Unfortunately, it's not possible. In early March, Facebook put out an update to their comments module that had a bug where the widget could no longer be made responsive. Until that issue, JFBConnect fully supported a responsive comments layout.
We're following the bug report, below, and hoping it will be fixed soon:
developers.facebook.com/bugs/256568534516879/
Please use the "Subscribe" link in the top right of that page to add yourself to the list. The more people watching the bug, the faster it should be fixed.
I hope that helps answer your questions,
Alex