Fix to allow page to expand to width of browser

Please help.

I inherited the task of editing my agency’s website from the person who designed it. I know a little about this sort of thing but nothing advanced. For instance, I do not know if the customizations done to our webpage up to this point were made with a child theme or not. IMW Custom Theme is what is shown as the active theme but it seems this is based on the 2011 theme. Is IMW then a child theme of 2011 since it is based on it? If not, all of the customizations up to this point have been made on this IMW Custom Theme… should they have been made to a child themen instead and how to correct that? Do I need to create a child theme if I want to modify further How would I do that considering all the changes that have been made to it thus far have been made in the IMW Custom theme, not a child theme. Hopelessly confused.

PLS help.

Also, I simply cannot figure out what padding needs to be removed in order to get the big chunky block of purple padding/margin on the right side of our webpage. Pls help me get rid of the right margin or padding or whatever it is. My boss wants the title, body and footer to fit the browser width, not be centered or aligned right/left.

Thanks so much

our website is:
https://www.theopendoornj.com

The CSS is:

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