Change width of sidebar

I am very new to wordpress and am trying to maintain my company’s website. I am using the InFocus theme and would like to decrease the width of my sidebar in hopes that a map plug-in that I added will be completely visible (the pop-up windows on the right side are currently cut off).

The page I am specifically trying to change is https://www.brazosurethane.com/contactus.

I’ve looked through some other posts, and have looked on the style sheet for the current widths of the sidebar, but I don’t see any listed. Any help you can offer would be greatly appreciated!