Fit4America on "[Plugin: s2Member Framework (Member Roles, Capabilities, Membership, PayPal Members)] How do I make the S2Member Login Page Responsive?"

I am using the Free S2member on my site http://www.Fit4America.com and have found that nearly all my users login with their iphones. However the the "Member's Login" is unresponsive on their phones and "floats" all around. How can I correct this? Thanks in advance for your help.

http://wordpress.org/plugins/s2member/