moving plugin code to external file

Hi:
Built our first site in WP; designed our own theme. Still learning! Question: we used a plugin called Post Tabs by Leo Germani to add some tabs within some of the site pages. The plugin has a bunch of css code that is now appearing in the source code on every page. Can I move that css code to my style sheet somehow? I can’t quite see how I would do that, but I’d like to not have all that code loading on every page.

Site is live at: https://www.thdesigninc.com

Thanks!