For Lua code you should just rely on the
ZO_ColorDef class which handles all the tedious stuff:
Lua Code:
-- declare your color once in your initialization code
local MINT_GREEN = ZO_ColorDef:New("c8ffd2")
-- assign it to the control whenever you need it
Nyght_Status_Window_StatusBar:SetColor(MINT_GREEN:UnpackRGBA())