Hi @RobertB,
I will point out a few things:
1. The error is due to line 2946 in your style.css, which is as follows:
#site-branding, #main, #content_sidebar_wrap, #content_sidebar_wrap #main, .sidebar-primary {
width: 50%;
}
This should be as follows, and this issue will go away:
#site-branding, #main, #content_sidebar_wrap, #content_sidebar_wrap #main, .sidebar-primary {
width: 100%;
}
2. You should never edit the main theme files. If you do this, all changes will be lost on updating the theme.
If you want to change the CSS, you can simply go to “Appearance=> Customize=> Theme Options=> Custom CSS” box and add in new CSS if they are a few. This will override the original CSS.
If there is a lot of CSS to be changed, it should be done via child theme. The details on child theme is here.
Let me know if things work out or not.
Regards,
Pratik