How to Remove Unwanted Top Border?

I made some Widget adjustments to my Left Sidebar and now the main page has a large border/margin at the top — as viewed in the browser (I’m using Firefox).

One of the adjustments involved placing a print icon at the top of the page, which widened the top border. When I moved the icon to another location, the widened border remained and I have been unable to restore it to its original width. (There is no line space — which I removed — remaining in the template code.)

I don’t see anything in the Header Template or under Styles (reset-fonts-grids-tabs.css) that appears to be creating the border/margin.

Is there some element of WP code– or code phrase– that can be inserted to close the gap? (i.e., remove/delete the space)?

Thanks for helping.