How do you make a GUI which changes colour?

Hi,

I've been trying to make a GUI which can change colours. It doesn't seem to work, despite changing the repeat loop to a while true loop. This is what I have got so far:

box = script.Parent
while true do
     for i = 1,0,1/255 do
      box.TextColor3 = Color3.new(i,i,i)
      wait()
     end
 wait ()
end