How do you say your very welcome in spanish?

Estás muy bienvenido. (As in, "you're very welcome at my house.")

or

No fue nada. (As in, "Thank you." "You're very welcome.")

There are other, more common, options, such as "de nada" or "por nada", but none of them are stronger than "you're welcome". "No fue nada" isn't really, either, but it's about as close as it gets.