I have a layout where the sidebars appear only on some pages. On pages where there are no sidebars, I'd like the center column to have no padding on the right side. I was hoping to avoid having to use a css insert to specify a revised padding listing each of those pages. I hoped I could deal with it via the sidebar styling in ATO or a css insert (because without it in the center column, text runs up to the border, of course). This site is getting handed off to a client, so I'd like to have it automatically be right if he adds a page of one type or the other.

Is it possible to add some margin or padding before the border in the right sidebar? I know I can push the text right relative to the border with the padding setting in ATO sidebar settings, but can I get space on both the left and right of that border in ATO or a css insert.

The page I'm working on is this, but it might change as I'm trying things: http://amirparsa.net/literary-oeuvre

Why not add an empty right inner sidebar the width you want

You can generally add padding or margin on any element. Which border in the right sidebar are you referring to?