My signup /registration button is overlapping the form on mobile

I need help with the css so on mobile the signup page button is not overlapping the form please. It looks fine on desktop but on mobile it sits on top of part of the sign up form and should be moved beneath it.
This is what I have now:

#buddypress .standard-form#signup_form div.submit {
    position: relative;
    top: -210px;
    right: 50px;
}
#buddypress .standard-form div.submit input {
    margin-right: 0px !important;
    padding: 10px 30px !important;
    font-size: 28px;
}

The page is http://solutionsfor.us/register/

Thanks
Joe