css for submit button in simplemodal-login

i’m trying to figure out how to change the look of the submit button for simplemodal-login. it seems almost grayed out in both the default and the osx.

i can find and change everything for the cancel button but the login (and the register) css must be somewhere else. does anybody know where to find it??

thanks

http://ww.wp.xz.cn/extend/plugins/simplemodal-login/