Plugin breaks Theme CSS

Hi man,

Im having some big difficulties, i was looking for plugin that will do all the things i want and i found it, its this one, and everything is perfect except one thing. The plugin breaks some css classes or whatever, causing buttons to have greenish look and background. I am develeoping my theme and i need to publish it in next few days so i would be glad for a quick answer.
Image: http://i57.tinypic.com/t9zfvp.jpg

https://wordpress.org/plugins/users-ultra/