!
Light Background for Game Entry Main Menu 1.0
Make your game entry main menu's background newer.