How to change the register/login module

Hi,

i would like to know how to change the register/login module? I would like to change its CSS style, so it will be better visible. My page is http://slorapfan.info - i mean in the top right corner where it says PRIJAVA

All custom code you can add to override.css and then enable 'Use override css' option in template settings. I advise you to use firebug to check what code you can add or modify.