Bug with theme my login, It might be a conflict with the theme

Hello,

I’m creating a website, with other people. I’m in charge to create the login page, disconnection, register….

We already have a theme, and pages already exist and are finished. In order to simplify the process I downloaded the plugin theme my login, it’s working really well, it is very usefull, but since I added the plugin, all the other page of the websites

has change, and it put everything in black boxes and deformed elements in page.

Here you can see some screenshots, of my plugin interface and then of my bugged sites.

Thanks for helping me.