Reduce top margin in Twenty Twelve

I’ve tried everything I can possibly find or think of (including Firebug, what seems like a thousand WordPress threads, and scanning the stylesheet personally) but I can’t seem to fix this issue. I’m trying to reduce the top margin of my page — the margin between my header logo and the top of the page. Nothing seems to work.

The URL is https://thestylistquo.com

and I am using a child theme.