[ALZA]

Nameplates are children of WorldFrame, not UIParent. So they're not affected by UIScale. Scaling WorldFrame or every nameplate is not an option also - it affects the position of frame. One way to "normalize" all sizes to be pixel-perfect looks like this:

local fix = 1
if(IsLoggedIn()) then -- in case we are back from /reload and not actually logging
	fix = GetCVar"UIScale"
else
	local fixframe = CreateFrame"Frame"
	fixframe:RegisterEvent"PLAYER_LOGIN"
	fixframe:SetScript("OnEvent", function()
		fix = GetCVar"UIScale"
	end)
end

So setting a size, position or offset will look like:

border:SetPoint("TOPLEFT", -1 * fix, 1 * fix)