Texas has a new law requiring public schools to display "In God We Trust" posters if donated.

What are the specifications of an item that would be required for mandatory display? I've seen that it has to be durable poster or framed, and it has to have state and US flags, and can't have other messages, but I was hoping for a full list of rules.

Are there size limitations? Font or color rules? Does the law apply to all primary schools, or only public schools?