theme css conflicting with Modal login css

hi, great plugin works really well.

However it seems that the css for the login box is being affected by some off the css from my theme.

Mainly the login/submit button when the login box is shown.

I have tried editing the css but to no avail.

The website is: http://mlm.dev-pixel-fx.co.uk/
Login link top left.

Regards
Chris H

http://ww.wp.xz.cn/plugins/wp-modal-login/