When you used this addon, and now your page is all scewed up, there can be a few things happening.
But first, let's see if we can make your page work.
As the last possebility is very unlikely we will focus on the other ones.
If the css or js selectors are incompatible this is easy to fix if you have access to the code.
You can find the selector messing things up, and rewrite it to target the element you want to control or style.
For the second. You can try running your page trough a html checkup like the w3c validator (http://validator.w3.org/).
For the third one, you can try to identify the addon that is incompatible, and contact both authors.