Varying browser results

I have a very simple 3 column Google Sheet displayed using IGSV. Viewing the page in Chrome, the table displays all 3 columns correctly, but in Firefox and IE it initially shows all 3 columns, then the display changes to 2 columns, requiring a click of a + button to show the 3rd column. I’m guessing that this is simply a factor of differing browser standards, and can’t be fixed via the IGSV shortcode.

The page I need help with: [log in to see the link]