Coursepress alters my CSS settings

Hi there, when I install and activate CoursePress, it changes the CSS settings (I think so) of the template which I am using.

Can you please guide me, how I can stop this?

The menu items become squashed and the overall page area becomes squeezed towards the left.

Before activating CoursePress:
Here is the menu item before activating CoursePress: https://www.dropbox.com/s/apiid1afni67bbx/Screenshot%202014-12-15%2020.50.53.png?dl=0
Other elements:
https://www.dropbox.com/s/dpm5js7odq3c2ur/Screenshot%202014-12-15%2021.05.40.png?dl=0

Here is what happens once I activate CoursePress: https://www.dropbox.com/s/v32lce2uqnykb82/Screenshot%202014-12-15%2020.48.30.png?dl=0
Other elements:
https://www.dropbox.com/s/bxh0z6bu4xhqa5q/Screenshot%202014-12-15%2021.04.19.png?dl=0