JSN Meetup "ADDITIONAL DATES" unusable due to inconsistent tab styles

I have been unable to use the "ADDITIONAL DATES" tab in an event submission page on the front end my site which is using your recommended JSN Meetup template. Links which bring up the "Add/Edit Event" page contain "BASIC INFORMATION" and "ADDITIONAL DATES" tabs. Data on the "BASIC INFORMATION" page looks OK while the information on the "ADDITIONAL DATES" tab is spread across the screen and well beyond its position. I cannot find where to edit and restyle this tab and I don't understand why it doesn't respond to styling the page in general since both tabs are accessed with the same menu link. Also event submission seems not to be among the modules or plugins.
I'm attaching a snapshot of a page to show the problem for a front end user.

Hello Richard

1. For the support related to this template, you need to contact the developer of JSN Meetup template and ask them to check it for you

2. However, by quick look at the screenshot, I'm afraid of the page is too narrow to use that plugin. You, somehow, need to use a different, wider layout to have that page displayed properly (Guess there should be no module at left and right side, just the submit event form on that page only)

Tuan