I believe this question is quite similar to What are the best practices for tooltips on mobile websites?, but this question is more specific (only focus on form fields) and to go deeper in how to show the same information in desktop and mobile version.
I'm thinking of a solution similar to this jQuery example:
But this solution doesn't fit into mobile devices. And probably this is not a good solution for desktop version.
So my first question is: Is this a good way to show extra information on form fields?
If so, what is the best way to make it compatible with mobile devices?
Thanks a lot!