Adjust Overall Form Width

I just found this plug-in and I really like it except for one thing. On any page I have a form embedded, the left sidebar on my site gets squished. I can’t find the right CSS combo to make the form a fixed width so it doesn’t affect my theme.

Here is a page with a form: https://www.w6ek.org/aboutsfarc
Here is a page without: https://www.w6ek.org/

Pay close attention to the black sidebar.

The page I need help with: [log in to see the link]