Empty space on the left

I want to embed the blog into a larger html document, but that pesky empty space on the left makes it look ridiculous. When you squeeze the browser window or iframe horizontally, the blank space on the left gradually disappears but at the expense of the sidebar on the right, which is of course unacceptable. I’ve tried tweaking the margin and align items to no avail. I’m using the Connections theme: which line item(s) causes that blank space to appear?