How do i make this BillboardGUI disapear,or get smaller, at a certain distance?

I make a script that does damage and shows you the damage done with a BillboardGUI but when i get further away from the BillboardGUI it starts to get bigger and bigger. How do i make the Billboard disappear at a certain distance, or slowly get smaller? Here is the script

light.Touched:connect(function(hit)
	
	if not db then return end
db = false
	local opponent = hit.Parent:findFirstChild("Humanoid") or hit.Parent.Parent:findFirstChild("Humanoid")
if opponent and opponent ~= player.Character.Humanoid then
	local effect = Instance.new("BillboardGui", opponent.Parent.Head)
	effect.Size = UDim2.new(0,200,0,200)
wait()
local distance = 5
	local text = Instance.new("TextBox")
	text.Parent = effect
	text.Text = tool.Animation.Script.Damage.Value
	text.TextSize = 60
	text.TextColor3 = Color3.new(255,0,0)
	text.TextStrokeColor3 = Color3.new(170,0,0)
	text.Font = "Cartoon"
	text.BackgroundTransparency = 1
	text.Size = UDim2.new(0,200,0,50)
	distance = 20


	
		opponent:TakeDamage(tool.Animation.Script.Damage.Value)

wait(0.4)
db = true




end
end)

If you use Scale instead of Offset to size both your BillboardGui and the Textbox, it will not get any bigger as you walk away.

UDim2 syntax: { xScale, xOffset }, { yScale, yOffset }

In your case, this would look something like:

--For the BillboardGui
effect.Size = UDim2.new(.2,0,.2,0)

--For the TextBox
text.Size = UDim2.new(.2,0,.05,0)