CSS Change for mobile device (extending registration page fields)

Hi
I need some help resolving this issue on the "registration" page. Currently when the page is smaller or when viewing on mobile devices the fields become too small. can they all be increased in width so that they tough the blue lines in the screenshot ? also the captcha code is currently cut off the screen on the left. can it be moved and aligned to the center of the page?

Please see Screenshot: http://monosnap.com/image/oJgBynMDZMcvy75akqBQfWgopqxcv5

Domain Link: http://tinyurl.com/pd2xs5o

Support access also open

Thanks
Tom