Ya, I actually did try that and the scrollbars were still there. I was just looking around and stumbled on this bug report for Alex G’s SyntaxHighlighter
https://bitbucket.org/alexg/syntaxhighlighter/issue/177/superfluous-vertical-scrollbars-in-chrome
People in the comments suggested changing to 1.2.
I tried on latest Safari & Chrome for Windows, Linux (no Safari), and Mac and 1.2 works.