Changing button style weird result

Hello,
I’m trying to change the button style according to the Tiny Forge docs.
But I”m getting a weird result on mouse over.
First the button was of type <input> and the btn class didn’t work.
So I changed the button to be of type <button> and now the mouse over color is weird.
I notice that the examples in the docs refer to buttons that are <link>s but I need a submit button.

Please look at the behavior of “Sign me up!” button in my website:
http://www.vibrantdad.com/

Thanks in advance for the help!