How to customize GuiNavigation layout of GuiService?

Well, I don’t really know what that’s called, but basically it’s what you select buttons on controls with.

Well, I don’t like the normal appearance of this one, since I don’t like the border and neither do I like its color. So I want to change the color of this, and if possible, round the edges.

I think you need to code it without a base, but to disable the default gui system is:

local guiService = game:GetService("GuiService")
guiService.AutoSelectGuiEnabled = false

and when you do, you can get when the controller buttons are pressed and do whatever you want like here:

local UserInputService = game:GetService("UserInputService")

UserInputService.InputBegan:Connect(function(input)
	if input.UserInputType == Enum.UserInputType.Gamepad1 then
		if input.KeyCode == Enum.KeyCode.ButtonA then
			print("Button A has been pressed. Click the button.")
		end
	end
end)

i hope it can help you!