Need Help: White box in left-sidebar not showing

Hello, I am very much a beginner and I know this might be an extremely simplistic question, but I would really appreciate any help/info.

I've installed the Acquia Marina theme (along w/ fusion). everything seems to be working, except for the sidebar-first (left-hand sidebar) - the white box that sits behind the text and the green title header isn't showing up and the icon doesn't sit properly - i.e. the bottom of the star overlaps with the first menu item.

I've tried to fix it through the "navigation block" settings, and deleted and reinstalled the theme files, but nothing has worked.

Thank you so much for any help you can offer.